Keyword: electron
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MOXPLM2 From Dreams to Reality: Prospects for Applying Advanced Accelerator Technology to Next Generation Scientific User Facilities plasma, laser, acceleration, wakefield 1
 
  • M. Ferrario
    INFN/LNF, Frascati, Italy
  • R.W. Aßmann
    DESY, Hamburg, Germany
 
  Recent years have seen spectacular progress in the development of innovative acceleration methods that are not based on traditional RF accelerating structures. These novel developments are at the interface of laser, plasma and accelerator physics and may potentially lead to much more compact and economical accelerator facilities. While primarily focusing on the ability to accelerate charged particles with much larger gradients than traditional RF, these new techniques have yet to demonstrate comparable performances to RF in terms of both beam parameters or reproducibility. To guide the developments beyond the necessary basic R&D and concept validations, a common understanding and definition of required performance and beam parameters for an operational user facility is now needed. These innovative user facilities can include "table-top" light sources, medical accelerators, industrial accelerators or even high-energy colliders. The talk will review the most promising developments in new acceleration methods, it will present the status of ongoing projects including the EU project EuPRAXIA and will identify the set of required specifications for the application under consideration.  
slides icon Slides MOXPLM2 [16.331 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOXPLM2  
About • paper received ※ 19 May 2019       paper accepted ※ 16 June 2019       issue date ※ 21 June 2019  
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MOZPLS2 Ion Collider Precision Measurements With Different Species target, operation, experiment, collider 28
 
  • G.J. Marr, E.N. Beebe, I. Blackler, W. Christie, K.A. Drees, P.S. Dyer, A.V. Fedotov, W. Fischer, C.J. Gardner, H. Huang, T. Kanesue, N.A. Kling, V. Litvinenko, C. Liu, Y. Luo, D. Maffei, B. Martin, A. Marusic, K. Mernick, M.G. Minty, C. Naylor, M. Okamura, I. Pinayev, G. Robert-Demolaize, T. Roser, P. Sampson, V. Schoefer, T.C. Shrey, D. Steski, P. Thieberger, J.E. Tuozzolo, K. Zeno, I.Y. Zhang
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC, under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Precedent to electron cooling commissioning and collisions of Gold at various energies at RHIC in 2018, the STAR experiment desired an exploration of the chiral magnetic effect in the quark gluon plasma (QGP) with an isobar run, utilizing Ruthenium and Zirconium. Colliding Zr-96 with Zr-96 and Ru-96 with Ru-96 create the same QGP but in a different magnetic field due to the different charges of the Zr (Z=40) and Ru (Z=44) ions. Since the charge difference is only 10%, the experimental program requires exacting store conditions for both ions. These systematic error concerns presented new challenges for the Collider, including frequent reconfiguration of the Collider for the different ion species, and maintaining level amounts of instantaneous and integrated luminosity between two species. Moreover, making beams of Zr-96 and Ru-96 is challenging since the natural abundances of these isotopes are low. Creating viable enriched source material for Zr-96 required assistance processing from RIKEN, while Ru-96 was provided by a new enrichment facility under commissioning at Oak Ridge National Laboratory.
 
slides icon Slides MOZPLS2 [4.758 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOZPLS2  
About • paper received ※ 11 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOZZPLM2 A Bunch Structure Measurement of Muons Accelerated by RFQ Using a Longitudinal Beam-Profile Monitor With High Time Resolution rfq, experiment, linac, background 37
 
  • Y. Sue, K. Inami
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
  • K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, M. Otani, T. Yamazaki
    KEK, Ibaraki, Japan
  • K. Hasegawa, R. Kitamura, T. Morishita
    JAEA/J-PARC, Tokai-mura, Japan
  • T. Iijima
    KMI, Nagoya, AIchi Prefecture, Japan
  • H. Iinuma, Y. Nakazawa
    Ibaraki University, Hitachi, Ibaraki, Japan
  • K. Ishida
    RIKEN Nishina Center, Wako, Japan
  • Y. Kondo
    JAEA, Ibaraki-ken, Japan
  • N. Saito
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • Y. Takeuchi
    Kyoto ICR, Uji, Kyoto, Japan
  • T. Ushizawa
    Sokendai, Ibaraki, Japan
  • H.Y. Yasuda
    University of Tokyo, Tokyo, Japan
  • M. Yotsuzuka
    Nagoya University, Nagoya, Japan
 
  Funding: This work is supported by JSPS KAKENHI Grant Numbers JP15H03666, JP15H05742, JP16H03987, JP16J07784, JP18H03707 and JP18H05226.
J-PARC E34 experiment intends to measure the anomalous magnetic moment and electric dipole moment of muon precisely by a different way from the previous experiment. In this experiment, a low-emittance muon beam is provided using the muons with the thermal energy and the four-stage linac. The demonstration of the first muon RF acceleration with an RFQ linac was conducted and the transverse profile of the accelerated muons was measured last year. As one of the remaining issues for the beam-diagnostic system, the longitudinal beam profile after the RFQ should be measured to match the profile to the designed acceptance of the subsequent accelerator. For this purpose, the new longitudinal beam monitor using the micro-channel plate is under development. The time resolution aims to be around 30 to 40 ps corresponding to 1 % of a period of an operation frequency of the accelerator, which is 324 MHz. On November 2018, the bunch structure of accelerated muons of 89 keV with the RFQ was measured using this monitor at the J-PARC MLF. The latest analysis result of this measurement will be reported in this poster.
 
slides icon Slides MOZZPLM2 [2.618 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOZZPLM2  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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MOZZPLS1 eRHIC Design Overview hadron, proton, storage-ring, luminosity 45
 
  • C. Montag, G. Bassi, J. Beebe-Wang, J.S. Berg, M. Blaskiewicz, A. Blednykh, J.M. Brennan, S.J. Brooks, K.A. Brown, K.A. Drees, A.V. Fedotov, W. Fischer, D.M. Gassner, W. Guo, A. Hershcovitch, C. Hetzel, D. Holmes, H. Huang, W.A. Jackson, J. Kewisch, Y. Li, C. Liu, H. Lovelace III, Y. Luo, F. Méot, M.G. Minty, R.B. Palmer, B. Parker, S. Peggs, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, S. Seletskiy, V.V. Smaluk, K.S. Smith, S. Tepikian, P. Thieberger, D. Trbojevic, N. Tsoupas, S. Verdú-Andrés, W.-T. Weng, F.J. Willeke, H. Witte, Q. Wu, W. Xu, A. Zaltsman, W. Zhang
    BNL, Upton, Long Island, New York, USA
  • E. Gianfelice-Wendt
    Fermilab, Batavia, Illinois, USA
  • Y. Hao
    FRIB, East Lansing, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The Electron-Ion Collider (EIC) is being envisioned as the next facility to be constructed by the DOE Nuclear Physics program. Brookhaven National Laboratory is proposing eRHIC, a facility based on the existing RHIC complex as a cost effective realization of the EIC project with a peak luminosity of 1034 cm-2 sec-1. An electron storage ring with an energy range from 5 to 18 GeV will be added in the existing RHIC tunnel. A spin-transparent rapid-cycling synchrotron (RCS) will serve as a full-energy polarized electron injector. Recent design improvements include reduction of the IR magnet strengths to avoid the necessity for Nb3Sn magnets, and a novel hadron injection scheme to maximize the integrated luminosity. We will provide an overview of this proposed project and present the current design status.
 
slides icon Slides MOZZPLS1 [5.428 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOZZPLS1  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW017 Feedback Design for Control of the Micro-Bunching Instability based on Reinforcement Learning bunching, storage-ring, feedback, controls 104
 
  • T. Boltz, T. Asfour, M. Brosi, E. Bründermann, B. Härer, P. Kaiser, A.-S. Müller, C. Pohl, P. Schreiber, M. Yan
    KIT, Karlsruhe, Germany
 
  The operation of ring-based synchrotron light sources with short electron bunches increases the emission of coherent synchrotron radiation (CSR) in the THz frequency range. However, the micro-bunching instability resulting from self-interaction of the bunch with its own radiation field limits stable operation with constant intensity of CSR emission to a particular threshold current. Above this threshold, the longitudinal charge distribution and thus the emitted radiation vary rapidly and continuously. Therefore, a fast and adaptive feedback system is the appropriate approach to stabilize the dynamics and to overcome the limitations given by the instability. In this contribution, we discuss first efforts towards a longitudinal feedback design that acts on the RF system of the KIT storage ring KARA (Karlsruhe Research Accelerator) and aims for stabilization of the emitted THz radiation. Our approach is based on methods of adaptive control that were developed in the field of reinforcement learning and have seen great success in other fields of research over the past decade. We motivate this particular approach and comment on different aspects of its implementation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW017  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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MOPGW018 Perturbation of Synchrotron Motion in the Micro-Bunching Instability bunching, synchrotron, storage-ring, radiation 108
 
  • T. Boltz, M. Brosi, E. Bründermann, B. Härer, A.-S. Müller, P. Schreiber, P. Schönfeldt, M. Yan
    KIT, Karlsruhe, Germany
 
  Short electron bunches in a storage ring are subject to complex longitudinal dynamics due to self-interaction with their own CSR. Above a particular threshold current, this leads to the formation of dynamically changing micro-structures within the bunch, generally known as the micro-bunching instability. The longitudinal dynamics of this phenomenon can be simulated by solving the Vlasov-Fokker-Planck equation, where the CSR self-interaction can be added as a perturbation to the Hamiltonian. This contribution particularly focuses on the comprehension of synchrotron motion in the micro-bunching instability and how it relates to the formation of the occurring micro-structures. Therefore, we adopt the perspective of a single particle and comment on its implications for collective motion. We explicitly show how the shape of the parallel plates CSR wake potential breaks homogeneity in longitudinal phase space and propose a quadrupole-like mode as potential seeding mechanism of the micro-bunching instability. The gained insights are verified using the passive particle tracking method of the Vlasov-Fokker-Planck solver Inovesa.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW018  
About • paper received ※ 15 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPGW021 Symplectic Tracking for the Robinson Wiggler wiggler, storage-ring, dynamic-aperture, linear-dynamics 120
 
  • J. Li, J. Feikes, T. Mertens, Y. Petenev, M. Ries, A. Schälicke
    HZB, Berlin, Germany
 
  A Robinson wiggler (RW) is considered to be installed in the Metrology Light Source (MLS) to lengthen the bunch and improve the Touschek lifetime by manipulating the damping partitions. Symplectic tracking is crucial to study the impact of the nonlinear field components introduced by the Robinson wiggler. This paper introduces a tracking method based on an implicit symplectic integrator to solve the exact Hamiltonian equations of particle motion in the wiggler. In addition, a numerical generating function method is implemented as an approach to realize fast tracking.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW021  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW027 Design Considerations for Permenant Magnetic Quadrupole Triplet for Matching Into Laser Driven Wake Field Acceleration Experiment at SINBAD laser, plasma, experiment, acceleration 143
 
  • S. Yamin, R.W. Aßmann, U. Dorda, F. Lemery, B. Marchetti, E. Panofski, P.A. Walker
    DESY, Hamburg, Germany
 
  SINBAD (Short and INnovative Bunches and Accelerators at DESY) facility aims to produce ultrashort bunches (sub-fs) at ~100 MeV, suitable for injection into novel accelerators e.g. dielectric Laser acceleration (DLA) and Laser Driven Wakefield acceleration (LWFA). The LWFA experiment demands β functions to be of the order of 1 mm to reduce energy spreads and emittance growth from nonlinearities. Matching such a space charge dominated beam to such constraints with conventional electromagnets is challenging. A Permanent Magnetic Quadrupole (PMQ) triplet is one promising focusing strategy. In this paper, we investigate the performance of a PMQ triplet to fit the requirements of the electron beam properties in a plasma cell and discuss the realizable phase spaces for the LWFA experiment planned at SINBAD.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW027  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW028 Study for the Alignment of Focusing Solenoid of ARES RF Gun and Effect of Misalignment of Solenoid on Emittance of Space Charge Dominated Electron Beam solenoid, alignment, emittance, gun 147
 
  • S. Yamin, R.W. Aßmann, B. Marchetti
    DESY, Hamburg, Germany
 
  SINBAD (Short and INnovative Bunches and Accelerators at DESY) facility will host multiple experiments relating to ultra-short high brightness beams and novel experiments with ultra-high gradient. ARES (Accelerator Research Experiment at SINBAD) Linac is an S-band photo injector to produce such electron bunches at around 100 MeV. The Linac will be commissioned in stages with the first stage corresponding to gun commissioning. In this paper, we present studies about the scheme adopted for the alignment of focusing solenoid for the ARES gun. The method is bench marked using ASTRA simulations. Moreover the effect of misalignment of the solenoid on the emittance of space charge dominated scheme and its compensation is also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW028  
About • paper received ※ 26 April 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPGW029 Preliminary Study of Bunch Compression in the Hefei Light Source lattice, storage-ring, radiation, synchrotron-radiation 151
 
  • W. Li, Z.H. Bai, W. Li, J.G. Wang, D.R. Xu, Z. Zhao
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  Funding: This work was supported by the Fundamental Research Funds for the Central Universities (Grant No.WK2310000082 and WK2310000077), and the National Natural Science Foundation of China(GrantNo.11475167).
Short electron bunch has interesting applications in the synchrotron radiation light sources, such as the production of powerful coherent THz radiation, time resolving spectrum analysis, etc. In this work, we are interested in acquiring the short bunch in the storage ring with a small circumference like Hefei Light Source. In this paper, we tried to approach the short bunch in two separate methods: by increasing the higher harmonic cavity voltage and by reducing the momentum compaction factor. The preliminary result and observations are shown and discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW029  
About • paper received ※ 16 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW053 Residual Gas Lifetime In High Energy Photon Source (HEPS) scattering, dynamic-aperture, vacuum, photon 210
 
  • S.K. Tian, H.S. Xu
    IHEP, Beijing, People’s Republic of China
 
  High vacuum has always been mandatory in particle accelerators. This is especially true for circular machines, where the beam makes thousands or millions turns, and beam lifetime is heavily affected by the residual gas scattering. At the beginning of storage ring operation the lifetime was very short mostly dominated by residual gas scattering. The residual gas lifetime is comprised of the elastic and inelastic scattering on electrons and elastic and inelastic scattering on nuclei. One usually calculates only the elastic scattering on nuclei (single Coulomb scattering) and inelastic scattering on nuclei (bremsstrahlung) of the residual gas scattering lifetime component. The analytic calculation the residual gas scattering lifetime and simulations of the beam interaction with the residual gas with code will be shown in this presentation  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW053  
About • paper received ※ 15 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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MOPGW054 Study on Spherical Aberration Correction of Solenoid Lens in Ultrafast Electron Diffraction induction, solenoid, emittance, focusing 213
 
  • Y.T. Yang, K. Fan, J.J. Li
    HUST, Wuhan, People’s Republic of China
  • Y. Song
    Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China
 
  High electron beam quality is required in Ultrafast Electron Diffraction (UED) to achieve high spatial resolution. However, aberrations mainly induced by solenoid lens will deteriorate the beam quality and limit the resolution. Spherical aberration introduces the largest distortion which is unavoidable in the case of static cylindrically symmetric electromagnetic fields on the basis of Scherzer’s theorem. In order to reduce the spherical aberrations, different models have been designed which are composed of three symmetrical lens and one asymmetrical lens. We obtain the magnetic field distribution and calculate the aberration of each model by OPERA, and the result is that the solenoid without poles has the minimum aberration and meets the design requirement best.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW054  
About • paper received ※ 13 May 2019       paper accepted ※ 17 May 2019       issue date ※ 21 June 2019  
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MOPGW058 Towards a Sextupole-Free Electron Storage Ring vacuum, impedance, storage-ring, feedback 217
 
  • T.-Y. Lee, T. Ha
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  This paper studies if it is possible to build an electron storage ring with no or a small number of sextupole mag-nets. If it is possible, the electron storage ring will be great-ly simplified. For the purpose, two methods are presented in the paper to handle head-tail instability: One is to use dielectric vacuum chamber made of such materials as ceramic or glass to reduce broadband impedance signifi-cantly. Then head-tail instability would be extremely weak. The other method is to install a bunch-by-bunch feedback system to suppress the already weak head-tail instability due to the dielectric vacuum chamber.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW058  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW062 Radiation of a Charge Moving in a Wire Structure radiation, FEL, simulation, lattice 231
 
  • S.N. Galyamin, A.V. Tyukhtin, V.V. Vorobev
    Saint Petersburg State University, Saint Petersburg, Russia
  • A.I. Benediktovitch
    EuXFEL, Hamburg, Germany
  • A.I. Benediktovitch
    BSU, Minsk, Belarus, Belarus
 
  Funding: This work is supported by the grant from Russian Foundation for Basic Research (No. 17-52-04107).
In the X-ray frequency region, interaction of relativistic electrons with crystals results in parametric X-ray radiation (PXR), with its frequency being determined by distance between crystallographic planes and direction of electron motion. If instead of crystal one considers an artificial periodic structure with periods of the order of mm, one can expect emission of radiation of a similar nature at terahertz (THz) frequencies. This frequency range is of significant interest during last decade due to its prospective applications. Moreover, artificial wire-like structures are considered as a promising alternative to conventional dielectric structures for wakefield acceleration*. Here we consider electromagnetic (EM) field produced by a charged particle bunch moving through a lattice of parallel conducting wires. We present several approaches for analysis of EM field in the described wire structure. First, conventional two-wave approximation for describing the "short-wave response" is developed. Second, we use the effective medium approach and describe the "long-wave" part of the spectrum. Third, we develop a method based on vibrator antenna theory which can be useful for finite length wire structure.
* P.D. Hoang, et al., Phys. Rev. Lett., V. 120, P. 164801 (2018).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW062  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW073 Beam Manipulation Using Self-Induced Fields at the SwissFEL Injector FEL, simulation, experiment, wakefield 266
 
  • S. Bettoni, P. Craievich, E. Ferrari, R. Ganter, F. Marcellini, E. Prat, S. Reiche
    PSI, Villigen PSI, Switzerland
  • A.A. Lutman
    SLAC, Menlo Park, California, USA
  • G. Penco
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  In the past years wakefield sources have been used to manipulate electron beams in accelerators. We recently installed corrugated structures for a total length of 2~m at the SwissFEL injector to test novel schemes for beam manipulations. We present simulations and early experimental results. We compare the model predictions with the measured data for the bunch energy losses and the kick factor, and show early results for the longitudinal phase space linearization and the production of current spikes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW073  
About • paper received ※ 09 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW086 Intensity Dependent Effects at ATF2, KEK simulation, collider, linear-collider, wakefield 308
 
  • P. Korysko, A. Latina
    CERN, Geneva, Switzerland
  • P. Burrows
    Oxford University, Physics Department, Oxford, Oxon, United Kingdom
  • A. Faus-Golfe
    LAL, Orsay, France
  • K. Kubo, T. Okugi
    KEK, Ibaraki, Japan
 
  The Accelerator Test Facility 2 (ATF2) at KEK is a prototype for the Final Focus Systems of the future e+e linear colliders, the International Linear Collider (ILC) and the Compact Linear Collider (CLIC). In this paper both simulation and experimental results are presented with special emphasis on intensity-dependent effects. The importance of these effects is shown using the PLACET code and realistic ATF2 machine simulations (including beam jitter, misalignment, wakefield, Beam Based Alignment (BBA) correction, …). The latest experimental results are also presented, in particular the impact of the beam intensity on the beam size at the IP.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW086  
About • paper received ※ 23 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW104 Equilibria and Synchrotron Stability in Two Energy Storage Rings storage-ring, damping, simulation, focusing 364
 
  • B. Dhital, J.R. Delayen, G.A. Krafft
    ODU, Norfolk, Virginia, USA
  • J.R. Delayen, Y.S. Derbenev, D. Douglas, G.A. Krafft, F. Lin, V.S. Morozov, Y. Zhang
    JLab, Newport News, Virginia, USA
 
  In a dual energy storage ring, the electron beam passes through two loops at markedly different energies EL, and EH, i.e., energies for low energy loop and high energy loop respectively. These loops use a common beamline where a superconducting linac at first accelerates the beam from EL to EH and then decelerates the beam from EH to EL in the next pass. There are two basic solutions to the equilibrium problems possible, i.e., ’Storage Ring’ (SR) equilibrium and ’Energy Recovery Linac’ (ERL) equilibrium. SR equilibrium mode more resembles the usual single loop storage ring with strong synchrotron motion and ERL equilibrium mode is the case where RF in two beam passes nearly cancels. Calculations based on linear transfer matrix formalism show that longitudinal stability exists for both SR mode and ERL mode in two energy storage rings.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW104  
About • paper received ※ 14 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPGW111 Start to End Simulation on Beam Dynamics in Coherent Electron Cooling Accelerator FEL, bunching, emittance, cavity 379
 
  • Y.C. Jing, V. Litvinenko, I. Petrushina, I. Pinayev, K. Shih, Y.H. Wu
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • K. Shih
    SBU, Stony Brook, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A Coherent electron Cooling (CeC) has a potential of substantial reducing cooling time of the high-energy hadrons and hence to boost luminosity in high-intensity hadron-hadron and electron-hadron colliders. In a CeC system, a high quality electron beam is generated, propagated and optimized through a beam line which was carefully designed with consideration of space charge effect, wakefields and nonlinear dynamics such as coherent synchrotron radiation and chromatic aberration. In this paper, we present our study on the beam dynamics of such a beam line and compare the simulation result with what was measured in experiment.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW111  
About • paper received ※ 17 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW112 Design of a Bunch Compressor with CSR Suppression to Achieve Hundreds of kA Peak Current emittance, optics, site, dipole 382
 
  • Y.C. Jing, V. Litvinenko
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A four dipole magnetic chicane is usually used to compress electron bunch to very short in modern accelerators which requires electron beams to have high peak current. The coherent synchrotron radiation (CSR) originated from the strong bending magnets in the chicane could greatly degrade the quality of the electron beam. In this paper, we present our design for a bunch compressing system with 30 to 100 fold in bunch length reduction and at the mean time suppress the effect of CSR on the e-beam’s quality. We discuss and detail the performance of such a compressor for potential FACET-II upgrade.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW112  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW116 Validation of a Novel Method for the Calculation of Near-Field Synchrotron Radiation acceleration, radiation, cyclotron, synchrotron 397
 
  • F.Y. Li, B.E. Carlsten, R. Garimella, C. Huang, T.J. Kwan
    LANL, Los Alamos, New Mexico, USA
 
  Funding: Work supported by the LDRD program at LANL.
The phenomenon of synchrotron radiation (SR) from electrons is at the core of modern accelerator based light sources. While SR in the far field has been well characterized, the near-field SR and its impacts on self-consistent electron beam dynamics remain an ongoing topic. Since it is difficult to experimentally characterize the near fields, it is desirable to develop accurate and efficient numerical methods for the design of these light sources. Here, we investigate a novel method, originally proposed by Shintake and which potentially has both high efficiency and accuracy. We focus on the field calculation of this method and show that the original idea has missed the important terms of fields due to electron acceleration and therefore only applies to a linear motion. To correct this limitation we developed a modified algorithm that gives consistent fields with direct calculations using the Liénard-Wiechert equation. Some basic signatures of the near-field SR fields are also drawn for a cyclotron motion by using this modified approach.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW116  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPMP002 Linac and Damping Ring Designs for the FCC-ee linac, emittance, positron, gun 420
 
  • S. Ogur, K. Oide, Y. Papaphilippou, L. Rinolfi, F. Zimmermann
    CERN, Geneva, Switzerland
  • A.M. Barnyakov, A.E. Levichev, P.V. Martyshkin, D.A. Nikiforov
    BINP SB RAS, Novosibirsk, Russia
  • I. Chaikovska, R. Chehab
    LAL, Orsay, France
  • K. Furukawa, N. Iida, T. Kamitani, F. Miyahara, K. Oide
    KEK, Ibaraki, Japan
  • E.V. Ozcan
    Bogazici University, Bebek / Istanbul, Turkey
  • S.M. Polozov
    MEPhI, Moscow, Russia
  • L. Rinolfi
    ESI, Archamps, France
  • F. Yaman
    IZTECH, Izmir, Turkey
 
  We report the design of the pre-injector chain for the Future Circular e+ e Collider (FCC-ee) system. The electron beam from a low-emittance RF gun is accelerated by an S-band linac up to 6 GeV. A damping ring at 1.54 GeV is required for emittance cooling of the positron beam. The intermediate energy step from the exit of the S-band linac at 6 GeV to the 20 GeV injection energy of the top-up booster can be provided by the modified Super Proton Synchrotron (SPS), serving as a pre-booster ring (PBR). An alternative option to reach 20 GeV energy would be to extend the S-band linac with a C- or X-band linac. An overall cost optimisation will determine the choice of the final configuration. Beam loss and emittance dilution in the linac due to space charge effects, wakefields, and misalignment of accelerator components can be mitigated by RF phasing and orbit steering. Start-to-end simulations examine the beam transport through the linac up to either 6 GeV or 20 GeV. The results indicate large design margins. Simulations of the beam dynamics in the damping ring (DR) demonstrate a sufficiently large momentum acceptance. Effects of intrabeam scattering and electron cloud instability in the DR are also studied.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP002  
About • paper received ※ 13 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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MOPMP003 Positron Source for FCC-ee positron, target, linac, collider 424
 
  • I. Chaikovska, R. Chehab, A. Faus-Golfe, Y. Han
    LAL, Orsay, France
  • A. Apyan
    ANSL, Yerevan, Armenia
  • Y. Enomoto, K. Furukawa, T. Kamitani, F. Miyahara, M. Satoh, Y. Seimiya, T. Suwada
    KEK, Ibaraki, Japan
  • P.V. Martyshkin
    BINP SB RAS, Novosibirsk, Russia
  • S. Ogur, K. Oide, Y. Papaphilippou, L. Rinolfi, P. Sievers, F. Zimmermann
    CERN, Geneva, Switzerland
 
  The FCC-ee is a high-luminosity, high-precision circular collider to be constructed in a new 100 km tunnel in the Geneva area. The physics case is well established and the FCC-ee operation is foreseen at 91 GeV (Z-pole), 160 GeV (W pair production threshold), 240 GeV (Higgs resonance) and 365 GeV (t-tbar threshold). Due to the large 6D production emittance and important thermal load in the production target, the positron injector, in particular the positron source, is one of the key elements of the FCC-ee, requiring special attention. To ensure high reliability of the positron source, conventional and hybrid targets are currently under study. The final choice of the positron target will be made based on the estimated performances. In this framework, we present a preliminary design of the FCC-ee positron source, with detailed simulation studies of positron production, capture and primary acceleration.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP003  
About • paper received ※ 03 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPMP012 Concepts of Longitudinally Polarized Electron and Positron Colliding Beams in the Circular Electron Positron Collider polarization, positron, resonance, wiggler 445
 
  • Z. Duan, J. Gao, X.P. Li, D. Wang, Y. Wang, W.H. Xia, Q.J. Xu, C.H. Yu, Y. Zhang
    IHEP, Beijing, People’s Republic of China
 
  Funding: Work supported by National Key Research and Development Program of China (No.2018YFA0404300).
This paper reports some preliminary study into the imple- mentation of longitudinally polarized e+/e colliding beams in the Circular Electron Positron Collider, at a center of mass energy of 91 GeV as a Z factory and energies beyond.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP012  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPMP044 Improving the Luminosity for Beam Energy Scan II at RHIC cavity, operation, space-charge, luminosity 540
 
  • C. Liu, M. Blaskiewicz, K.A. Drees, A.V. Fedotov, W. Fischer, C.J. Gardner, H. Huang, D. Kayran, Y. Luo, G.J. Marr, A. Marusic, K. Mernick, M.G. Minty, C. Montag, I. Pinayev, S. Polizzo, V.H. Ranjbar, D. Raparia, G. Robert-Demolaize, T. Roser, J. Sandberg, V. Schoefer, T.C. Shrey, S. Tepikian, P. Thieberger, A. Zaltsman, K. Zeno, I.Y. Zhang, W. Zhang
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The QCD (Quantum Chromodynamics) phase diagram has many uncharted territories, particularly the nature of the transformation from Quark-Gluon plasma (QGP) to the state of Hadronic gas. The Beam Energy Scan I (BES-I) at the Relativistic Heavy Ion Collider (RHIC) was completed but measurements had large statistical errors. To improve the statistical error and expand the search for first-order phase transition and location of the critical point, Beam Energy Scan II will commence in 2019 with a goal of improving the luminosity by a factor of 3-4. The beam lifetime at low energies was and will be limited by some physical effects of which the most significant are intrabeam scattering, space charge, beam-beam, persistent current effects. This article will review these potential limiting factors and introduce the countermeasures which will be in place to improve BES-II luminosity.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP044  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPMP049 6 T Cable-in-conduit Dipole to Double the Ion Energy for JLEIC dipole, collider, injection, luminosity 556
 
  • P.M. McIntyre, J. Breitschopf, J. Gerity
    Texas A&M University, College Station, USA
  • J. Breitschopf, D.C.V. Chavez, J.N. Kellams, A. Sattarov
    ATC, College Station, Texas, USA
 
  The proposed electron-ion collider JLEIC would make high-luminosity collisions of polarized ions and polarized electrons with electron energy up to 12 GeV and ion energy up to 40 GeV/u. Both the luminosity and the collision energy could be increased by doubling the dipole field in the ion ring from 3 T to 6 T, and the enhanced performance would access the full range of parameters for the physics objectives of the project. The Texas A&M group has developed the large-aperture 3 T dipoles for the baseline project, based upon a novel superconducting cable-in-conduit. (CIC). A closely similar 6 T design is being developed, utilizing a 2-layer CIC. Details of the magnet design and development of the 2-layer CIC will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP049  
About • paper received ※ 19 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPMP050 Performance of CeC PoP Accelerator FEL, gun, SRF, hadron 559
 
  • I. Pinayev, Z. Altinbas, J.C. Brutus, A.J. Curcio, A. Di Lieto, T. Hayes, R.L. Hulsart, P. Inacker, Y.C. Jing, V. Litvinenko, J. Ma, G.J. Mahler, M. Mapes, K. Mernick, K. Mihara, T.A. Miller, M.G. Minty, G. Narayan, F. Severino, K. Shih, Z. Sorrell, J.E. Tuozzolo, E. Wang, G. Wang, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Coherent electron cooling experiment is aimed for demonstration of the proof-of-principle demonstration of reduction energy spread of a single hadron bunch circulating in RHIC. The electron beam should have the required parameters and its orbit and energy should be matched to the hadron beam. In this paper we present the achieved electron beam parameters including emittance, energy spread, and other critical indicators. The operational issues as well as future plans are also discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP050  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB013 Focusing of High-Brightness Electron Beams with Active-Plasma Lenses plasma, emittance, focusing, experiment 601
 
  • R. Pompili
    INFN/LNF, Frascati, Italy
 
  Plasma-based technology promises a tremendous reduction in size of accelerators used for research, medical, and industrial applications, making it possible to develop tabletop machines accessible for a broader scientific community. By overcoming current limits of conventional accelerators and pushing particles to larger and larger energies, the availability of strong and tunable focusing optics is mandatory also because plasma-accelerated beams usually have large angular divergences. In this regard, active-plasma lenses represent a compact and affordable tool to generate radially symmetric magnetic fields several orders of magnitude larger than conventional quadrupoles and solenoids. However, it has been recently proved that the focusing can be highly nonlinear and induce a dramatic emittance growth. Here, we present experimental results showing how these nonlinearities can be minimized and lensing improved. These achievements represent a major breakthrough toward the miniaturization of next-generation focusing devices.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB013  
About • paper received ※ 13 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB031 Progress of Conceptual Study for the Accelerators of a 2-7GeV Super Tau Charm Facility at China collider, luminosity, factory, operation 643
 
  • Q. Luo, W. Li, D.R. Xu
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  • W.W. Gao, J.Q. Lan
    Fujian University of Technology, Fuzhou, People’s Republic of China
 
  Funding: Supported by National Natural Science Foundation of China U1832169 and the Double Fist-Class University Project Foundation of USTC.
This paper shows the progress of the conceptual study for the accelerators of a super tau charm facility in China. Since the BEPCII will finish its historical mission in 5~10 years and its upgrade plan will only achieve a small luminosity enhancement of 3~5 times, a new next generation tau-charm collider will play an irreplaceable role in future high energy physics study. The luminosity of this successor is about 5×1034cm−2s−1 pilot and 1×1035cm−2s−1 nominal, with the electron beam longitudinally polarized at the IP. The general scheme of the accelerators and the beam pa-rameters are shown. Several key technologies such as beam polarization and beam emittance diagnostics are also discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB031  
About • paper received ※ 14 May 2019       paper accepted ※ 17 May 2019       issue date ※ 21 June 2019  
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MOPRB052 Gamma Factory at CERN: Design of a Proof-of-Principle Experiment photon, laser, experiment, cavity 685
 
  • Y. Dutheil, R. Alemany-Fernández, H. Bartosik, N. Biancacci, R. Bruce, P. Czodrowski, V. Fedosseev, B. Goddard, S. Hirlaender, J.M. Jowett, R. Kersevan, M. Kowalska, M. Lamont, D. Manglunki, J. Molson, A.V. Petrenko, M. Schaumann, F. Zimmermann
    CERN, Geneva, Switzerland
  • S. E. Alden, A. Bosco, S.M. Gibson, L.J. Nevay
    JAI, Egham, Surrey, United Kingdom
  • A. Apyan
    ANSL, Yerevan, Armenia
  • E.G. Bessonov
    LPI, Moscow, Russia
  • A. Bosco, S.M. Gibson, L.J. Nevay
    Royal Holloway, University of London, Surrey, United Kingdom
  • F. Castelli
    Università degli Studi di Milano, Milano, Italy
  • F. Castelli, C. Curatolo, L. Serafini
    INFN-Milano, Milano, Italy
  • K. Kroeger
    FSU Jena, Jena, Germany
  • A. Martens
    LAL, Orsay, France
  • V. Petrillo
    Universita’ degli Studi di Milano, Milano, Italy
  • M. Sapinski, T. Stöhlker
    GSI, Darmstadt, Germany
  • G. Weber
    IOQ, Jena, Germany
  • Y.K. Wu
    FEL/Duke University, Durham, North Carolina, USA
 
  The Gamma Factory (GF) initiative proposes to create novel research tools at CERN by producing, accelerating and storing highly relativistic partially stripped ion beams in the LHC rings and by exciting their atomic degrees of freedom by lasers, to produce high-energy photon beams. Their intensity would be several orders of magnitude higher than those of the presently operating light sources in the particularly interesting gamma-ray energy domain reaching up to 400 MeV. In this energy domain, the high-intensity photon beams can be used to produce secondary beams of polarized electrons, polarized positrons, polarized muons, neutrinos, neutrons and radioactive ions. Over the years 2017-2018 we have demonstrated that these partially stripped ion beams can be successfully produced, accelerated and stored in the CERN accelerator complex, including the LHC. The next step of the project is to build a proof of principle experiment in the SPS to validate the principal GF concepts. This contribution will present the initial conceptual design of this experiment along with its main challenge - the demonstration of the fast cooling method of partially stripped ion beams.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB052  
About • paper received ※ 19 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB056 THz Radiator Based on Photonic Band Gap Crystal for SwissFEL photon, GUI, experiment, FEL 693
 
  • L. Shi, R. Ischebeck, S. Reiche
    PSI, Villigen PSI, Switzerland
 
  Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 701647.
The electromagnetic radiation in 1-20 THz has many unique properties when it interacts with matter due to its non-ionizing excitation in matter. Especially the dynamics of the excited matter can be probed with the help of X-ray pulses at a free electron laser facility, e.g. SwissFEL, to deepen our understanding of a wide range of phenomena. Due to its high research potential, various means of THz generation have been proposed and demonstrated. We investigate preliminarily here its generation based on a relativistic electron bunch and a photonic band gap crystal (PBG) made of dielectric rods. The PBG provides additional degrees of freedom for the THz pulse tuning. Additionally, the unwanted radiation parts can be damped by the structure in order to minimize the deleterious beam dynamics effects. The crystal also promises the integration of generation, filtering and coupling for transport into a single piece.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB056  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPRB060 Simulating Novel Collimation Schemes for High-Luminosity LHC With Merlin++ proton, scattering, collimation, simulation 708
 
  • S.C. Tygier, R.B. Appleby
    UMAN, Manchester, United Kingdom
  • R.J. Barlow, S. Rowan
    IIAA, Huddersfield, United Kingdom
 
  Due to the large stored beam energy in the HL-LHC new collimation technologies must be used to protect the machine. Active halo control of the proton beam halo with a Hollow Electron Lens can give a kick to protons at the edge of the beam without effecting the core. Various modes of operation are possible for example the electron lens can have a continuous current or it can be pulsed to different amplitudes for each passage of the proton beam. In this article we use Merlin++ simulations to show the performance of these modes for HL-LHC parameters. We also present recent simulations comparing scattering models in Merlin++.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB060  
About • paper received ※ 08 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB061 Simulations and Measurements of Coherent Synchrotron Radiation at the MAX-IV Short Pulse Facility radiation, detector, simulation, dipole 712
 
  • B.S. Kyle
    University of Manchester, Manchester, United Kingdom
  • R.B. Appleby
    UMAN, Manchester, United Kingdom
  • M. Brandin, E. Mansten, S. Thorin
    MAX IV Laboratory, Lund University, Lund, Sweden
  • T.H. Pacey
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • P.H. Williams
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • J. Wolfenden
    The University of Liverpool, Liverpool, United Kingdom
 
  The Coherent Synchrotron Radiation (CSR) interaction is a source of unwanted correlated energy spread in short-bunch Free-Electron Lasers (FEL), diluting the desired FEL spectrum and reducing the total brightness of the light source. Many accelerator codes make use of 1-dimensional approximations in the calculation of the CSR-wake, which breaks down for bunch dimensions typical within bunch compressor dipoles in FELs. General Particle Tracer simulations of the CSR interaction make use of the 3-dimensional bunch distribution, making it advantageous in modelling the short-bunch, high aspect ratio regimes typical of modern 4th-generation light sources. Measurements of THz CSR emitted from the final bunch compressor dipole of the SP02 beamline at the MAX-IV Short Pulse Facility (SPF) were used, alongside start-to-end GPT and Elegant simulations, to characterize coherent radiation emission across a broad range of bunch lengths.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB061  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB067 High-gradient Single Cycle Terahertz Accelerating Structures GUI, gun, acceleration, cathode 731
 
  • S.P. Antipov, E. Gomez, S.V. Kuzikov
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • A.A. Vikharev
    IAP/RAS, Nizhny Novgorod, Russia
 
  Recently, gradients on the order of 1 GV/m level have been obtained in a form of single cycle (~1 ps) THz pulses produced by conversion of a high peak power laser radiation in nonlinear crystals (~1 mJ, 1 ps, up to 3% conversion efficiency). These pulses however are broadband (0.1-5 THz) and therefore a new accelerating structure type is required. For electron beam acceleration with such pulses we propose arrays of parabolic focusing micro-mirrors with common central. These novel structures could be produced by a femtosecond laser ablation system developed at Euclid Techlabs. This technology had already been tested for production of several millimeters long, multi-cell structure which has been testing with electron beam. We also propose using of structures where necessary GV/m E-fields are excited by a drive bunch travelling in the corrugated waveguide. The radiated by drive bunch sequence of short range delayed wakes are guided in this case by metallic disks and reflected back being focused exactly at time when the witness bunch arrives.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB067  
About • paper received ※ 21 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPRB072 eRHIC in Electron-Ion Operation operation, collider, heavy-ion, hadron 738
 
  • W. Fischer, E.C. Aschenauer, E.N. Beebe, M. Blaskiewicz, K.A. Brown, D. Bruno, K.A. Drees, C.J. Gardner, H. Huang, T. Kanesue, C. Liu, M. Mapes, G.T. McIntyre, M.G. Minty, C. Montag, S.K. Nayak, M. Okamura, V. Ptitsyn, D. Raparia, J. Sandberg, K.S. Smith, P. Thieberger, N. Tsoupas, J.E. Tuozzolo, F.J. Willeke, A. Zaltsman, A. Zelenski
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy.
The design effort for the electron-ion collider eRHIC has concentrated on electron-proton collisions at the highest luminosities over the widest possible energy range. The present design also provides for electron-nucleon peak luminosities of up to 4.7·1033 cm-2s−1 with strong hadron cooling, and up to 1.7·1033 cm-2s−1 with stochastic cooling. Here we discuss the performance limitations and design choices for electron-ion collisions that are different from the electron-proton collisions. These include the ion bunch preparation in the injector chain, acceleration and intrabeam scattering in the hadron ring, path length adjustment and synchronization with the electron ring, stochastic cooling upgrades, machine protection upgrades, and operation with polarized electron beams colliding with either unpolarized ion beams or polarized He-3.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB072  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB075 Radiation Limits on Permanent Magnets in CBETA radiation, vacuum, permanent-magnet, focusing 745
 
  • V.O. Kostroun, C.M. Gulliford
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  The Cornell Brookhaven Energy Recovery Linac Test Accelerator (CBETA), under construction at Cornell, uses Fixed Field Alternating Gradient (FFAG) Halbach magnets made from grade N35EH NdFeB. To reduce the 1% level magnetization errors in fabricated blocks to magnets with better than 0.001 field accuracy, iron wire shimming is necessary. This also limits magnetization changes by external influences to the ~1% level. The ambient radiation field present during CBETA operation can induce permanent magnet demagnetization. The radiation field arises from electrons in the beam halo hitting the vacuum chamber and from residual gas, Touschek and Intra-Beam scattering. The radiation dose rate due to electrons striking the vacuum chamber of a 4 cell straight section of CBETA FFAG magnets was calculated using the many particle Monte Carlo radiation code MCNP6.2. MCNP6.2 has a track-length heating tally for different particles and a collision heating tally that gives energy deposition/mass from all particles in the problem. Calculations show that electron loss has to be a fraction of a watt/m to keep the dose rate at an acceptable level during the accelerator lifetime.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB075  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPRB076 CBETA Beam Commissioning Results linac, MMI, permanent-magnet, lattice 748
 
  • C.M. Gulliford, N. Banerjee, A.C. Bartnik, I.V. Bazarov, J.A. Crittenden, K.E. Deitrick, A. Galdi, G.H. Hoffstaetter, P. Quigley, K.W. Smolenski
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J.S. Berg, S.J. Brooks, R.J. Michnoff, D. Trbojevic
    BNL, Upton, Long Island, New York, USA
 
  We report on the first results of commissioning CBETAwith a fully closed return loop. We repeat much of our early commissioning from the fractional arc test, namely setting up the injection system, calibrating the main linac, and steering the beam through the first splitter line. Most importantly, first results from sending the beam all the way through the FixedField Alternating gradient permanent magnet return arc are described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB076  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPRB080 Transient Beam Loading and Mitigation in JLEIC Collider Rings cavity, klystron, luminosity, beam-loading 758
 
  • J. Guo, R.A. Rimmer, H. Wang, S. Wang
    JLab, Newport News, Virginia, USA
  • J.D. Fox
    Stanford University, Stanford, California, USA
  • T. Mastoridis
    CalPoly, San Luis Obispo, California, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, with additional support from U.S. DOE Award Number DE-SC-0019287
The Jefferson Lab Electron-Ion Collider (JLEIC) is an asymmetric high luminosity ring-ring collider proposed as the next major R&D facility for the nuclear physics community. Both of JLEIC’s electron and ion collider rings have high beam current with gaps serving the pur-poses of beam abort, ion clearing, etc. Such a time-varying beam loading in the RF cavities would generate modulation in cavity RF phase/voltage, causing cyclic shift of collision point and potential luminosity loss. We studied a few approaches to mitigate the RF phase modu-lation and IP shift, such as correcting the RF phase/voltage modulation with traditional LLRF feed-back, one-turn feedback (OTFB), or RF feedforward (FF); optimizing the bunch fill pattern to limit the RF phase/voltage modulation to a small fraction of the bunch trains in the collider ring; or matching the RF phase modulation in the two rings. The preliminary re-sults are discussed in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB080  
About • paper received ※ 23 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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MOPRB081 Electron Beam’s Closed Orbit in the Crab Crossing Scheme of Future Electron-Ion Colliders closed-orbit, luminosity, cavity, simulation 762
 
  • Y. Hao, V. Ptitsyn
    BNL, Upton, Long Island, New York, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
 
  In crab-crossing collision geometry the closed orbit of the electron beam will be altered by the beam-beam interaction and the tilted head and tail of the ion beam. We will present the linear model to determine the closed orbit and compare with the simulation. Also, the relation of the closed orbit and the synchro-betatron resonance will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB081  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB082 Scaling Properties of the Synchro-Beta Resonance in Crab Crossing Scheme of Future Electron Ion Collider luminosity, resonance, simulation, cavity 766
 
  • Y. Hao, Y. Luo, V. Ptitsyn
    BNL, Upton, Long Island, New York, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
 
  The synchro - beta resonance due to the beam-beam interaction was predicted by the strong-strong simulation in the future electron-ion collider designs. In this paper, we study the scaling properties of the degradation rate of this unwanted resonance. These studies motivated the possible countermeasures of the luminosity degradation associated with the resonance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB082  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB085 First Results from Commissioning of Low Energy RHIC Electron Cooler (LEReC) cavity, MMI, gun, cathode 769
 
  • D. Kayran, Z. Altinbas, D. Bruno, M.R. Costanzo, K.A. Drees, A.V. Fedotov, W. Fischer, M. Gaowei, D.M. Gassner, X. Gu, R.L. Hulsart, P. Inacker, J.P. Jamilkowski, Y.C. Jing, J. Kewisch, C.J. Liaw, C. Liu, J. Ma, K. Mernick, T.A. Miller, M.G. Minty, L.K. Nguyen, M.C. Paniccia, I. Pinayev, V. Ptitsyn, V. Schoefer, S. Seletskiy, F. Severino, T.C. Shrey, L. Smart, K.S. Smith, A. Sukhanov, P. Thieberger, J.E. Tuozzolo, E. Wang, G. Wang, A. Zaltsman, H. Zhao, Z. Zhao
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The brand new non-magnetized bunched beam electron cooler (LEReC) [1] has been built to provide luminosity improvement for Beam Energy Scan II (BES-II) physics program at the Relativistic Heavy Ion Collider (RHIC) BES-II [2]. The LEReC accelerator includes a photocathode DC gun, a laser system, a photocathode delivery system, magnets, beam diagnostics, a SRF booster cavity, and a set of Normal Conducting RF cavities to provide sufficient flexibility to tune the beam in the longitudinal phase space. This high-current high-power accelerator was successfully commissioned in period of March -September 2018. Beam quality suitable for cooling has been demonstrated. In this paper we discuss beam commissioning results and experience learned during commissioning.
[1] A. Fedotov et al., ’Status of bunched beam electron cooler LEReC’ in these proceedings.
[2] C.Liu et al., ’Improving luminosity of Beam Energy Scan II at RHIC’ in these proceedings.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB085  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB087 Proposal for a High Transformer Ratio CW Dielectric Accelerator SRF, experiment, wakefield, operation 773
 
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  • J.C. Brutus, Y.C. Jing, I. Pinayev, G. Wang
    BNL, Upton, Long Island, New York, USA
  • M.E. Conde, C.-J. Jing, J.G. Power
    ANL, Argonne, Illinois, USA
  • A. Kanareykin
    Euclid Beamlabs LLC, Bolingbrook, USA
  • N. Vafaei
    UCLA, Los Angeles, California, USA
 
  Advanced CW accelerators are one of high priority directions identified by Advanced Accelerator Concepts Research Roadmap Workshop Report *. High transformer ratio of beam-driven accelerators is critically important for cost-effective FEL systems. We present a proposed experiment for demonstrating a high transformer ratio CW dielectric accelerator using operational SRF accelerator built for Coherent electron Cooling experiment. This accelerator operates with CW electron beam comprised of 78 kHz train of electron bunches. Electron bunches with controllable longitudinal and charge up to 10 nC per bunch are generated in 1.25 MV SRF photo-electron gun. This bunches are ballistically compressed to duration of 10-to-30 psec and accelerated to 15 MeV in SRF linac**. Such bunches would be excellent drivers of high-transformer ratio DWA accelerators. In this paper we present expected performance of proposed CW DWA accelerator.
*Advanced Accelerator Concepts Research Roadmap Workshop Report, 2016,
*V.N. Litvinenko et al., In proc.of FEL’17, Santa Fe, NM, USA, August 20-25, 2017, p. 132
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB087  
About • paper received ※ 19 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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MOPRB088 Study of Fluctuations in Undulator Radiation in the IOTA Ring at Fermilab experiment, undulator, radiation, photon 777
 
  • I. Lobach
    University of Chicago, Chicago, Illinois, USA
  • A. Halavanau, Z. Huang, V. Yakimenko
    SLAC, Menlo Park, California, USA
  • K. Kim
    ANL, Argonne, Illinois, USA
  • V.A. Lebedev, S. Nagaitsev, A.L. Romanov, G. Stancari, A. Valishev
    Fermilab, Batavia, Illinois, USA
  • A.Y. Murokh
    RadiaBeam, Los Angeles, California, USA
  • T.V. Shaftan
    BNL, Upton, Long Island, New York, USA
 
  We study turn-by-turn fluctuations in the number of emitted photons in an undulator, installed in the IOTA electron storage ring at Fermilab with an InGaAs PIN photodiode and an integrating circuit. Our study was motivated by the previous experiment *. We propose a theoretical model for the experimental data from * and in our own experiment we attempted to verify the model in an independent and more systematic way. Moreover, these fluctuations are an interesting subject for a study by itself, since they act as a seed for SASE in FELs. We improve the precision of the measurements from * by subtracting the average signal amplitude using a comb filter with a one-turn IOTA delay, and by using a special algorithm for noise subtraction. We obtain a reasonable agreement between our theoretical model and experiment. Along with repeating the experiment from *, which was performed at a constant beam current, we also collect data for fluctuations in undulator light at different beam current values. Lastly, in our experiment we were able to see the transition from Poisson statistics to Super-Poisson statistics for undulator light, whereas in * only the latter statistics was observed.
* M. Teich et al., PRL, vol. 65, no. 27, p. 3393 (1990).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB088  
About • paper received ※ 14 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPRB089 Experimental Study of a Single Electron in a Storage Ring via Undulator Radiation photon, undulator, experiment, radiation 781
 
  • S. Nagaitsev, A.L. Romanov, G. Stancari
    Fermilab, Batavia, Illinois, USA
  • A. Arodzero, A.Y. Murokh, M. Ruelas
    RadiaBeam, Santa Monica, California, USA
  • I. Lobach
    University of Chicago, Chicago, Illinois, USA
  • T.V. Shaftan
    BNL, Upton, Long Island, New York, USA
 
  A single electron orbiting around a ring and emitting single quanta at the rate of about one event per hundred turns could produce a wealth of information about physical processes in large traps (i.e. storage rings) for charged particles. It should be noted that Paul and Penning traps in the 1980s led to the Nobel prize for studying state and motion of single quantum particles, and just recently the Penning trap technique has enabled the measurement of a single proton magnetic moment with an unprecedented precision of 10 decimal places. The information from the storage ring traps could also be used for characterization of a quantum system as well as the "trap" itself, i.e. measuring properties of the storage ring lattice and electron interaction with the laser fields. Although, the interest in single electron quantum processes today is mostly academic in nature, the diagnostics and methodology developed for single electron radiation studies could find subsequent applications in a variety of applied disciplines in quantum technology, including quantum communications and quantum computing.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB089  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB090 Simulation Challenges for eRHIC Beam-Beam Study proton, simulation, damping, emittance 785
 
  • Y. Luo, F.J. Willeke
    BNL, Upton, Long Island, New York, USA
  • Y. Hao
    FRIB, East Lansing, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
  • Y. Roblin, H. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The 2015 Nuclear Science Advisory Committee Long Rang Plan identified the need for an electron-ion collider (EIC) facility as a gluon microscope with capabilities beyond those of any existing accelerator complex. To reach the required high energy, high luminosity, and high polarization, the eRHIC design, based on the existing heavy ion and polarized proton collider RHIC, adopts a very small \beta-function at the interaction points, a high collision repetition rate, and a novel hadron cooling scheme. A full crossing angle of 22 mrad and crab cavities for both electron and proton rings are required. In this article, we will present the high priority R\&D items related to the beam-beam interaction studies for the current eRHIC design, the simulation challenges, and our plans and methods to address them. Recent progresses on this project are reported too.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB090  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB091 Combined Strong-Strong and Weak-Strong Beam-Beam Simulations for Crabbed Collision in eRHIC proton, simulation, luminosity, cavity 788
 
  • Y. Luo, G. Bassi, M. Blaskiewicz, W. Fischer, Y. Hao, C. Montag, V. Ptitsyn, V.V. Smaluk, F.J. Willeke
    BNL, Upton, Long Island, New York, USA
  • K. Ohmi
    KEK, Ibaraki, Japan
  • J. Qiang
    LBNL, Berkeley, California, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In the eRHIC, to compensate the geometric luminosity loss, local crab cavities on both sides of the interaction points are to adopted. The previous strong-strong beam-beam simulations showed that the luminosity degradation depends on the crab cavity frequency, proton synchrotron tune, proton bunch length and so on. In this article, we apply a combined strong-strong and weak-strong beam-beam simulation to investigate the incoherent and coherent beam motions with crabbed collison, and to calculate more realistic beam emittance growth rates and luminosity degradation rate.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB091  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB092 Symplectic and Exact Tracking of Low Energy 197Au78+ in the Relativistic Heavy Ion Collider quadrupole, simulation, storage-ring, lattice 791
 
  • Y. Luo, W. Fischer, F. Méot, G. Robert-Demolaize
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In the coming RHIC low energy scan, the electron cooling technique is to be used to cool the ions 197Au79+ with its energy range between 3.85~GeV/nucleon to 5.75~GeV/nucleon. To overlap the electron beam and the 197Au79+ beam at the cooling section, a recombination monitor is to be used to detect the maximum flux of 197Au78+ ions generated in the cooling section. In the previous studies, we tracked 197Au78+ ions through the RHIC lattice defined with 197Au79+ with an equivalent momentum deviation. In the article, we explode different symplectic ways to track 197Au78+ ions exactly. We calculate and compare the trajectories and loss map of 197Au78+ ions through the RHIC ring.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB092  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB093 eRHIC Electron Ring Design Status polarization, storage-ring, solenoid, radiation 794
 
  • C. Montag, M. Blaskiewicz, C. Hetzel, D. Holmes, Y. Li, H. Lovelace III, V. Ptitsyn, K.S. Smith, S. Tepikian, F.J. Willeke, H. Witte, W. Xu
    BNL, Upton, Long Island, New York, USA
  • E. Gianfelice-Wendt
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
For the proposed electron-ion collider eRHIC, an electron storage ring will be installed in the existing RHIC tunnel. To reach the high luminosity of up to 1034 cm-2 sec-1, beam currents up to 2.5A have to be stored. Besides high luminosity the physics program requires spin polarization levels of 70 percent, with both spin "up" and spin "down" orientations present in the fill. This is only feasible by using a full-energy spin polarized injector that replaces bunches faster than the depolarization rate. To limit the repetition rate of that injector to about one hertz, the polarization lifetime in the storage ring has to be maximized by proper spin matching and countermeasures for the machine misalignments. We will give an overview of the electron storage ring design.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB093  
About • paper received ※ 13 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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MOPRB098 An Increased Extraction Energy Booster Complex for the Jefferson Lab Electron Ion Collider booster, collider, extraction, proton 797
 
  • E.A. Nissen
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, world-wide license to publish or reproduce this manuscript.
The proposed Jefferson Lab Electron Ion Collider (JLE-IC) envisions an ion complex composed of an ion linac, two booster synchrotrons and a collider ring. The evolving design of the JLEIC booster required an increase in the extraction energy of the booster from 8 to 12.1 GeV kinetic energy, necessitating two machines instead of one. The decision was also made to switch to warm magnets, thus increasing the total radius of the 8 GeV booster. The second booster is now the same size as the collider rings. In this work we present the new designs for JLEIC’s Low Energy Booster (LEB) and High Energy Booster (HEB).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB098  
About • paper received ※ 14 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPRB100 An Improved eRHIC Interaction Region Design Without High Field Nb3Sn Magnets hadron, quadrupole, dipole, proton 799
 
  • B. Parker, R.B. Palmer, H. Witte
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The IR magnets for the eRHIC Collider proposed at BNL must provide strong fields for the high momentum hadron beam and yet protect the nearby electron beam focusing channel from these fields. In our initial design the electron and hadron magnets were staggered so their respective cold masses did not overlap; however, this restricts the longitudinal space for the first hadron quadrupole and led to the challenge of making a high-field Nb3Sn main coil structure fit inside limited radial space within an external field active shield coil. In our new layout the crossing angle increased from 22 to 25 mrad and the electron and hadron cold masses are now side-by-side. This layout allows longer magnetic lengths for reducing the coil peak fields; NbTi conductor can now be used everywhere. Of course we must take care to control magnetic cross talk between neighboring apertures. One trick we will use to accomplish this is to maximize the yoke material thickness between the beams by tapering (i.e. change coil radius as a function of longitudinal position) some of the electron coils. The new eRHIC IR layout and magnet design is reported in this paper along with ongoing R&D to wind tapered coils.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB100  
About • paper received ※ 15 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPRB106 3D Theory of Microbunched Electron Cooling for Electron-Ion Colliders hadron, kicker, simulation, betatron 814
 
  • G. Stupakov, P. Baxevanis
    SLAC, Menlo Park, California, USA
 
  Funding: This work was supported by the Department of Energy, Contract No. DE-AC02-76SF00515.
The Microbunched Electron Cooling (MBEC) * is a promising cooling technique that can find applications in future hadron and electron-ion colliders. A 1D model of MBEC has been recently developed in Ref. **. This model predicts the cooling time below two hours for eRHIC 255 GeV proton beams, when two amplification sections are used in the cooling system. In this work, we go beyond the 1D model of Ref. * and develop a realistic 3D theory of MBEC. Our approach is based on the analysis of the dynamics of microscopic 3D fluctuations in the electron and hadron beams during their interaction and propagation through the system. We derive an analytical expression for the cooling rate and optimize it for the parameters of eRHIC. Our analytical results are in reasonable agreement with simulations.
* D. Ratner. Phys. Rev. Lett. 111, 084802 (2013).
** G. Stupakov. PRAB 21, 114402 (2018)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB106  
About • paper received ※ 29 April 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPRB109 Cavity Design for the Updated eRHIC Crabbing System cavity, proton, operation, hadron 818
 
  • S. Verdú-Andrés, Q. Wu
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates LLC under contract no. DE-SC0012704 with the U.S. Department of Energy.
The electron-ion collider eRHIC proposed by Brookhaven National Laboratory includes a crabbing system to reestablish head-on collisions for a maximum geometric overlap of the colliding bunches. Since the last cavity design, the crossing angle has increased from 22 to 25 mrad to relax the field strength requirement in one of the IR magnets - increasing the deflecting kick required to collider the bunches head on - and one of the considered options is to have both proton and electron crab cavities work at 200 MHz. The present paper discusses the RF design of the 200 MHz crab cavities for the electron and hadron beams of eRHIC.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB109  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB110 Simulation Study of the Emittance Measurements in Magnetized Electron Beam solenoid, emittance, cathode, gun 822
 
  • S.A.K. Wijethunga, J.R. Delayen, G.A. Krafft
    ODU, Norfolk, Virginia, USA
  • J. F. Benesch, F.E. Hannon, G.A. Krafft, M.A. Mamun, G.G. Palacios Serrano, M. Poelker, R. Suleiman, S. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development funding, under contract DE-AC05-06OR23177
Electron cooling of the ion beam is key to obtaining the required high luminosity of proposed electron-ion colliders. For the Jefferson Lab Electron Ion Collider, the expected luminosity of 1034 〖 cm〗-2 s-1 will be achieved through so-called ’magnetized electron cooling’, where the cooling process occurs inside a solenoid field, which will be part of the collider ring and facilitated using a circulator ring and Energy Recovery Linac (ERL). As an initial step, we generated magnetized electron beam using a new compact DC high voltage photogun biased at -300 kV employing an alkali-antimonide photocathode. This contribution presents the characterization of the magnetized electron beam (emittance variations with the magnetic field strength for different laser spot sizes) and a comparison to GPT simulations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB110  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS002 Linac Energy Jitter Measurements with SPARK BPMs at ALBA linac, electronics, klystron, operation 833
 
  • R. Muñoz Horta, D. Lanaia, E. Marín, A. Olmos, F. Pérez
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
 
  At ALBA four Beam Position Monitors (BPMs) measure the beam position along the Linac to Booster Transfer Line. The BPM electronics (Libera Spark type) have been recently upgraded in order to be sensitive to single-pass beam detection. As a result, the position resolution measured in LTB BPMs has been increased by a factor 10 with respect to the former electronics. The increased resolution enables us to resolve the energy jitter of the Linac beam, providing an on-line measurement of the Linac energy during regular operation. In this paper a study of the Linac energy jitter is presented as well as its correlation with the jitter sources.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS002  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS014 The Experimental Area at the ARES LINAC experiment, laser, linac, acceleration 867
 
  • F. Burkart, R.W. Aßmann, U. Dorda, J. Hauser, S. Lederer, F. Lemery, B. Marchetti, F. Mayet, E. Panofski, P. Wiesener
    DESY, Hamburg, Germany
  • M. Trunk
    University of Hamburg, Hamburg, Germany
 
  The ARES (Accelerator Research Experiment at SINBAD) linac at the accelerator R&D facility SINBAD (Short innovative bunches and accelerators at DESY) will drive multiple independent experiments including the acceleration of ultrashort electron bunches. In addition the linac will host an experimental area, open for transnational access, to study advanced high gradient, laser driven, acceleration concepts, like the ones studied within the ACHIP (accelerator on a chip) project. The area will be operational mid-2019. This paper will report on the current status of the experimental area, including hardware parameters, beam optics, achievable beam parameters, design of the experimental chamber and commissioning plans. The modification plans for a micro-bunching experiment in the frame of the ACHIP experiment and future upgrade plans will be shown and discussed in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS014  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS018 First Electron Beam at the Linear Accelerator FLUTE at KIT laser, MMI, linac, klystron 882
 
  • M.J. Nasse, A. Bernhard, E. Bründermann, A. Böhm, S. Funkner, B. Härer, I. Križnar, A. Malygin, S. Marsching, W. Mexner, A.-S. Müller, G. Niehues, R. Ruprecht, T. Schmelzer, M. Schuh, N.J. Smale, P. Wesolowski, M. Yan
    KIT, Karlsruhe, Germany
 
  Funding: The SRR project has received funding from the European Union’s Horizon 2020 Research and Innovation program under Grant Agreement No 730871.
The first electron beams were generated in the 7 MeV section of the short-pulse linear accelerator test facility FLUTE (Ferninfrarot Linac- Und Test-Experiment) at the Karlsruhe Institute of Technology (KIT). In this contribution we show images of the electron beam on a YAG-screen (yttrium aluminum garnet) as well as signals from an integrating current transformer (ICT) and a Faraday cup. Furthermore, the progress of tuning the FLUTE electron bunches for experiments is presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS018  
About • paper received ※ 10 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS023 Conditioning of the Frontline Cavities of the MYRRHA Injector rfq, cavity, multipactoring, MMI 895
 
  • S. Lamprecht, T. Conrad, K. Kümpel, N.F. Petry, H. Podlech
    IAP, Frankfurt am Main, Germany
  • J. Belmans, D. Davin, W. De Cock, F. Pompon, D. Vandeplassche
    SCK•CEN, Mol, Belgium
 
  The MYRRHA Project (Multi-purpose hYbrid Research Reactor for High-tech Applications) in Mol, Belgium, is an upcoming accelerator driven system (ADS) for the transmutation of long-living radioactive waste. In the injector section of the accelerator, consisting of a 4-rod RFQ and a normal conducting CH-cavity section, the protons will be accelerated up to 17 MeV before entering the superconducting gap-spoke cavity section with an output energy of 600 MeV. A shortened test-injector with an output energy of 5.9 MeV is currently being installed at the SCK. CEN in Louvein-la- Neuve, Belgium. This test-injector serves the purpose of testing the reliability of the planned injector. When commissioning a cavity, it first has to be fed very little power to avoid damage to the structure by flashovers, discharges and multipacting. The power is then slowly increased up to full operation level. In this process, the surfaces are cleaned by heating/outgasing so that the effects disturbing operation described above do no longer occur. This paper will report on the status of the conditioning of the 176.1 MHz 4-rod RFQ up to 120 kW of the MYRRHA-injector and additional measurements concerning the gap voltage which are currently being performed at the SCK. CEN.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS023  
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPTS025 Overview of the ARES Bunch Compressor at SINBAD laser, plasma, linac, simulation 902
 
  • F. Lemery
    University of Hamburg, Hamburg, Germany
  • R.W. Aßmann, U. Dorda, K. Flöttmann, J. Hauser, M. Hüning, G. Kube, M. Lantschner, S. Lederer, B. Marchetti, N. Mildner, M. Pelzer, M. Rosan, J. Tiessen, K. Wittenburg
    DESY, Hamburg, Germany
 
  Funding: This project has received funding from the European Unions Horizon 2020 Research and Innovation programme under Grant Agreement No 730871.
Bunch compressors are essential for the generation of short bunches with applications in e.g. colliders, free electron lasers, and advanced accelerator concepts. The up-and-coming ARES accelerator located at SINBAD, DESY will support the formation of ~100~MeV, pC, sub-fs electron bunches for LWFA research and development. We give an overview on the ARES bunch compressor, providing start-to-end simulations of the machine and an update on its technical design.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS025  
About • paper received ※ 17 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS026 Status Report of the SINBAD-ARES RF Photoinjector and LINAC Commissioning gun, linac, laser, experiment 906
 
  • E. Panofski, R.W. Aßmann, F. Burkart, U. Dorda, K. Flöttmann, M. Hüning, B. Marchetti, D. Marx, F. Mayet, P.A. Walker, S. Yamin
    DESY, Hamburg, Germany
 
  The accelerator R&D facility SINBAD (Short innovative bunches and accelerators at DESY) will drive multiple independent experiments including the acceleration of ultrashort electron bunches and the test of advanced high gradient acceleration concepts. The SINBAD-ARES (Accelerator Research Experiment at SINBAD) setup hosts a normal conducting RF photoinjector generating a low charge electron beam that is afterwards accelerated to 100 MeV by an S-band linac section. The linac as well as a magnetic chicane allow the production of ultrashort pulses with an excellent arrival-time stability. The high brightness beam has then the potential to serve as a test beam for next generation compact acceleration schemes. The setup of the SINBAD-ARES facility will proceed in stages. We report on the current status of the ARES RF gun and linac commissioning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS026  
About • paper received ※ 22 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS054 Status of the CLEAR Electron Beam User Facility at CERN experiment, radiation, plasma, operation 983
 
  • K.N. Sjobak, E. Adli, C.A. Lindstrøm
    University of Oslo, Oslo, Norway
  • M. Bergamaschi, S. Burger, R. Corsini, A. Curcio, S. Curt, S. Döbert, W. Farabolini, D. Gamba, L. Garolfi, A. Gilardi, I. Gorgisyan, E. Granados, H. Guerin, R. Kieffer, M. Krupa, T. Lefèvre, S. Mazzoni, G. McMonagle, N. Nadenau, H. Panuganti, S. Pitman, V. Rude, A. Schlogelhofer, P.K. Skowroński, M. Wendt, A. P. Zemanek
    CERN, Geneva, Switzerland
  • A. Lyapin
    UCL, London, United Kingdom
 
  The CERN Linear Electron Accelerator for Research (CLEAR) has now finished its second year of operation, providing a testbed for new accelerator technologies and a versatile radiation source. Hosting a varied experimental program, this beamline provides a flexible test facility for users both internal and external to CERN, as well as being an excellent accelerator physics training ground. The energy can be varied between 60 and 220 MeV, bunch length between 1 and 4 ps, bunch charge in the range 10 pC to 2 nC, and number of bunches in the range 1 to 200, at a repetition rate of 0.8 to 10 Hz. The status of the facility with an overview of the recent experimental results is presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS054  
About • paper received ※ 12 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS065 Alternative Design of CEPC LINAC linac, positron, booster, collider 1005
 
  • C. Meng, J. Gao, X.P. Li, G. Pei, J.R. Zhang
    IHEP, Beijing, People’s Republic of China
 
  Circular Electron-Positron Collider (CEPC) is a 100 km ring e+ e collider for a Higgs factory. The injector is composed of a Linac and a Booster. The baseline design of CEPC Linac is a normal conducting S-band linear accelerator with frequency in 2860 MHz, which can provide electron and positron beam at an energy up to 10 GeV and bunch charge up to 3 nC. To reduce the design difficulty of booster and booster magnet at low energy part, an alternative design of the Linac with C-band accelerating structure at high energy part is proposed and the energy is up to 20 GeV. The compre-hensive consideration of Linac design and damping ring design will be discussed. In this paper, the physics design of this scheme is presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS065  
About • paper received ※ 16 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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MOPTS067 The Progress in Physics Design of HEPS LINAC linac, wakefield, bunching, emittance 1008
 
  • C. Meng, D.Y. He, X. He, J.Y. Li, Y.M. Peng, S.C. Wang, O. Xiao, J.R. Zhang, S.P. Zhang
    IHEP, Beijing, People’s Republic of China
 
  The High Energy Photon Source (HEPS) is a 6-GeV, ultralow-emittance light source to be built in China. The injector is composed of a 500-MeV Linac and a full energy booster. According to the study and com-missioning consideration of on-axis swap-out injec-tion system, a high bunch charge injector is desirable and a Linac that can provide 7nC per bunch electron beam to booster is needed. This paper present different bunching system schemes and the performance of different schemes are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS067  
About • paper received ※ 14 May 2019       paper accepted ※ 17 May 2019       issue date ※ 21 June 2019  
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MOPTS073 Bunching System Optimization Based on MOGA bunching, linac, emittance, solenoid 1018
 
  • S.P. Zhang, J.Y. Li, C. Meng
    IHEP, Beijing, People’s Republic of China
 
  Multiobjective Genetic Algorithms (MOGA) is effective in dealing with optimization problems with multiple objectives. The bunching system of the High Energy Photon Source (HEPS) linac adopts a traditional bunching system for compressing electron beams with a pulse charge of 4 nC. The bunching system is optimized using MOGA. The optimization include minimizing the normalized emittance and maximizing transmission efficiency. The optimization results have reached the design target, and are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS073  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPTS089 Transverse Beam Dynamics Studies With High Intensity LHC Beams in the SPS injection, octupole, emittance, impedance 1062
 
  • M. Carlà, H. Bartosik, M.S. Beck, L.R. Carver, V. Kain, G. Kotzian, K.S.B. Li, G. Rumolo, C. Zannini
    CERN, Geneva, Switzerland
 
  In order to reach the target beam parameters of the LHC injectors upgrade (LIU), about twice the presently operational intensity of LHC type beams has to be achieved. Although the planned upgrade of the main RF system will occur during the long shutdown, a series of measurements have been performed to assess the beam dynamics challenges with these very high intensity beams on the long SPS injection plateau. Bunch-by-bunch transverse emittance blow-up measurements suggested the presence of electron-cloud. After a period of running with the high intensity beam for a couple of days, a clear improvement of beam quality was observed which is attributed to scrubbing. In addition, a horizontal headtail instability is encountered for the usual operational settings of chromaticity and transverse damper. The stability limit as a function of chromaticity and Landau octupole settings has been explored and will be discussed, together with possible sources of the instability and mitigation strategies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS089  
About • paper received ※ 06 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPTS098 A Primary Electron Beam Facility at CERN linac, injection, emittance, proton 1098
 
  • Y. Papaphilippou, R. Corsini, Y. Dutheil, L.R. Evans, B. Goddard, A. Grudiev, A. Latina, S. Stapnes
    CERN, Meyrin, Switzerland
  • T.P.Å. Åkesson
    Lund University, Department of Physics, Lund, Sweden
 
  This paper describes the concept of a primary electron beam facility at CERN, to be used for dark gauge force and light dark matter searches. The electron beam is produced in three stages: A Linac accelerates electrons from a photo-cathode up to 3.5 GeV. This beam is injected into the Super Proton Synchrotron, SPS, and accelerated up to a maximum energy of 16 GeV. Finally, the accelerated beam is slowly extracted to an experiment, possibly followed by a fast dump of the remaining electrons to another beamline. The beam parameters are optimized using the requirements of the Light Dark Matter eXperiment, LDMX, as benchmark.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS098  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS099 The Development Programme of Cathodes and Electron Guns for the Hollow Electron Lenses of the High Luminosity LHC Project cathode, gun, luminosity, proton 1102
 
  • D. Perini, G. Gobbi
    CERN, Geneva, Switzerland
  • D.J. Crawford, J. Ruan, G. Stancari, L.R. Valerio
    Fermilab, Batavia, Illinois, USA
  • J. Feng, Z. Li, W. Shao, K. Zhang
    BVERI, Beijing, People’s Republic of China
  • W. Liu, J. Wang, Y. Wang, Y. Yang
    Beijing University of Technology, Beijing, People’s Republic of China
 
  Funding: Research supported by the HL-LHC project
The High Luminosity LHC project (HL-LHC) foresees the construction and installation of important new equipment to increase the performance of the LHC machine. The Hollow Electron Lens (HEL) is a promising system to control the beam halo. It improves the beam collimation system of the HL-LHC and mitigates possible equipment damage in case of failure scenarios from halo losses. The halo can store up to 30 MJ energy. The specifications for this new device are quite demanding. The source, an electron gun with an annular shaped cathode, has to deliver a current up to 5 A. This is five times higher than the current in the existing electron lenses in Fermi and Brookhaven national laboratories. This note describes the programme carried out to design and test high-perveance guns equipped with two types of high-performance scandate cathodes. The size of the final gun is now considerably smaller than the one of the first prototype, allowing a reduction of diameter and cost of the superconducting magnet system used to steer the electron beam. The tests carried out at FNAL, BVERI and BJUT demonstrated that the developed cathodes fulfil the specifications and can supply a 5 A fully Space Charge Limited (SCL) current.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS099  
About • paper received ※ 17 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPTS104 A Toolkit for Tracing Electron Beam Envelope at Low Energy Section of TPS Linac simulation, linac, operation, gun 1122
 
  • H.H. Chen, H.C. Chen, K.-K. Lin, Y.K. Lin
    NSRRC, Hsinchu, Taiwan
 
  Based on calculated Bz of solenoids installed at the TPS linac low energy section, the electron beam envelope along beam centerline has been explored in this work using the initial and boundary conditions provided in the linac specifications. Concept of magnetic flux compression is adopt to analyze the beam size variation along linac centerline. The calculated result of selected checkpoints has been experimentally verified using screen monitors. In order to benefit tuning capability in routine operation, the display of beam size variation along centerline is integrated into the previously developed toolkit ’linac’. It is hope that it will provide an interactive approach for linac tune-up process and would be helpful to its routine operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS104  
About • paper received ※ 23 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS105 The High Brightness Photo-injector for THz CUR/VUV FEL at NSRRC radiation, emittance, quadrupole, linac 1125
 
  • A.P. Lee, M.C. Chou, H.P. Hsueh, J.-Y. Hwang, W.K. Lau
    NSRRC, Hsinchu, Taiwan
  • P. Wang
    NTHU, Hsinchu, Taiwan
 
  A high brightness photo-injector has been build for THz coherent undulator radiation and VUV free electron laser test facility at NSRRC. In the first phase, the photo-injector was used to produce ultra-short electron bunches for THz CUR generation. The electron beam is generated form a photocathode rf gun followed by a solenoid for emittance compensation. Then A 5.2 m S-band linac accelerates the electron beam and compresses the beam by velocity bunching. Since the beam emittance will grow during the velocity bunching process, a solenoid system was installed to reduce the emmitance growth. Downstream the linac, a quadruple magnet was use for emittance measurement by quadruple scan method and the bunch length was measured by the coherent transition radiation. Finally, the ultra-short electron bunch with about few hundreds picoseconds passes through a U100 planer undulator can produce THz coherent undulator radiation. The instrument setup and results of measurement are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS105  
About • paper received ※ 14 May 2019       paper accepted ※ 17 May 2019       issue date ※ 21 June 2019  
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MOPTS117 Exploration of High-Gradient Structures for 4th Generation Light Sources cavity, FEL, linac, cryogenics 1155
 
  • S.J. Smith, S. Biedron, S.I. Sosa Guitron
    University of New Mexico, Albuquerque, USA
  • T.B. Bolin
    Element Aero, Chicago, USA
  • B.E. Carlsten, F.L. Krawczyk
    LANL, Los Alamos, New Mexico, USA
  • J.R. Cary, D.M. Cheatham
    Tech-X, Boulder, Colorado, USA
 
  As the energy, scale and therefore the cost of large-scale accelerator projects, such as X-ray free-electron lasers (XFELs) increases, new technologies must be developed in order to minimize costs and maximize efficiency wherever possible. One obvious way to reduce costs is to reduce the length of accelerating sections by utilizing higher accelerating gradients. Here we present the results of a study into the various structure options for FEL linacs, contrasting different frequencies, geometries and operating modes. An investigation into the possibility of using cryo-cooled travelling wave (TW) electron structures which allow for higher gradient operation by exploiting the anomalous skin effect is also detailed. Finally, we give simulation results from a number of commercial codes including VSim 9, for a hypothetical TW high gradient C-band structure design employing cryo-cooled technology. Breakdown effects, pulsed heating, tolerances, efficiencies and potential rf sources are also explored, all within the framework of typical FELs and their requirements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS117  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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TUXXPLM3 First Operation of a Hybrid e-Gun at the Schlesinger Center for Compact Accelerators in Ariel University gun, laser, solenoid, klystron 1171
 
  • A. N. Nause, A. Fukasawa, J.B. Rosenzweig, R.J. Roussel
    UCLA, Los Angeles, USA
  • A. Friedman
    Ariel University, Ariel, Israel
  • B. Spataro
    INFN/LNF, Frascati, Italy
 
  Funding: Israel Ministry of Defence Israel Ministry of Science
A novel hybrid photo injector was designed and partially tested at the UCLA Particle Beam Physics Laboratory. It was later commissioned at Ariel University in Israel as an on-going collaboration between the two universities. This unique, new generation design provides a radically simpler approach to RF feeding of a gun/buncher system, leading to a much shorter beam via velocity bunching owed to an attached traveling wave section of the photo-injector. This design results in better performance in beam parameters, providing a high quality electron beam, with energy of 6 MeV, emittance of app 3 μm, and a 150 fs pulse duration at up to 1 nC per pulse. The Hybrid gun is driven by a SLAC XK5 Klystron as the high power RF source, and third harmonic of a fs level IR Laser amplifier (266 nm) to drive the Cathode. The unique e-gun will produce an electron pulse for a THz FEL, which will operate at the super-radiance regime, and therefore requires extraordinary beam properties. This paper briefly describes the gun and presents initial operational results from the gun and its sub-systems.
 
slides icon Slides TUXXPLM3 [9.526 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUXXPLM3  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUXXPLS2 Negative Muonium Ion Production With a C12A7 Electride Film target, experiment, positron, acceleration 1175
 
  • M. Otani, Y. Fukao, K. Futatsukawa, N. Kawamura, T. Mibe, Y. Miyake, K. Shimomura, T. Yamazaki
    KEK, Tsukuba, Japan
  • K. Hasegawa, Y. Kondo, T. Morishita
    JAEA/J-PARC, Tokai-mura, Japan
  • T. Iijima, Y. Sue
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
  • H. Iinuma, Y. Nakazawa
    Ibaraki University, Ibaraki, Japan
  • K. Inami, M. Yotsuzuka
    Nagoya University, Nagoya, Japan
  • K. Ishida
    RIKEN Nishina Center, Wako, Japan
  • R. Kitamura, H.Y. Yasuda
    University of Tokyo, Tokyo, Japan
  • N. Saito
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
 
  Funding: This work was supported by OSPS KAKENHI Grant Numbers JP15H03666, JP 16H03987, JP18H03707.
Negative muonium ion production is one of methods to cool muons. Since its discovery in 1987 by interactions of muons with a metal foil, it has been discussed that the production efficiency would be improved using a low-work function material. C12A7 (12CaO·7AlO3) was a well-known insulator as a constituent of alumina cement, but was recently confirmed to exhibit electric conductivity by electron doping. The C12A7 electride has lower work function (2.9 eV) and it was reported that nearly the same negative current signal as that with a bi-alkali material coated metal were observed in H formation. In this poster, the negative muonium production measurement with a Al foil and C12A7 electride film will be presented.
 
slides icon Slides TUXXPLS2 [2.680 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUXXPLS2  
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUYPLM1 XFEL Performance Achieved at PAL-XFEL FEL, undulator, photon, emittance 1182
 
  • H. Heo, M.-H. Cho, J.H. Han, H.-S. Kang, C. Kim, G. Kim, M.J. Kim, J.H. Ko, H.-S. Lee, C.-K. Min, I.H. Nam, K.-H. Park, C.H. Shim, H. Yang
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  The hard X-ray free electron laser at Pohang Accelerator Laboratory (PAL-XFEL) successfully completed the commissioning of SASE and started user operation in late 2016. Since then, the facility has demonstrated excellent stability with very small timing jitter of about 20 fs, and commissioned the self-seeding system over a wide range of photon energies, etc. The talk will provide an overview of the last three years at the PAL-XFEL, including some detailed experimental results, as well as future prospects for the laboratory.  
slides icon Slides TUYPLM1 [7.516 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUYPLM1  
About • paper received ※ 20 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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TUYPLM3 Status of the MAX IV Accelerators storage-ring, sextupole, linac, vacuum 1185
 
  • P.F. Tavares, E. Al-Dmour, Å. Andersson, J. Breunlin, F.J. Cullinan, E. Mansten, S. Molloy, D.K. Olsson, D. Olsson, M. Sjöström, S. Thorin
    MAX IV Laboratory, Lund University, Lund, Sweden
 
  The MAX IV facility in Lund, Sweden, consists of three electron accelerators and their respective synchrotron radiation beamlines: a 3 GeV ring, which is the first implementation worldwide of a multi-bend achromat lattice, a 1.5 GeV ring optimized for soft X-Rays and UV radiation production and a 3 GeV linear accelerator that acts as a full-energy injector into both rings and provides electron pulses as short as 100 fs that produce X-rays by spontaneous emission in the undulators of the short-pulse facility (SPF). In this paper, we review the latest achieved accelerator performance and operational results.  
slides icon Slides TUYPLM3 [9.108 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUYPLM3  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUZPLM1 Adding Data Science and More Intelligence to Our Accelerator Toolbox controls, network, laser, simulation 1191
 
  • S. Biedron
    University of New Mexico, Albuquerque, USA
  • S. Biedron
    Element Aero, Chicago, USA
 
  Requirements for recent accelerators are becoming more and more stringent and sophisticated machine tuning is necessary. A large amount of data is acquired from accelerator components as an assistant of machine tuning. It is hard for operators to utilize all the accelerator data for machine tuning. Therefore, machine learning, data mining and big data handling are recently applied to accelerators. For instance, Bayesian optimization is used for maximizing a target performance, a clustering algorithm is used for anomaly detection, and hidden correlation finding is utilized for discovering new aspects of a machine. This talk reviews recent progress of machine learning applications and big data handling in accelerators.  
slides icon Slides TUZPLM1 [11.978 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUZPLM1  
About • paper received ※ 20 May 2019       paper accepted ※ 16 June 2019       issue date ※ 21 June 2019  
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TUZZPLM2 Status of Automated Optimization Procedures at the European XFEL Accelerator FEL, feedback, undulator, status 1212
 
  • S. Tomin
    EuXFEL, Schenefeld, Germany
  • L. Fröhlich, M. Scholz
    DESY, Hamburg, Germany
 
  The European XFEL is in the operational stage since fall 2017. Since then, tuning of the FEL performance (e.g. of the photon pulse energy) has become increasingly important. Due to a large number of parameters to which FEL facilities are highly sensitive and their complex correlations, controlling and optimizing them in a speedy manner is becoming a very important and challenging task. Several automated optimization procedures were developed to optimize the FEL beam quality. In this work, we present the status and the results of these activities, as well as the optimization statistics.  
slides icon Slides TUZZPLM2 [5.882 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUZZPLM2  
About • paper received ※ 13 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUZZPLS3 New Method of Calculation of the Wake due to Radiation and Space Charge Forces in Relativistic Beams radiation, wakefield, space-charge, synchrotron-radiation 1223
 
  • G. Stupakov
    SLAC, Menlo Park, California, USA
 
  Funding: This work was supported by the Department of Energy, Contract No. DE-AC02-76SF00515.
Radiation reaction force in a relativistic beam, also known as a CSR wakefield, is often computed using a 1D model of a line charge beam. While this model can serve as a useful tool for a quick calculation, in some cases, it may not be sufficiently accurate. In particular, this model misses the so-called compression effects associated with the change of the electromagnetic energy when the beam is compressed longitudinally or transversely. The existing 3D simulation codes that take this effect into account are often slow and are not easy to use. In this work, we propose a new approach to the calculations of radiation and space charge longitudinal forces based on the use of the integrals for the retarded potentials. Our main result expresses the rate of change of particles energy through 2D (in a 2D model) or 3D integrals for a given orbit of the beam. It generalizes the 1D model and includes the transient effects of at the entrance and the exit from the magnet. For a given beam line with known magnetic lattice, and a known distribution function of the beam, the calculation reduces to taking 2D or 3D integrals along the orbit.
 
slides icon Slides TUZZPLS3 [2.080 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUZZPLS3  
About • paper received ※ 29 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPMP003 Development of Remote Handleable Axially Decoupled Radiation Resistant Vacuum Seal vacuum, target, interface, operation 1233
 
  • R.R. Nagimov, Y. Bylinskii, L. Egoriti, A. Gottberg, G.W. Hodgson, A.N. Koveshnikov, D. Yosifov
    TRIUMF, Vancouver, Canada
 
  Funding: ARIEL is funded by the Canada Foundation for Innovation (CFI), the Provinces of AB, BC, MA, ON, QC, and TRIUMF. TRIUMF receives federal funding via a contribution agreement with the NRC of Canada.
Advanced Rare IsotopE Laboratory (ARIEL) facility is a major expansion of TRIUMF’s rare isotope research program. Aiming to triple the production of rare isotopes, ARIEL facility includes the new electron linac driver and two target stations for electron and proton beams. Particularities of ARIEL target stations design define the requirements for vacuum interfaces with both primary electron and proton beamlines and rare-isotope beamlines. None of the existing products fully met the requirements, driving the development of custom vacuum interfaces. The design of new vacuum seals is driven both by unique design specifications (limited amount of allowed axial forces, extreme radiation resistance, remote handleability and high repeatability) as well as limitations of the proposed design of beamline infrastructure in the target hall (limited available space and the choice of materials for certain components). This paper discusses preliminary results of the vacuum seal development and presents first results of prototype testing.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP003  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPMP004 Dynamic Pressure in the LHC - Influence of Ions Induced by Ionization of Residual Gas by Both the Proton Beam and the Electron Cloud proton, vacuum, experiment, ECR 1236
 
  • S. Bilgen, C. Bruni, B. Mercier, G. Sattonnay
    LAL, Orsay, France
  • V. Baglin
    CERN, Geneva, Switzerland
 
  Funding: work supported by FCC project (CERN & LAL-CNRS-IN2P3)
Ultra-High Vacuum is an essential requirement to reach design performances in high-energy particle colliders. For the future HL-LHC or FCC study, the understanding of the beam interactions with the vacuum chamber is fundamental to provide solutions to mitigate the pressure rises induced by electronic, photonic and ionic molecular desorption. Studies were performed on the ions, produced by molecular ionization generated by the proton beam and the electron cloud, and stimulating molecular desorption by the surface bombardment. In-situ measurements were carried out, on the LHC Vacuum Pilot Sector (VPS)*, to monitor the dynamic pressure, and to collect the electrical signals due to the electron cloud and to the ions interacting with the vacuum chamber walls. Experimental measurements of electrical signals recorded by copper electrodes were compared to calculations taking into account both the Secondary Electron Yield of copper and electron energy distribution. Finally, it seems that copper electrodes were not fully conditioned and an ion current could be estimated.
* THE LHC VACUUM PILOT-SECTOR PROJECT
B. Henrist, V. Baglin, G. Bregliozzi, and P. Chiggiato, CERN, Geneva, Switzerland
Proceedings of IPAC2014, Dresden, Germany.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP004  
About • paper received ※ 01 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPMP007 DYVACS (DYnamic VACuum Simulation) Code: Calculation of Gas Density Profiles in Presence of Electron Cloud vacuum, proton, photon, experiment 1244
 
  • G. Sattonnay, S. Bilgen, B. Mercier
    LAL, Orsay, France
  • V. Baglin
    CERN, Meyrin, Switzerland
 
  The computation of residual gas density profiles in particle accelerators is an essential task to optimize beam pipes and vacuum system design. In a hadron collider such as the LHC, the beam induces dynamic effects due to ion, electron and photon-stimulated gas desorption. The well-known VASCO* code developed at CERN in 2004 (and then PyVASCO**) is already used to estimate vacuum stability and density profiles in steady state conditions. Nevertheless, some phenomena are not taken into account such as the ionization of residual gas by the electron clouds. Therefore, we propose an upgrade of this code by introducing electron cloud maps*** to estimate the electron density and the ionization of gas by electrons, leading to an increase of both electron- and ion-induced desorption. Results obtained with the new code (called DYVACS for DYnamic VACuum Simulation) will be compared to pressure measurements in the VPS sector**** of the LHC.
* A. Rossi, Tech. Rep., LHC Proj. Note 341
** I. Aichinger, et al arXiv:1707.07525
*** T. Demma et al Phys. Rev. Acceler. and Beams 10, 114401 (2007)
**** B. Henrist et al, Proc. IPAC2014, Dresden
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP007  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPMP021 Comparison of TiZrV Non-evaporable Getter Films Deposited by DC Magnetron Sputtering or Quantitative Deposition vacuum, site, target, interface 1283
 
  • X.Q. Ge, W. Li, J.Q. Shao, S. Wang, Y.G. Wang, Y. Wang, W. Wei, B. Zhang, Y.X. Zhang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  Ti-Zr-V non-evaporable getter (NEG) films have been widely used in vacuum chambers of various accelerators since their discovery. Recently, we have used a new method called ’quantitative deposition’ to deposit Ti-Zr-V NEG films on nichrome substrates. The surface morphology and surface chemical bonding information were collected by scanning electron microscopy. Although the film deposited by DC magnetron sputtering has more uniform grain growth, smoother grain boundaries and higher porosity, the two films all have porous network structure and can be used as getter films.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP021  
About • paper received ※ 24 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPMP029 Establishing a Laser Treatment to Suppress the Secondary Electron Emission laser, experiment, synchrotron, focusing 1303
 
  • Y.G. Wang, X.Q. Ge, X.T. Pei, S.W. Wang, Y. Wang, B. Zhang, B.L. Zhu
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  Laser treatment has a significant inluent on suppressing the secondary electron emission(SEE). The new synchrotron radiation light source, the Hefei Advanced Light Source(HALS) has a strict requirement on the SEE. In this paper, we used a 355nm laser to process copper sample. After the laser treatment, the secondary electron yield(SEY) reduced from 2.05 to 0.86. We used the scanning electron microscope(SEM) to analysis the surface of sample after the laser treatment.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP029  
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPMP031 Research on Secondary Electron Emission Characteristics of Diamond-like Carbon Thin Films vacuum, experiment, laser, gun 1306
 
  • Y.X. Zhang, X.Q. Ge, W. Li, J.Q. Shao, S. Wang, Y.G. Wang, Y. Wang, W. Wei, B. Zhang, B.L. Zhu
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  In modern particle accelerators, the build-up of electron cloud is a main limiting factor for the achievement of high-quality beam. Among the techniques to mitigate it, coating the internal walls of the beam pipes with a thin film which has a low secondary electron yield (SEY) is considered to be one of the most effective means. From several earlier studies, it was found that diamond-like carbon (DLC) thin films are potential coatings. This paper is mainly about the research on secondary electron emission characteristics of DLC thin films. The secondary electron emission (SEE) tests were done at temperature of 298 K and vacuum pressure of 2×10-9 Torr. Here, we obtained the characteristics of the SEE from DLC film coatings with different thickness under ultrahigh-vacuum (UHV) conditions. The maximum secondary electron yield (SEY), δmax, of the DLC thin films under different primary electron doses were also obtained, respectively.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP031  
About • paper received ※ 26 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPMP034 A Modular Optical Firing Interface for CERN’s Generic Power Converter Control Platform controls, interface, ISOL, status 1315
 
  • M. Di Cosmo, T.G. Gaime, B. Todd
    CERN, Geneva, Switzerland
 
  The power converters group at CERN has developed a third generic converter controller (FGC3) and regulation platform (RegFGC3), capable of controlling any of CERN’s power converters. This platform provides electrical connections to the low-level control elements of power converters, and in some cases a galvanic isolation is required between the converter controller output, and the power converter under control. To meet these requirements, a generic modular optical firing platform has been developed, which converts the electrical firing pulses from the RegFGC3 and FGC3 platforms into optical drive signals. Designed to be fully scalable, this platform provides various protection mechanisms to verify the integrity of the firing information. For example, checking for illegal firing states, dead-time, and drive errors. This paper describes the modular optical firing interface, the basic principles, and the configurations which are in use, or are planned to be used at CERN.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP034  
About • paper received ※ 15 May 2019       paper accepted ※ 17 May 2019       issue date ※ 21 June 2019  
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TUPMP036 Results on the FCC-hh Beam Screen Sawtooth at the Kit Electron Storage Ring Kararesults on the Fcc-Hh Beam Screen Sawtooth at the Kit Electron Storage Ring Kara photon, radiation, vacuum, experiment 1323
 
  • L.A. Gonzalez, V. Baglin, I. Bellafont, P. Chiggiato, C. Garion, R. Kersevan
    CERN, Geneva, Switzerland
  • I. Bellafont, F. Pérez
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • S. Casalbuoni, E. Huttel
    KIT, Eggenstein-Leopoldshafen, Germany
 
  Funding: * The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 654305.
In the framework of the EuroCirCol collaboration (work package 4 "Cryogenic Beam Vacuum System"), the fabrication of the FCC-hh beam screen (BS) prototype has been carried out with the aim of testing it at room temperature on the Karlsruhe Institute of Technology (KIT) 2.5 GeV electron storage ring KARA (KArlsruhe Research Accelerator) light source. The BS prototype was tested on a beamline installed by the collaboration, named as BEam Screen TEstbench EXperiment (BESTEX). KARA has been chosen because its synchrotron radiation (SR) spectrum, photon flux and power match quite well the one foreseen for the 50+50 TeV FCC-hh proton collider. The BS prototype (2 m in length) was manufactured according to the base line design (BD) of the FCC-hh BS. It implements a saw-tooth profile designed to absorb the SR generated at the bending magnets. Also, a laser-ablated anti-electron cloud surface texturing [2] was applied at the BS inner walls. We present here the results obtained at BESTEX and the comparison of the results obtained during irradiation of the saw-tooth profile at different geometric configurations.
This activity has been carried out in the framework of the EuroCirCol* collaboration (work package 4 "Cryogenic Beam Vacuum System").
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP036  
About • paper received ※ 13 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPMP038 Summary of Modelling Studies on the Beam Induced Vacuum Effects in the FCC-hh vacuum, photon, collider, synchrotron 1331
 
  • I. Bellafont, R. Kersevan, L. Mether
    CERN, Geneva, Switzerland
 
  Funding: The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 654305.
EuroCirCol is a conceptual design study of a Future Circular Collider (FCC-hh) which aims to expand the current energy and luminosity frontiers that the LHC has established. The vacuum chamber of this 50 TeV, 100 km collider, will have to cope with unprecedented levels of synchrotron radiation power for proton colliders, dealing simultaneously with a tighter magnet aperture. Since the high radiation power and photon flux will release large amounts of gas into the system, the difficulty to keep a low level of residual gas density increases considerably compared with the LHC. This article presents a study of the beam induced vacuum effects for the FCC-hh novel conditions, the different phenomena which, owing to the presence of the beam, have an impact on the vacuum level of the accelerator. To achieve this, a novel beam screen has been proposed, featuring specific mitigating measures aimed at dealing with the beam induced effects. It is concluded that thanks to the new beam screen design, the vacuum level in the FCC-hh shall be adequate, allowing to reach the molecular density requirement of better than 1015 H2/m3 with baseline beam parameters within the first months of conditioning.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP038  
About • paper received ※ 10 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPMP048 Current Status of Turkish Accelerator and Radiation Laboratory radiation, cavity, FEL, status 1359
 
  • A.A. Aksoy, O.F. Elçim
    Ankara University Institute of Accelerator Technologies, Golbasi, Turkey
  • Ö. Karslı, C. Kaya, B. Koc
    Ankara University, Accelerator Technologies Institute, Golbasi, Turkey
 
  Funding: T.R. Presidency Strategy and Budget Office Grand No: 2006K-120470
Turkish Accelerator and Radiation Laboratory (TARLA) which is designed to deliver various accelerator based radiation sources, aims to be outstanding research instrument for users from both Turkey and region. Within the current scope of TARLA its superconducting accelerator will drive two of free electron laser (FEL) beamlines in order to provide Continuous Wave (CW) tunable radiation of high brightness in the mid- and far-infrared range as well as a Bremmstrahlung radiation station. Main components of TARLA, such as injector, superconducting accelerating modules and cryoplant are under commissioning currently. In this paper commissioning results and current status of facility are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP048  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPMP051 MULTIPACTOR SUPPRESSION BY LASER ABLATION SURFACE ENGINEERING FOR SPACE APPLICATIONS laser, multipactoring, GUI, controls 1365
 
  • R. Valizadeh, A.N. Hannah, O.B. Malyshev, B.S. Sian
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • J.S. Colligon
    University of Huddersfield, Huddersfield, United Kingdom
  • Y. Dan
    Hitachi High-Technologies Corp., Ibaraki-ken, Japan
  • V. R. Dhanak
    The University of Liverpool, Liverpool, United Kingdom
  • J. Mutch
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • B.S. Sian
    UMAN, Manchester, United Kingdom
  • N. Sykes
    Micronanics Laser Solution Center, Didcot, United Kingdom
 
  Developing a surface with low Secondary Electron Yield (SEY) is one of the main ways of mitigating electron cloud and beam-induced electron multipacting in high-energy charged particle accelerators and space-borne RF equipment for communication purposes. In this study we report on the secondary electron yield (SEY) measured from silver coated aluminium alloy as-received and after laser ablation surface engineering (LASE). Analysis shows the SEY can be reduced by 43% using LASE. EDX and SEM analysis shows it is possible to reduce the SEY whilst maintaining the original surface composition.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP051  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPGW006 Measurements of the Momentum Compaction Factor of the ESRF Storage Ring radiation, undulator, SRF, synchrotron 1392
 
  • N. Carmignani, W. De Nolf, A. Franchi, C. Sahle, L. Torino
    ESRF, Grenoble, France
  • B. Nash
    RadiaSoft LLC, Boulder, Colorado, USA
 
  In a storage ring, the momentum compaction factor can be obtained by measuring the variation of the beam energy as a function of the RF frequency. In this paper we present the measurement of the momentum compaction factor from two different methods. With the first, we measure the variation of the undulator spectra for different RF frequencies. With the second, we measure the variation of the hard x-rays flux produced by a dipole for different RF frequencies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW006  
About • paper received ※ 29 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPGW024 Pulse Shaping Methods for Laser-Induced Generation of THz Radiation at the Delta Storage Ring laser, radiation, storage-ring, experiment 1453
 
  • C. Mai, B. Büsing, A. Glaßl, S. Khan, D. Krieg, A. Meyer auf der Heide
    DELTA, Dortmund, Germany
 
  At DELTA, a 1.5-GeV electron storage ring operated as a synchrotron light source by the TU Dortmund University, a dedicated beamline is used for experiments with (sub-)THz radiation. Here, an interaction of short laser pulses with electron bunches to give rise to coherently emitted broadband as well as tunable narrowband radiation from 75 GHz to 5.6 THz. For the narrowband operation of the source, a laser pulse with periodic intensity modulation is used. An interferometric approach, the chirped-pulse beating technique, is routinely employed for this purpose. Recently, pulse shaping techniques using spatial light modulators are investigated to gain more flexible control of the laser pulse shape and the spectrotemporal properties of the resulting THz pulses.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW024  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPGW025 The DELTA Short-Pulse Source: Upgrade Plans from CHG to EEHG laser, undulator, radiation, optics 1457
 
  • A. Meyer auf der Heide, B. Büsing, S. Khan, D. Krieg, C. Mai, F. Teutenberg
    DELTA, Dortmund, Germany
 
  At the synchrotron light source DELTA operated by the TU Dortmund University, coherent harmonic generation (CHG) is employed to provide ultrashort pulses in the vacuum ultraviolet and terahertz (THz) regime. Here, a modulation of the electron energy induced by an interaction of an ultrashort laser pulse with an electron bunch is transformed into a density modulation by a magnetic chicane. This results in coherent emission at harmonics of the laser wavelength as well as THz radiation. With the planned upgrade towards echo-enabled harmonic generation (EEHG), much higher harmonics can be achieved by adding a second laser-electron interaction. The necessary major modifications of the DELTA storage ring and investigations of the laser-electron interaction will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW025  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPGW033 Status of Test-Accelerator as Coherent THz Source (t-ACTS) at ELPH, Tohoku University radiation, undulator, polarization, FEM 1475
 
  • S. Kashiwagi, H. Hama, F. Hinode, K. Kanomata, S. Miura, N. M. Morita, T. Muto, I. Nagasawa, K. Nanbu, S. Ninomiya, H. Saito, K. Takahashi, H. Yamada
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
 
  A test-Accelerator as Coherent Terahertz Source (t-ACTS) has been under development at the Research Center for Electron Photon Science (ELPH), Tohoku University, in which an intense coherent terahertz radiation is generated from the femtosecond electron pulses. Velocity bunching scheme in a traveling accelerating structure is employed to generate femtosecond electron pulses, and the generation of femtosecond electron pulses was confirmed by spectrum analysis of coherent transition radiation using Michelson interferometer. Coherent transition radiation and coherent undulator radiation in the terahertz (THz) region from the short electron pulses has been demonstrated, and their characteristics such as frequency spectrum, spatial distribution and polarization were measured and compared with theoretical calculations. We have succeeded to generate the coherent transition radiation up to approximately 5 THz and the coherent undulator radiation with narrow bandwidth from 2.6 to 3.4 THz. At present, development of a variable polarized THz light source using a crossed-undulator system is being carried out. In addition, we are developing a nondestructive beam monitor using Cherenkov radiation emitted from the electron pulses. The status of t-ACTS will be presented in this conference.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW033  
About • paper received ※ 17 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPGW037 Systematic Measurements of the Coherent THz Spectra by Magnetic Bunch Compression at the Compact ERL optics, radiation, sextupole, linac 1486
 
  • M. Shimada, Y. Honda, R. Kato, T. Miyajima, N. Nakamura, T. Obina, T. Uchiyama
    KEK, Ibaraki, Japan
  • T. Hotei
    Sokendai, Ibaraki, Japan
 
  Short electron bunch beam is one of the key elements of a Free Electron Laser (FEL) or intense THz coherent light source. The Energy Recovery Linac (ERL) has the strong advantage of operation of such an electron bunch at high repetition rate and is expected to increase the photon flux. At the Compact ERL in KEK site, we have demonstrated the magnetic bunch compression at the 180-degree return arc and measured the THz spectra of the Coherent Transition Radiation (CTR). This paper reports the revamped THz beamline and the improvement of the beam tuning as well as the systematic measurements of the THz spectra by magnetic bunch compression.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW037  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPGW038 Study on Coherent THz Radiation Using Tilt Control of Electron Beam radiation, solenoid, target, experiment 1489
 
  • Y. Tadenuma, M. Brameld, T. Murakami, K. Sakaue, M. Washio
    Waseda University, Tokyo, Japan
 
  Funding: This work was supported by a research granted from JSPS KAKENHI 17H02821.
The terahertz wave is located in the intermediate frequency band between radio waves and light waves, and researches on the light sources such as terahertz quantum cascade laser and femtosecond laser based THz sources are being conducted*. As a new terahertz light source, we are studying coherent Cherenkov radiation by using the tilt control of electron beam and irradiating the target medium. Since the radiation intensity of Cherenkov radiation depends on the target medium, comparison of three kinds of medium with different refractive index and density, and optimization of the target shape were performed. In addition, we are going to try quasi monochromatization of radiation by using multi slit to control the form factor of the electron beam. In this presentation, we will report the experimental results of target optimization and quasi monochromatization and the future prospects.
*S. S. Dhillon, et al., The 2017 terahertz science and technology roadmap, J. Phys. D: Appl. Phys., 50 (2017) 043001.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW038  
About • paper received ※ 12 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPGW045 Lattice Design for the Reversible SSMB radiation, emittance, storage-ring, bunching 1507
 
  • C.L. Li
    SINAP, Shanghai, People’s Republic of China
  • A. Chao
    SLAC, Menlo Park, California, USA
  • C. Feng, B.C. Jiang
    Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China
 
  Steady State Microbunching (SSMB) aiming at producing high average power radiation in the electron storage ring has been proposed by Ratner and Chao years ago. Reversible seeding scheme is one of the promising scenarios with less challenges on the storage ring lattice design. The key problem for reversible SSMB is the precise cancelation of the laser modulation which will allow producing turn-by-turn coherent radiation without spoiling the transverse emittances and energy spread. In this paper the lattice design for the microbunching generation and its cancelation will be presented. Also a storage ring lattice design will be shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW045  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPGW051 Generation of Two Terahertz Radiation Pulses with Continuously Tunable Frequency and Time Delay radiation, laser, cathode, gun 1518
 
  • W.X. Wang, Z.G. He, S.M. Jiang, H.R. Zhang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  We propose to generate two narrow band terahertz pulses radiated from two temporally modulated relativistic electron beams, which are generated in a photo-injector. The temporal profile of the drive laser is modulated by means of the paired chirped pulses beating technique, leading to the generation of two pre-bunched electron beams. Coherent transient radiation (CTR) is considered as the mechanism for terahertz radiation generation. The frequencies of the two terahertz pulses can be independently tuned by adjusting the paired beating frequencies, and the interval between the two terahertz pulses can be adjusted by the optical delay line.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW051  
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPGW059 Studies of The Electron Beam Lifetime in Solaris Electron Storage Ring storage-ring, cavity, scattering, vacuum 1541
 
  • R. Panas, A.M. Marendziak, A.I. Wawrzyniak, M. Wisniowski
    Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland
 
  Solaris storage ring is a recently constructed and commissioned machine operated in decay mode. With total accumulated beam dose near to 1000 A.h the measured total lifetime has reached 16 h for 270mA of a stored current. In this paper, the beam lifetime studies are presented using measured residual gas analysis and vertical scraper position for tuned and detuned Landau cavities. It shows that for stable beam the lifetime is dominated by the interaction of the electron with residual gas (vacuum lifetime) and between electrons interaction within a bunch (Touschek lifetime). The estimated vacuum, Touschek and total beam lifetimes from theoretical analysis are also compared with the measured beam lifetime.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW059  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPGW085 A Hard X-Ray Compact Compton Source at CBETA laser, photon, scattering, brilliance 1604
 
  • K.E. Deitrick, C. Franck, G.H. Hoffstaetter, V.O. Kostroun, K.W. Smolenski
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J. Crone, H.L. Owen
    UMAN, Manchester, United Kingdom
  • B.D. Muratori
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  Compton backscattering at energy recovery linacs (ERLs) promises high flux, high energy x-ray sources in the future, made possible by high quality, high repetition rate electron beams produced by ERLs. CBETA, the Cornell-BNL ERL Test Accelerator currently being built and commissioned at Cornell, is an SRF multi-turn ERL using Non-Scaling Fixed Field Alternating-gradient (NS-FFA) arcs. CBETA has high quality design parameters with an anticipated top energy of 150 MeV on the fourth pass. The expected parameters of a Compton source at CBETA include a top x-ray energy of over 400 keV with a flux on the order of 1012 ph/s. In this paper, we present anticipated parameters and potential applications in science and engineering for this source.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW085  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPGW086 Energy and RF Cavity Phase Symmetry Enforcement in Multi-Turn ERL Models cavity, linac, acceleration, target 1606
 
  • R.M. Koscica, N. Banerjee, C.M. Gulliford, G.H. Hoffstaetter, W. Lou
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  In a multi-pass Energy Recovery Linac (ERL), each cavity must regain all energy expended from beam acceleration during beam deceleration, and the beam should achieve specific energy targets during each loop that returns it to the linac. For full energy recovery, and for every returning beam to meet loop energy requirements, we must optimize the phase and voltage of cavity fields in addition to selecting adequate flight times. If we impose symmetry in time and energy during acceleration and deceleration, fewer parameters are needed, simplifying the optimization. As an example, we present symmetric models of the Cornell BNL ERL Test Accelerator (CBETA) with solutions that satisfy the optimization targets of loop energy and zero cavity loading.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW086  
About • paper received ※ 14 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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TUPGW098 Fabrication & Cold Tests of a Millimeter-Period RF Undulator undulator, laser, FEL, GUI 1643
 
  • F. Toufexis, B. J. Angier, D. Gamzina, S.G. Tantawi
    SLAC, Menlo Park, California, USA
 
  Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437.
To reduce the linac energy required for an FEL radiating at a given wavelength, and hence its size, a smaller undulator period with sufficient field strength is needed. Previous work from our group successfully demonstrated a microwave undulator at 11.424GHz, using a corrugated cylindrical waveguide operating at the HE11 modes. We have designed a mm-wave undulator cavity at 91.392GHz* with an equivalent undulator period of 1.75 mm. This undulator requires 1.4 MW for sub microsecond pulses for an equivalent K value of 0.1. In this work we present the mechanical design and fabrication of this 91.392 GHz RF Undulator, as well as preliminary cold test data.
* F. Toufexis and S.G. Tantawi, "A 1.75-mm Period RF-Driven Undulator", Proceedings of IPAC17.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW098  
About • paper received ※ 10 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPGW102 CBETA - Novel Superconducting ERL linac, MMI, operation, cryomodule 1651
 
  • R.J. Michnoff, J.S. Berg, S.J. Brooks, J. Cintorino, Y. Hao, C. Liu, G.J. Mahler, F. Méot, S. Peggs, V. Ptitsyn, T. Roser, P. Thieberger, S. Trabocchi, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, F.J. Willeke, H. Witte
    BNL, Upton, Long Island, New York, USA
  • N. Banerjee, J. Barley, A.C. Bartnik, I.V. Bazarov, D.C. Burke, J.A. Crittenden, L. Cultrera, J. Dobbins, S.J. Full, F. Furuta, R.E. Gallagher, M. Ge, C.M. Gulliford, B.K. Heltsley, G.H. Hoffstaetter, D. Jusic, R.P.K. Kaplan, V.O. Kostroun, Y. Li, M. Liepe, W. Lou, J.R. Patterson, P. Quigley, D.M. Sabol, D. Sagan, J. Sears, C.H. Shore, E.N. Smith, K.W. Smolenski, V. Veshcherevich, D. Widger
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • D. Douglas
    Douglas Consulting, York, Virginia, USA
  • M. Dunham, C.E. Mayes
    SLAC, Menlo Park, California, USA
 
  Funding: New York State Research&Development Authority - NYSERDA agreement number 102192
We are successfully commissioning a unique Cornell University and Brookhaven National Laboratory Electron Recovery Linac (ERL) Test Accelerator ’CBETA’ [1]. The ERL has four accelerating passes through the supercon-ducting linac with a single Fixed Field Alternating Linear Gradient (FFA-LG) return beam line built of the Halbach type permanent magnets. CBETA ERL accelerates elec-trons from 42 MeV to 150 MeV, with the 6 MeV injec-tor. The novelties are that four electron beams, with ener-gies of 42, 78, 114, and 150 MeV, are merged by spreader beam lines into a single arc FFA-LG beam line. The elec-tron beams from the Main Linac Cryomodule (MLC) pass through the FFA-LG arc and are adiabatically merged into a single straight line. From the straight section the beams are brought back to the MLC the same way. This is the first 4 pass superconducting ERL and the first single permanent magnet return line.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW102  
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB002 The Conceptual Design of a 36 GHz RF Undulator undulator, cavity, GUI, photon 1676
 
  • D. Zhu
    ASCo, Clayton, Victoria, Australia
  • A.W. Cross, L. Zhang
    USTRAT/SUPA, Glasgow, United Kingdom
  • Y.E. Tan
    AS - ANSTO, Clayton, Australia
 
  The CompactLight project supported by European H2020 is to design a hard X-ray FEL facility beyond today’s state of the art. The project integrates photo injector, X-band acceleration and innovative compact short-period undulators together to make the machine more compact. RF undulator has an extraordinary advantage of working at very short undulator period. A conceptual design for a RF undulator at 36 GHz using a corrugated cylindrical waveguide operating in the HE11 mode is presented in this paper. Based on beam dynamics simulation and photon beam radiation simulations, the possibility of RF undulator to be used in CompactLight project is evaluated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB002  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB008 LUXE - a QED Experiment at the European XFEL experiment, FEL, laser, photon 1694
 
  • F. Burkart, R.W. Aßmann, R. Brinkmann, W. Decking, N. Golubeva, B. Heinemann, M. Hüning, J. List, M. Wing
    DESY, Hamburg, Germany
  • M. Wing
    UCL, London, United Kingdom
 
  The proposed experiment aims to measure QED in the presence of strong fields and above the Schwinger critical field. An experiment is being considered at the European XFEL, which should be able to measure non-perturbative QED and its transition from the perturbative regime. This paper presents the current status of the LUXE (Laser und XFEL Experiment) design study. First layout considerations; accelerator beam line design, electron and laser beam parameters, radioprotection issues and first results of the start to end simulations will be presented and discussed in detail. An outlook concerning the implementation into the XFEL schedule and timeline of this experiment will be given.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB008  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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TUPRB012 Design of High Power CW IR-THz Source for the Radiation Source ELBE Upgrade undulator, radiation, FEL, linac 1702
 
  • P.E. Evtushenko, T.E. Cowan, U. Lehnert, P. Michel
    HZDR, Dresden, Germany
 
  The Radiation Source ELBE at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) is a user facility based on a 1 mA - 40 MeV CW SRF LINAC. Presently HZDR is considering upgrade options for the ELBE or its replacement with a new CW, SRF LINAC-based user facility. A part of the user requirements is the capability to generate IR and THz pulse in the frequency range from 0.1 through 30 THz, with pulse energies in the range from 100 uJ through a few mJ, at the repetition rate between 100 kHz and 1 MHz. This corresponds to the pulse energy increase, dependent on the wavelength by a factor from 100 through 1000. In this contribution, we outline key aspects of a concept, which would allow to achieve such parameters. Such key aspects are: 1 - use of a beam with longitudinal density modulation and bunching factor of about 0.5 at the fundamental frequency; 2 - achieving the density modulation through the mechanism similar to the one used in optical klystron (OK) and HGHG FEL; 3 - generating necessary for the modulation optical beam by an FEL oscillator, and 4 - using two electron injectors, where one injector provides beam for the FEL oscillator while second high charge injector provides beam for the high energy per pulse generation for user experiments. All-in-all the concept of the new radiation source is very similar to an OK, but operating with two beams simultaneously.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB012  
About • paper received ※ 21 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB013 Simulation Studies for a EEHG seeded FEL in the XUV laser, bunching, FEL, simulation 1705
 
  • V. Grattoni, S. Ackermann, R.W. Aßmann, B. Faatz, T. Lang, C. Lechner, M.M. Mohammad Kazemi, G. Paraskaki, J. Zemella
    DESY, Hamburg, Germany
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • S. Reiche
    PSI, Villigen PSI, Switzerland
 
  Echo-enabled harmonic generation (EEHG) is a promising technique for seeded free electron lasers (FELs) not only to go down to wavelengths of 4 nm, but also to simplify the schemes that are currently used to achieve a similar wavelength range (double cascade HGHG). Thus a study optimizing the EEHG performance in the wavelength range from 60 to §I{4}{nm} has been performed. The more critical working point, at 4 nm, is here analyzed in terms of seed laser energy stability for two different seed laser frequencies: visible and UV.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB013  
About • paper received ※ 30 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB018 Design Studies of a Proof-of-Principle Experiment on THz SASE FEL at PITZ FEL, undulator, laser, experiment 1713
 
  • X. Li, P. Boonpornprasert, Y. Chen, J.D. Good, M. Groß, H. Huck, I.I. Isaev, C. Koschitzki, M. Krasilnikov, S. Lal, O. Lishilin, G. Loisch, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, H. Shaker, S. Shu, F. Stephan, G. Vashchenko
    DESY Zeuthen, Zeuthen, Germany
 
  A free-electron laser based THz source is undergoing design studies at the Photo Injector Test facility at DESY in Zeuthen (PITZ). It is considered as a prototype for pump-probe experiments at the European XFEL, benefiting from the fact that the electron beam from the PITZ facility has an identical pulse train structure as the XFEL pulses. In the proposed proof-of-principle experiment, the electron beam (up to 4 nC bunch charge and 200 A peak current) will be accelerated to 16-22 MeV/c to generate SASE radiations in an LCLS-I undulator in the THz range between 60 and 100 µm with an expected energy of up to ~1 mJ/pulse. In this paper, we report our simulations on the optimization of the photo-injector and the design of the transport and matching beamline. Experimental investigations on the generation, characterization and matching of the high charge beam in the existing 22-m-long beamline will also be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB018  
About • paper received ※ 30 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB020 Status of the European XFEL FEL, operation, photon, MMI 1721
 
  • W. Decking, F. Brinker, L. Fröhlich, R. Kammering, T. Limberg, S. Liu, D. Nölle, M. Omet, M. Scholz, T. Wamsat
    DESY, Hamburg, Germany
 
  The European XFEL is a Hard X-ray Free Electron Laser based on superconducting accelerator technology. In operation since 2017, it now serves 3 FEL beamlines simultaneously for user experiments. We will report on the present operation of the linear accelerator, the beam distribution to the various beamlines and the performance of the FEL radiators.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB020  
About • paper received ※ 15 May 2019       paper accepted ※ 17 May 2019       issue date ※ 21 June 2019  
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TUPRB023 Considerations for the Ultrahard X-ray Undulator Line of the European XFEL undulator, FEL, photon, operation 1732
 
  • E. Schneidmiller, V. Balandin, W. Decking, M. Dohlus, N. Golubeva, D. Nölle, M.V. Yurkov, I. Zagorodnov
    DESY, Hamburg, Germany
  • G. Geloni, Y. Li, S. Molodtsov, J. Pflüger, S. Serkez, H. Sinn, T. Tanikawa, S. Tomin
    EuXFEL, Schenefeld, Germany
 
  The European XFEL is a multi-user X-ray FEL facility based on superconducting linear accelerator. Presently, three undulators (SASE1, SASE2, SASE3) routinely deliver high-brightness soft- and hard- X-ray beams for users. There are two empty undulator tunnels that were originally designed to operate with spontaneous radiators in the range 20-90 keV. We consider, instead a possible installation of two FEL undulators. One of them (SASE4) is proposed for operation in a standard (7-25 keV) range as well as in ultrahard (25-100 keV) regime. We discuss a possible location and length of SASE4, modifications of electron beam transport, beam dynamics, choice of undulator technology, different operation modes (SASE and advanced lasing concepts) etc.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB023  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB024 A Concept for Upgrade of FLASH2 Undulator Line undulator, FEL, polarization, operation 1736
 
  • E. Schneidmiller, B. Faatz, I. Hartl, S. Schreiber, M. Tischer, M. Vogt, M.V. Yurkov, J. Zemella
    DESY, Hamburg, Germany
  • W. Wurth
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  FLASH is the first soft X-ray FEL user facility, routinely providing brilliant photon beams for users since 2005. There are plans to upgrade both existing undulator lines of this facility, FLASH1 and FLASH2. FLASH1 will mainly operate in XUV range in seeding and SASE modes, while FLASH2 will use the standard SASE regime as well as new lasing concepts aiming at production of brilliant photon beams on the fundamental and harmonics down to 1nm. In this paper we present a concept for FLASH2 upgrade, and discuss different advanced options.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB024  
About • paper received ※ 30 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB026 Optics & Compression Schemes for a Possible FLASH Upgrade FEL, emittance, laser, simulation 1744
 
  • J. Zemella, M. Vogt
    DESY, Hamburg, Germany
 
  The proposed FLASH upgrade will rely on high quality electron beams provided to all undulator beamlines. Here we describe possible modifications to the FLASH lattice and the compression scheme that aim at improving the beam quality and the ability to control critical beam properties along the machine - simultaneously and independently for all beamlines.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB026  
About • paper received ※ 11 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB027 Upgrade Plans for FLASH for the Years After 2020 laser, FEL, undulator, operation 1748
 
  • M. Vogt, K. Honkavaara, J. Rönsch-Schulenburg, S. Schreiber, J. Zemella
    DESY, Hamburg, Germany
 
  FLASH is a unique superconducting soft X-ray FEL capable of producing up to 8000 photon pulses per second. A substantial upgrade is planned to keep FLASH attractive and competitive. Several upgrade scenarios are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB027  
About • paper received ※ 14 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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TUPRB031 FERMI Configuration for the Echo Enabled Harmonic Generation Experiment laser, FEL, experiment, photon 1752
 
  • E. Allaria, D. Castronovo, M. Cautero, I. Cudin, M.B. Danailov, B. Diviacco, L. Giannessi, M. Veronese, M. Zangrando
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  The FERMI FEL-2 undulator line, normally operated in the double stage high gain harmonic generation with the fresh bunch (HGHG-FB) has been temporary modified to allow operating the FEL in the Echo Enabled Harmonic Generation (EEHG) scheme. An increase of the dispersion in the delay-line was required together with a replacement of the second stage modulator allowing the electron beam to resonantly interact with a second seed laser. Another critical component of the EEHG setup is a new manipulator installed in the delay-line chicane and hosting additional diagnostic components. In this work we describe in some detail these new components that allowed a successful demonstration of the EEHG at harmonics as high as 101.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB031  
About • paper received ※ 17 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB032 The CompactLight Design Study Project FEL, linac, undulator, brightness 1756
 
  • G. D’Auria, S. Di Mitri, R.A. Rochow
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • M. Aicheler
    HIP, University of Helsinki, Finland
  • A.A. Aksoy
    Ankara University, Accelerator Technologies Institute, Golbasi, Turkey
  • D. Alesini, M. Bellaveglia, B. Buonomo, F. Cardelli, M. Croia, M. Diomede, M. Ferrario, A. Gallo, A. Giribono, L. Piersanti, B. Spataro, C. Vaccarezza
    INFN/LNF, Frascati, Italy
  • R. Apsimon, A. Castilla
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • J.M. Arnesano, F. Bosco, L. Ficcadenti, A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
  • A. Bernhard, J. Gethmann
    KIT, Karlsruhe, Germany
  • G. Burt
    Lancaster University, Lancaster, United Kingdom
  • M. Calvi, T. Schmidt, K. Zhang
    PSI, Villigen PSI, Switzerland
  • H.M. Castaneda Cortes, J.A. Clarke, D.J. Dunning, N. Thompson
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • A.W. Cross, L. Zhang
    USTRAT/SUPA, Glasgow, United Kingdom
  • G. Dattoli, F. Nguyen, A. Petralia
    ENEA C.R. Frascati, Frascati (Roma), Italy
  • R.T. Dowd, D. Zhu
    AS - ANSTO, Clayton, Australia
  • W.D. Fang
    SINAP, Shanghai, People’s Republic of China
  • A. Faus-Golfe, Y. Han
    LAL, Orsay, France
  • E.N. Gazis, N. Gazis
    National Technical University of Athens, Athens, Greece
  • R. Geometrante, M. Kokole
    KYMA, Trieste, Italy
  • V.A. Goryashko, M. Jacewicz, R.J.M.Y. Ruber
    Uppsala University, Uppsala, Sweden
  • X.J.A. Janssen, J.M.A. Priem
    VDL ETG, Eindhoven, The Netherlands
  • A. Latina, X. Liu, C. Rossi, D. Schulte, S. Stapnes, X.W. Wu, W. Wuensch
    CERN, Geneva, Switzerland
  • O.J. Luiten, P.H.A. Mutsaers, X.F.D. Stragier
    TUE, Eindhoven, The Netherlands
  • J. Marcos, E. Marín, R. Muñoz Horta, F. Pérez
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • G. Taylor
    The University of Melbourne, Melbourne, Victoria, Australia
 
  Funding: This project has received funding from the European Union’s Horizon2020 research and innovation programme under grant agreement No 777431
The H2020 CompactLight Project (www. CompactLight.eu) aims at designing the next generation of compact X-rays Free-Electron Lasers, relying on very high gradient accelerating structures (X-band, 12 GHz), the most advanced concepts for bright electron photo injectors, and innovative compact short-period undulators. Compared to existing facilities, the proposed facility will benefit from a lower electron beam energy, due to the enhanced undulators performance, and will be significantly more compact, with a smaller footprint,  as a consequence of the lower energy and the high-gradient X-band structures. In addition, the whole infrastructure will also have a lower electrical power demand as well as lower construction and running costs.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB032  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB033 Fixed-gap Undulators for Elettra and FERMI undulator, polarization, FEL, operation 1760
 
  • B. Diviacco, R. Bracco, D. Millo
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  In the context of an R&D program on alternative undulator schemes, two fixed-gap, linearly polarised, adjustable-phase undulators (APUs) were built and successfully tested, the first on the FERMI free electron laser, the second on the Elettra storage ring. The latter is now in regular operation for the ALOISA surface science beam line. As a further elaboration on the fixed-gap concept, two elliptically polarised undulators (EPUs) are now being developed for FERMI and for Elettra. We have also started the construction of a double period APU providing an extended tuning range to the TwinMic soft X-Ray microscopy beam line. We present here the main design and construction aspects of the new undulators under development.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB033  
About • paper received ※ 09 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB035 Stimulated Emission of THz Coherent Diffraction Radiation in an Optical Cavity by a Multibunch Electron Beam cavity, experiment, radiation, resonance 1763
 
  • Y. Honda, A. Aryshev, R. Kato, T. Miyajima, T. Obina, M. Shimada, R. Takai, T. Uchiyama, N. Yamamoto
    KEK, Ibaraki, Japan
 
  Funding: JSPS KAKENHI
Accelerator-based terahertz (THz) radiation has been expected to realize a high-power broad-band source. Employing a low-emittance and short-bunch electron beam at a high repetition rate, a scheme to resonantly excite optical cavity modes of THz spectrum range via coherent diffraction radiation has been proposed. The confocal cavity design is the special case that resonance conditions of all the eigen modes coincide, resulting in realizing broad-band excitation. But in general cases of non-confocal cavities, the resonance condition depends on the mode, and the resonance peak becomes wide and weak. We performed an experiment with a non-confocal cavity as a follow-up experiment of that we have done with a confocal cavity. The result confirmed that the confocal design is the key for a broad-band source.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB035  
About • paper received ※ 26 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB038 Characteristics of Polarized Coherent Radiation in Thz Region From a Crossed-Undulator undulator, radiation, polarization, experiment 1769
 
  • H. Saito, H. Hama, F. Hinode, K. Kanomata, S. Kashiwagi, S. Miura, N. M. Morita, T. Muto, I. Nagasawa, K. Nanbu, S. Ninomiya, K. Takahashi, H. Yamada
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
 
  A variable polarized THz light source using a crossed-undulator configuration has been developed at Research Center for Electron Photon Science (ELPH), Tohoku University. It consists of two planar undulators of which deflecting planes cross at right angles and a phase shifter for phase adjustment. Polarization of the crossed-undulator has observation angle dependence due to that of radiation wavelength and optical path length difference between two radiations. That limits an angular range maintaining the identical polarization state. Assuming undulator parameters for our experiment (a fundamental frequency 1.9 THz and a number of periods seven) degree of circular polarization larger than 0.9 can be obtained only in the range of 2.2 mrad, i. e. 13% of the radiation angular spread.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB038  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB039 Research of Coherent Edge Radiation Generated by Electron Beams Oscillating Free-Electron Lasers FEL, radiation, cavity, experiment 1772
 
  • N. Sei, H. Ogawa
    AIST, Tsukuba, Ibaraki, Japan
  • K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, Y. Sumitomo, Y. Takahashi, T. Tanaka
    LEBRA, Funabashi, Japan
  • H. Ohgaki, H. Zen
    Kyoto University, Kyoto, Japan
 
  Funding: JSPS KAKENHI Grant Number JP16H03912
We have studied far-infrared coherent radiation with an S-band linac at Laboratory for Electron Beam Research and Application (LEBRA) at Nihon University. We have already developed a couple of terahertz-wave sources based on coherent synchrotron radiation and coherent transition radiation*, which have been applied to spectroscopic research**. Moreover, we developed coherent edge radiation (CER) at the downstream bending magnets in the FEL sections. Because the edge radiation has an annular shape distribution characterized by the asymmetric first-order Laguerre-Gaussian mode, the CER can be extracted from an optical cavity of the FEL system without a diffraction loss of the FEL beam***. The root-mean-squared bunch length of the electron beam was evaulated by measuring the CER spectra, which was about the same level as the FEL micropulse width. Although the infrared FELs at LEBRA had a long slippage length, the CER intensity can be a guidepost enhancing the FEL power because of the existence of their correlation. In this presentation, the characteristics of the CER including correlation between the CER and the FEL will be reported.
* N. Sei et al., Jpn. J. Appl. Phys. 56, (2017) 032401.
** N. Sei et al., J. Opt. Soc. Am. B, 31, (2014) 2150.
*** N. Sei et al., Phys. Lett. A in press.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB039  
About • paper received ※ 19 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB040 Development of Coherent Terahertz Wave Sources and Transport Systems at LEBRA Linac FEL, linac, radiation, vacuum 1775
 
  • T. Sakai, K. Hayakawa, Y. Hayakawa, K. Nogami, Y. Sumitomo, T. Tanaka
    LEBRA, Funabashi, Japan
  • H. Ogawa, N. Sei
    AIST, Tsukuba, Ibaraki, Japan
 
  Funding: This work was supported by JSPS KAKENHI (Grant-in-Aid for Young Scientists (B)) Grant Number JP16K17539 and JP16H03912.
Development of a 125 MeV S-band electron linac for the generation of Free Electron Laser (FEL), Parametric X-ray Radiation (PXR) and coherent terahertz waves (THz waves) has been underway at LEBRA of Nihon University as a joint research with KEK and National Institute of Advanced Industrial Science and Technology (AIST). The high power coherent transition radiation (CTR), coherent edge radiation (CER) and the coherent synchrotron radiation (CSR) wave sources development has been carried out since 2011 at LEBRA. The transport systems of the each THz wave were installed in the vacuum chamber on the downstream side of the 45 degrees bending magnet of the PXR and FEL beam-line. In particular, a CER of the generated the FEL beam line can also be guided without disturbing the FEL oscillations. Additionally, a part of the mirror of the transport optical system is constructed using Indium Tin Oxide (ITO) mirror with the optimized for the transport of the THz wave. In this report, construction of the THz transport beam lines and the property of the THz lights are discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB040  
About • paper received ※ 19 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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TUPRB041 Simulation of Short-Pulse Generation from a Dynamically Detuned IR-FEL Oscillator and Pulse Stacking at an External Cavity FEL, cavity, simulation, radiation 1778
 
  • Y. Sumitomo, Y. Hayakawa, T. Sakai
    LEBRA, Funabashi, Japan
  • R. Hajima
    QST, Tokai, Japan
 
  Funding: Q-LEAP program supported by Ministry of Education, Culture, Sports, Science and Technology, Japan
At the LEBRA facility of Nihon U., we have an IR-FEL oscillator to generate radiations in the range of wavelengths 1-6 um for various experiments. A research program has been established to explore the application of the IR-FEL to generate attosecond UV and X-ray pulses through the high harmonic generation (HHG) in noble gases, where the IR-FEL pulses must have a high-peak power and a short-pulse duration. The property of generated FEL pulse is affected by the cavity length detuning of FEL oscillator as well as the small signal gain and the cavity loss. The operation at a small- or zero-detuning length is necessary to generate a FEL pulse shorter than the bunch length, although it requires a long macro-pulse to reach the saturation. For the short FEL pulse generation within a limited macro-pulse length at the LEBRA LINAC, we apply a dynamical modulation to the electron bunch repetition, that is equivalent to a dynamical detuning of the FEL cavity length. We illustrate the potential performance of the IR-FEL with the dynamical detuning by time-dependent 3D FEL simulations. We also evaluate the enhancement of the FEL pulses by an external cavity stacking for the sake of the HHG application.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB041  
About • paper received ※ 29 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB042 Design Study of Nonlinear Energy Chirp Correction Using Sextupole Magnets at the Soft X-Ray Free-Electron Laser Beamline of SACLA sextupole, FEL, linac, cavity 1782
 
  • K. Togawa, T. Hara, H. Tanaka
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
 
  At the x-ray free-electron laser (FEL) facility, SACLA, a soft x-ray FEL beamline (SCSS+) is driven by a dedicated 800-MeV electron accelerator and being operated in parallel with two hard x-ray FEL beamlines. Responding to the demands of short laser pulses from users, a nonlinearity correction system using sextupole magnets is under consideration to obtain shorter electron bunches. Since the frequency of the SCSS+ injector is S-band, the nonlinearity correction of a bunch compression process using a harmonic correction cavity is not so efficient as the SACLA injector, whose frequency of the injector is L-band. Instead of a complex and costly correction cavity system, the sextupole magnets are simply installed in a dispersive section of the first bunch compressor chicane. In this report, we will present the basic design concept and some detail studies of the nonlinear correction.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB042  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB045 Stimulated Excitation by Seeding With Cherenkov Radiation in an Optical Cavity radiation, cavity, GUI, ion-source 1785
 
  • S.M. Jiang, Z.G. He, Q.K. Jia, W.W. Li, L. Wang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  • D. He
    Anhui Electrical Engineering Professional Technique College, Hefei, People’s Republic of China
 
  Funding: Work supported by National Foundation of Natural Sciences of China (11775216, 11705198, 11675178), and Fundamental Research Funds for the Central Universities (WK2310000061).
By seeding with narrow-band Cherenkov radiation from a dielectric loaded waveguide(DLW), stimulated excitation in an optical cavity is presented. The evolution and energy loss of the field oscillating in optical cavity is analysed by the theoretical and numerical calculation. The results show that the high order TM modes of the Cherenkov radiation can be better preserved after a large number of roundtrips in the optical cavity and this scheme offers a potential method of realizing high power Terahertz radiation source in a compact facility.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB045  
About • paper received ※ 30 April 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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TUPRB046 Second Order Intensity Correlation and Statistical Properties of a Soft X-Ray Free Electron Laser laser, FEL, radiation, simulation 1788
 
  • C.L. Li, J.H. Chen, Z.C. Chen, X.T. Wang, H.L. Wu
    SINAP, Shanghai, People’s Republic of China
  • B. Liu, T. Liu
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
 
  High degree of transverse field coherence is one of the unique properties of an FEL compared with a 3rd gen-eration storage ring light source. As a result, the FEL advances the development of innovative research and technology that was not previously feasible. A truly coherent source should be coherent in all orders de-scribed from the intensity correlation functions. In this paper, second order intensity correlation of FEL radia-tion is investigated based on the Hanbury Brown-Twiss intensity correlation method. The statistical properties of radiation produced from SASE was also investigated and compared with the statistical proper-ties of a phase-locked laser. The results show that the statistical properties of a SASE mode behave as a cha-otic source, which is significantly different from the properties of a phase-locked laser beam.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB046  
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB050 The Optical Resonator of CTFEL for Range of 1 to 2 THz FEL, GUI, radiation, coupling 1795
 
  • X.J. Shu, Y.H. Dou
    Institute of Applied Physics and Computational Mathematics, People’s Republic of China
 
  A high power THz free electron laser (FEL) facility is under construction at China Academy of Engineering Physics (CTFEL). The radiation frequency of the FEL facility will be tuned in range of 1~3 THz and the average output power is about 10 W. The system mainly consists of a GaAs photoemission DC gun, superconductor accelerator, hybrid wiggler, optical cavity. The first lasing is obtained on Aug. 29, 2017, and CTFEL is operated in range of 2-4THz, but cannot lasing at the frequency below 1.8 THz. The optical resonator of CTFEL must be optimized to ensure lasing in range of 1 to 2 THz.. The lasing strongly depends on the performance of the optical resonator including output efficiency, gain and round-trip loss. The optical resonator consists of metal-coated reflect mirror, the centre-hole output mirror, waveguide. The influence of waveguide on the quality of optical cavity is evaluated by the 3D OSIFEL code. The waveguide size and output hole radius is optimized to different frequencies between 1 THz to 2 THz.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB050  
About • paper received ※ 13 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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TUPRB052 The Mini-Period Permanent Magnet Staggered Undulator for Compact X-Ray Free Electron Laser undulator, FEL, permanent-magnet, radiation 1797
 
  • L.G. Yan, D.R. Deng, J. Wang
    CAEP/IAE, Mianyang, Sichuan, People’s Republic of China
 
  Funding: Work supported by National Natural Science Foundation of China under grant of 11505174, 11505173 and 11605190.
Miniaturization of X-ray free electron laser requires reduction of undulator period length. In this proceeding, a mini-period permanent magnet staggered undulator was proposed, which is free of superconducting solenoid and thus has advantages of easy-manufacture and low-cost. After optimization, it can generate periodic field of peak field 0.71 T with period length 10 mm and pole gap 2 mm, which has been verified on a prototype. Combined with X-band linac, the length of 1 nm XFEL facility using the permanent magnet staggered undulator can be confined within 44 m.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB052  
About • paper received ※ 30 April 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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TUPRB053 Injector Physics Design at SHINE laser, feedback, FEL, emittance 1801
 
  • Z. Wang, M.H. Zhao
    SINAP, Shanghai, People’s Republic of China
  • Q. Gu
    SSRF, Shanghai, People’s Republic of China
  • G.L. Wang
    DICP, Dalian, People’s Republic of China
 
  As a CW x-ray free electron laser facility, SHINE has a high requirement on the electron beam quality in the linac, as well as in the injector. SHINE injector consists of a 162.5 MHz normal conducting VHF gun, a NC 1.3 GHz RF buncher, a one cavity SC cryomodule, an eight cavity SC cryomodule and 3 solenoids along the injector layout. Some beam diagnostic element are inserted in the layout as well. In this paper, we try to introduce the injector physics design at shine.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB053  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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TUPRB054 The Beam-Based Alignment Simulation and Preliminary Experiment at SXFEL FEL, alignment, quadrupole, undulator 1804
 
  • L. Zeng, H.X. Deng, C. Feng, D. Gu, B. Liu, Z.T. Zhao
    SINAP, Shanghai, People’s Republic of China
  • G.L. Wang
    DICP, Dalian, People’s Republic of China
 
  The Shanghai soft X-ray Free-electron Laser facility (SXFEL) is now serving as an experimental platform for fundamental free-electron laser (FEL) principle tests. The machine puts very tight tolerance on the straightness of the electron beam orbit. It is hard to achieve the required trajectory due to the off-axis field of the misaligned quadrupoles and undulator segments especially for the SXFEL driven by low energy linac (840MeV). This tight requirement on electron beam straightness can only be met through the beam-based alignment (BBA) technology which achieved great success at LCLS, PAL-XFEL, European-XFEL and SCALA with high electron beam energies. But there has been no report about satisfactory BBA experiment results on soft X-ray FEL facility driven by relatively low energy linacs (on the order of 2 GeV or less) up to now. Here, we report the simulation results and preparatory experiment progress of the BBA at SXFEL with the method of dispersion-free steering (DFS). The experiment results show some improvements of the electron beam orbit and the phenomenon of the dispersion-free. The entire BBA experiment and a feedback system of electron beam trajectory may also be included.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB054  
About • paper received ※ 18 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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TUPRB057 THz-Pump and UV-Probe Scheme Based on Storage Ring laser, radiation, bunching, storage-ring 1811
 
  • H.R. Zhang, Z.G. He, S.M. Jiang, W.X. Wang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  We propose a THz-pump and UV-probe scheme based on storage ring for ultra-fast dynamics experiment. In which, two sequential laser pulses, one of which has a periodic intensity envelope, simultaneously interact with different parts of the long electron beam in a modulator; after a chicane, the part that interacts with the periodic pulse will bunch at THz domain and radiate through a bend magnet, another based on high-harmonic generation will bunch at UV domain and radiate at a radiator. The electron beam can be utilized circularly in the storage ring, which will increase its average power. The feasibility of this THz-pump and UV-probe scheme is verified in both theory and simulation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB057  
About • paper received ※ 30 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB061 Seeded Free-Electron Lasers Driven by a Transverse Tilted Electron Bunch laser, FEL, undulator, radiation 1817
 
  • Z. Zhao, Q.K. Jia, H.T. Li
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  Funding: Work supported by the China Postdoctoral Science Foundation (No. 2018M642542) and the Fundamental Research Funds for the Central Universities (WK2310000081).
A transverse tilt of the electron bunch is normally unwanted in free-electron laser (FEL) since only a portion of the bunch can contribute to the FEL radiation. However, the recent researches demonstrate that the tilted bunch can be used to generate FEL with some special features. In this work we investigate the generation of a large tilt of the bunch by using a corrugated structure and a dogleg separately. Based on the tilted bunch, the creation of ultra-short pulse and multi-color pulses are demonstrated in high-gain harmonic generation (HGHG) FEL.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB061  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB062 Coherence Time Characterization for Self-Amplified Spontaneous Emission Free-Electron Lasers FEL, laser, free-electron-laser, radiation 1820
 
  • G. Zhou, Y. Jiao, J.Q. Wang
    IHEP, Beijing, People’s Republic of China
  • T.O. Raubenheimer, J. Wu
    SLAC, Menlo Park, California, USA
  • C.-Y. Tsai
    HUST, Wuhan, People’s Republic of China
  • C. Yang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  One of the key challenges in scientific researches based on free-electron lasers (FELs) is the characterization of the coherence time of the ultra-fast hard x-ray pulse, which fundamentally influences the interaction process between x-ray and materials. Conventional optical methods, based on autocorrelation, is very difficult to realize due to the lack of mirrors. Here, we experimentally demonstrate a conceptually new coherence time characterization method and a coherence time of 174.7 attoseonds has been measured for the 6.92 keV FEL pulses at Linac Coherent Light Source. In our experiment, a phase shifter is adopted to control the cross-correlation between x-ray and microbunched electrons. This approach provides critical temporal coherence diagnostics for x-ray FELs, and is decoupled from machine parameters, applicable for any photon energy, radiation brightness, repetition rate and FEL pulse duration, etc.
The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB062  
About • paper received ※ 01 May 2019       paper accepted ※ 28 May 2019       issue date ※ 21 June 2019  
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TUPRB069 Study of FEL Operation Using Collimator without X-band Linearizer in HX Line at PAL-XFEL FEL, operation, linac, simulation 1824
 
  • H. Yang, C.-K. Min, I.H. Nam
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  Funding: This work is supported by MSIP, Korea.
A Hard X-ray (HX) line in PAL-XFEL consists of an e-gun, a Laser Heater (LH), S-band accelerators, an X-band LINearizer (XLIN), three Bunch Compressors (BC), a dog-leg, and an undulator line. It generates 2.5 - 15-keV FEL with over than 1-mJ pulse energy. The XLIN before BC1 is used for linearizing the energy chirp in the longitudinal phase space and provides the flexibility for FEL optimization and operation. However, it causes the instability of FEL by large jitters and drift because of higher frequency. We study the FEL operation without XLIN. The collimator in the center of BC1 is used removing the slices to cause nonlinear compression. We optimize the FEL by short electron bunch with under 30 fs. In this paper, we present details of the optimizing sequence and performance for the FEL operation without XLIN.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB069  
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB070 A Peak Finding Algorithm for FEL Spectra Characterization FEL, bunching, laser, background 1827
 
  • M.A. Pop
    MAX IV Laboratory, Lund University, Lund, Sweden
  • E. Allaria
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  We present a software tool aimed at investigating the spectra of photon sources in order to detect any instabilities in the electron beam that have a clear effect on the spectrum. The method has been developed for FERMI@Elettra but with a general approach on the particularities of FEL machines such as a high repetition frequency and significant shot to shot fluctuations. The software has two operating options: a mode, aimed at online usage, which only detects peaks and their corresponding valleys, offering no information about the peaks themselves; and a more comprehensive mode that fits peak functions (Gaussian, Lorentzian etc…) to the spectrum based on initial guesses of the fitting parameters. The algorithm can provide a collection of simple but valuable variables such as number of peaks, peak separation and ratio between peak heights, as well as more specialized variables like peak width statistics and decomposition of the raw spectrum in basic components.
Project done in collaboration with FERMI@Elettra
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB070  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB071 Considerations on Implementing EEHG with a Strong Linear Chirp bunching, FEL, linac, radiation 1830
 
  • M.A. Pop, S. Werin
    MAX IV Laboratory, Lund University, Lund, Sweden
 
  As the ECHO enabled harmonic generation (EEHG) scheme draws such intense focus from the FEL community, we conduct simulations to evaluate the challenges of implementing said scheme in different FEL layouts. Nonlinear processes such as this require extensive simulations to harmonize all system specific properties like seed lasers and electron beam properties. Along with optimizing the original EEHG scheme* one can consider, for example, altering the seed laser pulse to optimize the bunching for a machine specific chirp. We study the EEHG as a possible seeding method aimed at increasing coherence of the photon beam for the prospective SXL FEL beamline at MAXIV. The particular chirp of the electron beam through the MAXIV LINAC generates some specific requirements in implementing EEHG but may also offer an opportunity for exotic operation modes of this FEL.
* Xiang D. and Stupakov G. Echo-enabled harmonic generation free electron laser 10.1103/PhysRevSTAB.12.030702
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB071  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB074 Start-to-End Simulations of the Compact Light Project Based on an S-Band Injector and an X-Band LINAC lattice, linac, FEL, cavity 1836
 
  • E. Marín, R. Muñoz Horta, F. Pérez
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • A.A. Aksoy
    Ankara University, Accelerator Technologies Institute, Golbasi, Turkey
  • S. Di Mitri
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • A. Latina
    CERN, Geneva, Switzerland
  • S.B. van der Geer
    Pulsar Physics, Eindhoven, The Netherlands
 
  Funding: This project has received funding from the European Union’s Horizon2020 research and innovation programme under grant agreement No 777431
In this paper we report the start-to-end simulation results of one of the options under consideration for the CompactLight Project (XLS). The XLS is a hard X-ray Free Electron Laser under design, using the latest concepts for bright electron photo injectors, very high-gradient X-band structures, and innovative short-period undulators. Presently there exist various tracking codes to conduct the design process. Therefore identifying the most convenient code is of notable importance. This paper compares the tracking codes, Placet and General Particle Tracer, using the XLS lattice based on a S and X-band Injector. The calculation results in terms of beam quality and tracking performance of a full 6-D simulation are presented.
[*] The CompactLight Design Study Project, IPAC2019 proceedings.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB074  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPRB075 Higher Order Mode Spectra Study of 3.9 GHz Superconducting Radio Frequency Cavities for the European XFEL cavity, HOM, simulation, FEL 1840
 
  • L. Shi, S. Reiche
    PSI, Villigen PSI, Switzerland
  • N. Baboi, A.A. Sulimov, E. Vogel, T. Wamsat
    DESY, Hamburg, Germany
  • R.M. Jones, N.Y. Joshi
    UMAN, Manchester, United Kingdom
  • P. Pierini
    ESS, Lund, Sweden
 
  Funding: The work is part of EuCARD2 and was partly funded by the European Commission, GA 312453.
It is important to verify both by simulation and experiments the wakefields in superconducting radio frequency (SRF) cavities, which can degrade the electron beam quality considerably or impose excessive heat load if left undamped. In this paper, we investigate the Higher Order Mode (HOM) spectra of the 3.9 GHz SRF cavities, which are assembled in a cryogenic module and are used to linearize the longitudinal phase space of the electron beam in the injector of the European XFEL. The HOM spectra are significantly different from the ones from a single cavity due to the coupling of the modes amongst cavities. The measurements not only provide direct input for the beam dynamics studies but also for the beam instrumentation utilizing these modes. The mode spectra are also investigated with a number of numerical simulations and the comparison with measurements shows favorable agreement.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB075  
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB076 Free Electron Laser Driven by a High-Energy High-Current Energy-Recovery Linac FEL, radiation, linac, undulator 1844
 
  • F. Zimmermann
    CERN, Geneva, Switzerland
  • H. Aksakal
    KMSIU, Onikisubat / Kahramanmaras, Turkey
  • A.A. Aksoy
    Ankara University, Accelerator Technologies Institute, Golbasi, Turkey
  • Z. Nergiz
    Nigde University, Nigde University Science & Art Faculty, Nigde, Turkey
 
  Funding: This work was supported by the European Commission under the HORIZON 2020 project ARIES, grant agreement no. 730871.
The proposed electron-hadron collider LHeC, based on an energy recovery linac, employs an electron beam of 20 mA current at an energy of tens of GeV. This electron beam could also be used to drive a free electron laser (FEL) operating at sub-Angstrom wavelengths. Here we demonstrate that such FEL would have the potential to provide orders of magnitude higher peak power, peak brilliance and average brilliance, than any other FEL, either existing or proposed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB076  
About • paper received ※ 10 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB086 Four X-ray Pulses within 10 ns at LCLS laser, experiment, FEL, gun 1859
 
  • F.-J. Decker, W.S. Colocho, S.H. Glenzer, A.A. Lutman, A. Miahnahri, D.F. Ratner, J.C. Sheppard, S. Vetter
    SLAC, Menlo Park, California, USA
 
  The X-Ray FEL at SLAC or LCLS delivers typically one bunch at the time. Different schemes of two bunches have been developed: Two bucket, Twin bunch, split undulator, and fresh slice. Here we discuss a four bunch or even eight bunch setup, separated by 2 RF buckets or 0.7 ns. . The demand comes from MEC (Matter in Extreme Conditions) experiments, where high-power laser beams with Joule-class energies create impulsive pressure waves compressing materials on time scales of the order of ns. Eight snapshots for a single experiment will allow measuring the compression history, structural phase transitions into new high-pressure material states, and have the potential to resolve the transition kinetics time scales.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB086  
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB088 Generation of High Peak Power Hard X-Rays at LCLS-II with Double Bunch Self-seeding FEL, photon, laser, undulator 1863
 
  • A. Halavanau, F.-J. Decker, Y. Ding, C. Emma, Z. Huang, J. Krzywiński, A.A. Lutman, G. Marcus, C. Pellegrini, D. Zhu
    SLAC, Menlo Park, California, USA
 
  Funding: This work was supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515.
We propose to use existing LCLS copper S-band linac double bunch infrastructure to significantly improve LCLS-II hard X-ray performance. In our setup, we use the first bunch to generate a strong seeding X-ray signal, and the second bunch, initially traveling off-axis, to interact with the seed in the amplifier undulator and generate a near TW, 15 fs duration X-ray pulse in the 4 to 8 keV photon energy range. We investigate, via numerical simulations, the required transverse beam dynamics and the four crystals X-ray monochromator to be added to the existing LCLS-II beamline and discuss the final properties of the hard X-ray pulses and their potential application in high intensity, high-field physics experiments, including QED above the Schwinger critical field.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB088  
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB089 Undulator Radiation Generated by a Single Electron undulator, photon, experiment, radiation 1867
 
  • A. Halavanau, Z. Huang, C. Pellegrini, T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
  • I. Lobach
    University of Chicago, Chicago, Illinois, USA
  • S. Nagaitsev
    Fermilab, Batavia, Illinois, USA
  • D. Seipt
    HZDR, Dresden, Germany
 
  Funding: This work was supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515.
The facilities providing single electron beams are currently being commissioned at Fermilab and will be at SLAC. Recently, Fermilab’s IOTA ring routinely demonstrated circulation of a single electron at 100 MeV beam energy. Alternatively, SLAC is working on constructing LCLS-II an X-ray FEL driven by a 4 GeV SRF linac. A parasitic beamline, S30XL, is planned that will extract 4 GeV dark current from between the primary LCLS-II electron bunches. The dark current will be delivered to End Station A and can work independently of LCLS-II experiments. The dark current will be bunched at a frequency of 46 MHz while extracted current varied from single electrons to 10’s of nA. In the present paper, we estimate the feasibility of propagating single electron beams through a conventional undulator, placed in the IOTA and S30XL beamlines. We explore the possible observable effects and experimental parameters range. In addition, we focus on potential applications of such beams in systems for high fidelity quantum measurements.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB089  
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB092 Cherenkov Radiation in Periodic Wire Medium Formed by Transversely Modulated Electron Beams radiation, laser, cathode, experiment 1878
 
  • A. Halavanau
    SLAC, Menlo Park, California, USA
  • A.I. Benediktovitch
    EuXFEL, Hamburg, Germany
  • E.A. Gurnevich
    Belarussian State University, Scientific Research Institute of Nuclear Problems, Minsk, Belarus
 
  Funding: Work was supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515.
We investigate the properties of Cherenkov, quasi-Cherenkov (parametric) and diffraction radiation generated in the periodic conducting wire medium by transversely modulated electron beams. Such beams were recently obtained at Argonne Wakefield Accelerator (AWA) facility using microlens array (MLA) laser shaping technique. We consider in details the case of one dimensional periodic tungsten wire structure and transverse electron beamlets separation of mm scale. We look at possible enhancements of the radiation field due to transverse periodicity of the electron beam.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB092  
About • paper received ※ 14 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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TUPRB095 Superconducting Undulators for the Advanced Photon Source Upgrade undulator, vacuum, photon, operation 1884
 
  • M. Kasa, E.R. Anliker, J.D. Fuerst, Q.B. Hasse, Y. Ivanyushenkov, I. Kesgin, Y. Shiroyanagi, E. Trakhtenberg
    ANL, Argonne, Illinois, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The magnetic devices group at the Advanced Photon Source (APS) is in the process of designing and developing superconducting undulators (SCUs) for the APS upgrade. While similar in some aspects to previous SCU systems currently in operation at the existing APS, the new SCU systems will include two undulators installed in one cryostat which occupies an entire straight section of the storage ring. Straight sections containing planar undulators will either be configured as ’in-line’, where the two undulators behave as one source, or canted, where the two undulators are operated independently. Also under development is a superconducting arbitrary polarizing emitter (SCAPE) which can produce planar, elliptical, and helical undulator fields.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB095  
About • paper received ※ 14 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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TUPRB096 Test of an X-ray Cavity using Double-Bunches from the LCLS Cu-Linac FEL, cavity, laser, free-electron-laser 1887
 
  • K.-J. Kim, L. Assoufid, R.R. Lindberg, X. Shi, D. Shu, Yu. Shvyd’ko, M. White
    ANL, Argonne, Illinois, USA
  • F.-J. Decker, Z. Huang, G. Marcus, T.O. Raubenheimer, D. Zhu
    SLAC, Menlo Park, California, USA
 
  Funding: This work is supported by U.S. DOE, Office of Science, Office of BES, under Contract No. DE-AC02-06CH11357 (ANL) and DE-AC02-76SF00515 (SLAC).
We discuss a proposal to test the operation of an X-ray cavity consisting of Bragg reflectors. The test will con-stitute a major step demonstrating the feasibility of either an X-ray regenerative amplifier FEL or an X-ray FEL Oscillator. These cavity-based X-ray FELs will provide the full temporal coherence lacking in the SA-SE FELs. An X-ray cavity of rectangular path will be constructed around the first seven LCLS-II undulator units. The Cu-linac will produce a pair of electron bunches separated by the cavity-round-trip distance during each linac cycle. The X-ray pulse produced by the first bunch is deflected into the cavity and returns to the undulator where it is amplified due to the presence of the second bunch. The key challenges are: the preci-sion of the cavity mechanical construction, the quality of the diamond crystals, and the electron beam stability. When the LCLS-II super-conducting linac becomes available, the cavity can then be used for high-repetition rate studies of the X-ray RAFEL and XFELO concepts.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB096  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB097 Recent Progress on the Design of Normal Conducting APEX-II VHF CW Electron Gun cavity, gun, cathode, brightness 1891
 
  • D. Li, H.Q. Feng, D. Filippetto, M.J. Johnson, A.R. Lambert, T.H. Luo, C.E. Mitchell, J. Qiang, F. Sannibale, J.W. Staples, S.P. Virostek, R.P. Wells
    LBNL, Berkeley, California, USA
  • H.Q. Feng
    TUB, Beijing, People’s Republic of China
 
  Funding: Director of Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
We report recent progress on the design of a normal conducting CW electron gun, APEX-II (Advanced Photo-injector EXperiment-II) at Lawrence Berkeley National Laboratory. APEX-II is an upgrade of the successful APEX gun and the LCLS-II (Linac Coherent Light Source-II) injector, aiming at applications for Free electron laser (FEL) such as LCLS-II High Energy upgrade, UED (Ultrafast Electron Diffraction) and UEM (Ultrafast Electron Microscopy). The APEX-II adopted a two-cell cavity design with resonant frequency of 162.5 MHz. The APEX-II gun is targeting to achieve exceeding 30 MV/m of launch gradient at the cathode and output energy above 1.5 MeV with transverse emittance of 0.1 um at 100 pC. Advanced MOGA optimization technique has been used for both the RF cavity design and extensive beam dynamics studies using APEX-like and LCLS-II like injector layout. Detailed RF designs, beam dynamics studies, preliminary engineering design and FEA analysis will be presented, with cavity features that were demonstrated to be crucial in the operation of the APEX gun.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB097  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB102 Numerical Study of the Delta II Polarizing Undulator for LCLS II undulator, simulation, polarization, laser 1899
 
  • K. Tian, H.-D. Nuhn
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by US Department of Energy Contract DE-AC03-76SF00515.
The Delta undulator has been operated successfully in LCLS with full control of the polarization mode and K value of the device. In LCLS II, a new Delta II undulator will be based on a similar design but with some differences. In this paper, we will present numerical simulation results that provide guidance to choose the geometric shape of the magnet poles and define the required tolerance for assembling the undulator magnets.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB102  
About • paper received ※ 10 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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TUPRB106 Status of the Superconducting Soft X-Ray Free-Electron Laser User Facility Flash at DESY experiment, laser, operation, undulator 1909
 
  • J. Rönsch-Schulenburg, K. Honkavaara, M. Kuhlmann, S. Schreiber, R. Treusch, M. Vogt
    DESY, Hamburg, Germany
 
  FLASH, the free electron laser user facility at DESY (Hamburg, Germany), delivers high brilliance XUV and soft x-ray FEL radiation to photon experiments with different parameters at two undulator beamlines simultaneously. FLASH’s superconducting linac can produce bunch trains of up to 800 bunches within a 0.8 ms RF flat top at a repetition rate of 10 Hz. In standard operation during 2018, FLASH supplied up to 500 bunches in two bunch trains with independent fill patterns and compression schemes to each of the two beamlines. In 2018 first successful plasma accelerating experiments could be reported by the FLASHForward plasma wakefield acceleration experiment situated in a third beamline. We report on the highlights of FLASH operation in 2018/2019.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB106  
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPRB108 Mechanical Design of a Dielectric Wakefield Dechirper System for CLARA vacuum, FEL, wakefield, alignment 1912
 
  • M. Colling, D.J. Dunning, B.D. Fell, T.H. Pacey, Y.M. Saveliev
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  STFC Daresbury Laboratory are developing a compact electron beam energy dechirper system, based on dielectric wakefield structure, for the on-site electron accelerator CLARA (Compact Linear Accelerator for Research and Applications). CLARA will be an experimental free electron laser (FEL) facility operating at 250MeV and will be a test bed for a variety of novel FEL schemes. The dechirper dielectric quartz plates will induce wakefields within the structure which can remove the beam chirp that is initially introduced to compress the electron bunch longitudinally. Removing or adjusting the amount of chirp enables researchers to reduce or adjust the bunch energy/momentum spread, expanding the FEL capabilities. The attachment and alignment of the quartz plates present numerous mechanical design challenges that require high precision manufacturing and quartz plate positioning via fiducialisation. This paper will review the dechirper specifications, the chosen design solutions, measured mechanical performance, and the expected effect of the dechirper on CLARA FEL operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB108  
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB112 JLEIC: A High Luminosity Polarized Electron-Ion Collider at Jefferson Lab collider, luminosity, proton, emittance 1916
 
  • Y. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The recent National Academies of Science Review concluded the science questions that could be answered by an electron-ion collider are significant to advancing our understanding of the atomic nuclei that make up all visible matter in the universe. To meet this science need, a high luminosity polarized electron-ion collider (JLEIC) was envisioned at Jefferson Lab, based on the existing CEBAF recirculated SRF electron linac. Over the past 16 years, Jefferson Lab has been actively engaged in the design study and accelerator R&D for JLEIC, a comprehensive Pre-Conceptual Design Report has been completed recently. The JLEIC baseline design has also been continuously optimized including extending the CM energy to 100 GeV. In this paper, we present a summary of the JLEIC baseline design and also briefly discuss the accelerator R&D.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB112  
About • paper received ※ 07 June 2019       paper accepted ※ 07 June 2019       issue date ※ 21 June 2019  
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TUPRB113 Dynamic Aperture of JLEIC Electron Collider Ring with Errors and Correction alignment, multipole, optics, quadrupole 1920
 
  • Y.M. Nosochkov, Y. Cai
    SLAC, Menlo Park, California, USA
  • F. Lin, V.S. Morozov, Y. Zhang
    JLab, Newport News, Virginia, USA
 
  Funding: * This work is supported by the U.S. Department of Energy, Office of Science, and Office of Nuclear Physics under Contracts DE-AC05-06OR23177, DE-AC02-06CH11357, and DE-AC02-76SF00515.
Design of the Jefferson Lab Electron-Ion Collider (JLEIC) includes low-beta Interaction Region (IR) and spin rotator optics for high luminosity and polarization. Magnet errors, especially in the high-beta final focus quadrupoles, result in optics perturbations which need to be corrected in order to attain sufficient dynamic aperture (DA). We present design of orbit correction system for the electron ring and evaluate its performance. The DA is then studied including misalignment, magnet strength errors, non-linear field errors, and corrections.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB113  
About • paper received ※ 16 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPTS004 Development of a Penning Ion Source Test Stand for Production of Alpha Particles ion-source, cathode, plasma, cyclotron 1932
 
  • N. Savard
    UBC, Vancouver, B.C., Canada
  • M.P. Dehnel, P.T. Jackle, S.V. Melanson, D.E. Potkins, J.E. Theroux
    D-Pace, Nelson, British Columbia, Canada
  • G. M. Marcoux
    Carleton University, College of Natural Sciences, Ottawa, Ontario, Canada
 
  Medical cyclotron manufacturers are seeking less-costly and more compact ion sources than Electron Cyclotron Resonance Ion Sources (ECRIS) for alpha particle production, which are currently capable of generating beam currents up to 2 mA at energies of 30 keV for axial injection into these cyclotrons. Penning Ion Sources by comparison are relatively old technologies mostly used for cheap singly-charged ion production. However, these ion sources have been used in the past for high-current multiply-charged state ion production of heavy ions up to a few mA of current, and are much smaller, cheaper, and less complex than ECRISs. Therefore, we are developing a Penning Ion source test stand to produce high-current alpha-particles for medical cyclotrons. This requires designs and simulations of all the primary components of the ion source. This system will be used to fully characterize the output beam current and internal plasma properties as a function of varying gas pressure, ion source geometries, magnetic field strength, arc voltage/current, and material properties. The result will be a source optimized for maximum alpha particle beam currents, to be used as a prototype for a commercial Penning Ion Source.
* J. Bennet. A Review of PIG Sources for Multiply Charged Heavy Ions. IEEE Transactions on Nuclear Science, 1972.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS004  
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPTS009 Operating the SNS RF H Ion Source with a 10% Duty Factor ion-source, plasma, neutron, LEBT 1951
 
  • M.P. Stockli, M.E. Clemmer, S.M. Cousineau, B. Han, T.A. Justice, Y.W. Kang, S.N. Murray, T.R. Pennisi, C. Piller, R.F. Welton
    ORNL, Oak Ridge, Tennessee, USA
  • I.N. Draganic, R.W. Garnett, D. Kleinjan, G. Rouleau
    LANL, Los Alamos, New Mexico, USA
  • V.G. Dudnikov
    Muons, Inc, Illinois, USA
  • C. Stinson
    ORNL RAD, Oak Ridge, Tennessee, USA
 
  Funding: This work was performed at Oak Ridge National Laboratory under contract DE-AC05-00OR22725 and at Los Alamos National Laboratory under contract DE-AC52-06NA25396 for the U.S. Department of Energy.
The SNS (Spallation Neutron Source) (radio-frequency) RF-driven, H ion source injects ~50 mA of H beam into the SNS accelerator at 60 Hz with a 6% duty factor. It injects up to 7 A·hrs of H ions during its ~14-week service cycles, which is an unprecedented lifetime for small-emittance, high-current pulsed H ion sources. The SNS source also features unprecedented low cesium consumption and can be installed and started up in <10 h. Presently, the LANSCE (Los Alamos Neutron Science CEnter) accelerator complex in Los Alamos is fed by a filament-driven, biased converter-type H source that operates with a high plasma duty factor of 10%. It needs to be replaced every 4 weeks with a ~4 day startup phase. The measured negative beam current of 16-18 mA falls below the desired 21 mA acceptance of LANSCE’s accelerator especially since the beam contains several mA of electrons. LANSCE and SNS are exploring the possibility of using the SNS RF H source at LANSCE to increase the H beam current and the ion source lifetime while decreasing the startup time. For this purpose, the SNS H source has been tested at a 10% duty factor by operating it at 120 Hz with 840 µs plasma pulses generated with ~30 kW of 2 MHz RF power, and extracting ~25 mA around-the-clock for 28 days. This, and additional tests and other considerations are discussed in this paper.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS009  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS011 Vacuum Lifetime and Surface Charge Limit Investigations Concerning High Intensity Spin-polarized Photoinjectors cathode, vacuum, laser, experiment 1954
 
  • S. Friederich, K. Aulenbacher, C. Matejcek
    IKP, Mainz, Germany
  • K. Aulenbacher
    GSI, Darmstadt, Germany
  • K. Aulenbacher
    HIM, Mainz, Germany
 
  Funding: DFG excellence initiative PRISMA+, Bundesministerium für Bildung und Forschung "Verbundforschung FKZ 05K16UMA"
The Small Thermalized Electron Source at Mainz (STEAM) is a dc photoemission source. It is designed to operate at up to 200kV bias voltage with an accelerating field of up to 5 MV/m at the cathode surface. In several experiments, the properties of GaAs operating under the conditions of spin-polarized photoemission were investigated. Its performance, quantum efficiency lifetime and surface charge limit observations for bulk-GaAs will be discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS011  
About • paper received ※ 29 April 2019       paper accepted ※ 28 May 2019       issue date ※ 21 June 2019  
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TUPTS013 Characterization of an Electron Gun Test Setup Based on Multipacting cavity, cathode, multipactoring, gun 1961
 
  • C. Henkel, W. Hillert, V. Miltchev
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • K. Flöttmann
    DESY, Hamburg, Germany
 
  A multipacting electron gun (MEG) is a micro-pulse electron source, based on secondary electron emission in a resonant microwave cavity structure, for the generation of low emittance electron bunches in continuous wave operation. Based on numerical simulations, an experimental test setup for low-energy electron beams at 3 GHz has been established. In this contribution we show a detailed description and characterization of the RF test stand, supported by first results on charge collection measurements of the output current with respect to important operational parameters like power transmission and modifiable mechanical dimensions in the assembly of the experiment. This is a milestone in the development of a MEG setup for higher energetic electron beams and subsequent investigation of essential beam characteristics like emittance and energy distribution for the optimization with regard to best possible beam quality and future fields of application.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS013  
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPTS014 SINGLE SHOT CATHODE TRANSVERSE MOMENTUM IMAGING IN PHOTOINJECTORS cathode, solenoid, emittance, simulation 1964
 
  • P.W. Huang, Y. Chen, J.D. Good, M. Groß, I.I. Isaev, C. Koschitzki, M. Krasilnikov, S. Lal, X. Li, O. Lishilin, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, H. Shaker, F. Stephan, G. Vashchenko
    DESY Zeuthen, Zeuthen, Germany
  • D. Filippetto, F. Sannibale
    LBNL, Berkeley, California, USA
  • C.-X. Tang
    TUB, Beijing, People’s Republic of China
  • W. Wan
    ShanghaiTech University, Shanghai, People’s Republic of China
 
  In state of the art photoinjector electron sources, cathode performance determines the lower limit of achievable beam emittance. Measuring the thermal emittance at the photocathodes in electron guns is of vital importance for improving the injectors. Traditional methods, like solenoid scan, pepper-pot, need multi-shots and are time-consuming, therefore suffer from machine stability. Here we propose a new method, named cathode transverse momentum imaging. By tuning the gun solenoid focusing, the electrons’ transverse momentum at the cathode is imaged to a downstream screen, which enables a single shot measurement. Several experiments have been done at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) with a Cs2Te cathode. Measurements of cathode transverse momentum, the corresponding spectra, cathode transverse momentum map and its correlation with surface electric field are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS014  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPTS015 Design Steps Towards an Electron Source for Ultrafast Electron Diffraction at DELTA laser, cavity, gun, space-charge 1968
 
  • D. Krieg, S. Khan
    DELTA, Dortmund, Germany
  • T.J. Albert, K. Sokolowski-Tinten
    Universität Duisburg-Essen, Duisburg, Germany
 
  Funding: MERCUR Pr-2017-0002
Ultrafast electron diffraction (UED) is a pump-probe technique to explore the structural dynamics of matter, combining sub-angstrom De-Broglie wavelength of electrons with femtosecond time resolution. UED experiments require ultrashort laser pulses to pump a sample, electron bunches with small emittance and ultrashort length to analyze the state of the sample and excellent control of the delay between them. Electrons accelerated to a few MeV in a photocathode gun offer significant advantages compared to keV electrons from electrostatic electron sources regarding emittance, bunch length and, due to the reduction of space charge effects, bunch charge. Furthermore, thicker samples and hence a wider range of possible materials are enabled by the longer mean free path of MeV electrons. In this paper, design steps towards a university-based UED facility with ultrashort and low-emittance MeV electron bunches are presented, including the transverse and longitudinal focusing schemes, which minimize space charge effects and nonlinearities.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS015  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPTS025 Arc and Convertor Current Transient Studies for Multi-cusp Cesiated Surface Conversion H Source at Lansce ion-source, operation, plasma, extraction 1983
 
  • D. Kleinjan
    LANL, Los Alamos, New Mexico, USA
 
  The Multi-cusp Cesiated Surface Conversion H Ion Source at the Los Alamos Neutron Science Center (LANSCE) has provided beam at ~14 mA, 120 Hz, and 10% D.F. for many years of neutron science research. Recently, random high current transients were discovered in the arc current used to ionize hydrogen in the LANSCE H ion source, and in the convertor current used to convert protons to H ions. Most have no effect, but more severe transients can cripple beam output. Hypothesized causes are related to cesiation effects, plasma potential changes, tungsten filament vaporation/sputtering, or from the pulsed power system. A dedicated study was recently done on the LANSCE H Ion source test stand to determine the cause of these transients. Current understanding indicates that the more severe transients come from a combination of cesiation effects and plasma potential changes. The status of these current transient studies on the LANSCE H ion source will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS025  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS026 Negative Electron Affinity GaAs Cathode Activation With CsKTe Thin Film cathode, photon, vacuum, gun 1986
 
  • M. Kuriki
    KEK, Ibaraki, Japan
  • K. Masaki
    HU/AdSM, Higashi-Hiroshima, Japan
 
  Funding: This work is partly supported by Japan-US Cooperative grant for scientific studies, Grant aid for scientific study by MEXT Japan (KAKENHI).
Negative Electron Affinity (NEA) GaAs cathode is an unique device which can generate a highly polarized electron beam with circularly polarized light. The NEA surface is conventionally made by Cs and \rm O/NF3 adsorption on the cleaned p-doped GaAs crystal, but the robustness of the cathode is very limited, so that the electron emission is easily lost by residual gas adsorption, ion back-bombardment, etc. To improve the cathode robustness, NEA activation with a stable thin-film on GaAs surface according to Hetero junction hypothesis has been proposed by the author. An experiment of the NEA activation with CsKTe thin film was carried out at Hiroshima University and a significant electron emission with 1.43 eV photon was observed which strongly suggested NEA activation. The cathode showed 16 to 20 times improvement of lifetime comparing to GaAs activated with Cs and O.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS026  
About • paper received ※ 26 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS047 Improvement of 6D Brightness by a 1.4-cell Photocathode RF Gun for MeV Ultrafast Electron Diffraction gun, emittance, cathode, brightness 2033
 
  • Y. Song
    Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China
  • K. Fan, C.-Y. Tsai, Y.T. Yang
    HUST, Wuhan, People’s Republic of China
  • J. Yang
    ISIR, Osaka, Japan
 
  Recent research indicates that ultrafast electron diffraction and microscopy (UED/M) have unprecedented potential in probing ultrafast dynamic processes, especially in organic and biological materials. However, reaching the required brightness while maintaining high spatiotemporal resolution requires new design of electron source. In order to produce ultrashort electron beam with extreme high brightness, a 1.4-cell RF gun is being developed to reach higher acceleration gradient near the photocathode and thus suppress the space charge effect in the low energy region. Simulation of the 1.4-cell RF photocathode gun shows considerable improvement in bunch length, emittance and energy spread, which all lead to better temporal and spatial resolution comparing to traditional 1.6-cell RF photocathode gun. The results demonstrate the feasibility of sub-ps temporal resolution with normalized emittance less than 0.1 πmm·mrad while maintaining 1 pC electron pulse.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS047  
About • paper received ※ 24 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS050 Design and Analysis of the Cold Cathode Ion Source for 200 MeV Superconducting Cyclotron cathode, ion-source, proton, cyclotron 2040
 
  • S.W. Xu
    USTC, Hefei, Anhui, People’s Republic of China
  • L. Calabretta
    INFN/LNS, Catania, Italy
  • G. Chen, M. Xu
    ASIPP, Hefei, People’s Republic of China
  • O. Karamyshev, G.A. Karamysheva, G. Shirkov
    JINR, Dubna, Moscow Region, Russia
 
  SC200 is a superconducting isochronous cyclotron which generates 200 MeV, 400 nA proton beam for particle therapy. The cold-cathode-type Penning ion gauge (PIG) ion source for the internal ion source of SC200 has been selected as an alternative and preliminary designed. In this paper, design of ion source and test bench are demonstrated. Currently, the properties of ion source have been simulated for a variety of electric field distributions and magnetic field strengths. The secondary electron emission in electromagnetic field has been simulated. It provides reference for the optimization design of arc chamber. In addition, the sample of cold-cathode-type ion source has been tested on the test bench and extracted beam intensity has been measured over 200 μA.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS050  
About • paper received ※ 30 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS052 Conceptual Design of a High-Performance Injector Based on Rf-Gated Gridded Thermionic Gun for Thz Fel gun, linac, cathode, bunching 2046
 
  • P. Yang, H.M. Chen, T. Hu, J.J. Li, Y. Lu
    HUST, Wuhan, People’s Republic of China
  • G.Y. Feng, S.C. Zhang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  Free-Electron Laser (FEL) has higher requirements on electron beam properties, for example, low transverse emittance, small energy spread, short bunch length and high peak current. Taking compactness and economy into account, we aim to design a high-performance linear accelerator based on a RF-gated gridded thermionic electron gun, which will be used as the injector of the oscillator-type THz FEL facility at Huazhong University of Science and Technology of China. The RF-gated grid will be modulated with the fundamental and 3rd harmonic microwave of the LINAC frequency, which will be very helpful to get high electron capture efficiency and short bunch length. Concerning velocity bunching effect in the LINAC, electron bunch with good symmetry of current profile and bunch length less than 10 ps can be obtained at the exit of the injector. In this paper, design and beam dynamics simulation for the high-performance injector are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS052  
About • paper received ※ 26 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS053 Design of a 217 MHz VHF Gun at Tsinghua University gun, cathode, cavity, simulation 2050
 
  • L.M. Zheng, H. Chen, Y. C. Du, W.-H. Huang, R.K. Li, Z.Z. Li, C.-X. Tang
    TUB, Beijing, People’s Republic of China
  • B. Gao
    IHEP, Beijing, People’s Republic of China
 
  A 217 MHz VHF gun operating in CW mode is designing at Tsinghua University. The cathode gradient is designed to be 30 MV/m to accelerate the electron bunches up to 878 keV. The cavity profile is optimized in CST to minimize the input power, peak surface electric field, and peak wall power density. The multipacting analysis and the thermal analysis are also presented in this paper. Further gun shape optimization and mechanical design are ongoing.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS053  
About • paper received ※ 15 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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TUPTS054 1st+2nd Harmonic Photocathode Bimodal Gun R&D gun, emittance, cathode, cavity 2054
 
  • L. Wang
    SINAP, Shanghai, People’s Republic of China
  • W. Fang, Z.T. Zhao
    SSRF, Shanghai, People’s Republic of China
  • J.L. Hirshfield
    Yale University, Physics Department, New Haven, CT, USA
  • J.L. Hirshfield, S.V. Shchelkunov
    Omega-P, Inc., New Haven, Connecticut, USA
  • Y. Jiang, S.V. Shchelkunov
    Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
  • L. Wang
    University of Chinese Academy of Sciences, Beijing, People’s Republic of China
 
  Funding: U.S. Dept. of Energy
A novel Bimodal Electron Gun is designed to apply microwaves at two harmonically-related frequency in a 0.6 cell RF gun to increase the RF breakdown threshold and enhance the beam quality. This stratagem is intended to allow the RF gun structure to support a high accelera-tion gradient as well as to manipulate the emittance evolution in the half cell. By selecting a proper ampli-tude ratio and phase relationship between the first and second harmonic RF field components in the gun cavity, the superposition of the harmonic field components can provide a flat-top like RF profile to omitting the RF emittance component in the gun, while increase the RF breakdown threshold. The recent status of the Bimodal Electron Gun R&D is presented, including the designs of the novel two frequency RF structure and the simulation of the beam dynamic.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS054  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS066 Re-optimisation of the ALICE Gun Upgrade Design for the 500-pC Bunch Charge Requirements of PERLE cathode, gun, operation, laser 2071
 
  • B. Hounsell, M. Klein, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • B. Hounsell, B.L. Militsyn, T.C.Q. Noakes, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • B. Hounsell, W. Kaabi
    LAL, Orsay, France
  • B.L. Militsyn, T.C.Q. Noakes
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  The injector for PERLE, a planned ERL test facility, must be capable of delivering 500 pC bunches at a repetition rate of 40.1 MHz to provide a beam with 20 mA average current with a projected rms emittance of less than 6 mm mrad. This must be achieved at two different operational voltages 350 kV and 220 kV for unpolarised and polarised operation respectively. The PERLE injector will be based on an upgrade of a DC photocathode electron gun operated previously at ALICE ERL at Daresbury. The upgrade will add a load lock system for photocathode interchange. This paper presents the results of a re-optimisation of the electrode system as ALICE operated with a bunch charge of around 80 pC while PERLE needs a bunch charge of 500 pC. This re-optimisation was done using the many-objective genetic algorithm NSGAIII to minimise both the slice emittance and transverse beam size for both required operational voltages.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS066  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS070 Systematic Benchmarking of a Planar (N)UNCD Field Emission Cathode cathode, gun, experiment, ECR 2083
 
  • J.H. Shao, M.E. Conde, W. Liu, J.G. Power, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • S.V. Baryshev, M.S. Schneider
    Michigan State University, East Lansing, Michigan, USA
  • G. Chen
    IIT, Chicago, Illinois, USA
  • K. Kovi
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • L.K. Spentzouris
    Illinois Institute of Technology, Chicago, Illinois, USA
 
  Planar nitrogen-incorporated ultrananocrystalline diamond, (N)UNCD, is a unique and attractive field emission source because of the capability to generate high charge beam, the simplicity of production without shaped emitters, and the ease of handling with moderate vacuum requirement. In the presented study using an L-band normal conducting single-cell rf gun, a (N)UNCD cathode has been conditioned to 42 MV/m with a well-controlled manner and reached a maximum charge of 15 nC and an average emission current of 6~mA during a 2.5 us emission period. The systematic study of emission properties during the rf conditioning process illustrates the tunability of (N)UNCD in a wide range of surface gradients. This research demonstrates the versatility of (N)UNCD cathode which could enable multiple designs of field emission rf injector for industrial and scientific applications.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS070  
About • paper received ※ 20 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPTS073 Analysis of Electron Beam Divergence in Diamond Field Emitter Array Cathodes cathode, focusing, experiment, simulation 2090
 
  • D. Kim, H.L. Andrews, R.L. Fleming, C. Huang, J.W. Lewellen, K.E. Nichols, V.N. Pavlenko, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
  • B.K. Choi
    Cheju Halla University, Jeju-si, Republic of Korea
 
  Funding: Los Alamos National Laboratory (LANL) Laboratory Directed Research and Development (LDRD) program (Contract DE-AC52-06NA25396) and Sandia National Laboratories (Contract DE-NA-0003525).
At Los Alamos National Laboratory (LANL), we have recently established a capability to fabricate diamond array cathodes for electron beam sources. Our fabricated diamond field emitter arrays (DFEAs) are the arrays of micrometer-scale diamond pyramids with nanometer-scale sharp tips and produce high per-tip current (> 15 μA per-tip) in DC testing. For the beam divergence measurements, we designed and assembled a test stand consisting of a DFEA cathode, a mesh aperture of 0.375-inch for an anode, and AZO (ZnO:Al2O3) screen coated on a sapphire substrate for beam visualization. A negative voltage of about 40 kV is applied to the cathode, and the mesh and the screen are kept at ground. We measure a size of the electron beam on the AZO screen at different mesh to screen distances at a fixed cathode-mesh gap in order to calculate the beam divergence angles. We also perform the beam dynamics simulations with Computer Simulation Technology (CST) Studio and General Particle Tracer (GPT) using a single pyramidal shape with a nanowire tip model. In this presentation, the measured experimental results of the beam divergences will be compared to the beam dynamic simulations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS073  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS076 RF Design of APEX2 Cavities gun, cavity, cathode, brightness 2094
 
  • T.H. Luo, H.Q. Feng, D. Filippetto, M.J. Johnson, A.R. Lambert, D. Li, C.E. Mitchell, F. Sannibale, J.W. Staples, S.P. Virostek, R.P. Wells
    LBNL, Berkeley, California, USA
  • H.Q. Feng
    TUB, Beijing, People’s Republic of China
 
  Funding: Director of Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
APEX2 is a proposed high repetition rate, high brightness electron source based on CW normal conducting RF cavities, aiming to further extend the brightness performance for FEL and UED/UEM beyond APEX. APEX2 consists of two cavities, one gun cavity for generating photo-electrons and one following cavity for beam energy boosting. In this paper, we present the RF design of the APEX2 cavities. The design has considered both beam dynamics requirements and engineering feasibility. A novel geometry optimization method with Genetic Algorithm has been implemented in the design procedure.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS076  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS077 Design of a High Gradient THz-Driven Electron Gun gun, acceleration, experiment, FEL 2098
 
  • S.M. Lewis, V.A. Dolgashev, A.A. Haase, E.A. Nanni, M. A. K. Othman, A.V. Sy, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  • D. Kim, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
 
  Funding: This work was supported by Department of Energy contract DE-AC02-76SF00515. This work was also supported by NSF grants PHY-1734015.
We present the design of a high-gradient electron gun. The goal of this gun is to generate relativistic electrons using GV/m accelerating fields. The initial design is a standing-wave field-emission gun operating in the pi-mode with a cavity frequency of 110.08 GHz. A pulsed 110 GHz gyrotron oscillator will be used to drive the structure with power coupled in through a TM01 circular waveguide mode. The gun is machined in two halves which are bonded. This prototype will be used to characterize the electron beam and study RF breakdown at 110 GHz.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS077  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS078 Coherent Electron Cooling (CeC) Experiment at RHIC: Status and Plans FEL, experiment, SRF, simulation 2101
 
  • V. Litvinenko, K. Mihara
    Stony Brook University, Stony Brook, USA
  • Z. Altinbas, J.C. Brutus, A. Di Lieto, D.M. Gassner, T. Hayes, P. Inacker, J.P. Jamilkowski, Y.C. Jing, R. Kellermann, J. Ma, G.J. Mahler, M. Mapes, R.J. Michnoff, T.A. Miller, M.G. Minty, G. Narayan, M.C. Paniccia, D. Phillips, I. Pinayev, S.K. Seberg, F. Severino, J. Skaritka, L. Smart, K.S. Smith, Z. Sorrell, R. Than, J.E. Tuozzolo, E. Wang, G. Wang, Y.H. Wu, B. P. Xiao, T. Xin, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • K. Shih
    SBU, Stony Brook, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy and NSF Grant No. PHY-141525
We will present currents status of the CeC experiment at RHIC and discuss plans for future. Special focus will be given to unexpected experimental results obtained during RHIC Run 18 and discovery of a previously unknown type of microwave instability. We called this new phenomenon micro-bunching Plasma Cascade Instability (PCI). Our plan for future experiments includes suppressing this instability in the CeC accelerator and using it as a broad-band amplifier in the CeC system.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS078  
About • paper received ※ 19 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPTS079 Overcoming Multipacting Barriers in SRF Photoinjectors cavity, gun, cathode, SRF 2105
 
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • V. Litvinenko, G. Narayan, I. Pinayev, F. Severino, K.S. Smith
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
 
  Superconducting RF (SRF) photoinjectors are considered to be a potential breakthrough in the area of high brightness electron sources. However, there is always the very important question of the compatibility of SRF cavities and high quantum efficiency (QE) photocathodes. A deposition of active elements from high QE photocathodes on the surface of a cavity makes it more vulnerable to multipacting (MP) and could affect the operation of an SRF gun. On the other side, MP can significantly reduce the lifetime of a photocathode. It is well known in the SRF community that a strong coupling, high forward power and sufficient cleanliness of cavity walls are the key components to overcome a low-level MP zone. In this paper we present a theoretical model of passing a MP barrier which could help estimate the desirable conditions for successful operation of an SRF gun. We demonstrate our results for the 113 MHz SRF photo-injector for Coherent electron Cooling (CeC) alongside with the experimental observations and 3D simulations of the MP discharge in the cavity. The results of the theoretical model and simulations show good agreement with the experimental results, and demonstrate that, if approached carefully, MP zones can be easily passed without any harm to the photocathode.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS079  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS083 Simulations and Experimental Plans for a High-Repetition-Rate Field-Enhanced Conduction-Cooled Superconducting RF Electron Source cavity, cathode, SRF, simulation 2113
 
  • O. Mohsen, A. McKeown, D. Mihalcea, P. Piot, I. Salehinia
    Northern Illinois University, DeKalb, Illinois, USA
  • R. Dhuley, M.G. Geelhoed, D. Mihalcea, P. Piot, J.C.T. Thangaraj
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work supported by DOE awards DE-SC0018367 with NIU and DE-AC02-07CH11359 with Fermilab.
We present a novel RF design for a field enhanced electron source driven by field emission cathodes. The proposed electron source relies on the enhanced high electric field gradients at the cathode to simultaneously extract and accelerate electrons. The system will be tested in a conduction-cooled superconducting radio-frequency cavity recently demonstrated at Fermilab. In this paper, we present electromagnetic and thermal simulations of the setup that support the feasibility of the design.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS083  
About • paper received ※ 18 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS084 Performances of Silicon-Based Field-Emission Cathodes Coated with UltraNano Crystalline Diamond cathode, experiment, vacuum, simulation 2117
 
  • O. Mohsen, V. Korampally, A. Lueangaramwong, P. Piot, V. Valluri
    Northern Illinois University, DeKalb, Illinois, USA
  • R. Divan, A.V. Sumant
    Argonne National Laboratory, Argonne, Illinois, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work supported by NSF grant PHY-1535401 and DOE award DE-SC0018367 with NIU
Field-emission electron sources have been considered as possible candidates for the production of bright or high-current electron bunches. In this paper, we report on the experimental characterization of silicon-based field-emitter arrays (FEA) in a DC high voltage gap. The silicon cathodes are produced via a simple self-assembling process. The measurement reported in this paper especially compares the field-emission properties of a nanostructured and planar diamond-coated Si-based cathode.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS084  
About • paper received ※ 17 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS088 A Normal Conducting RF Gun as an Electron Source for JLEIC Cooling gun, emittance, cathode, solenoid 2127
 
  • F.E. Hannon, R.A. Rimmer
    JLab, Newport News, Virginia, USA
 
  The baseline design for a magnetized injector for the bunched-beam electron cooler ring, as part of the Jeffer-son Lab Electron Ion Collider (JLEIC) uses a DC photo-cathode electron gun as the source. A challenging aspect of this concept is transporting a 3.2nC electron bunch at low energy and preserving the angular momentum. An RF gun source has been investigated to gauge the potential advantages of high gradient on the photocathode and higher exit energy. The design is presented and compared with the baseline results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS088  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS089 Observations of the Femtosecond Laser-Induced Emission From the Diamond Field Emitter Tips laser, cathode, photon, experiment 2130
 
  • E.I. Simakov, H.L. Andrews, R.L. Fleming, D. Kim, V.N. Pavlenko
    LANL, Los Alamos, New Mexico, USA
  • D.S. Black, K.J. Leedle
    Stanford University, Stanford, California, USA
 
  Funding: Los Alamos National Laboratory LDRD Program
We present the results of experimental observation of emission from single diamond field emitter tips when triggered by an ultra-short laser pulse. Diamond field emitter array (DFEA) cathodes were originally proposed for applications that require large current densities. DFEAs represent periodic arrays of diamond pyramids with micron-size dimensions and tips with diameters of the order of tens of nanometers. DFEAs are known to produce significant currents in field emission regime under direct current (DC) fields and in radio-frequency (RF) guns. It has been proposed that single diamond tip emitters can be employed for production of small tightly focused electron beams for dielectric laser accelerators (DLAs) that accelerate particles using the energy of light produced by infrared lasers. To generate short electron bunches required by DLAs diamond pyramids may be triggered with a laser. We have recently observed emission produced by a single diamond pyramid when triggered by a laser at different wavelengths from 256 nm to 2020 nm. We have conducted studies with the goal to understand mechanism of the emission. We clearly observed the change in emission mechanism when the wavelength changed from 256 nm to 512 nm. We believe that while the emission at 256 nm is a clear photoemission, the emission at longer wavelengths is likely the field emission caused by intense electric fields of the laser.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS089  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS091 Physics of Electron Beam Generation and Dynamics From Diamond Field Emitter Arrays simulation, cathode, ECR, experiment 2137
 
  • C. Huang, H.L. Andrews, R.C. Baker, R.L. Fleming, D. Kim, T.J. Kwan, V.N. Pavlenko, A. Piryatinski, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
 
  Funding: Work supported by the LDRD program at Los Alamos National Laboratory
Many applications such as compact accelerators and electron microscopy demand high brightness electron beams with small beam size and low emittance. Electric-field-assisted diamond emitters manufactured from semiconductor processes are strong candidates for cathodes in such sources. The micro-scale pyramid structure of the emitter has the desirable attribute of significant field enhancement at the sharp interfaces (apex and edges) to facilitate electron emission. We use the LSP particle-in-cell code to simulate the diamond emitter in a diode setup and obtain the beam size and divergence. An empirical fit of the fields around the apex is extracted for detail study. The trend of the beam divergence observed in the simulation is further corroborated using electron’s trajectory in the empirical field model.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS091  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS093 Magnetized Gridded Thermionic Electron Source gun, cathode, emittance, simulation 2140
 
  • M.S. Stefani
    ODU, Norfolk, Virginia, USA
  • C.M. Gulliford, V.O. Kostroun, C.E. Mayes, K.W. Smolenski
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • F.E. Hannon, M. Poelker, R. Suleiman
    JLab, Newport News, Virginia, USA
 
  Funding: This manuscript has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy.
The study of magnetized electron beam has become a high priority for its use in ion beam cooling as part of Electron Ion Colliders and the potential of easily forming flat beams for various applications. The demand for high average current for effective ion beam cooling has caused consideration of using bunched magnetized electron beam produced by a gridded thermionic electron gun. This paper presents the design of a potential electron source for JCIEC first measurements characterizing the beam properties of a magnetized thermionic gun.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS093  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS095 Global Model of Multi-Chamber Negative Hydrogen Ion Sources with Updated Hydrogen Plasma Chemistry simulation, plasma, ion-source, interface 2144
 
  • S.N. Averkin, S.A. Veitzer
    Tech-X, Boulder, Colorado, USA
 
  Funding: This work was performed under the auspices of the Department of Energy, Office of Basic Energy Sciences Award #DE-SC0009585.
Global models of plasma discharges are used to calculate volume averaged number densities and temperatures of plasma components. The wall fluxes are estimated based on heuristic expressions that "patch" together analytic and semi-analytic solutions covering from low-pressure to high-pressure regimes. Due to the nature of the wall fluxes estimation, the global models are limited to single chamber designs. We present the extension of the Global Enhanced Vibrational Kinetic Model (GEVKM) * for the multi-chamber design with the updated hydrogen plasma chemistry **. The extended GEVKM consists of separate global models for macroscopic parameters of all species in each chamber coupled through interface boundary conditions. We compare our model with fluid simulation results for a plasma composition and species temperatures in the negative hydrogen ion source developed at IPP Garching.
* Averkin S.N. et al, IEEE Trans. Plasma Sci., Vol. 43, N. 6, pp. 1926-1943, 2015.
** Yang W. et al, Phys. Plasmas, 25, 113509, 2018.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS095  
About • paper received ※ 21 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS096 Fluid Models of Inductively Coupled Plasma Sources for Negative Hydrogen Ion Sources plasma, ion-source, simulation, neutron 2147
 
  • S.A. Veitzer, P. Stoltz
    Tech-X, Boulder, Colorado, USA
 
  Funding: This work was performed under the auspices of the Department of Energy, Office of Basic Energy Sciences Award #DE-SC0009585.
Negative hydrogen ion sources are widely used to produce neutron beams via spallation both for neutron science in its own right, and as neutron sources for fusion devices. Numerical modeling is a useful tool for trying to optimize negative hydrogen ion sources. However there are significant numerical and computational challenges that have to be overcome, including code performance and resolution of separation of time scales between ion and electron motions. One method is to utilize fluid models to simulate inductively coupled ion sources (ICPs). We have been developing algorithms to simulate negative hydrogen production in high-power, external-antenna ICP sources. We present simulation results using the USim*,** framework to model plasma chemistry that produces negative hydrogen, and model the effects of electron temperature on overall production rates. The numerical plasma chemistry models include processes of ionization, dissociation, recombination, as well as reactive dissociation of vibrationally resolved states and de-excitation of atomic hydrogen. We benchmark our plasma chemistry model results using plasma parameters relevant to experiments being carried out at the D-Pace Ion Source Test Facility. We have also been developing fluid-based drift/diffusion models for multi-component plasmas, such as those in negative hydrogen sources. These simulation results demonstrate enhancement of the effective diffusion rates in plasmas that contain both electrons and negative ions.
* J. Loverich and A. Hakim, J. Fusion Sci., 29(6), 2010.
** J. Loverich et al., AIAA, Vol. 4012, 2011.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS096  
About • paper received ※ 19 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS099 Predicting the Performances of Coherent Electron Cooling with Plasma Cascade Amplifier plasma, kicker, space-charge, collider 2150
 
  • G. Wang, V. Litvinenko, J. Ma
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Recently, we proposed a new type of instability, Plasma Cascade Instability (PCI), to be used as the amplification mechanism of a Coherent Electron Cooling (CeC) system, which we call Plasma Cascade Amplifier (PCA). In this work, we present our analytical estimate of the cooling force as expected from a PCA- based CeC system and compare it with the simulation results. As examples, we apply our analysis to a few possible CeC systems and investigate the evolution of the circulating ion beams in the presence of cooling.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS099  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS101 Bi-Alkali Antimonide Photocathodes for LEReC DC Gun cathode, gun, vacuum, laser 2154
 
  • E. Wang, A.V. Fedotov, M. Gaowei, D. Kayran, D. Lehn, C.J. Liaw, T. Rao, J.E. Tuozzolo, J. Walsh
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Low Energy RHIC electron cooling (LEReC) is a bunched electron cooler at RHIC. The Bi-alkali photocathodes are chosen as electron source due to its long lifetime and high QE at visible wavelength. Because the DC gun needs to produce 24/7 beams over several months, cathode production system and multiple cathodes transferring systems are designed, commissioned and in operation. In this report, we will describe our photocathodes production and discuss the cathode’s performance from cathode growth system to the DC gun.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS101  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPTS102 New Activation Techniques for Higher Charge Lifetime from GaAs Photocathodes cathode, gun, laser, site 2157
 
  • O.H. Rahman, M. Gaowei, W. Liu, E. Wang
    BNL, Upton, Long Island, New York, USA
  • J.P. Biswas
    Stony Brook University, Stony Brook, USA
 
  GaAs is the choice of photocathode material for polarized electron sources. The well established method of activating GaAs for beam extraction is to use Cs and Oxygen to create a ’Negative Electron Affinity’(NEA) layer. However, this layer is highly sensitive to vacuum and gets damaged due to ion back bombardment in DC guns. In this work, we explore activation methods that used Tellurium in conjunction with the usual Cs and Oxygen. We report our method to activate GaAs and show charge lifetime results for our activation method. Our results show that the use of Te could potentially help with longer charge lifetimes from GaAs cathodes in DC guns.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS102  
About • paper received ※ 14 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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TUPTS103 The Progress of High Current High Bunch Charge Polarized Electron HVDC Gun cathode, gun, vacuum, high-voltage 2160
 
  • E. Wang, I. Ben-Zvi, R.F. Lambiase, W. Liu, O.H. Rahman, J. Skaritka, F.J. Willeke
    BNL, Upton, Long Island, New York, USA
  • I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The high current and high bunch charge polarized electron source is essential for cost reduction of eRHIC. It aims to deliver electron beam with 10 mA average current and 5.3 nC bunch charge. We analyzed the mechanism of cathode degradation and proposed using a large strain superlattice GaAs photocathode in a high voltage DC gun to increase the charge lifetime above kilo Coulomb. The gun has been designed and fabricated and expected to start commissioning by the mid of this year. In this paper, we will present the modeling of ion back bombardment and cathode degrading. We proposed an anode offset scheme to increase cathode lifetime. Also, we will describe the details of gun design and the strategies to demonstrate high current high charge polarized electron beam from this source.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS103  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS104 Spatio-Temporal Shaping of the Photocathode Laser Pulse for Low-Emittance Shaped Electron Bunches laser, cathode, emittance, simulation 2163
 
  • T. Xu, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • C.-J. Jing, A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
  • J.G. Power
    ANL, Argonne, Illinois, USA
 
  Funding: This work is supported by the U.S. DOE contract No. DE- SC0017750 with Euclid Techlabs LLC., No. DE-SC0018656 with NIU, and No. DE-AC02-06CH11357 with ANL.
Photocathode laser shaping techniques to generate temporally shaped electron bunches are appealing owing to their simplicity. Such technique is being considered to form shaped electron bunches to enhance the transformer ratio in beam-driven accelerators. At low energy (i.e. during the emission process) the transverse and longitudinal space charge effects are coupled so that attaining a low beam transverse emittance require the laser to be spatiotemporal shaped. In this paper, we explore the generation of a linearly-ramped bunch with optimized transverse emittance by temporally and radially shaping the laser pulse to provide an adequate initial distribution. We discuss a possible implementation of the optical shaping technique and describe a planned experiment.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS104  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS105 High Current High Charge Magnetized and Bunched Electron Beam from a DC Photogun for JLEIC Cooler cathode, laser, gun, emittance 2167
 
  • S. Zhang, P.A. Adderley, J. F. Benesch, D.B. Bullard, J.M. Grames, J. Guo, F.E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, G.A. Krafft, M.A. Mamun, M. Poelker, R. Suleiman, M.G. Tiefenback, Y.W. Wang
    JLab, Newport News, Virginia, USA
  • J.R. Delayen, G.A. Krafft, Y.W. Wang, S.A.K. Wijethunga
    ODU, Norfolk, Virginia, USA
 
  Funding: This project was supported by the U.S. DOE Basic Energy Sciences under contract No. DE-AC05-060R23177. Additional support comes from Laboratory Directed Research and Development program.
A high current, high charge magnetized electron beamline that has been under development for fast and efficient cooling of ion beams for the proposed Jefferson Lab Electron Ion Collider (JLEIC). In this paper, we present the latest progress over the past year that include the generation of picosecond magnetized beam bunches at average currents up to 28 mA with exceptionally long photocathode lifetime, and the demonstrations of magnetized beam with high bunch charge up to 700 pC at 10s of kHz repetition rates. Detailed studies on a stable drive laser system, long lifetime photocathode, beam magnetization effect, beam diagnostics, and a comparison between experiment and simulations will also be reported. These accomplishes marked an important step towards the essential feasibility for the JLEIC cooler design using magnetized beams.
(To be inserted)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS105  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS106 First Commissioning of LCLS-II CW Injector Source gun, cavity, operation, vacuum 2171
 
  • F. Zhou, C. Adolphsen, A.L. Benwell, G.W. Brown, W.S. Colocho, Y. Ding, M.P. Dunning, K. Grouev, B.T. Jacobson, X. Liu, T.J. Maxwell, J.F. Schmerge, T.J. Smith, T. Vecchione, F.Y. Wang, C.M. Zimmer
    SLAC, Menlo Park, California, USA
  • G. Huang, F. Sannibale
    LBNL, Berkeley, California, USA
 
  Funding: The work is supported by DOE under grant No. DE-AC02-76SF00515
The LCLS-II injector source includes a 186MHz CW rf-gun, a 1.3 GHz CW rf-buncher, a loadlock system for photocathode change, two main solenoids, and a few essential diagnostics. The electron beam is designed to operate at a high repetition rate, up to 1-MHz. Since summer of 2018 we started LCLS-II injector source commissioning immediately after the major installation was completed. Initial commissioning showed the rf-gun was severely contaminated with hydrocarbons and very limited power <600W could be fed into the gun cavity. After a few significant processes, we eventually removed the hydrocarbons and successfully delivered desired rf power of 80 kW to the gun. This paper reports first com-missioning results including gun bakeout and vacuum processing, CW RF-gun and buncher operation with nom-inal power, and measurements of rf stability and dark current.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS106  
About • paper received ※ 10 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS111 Study on Improving Durability of Cs-Te Photocathode for an RF-gun cathode, gun, vacuum, brightness 2182
 
  • T. Tamba, J. Miyamatsu, K. Sakaue, M. Washio
    Waseda University, Tokyo, Japan
 
  At Waseda University, we have been studying for high quality electron beam generation using 1.6 cell Cs-Te photocathode rf-gun. We use photocathode as the electron source, which can generate high- quality electron beam such as low emittance, and short bunch. The performance of photocathode is evaluated mainly in terms of quantum efficiency (Q.E.) and lifetime. Cs-Te photocathode used in the rf-gun is known for high Q.E. about 10% with UV light and relatively longer lifetime among semiconductor photocathodes. Since it is a hard environment for photocathode inside the gun, it is necessary to replace the photocathode every several months. In other words, in order to achieve long-term operation of rf-gun, it is necessary to find highly durable photocathode recipe. It has been reported that the Cs-Te photocathode by co-evaporation can produce a photocathode having a longer lifetime as compared with the sequential evaporation. Moreover, we have done studies to improve lifetime and durability of Cs-Te photocathode by coating the cathode surface with CsBr thin film. In this conference, we report the evaluation results of Cs-Te photocathode by co-evaporation, CsBr coating and future prospects.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS111  
About • paper received ※ 12 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPTS113 Microwave Thermionic Electron Gun for Synchrotron Light Sources gun, cathode, cavity, coupling 2189
 
  • S.V. Kutsaev, R.B. Agustsson, R.D. Berry, D. Chao, O. Chimalpopoca, A.Yu. Smirnov, K.V. Taletski, A. Verma
    RadiaBeam, Santa Monica, California, USA
  • M. Borland, A. Nassiri, Y. Sun, G.J. Waldschmidt, A. Zholents
    ANL, Argonne, Illinois, USA
 
  Funding: This work was supported by the U.S. Department of Energy, Office of Basic Energy Science, under contracts DE-SC0015191 and DE- AC02-06CH11357.
Thermionic RF guns are the source of electrons used in many practical applications, such as drivers for synchrotron light sources, preferred for their compactness and efficiency. RadiaBeam Technologies has developed a new thermionic RF gun for the Advanced Photon Source at Argonne National Laboratory, which would offer substantial improvements in reliable operations with a robust interface between the thermionic cathode and the cavity, as well as better RF performance, compared to existing models. This improvement became possible by incorporating new pi-mode electromagnetic design, robust cavity back plate design, and a cooling system that will allow stable operation for up to 1 A of beam current and 100 Hz rep rate at 1.5 μs RF pulse length, and 70 MV/m peak on-axis field in the cavity. In this paper, we discuss the electromagnetic and engineering design of the cavity and provide the test results of the new gun.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS113  
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPTS114 Electron Stimulated Desorption from Cryogenic NEG-Coated Surfaces vacuum, cryogenics, experiment, site 2193
 
  • R. Sirvinskaite, M.D. Cropper
    Loughborough University, Loughborough, Leicestershire, United Kingdom
  • A.N. Hannah, O.B. Malyshev, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • S. Wang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  Non-Evaporable Getter (NEG) coating has been used for years in many particle accelerators due to its advantages like evenly distributed pumping speed, low thermal outgassing, and low photon, electron and ion stimulated desorption yields. Although NEG coating has been tested at room temperatures intensively, there is little data on its behaviour at cryogenic temperatures. Tests in this environment are important for the Future Circular Collider (FCC) study and other accelerator facilities where the operational conditions of the beam screen are restricted to cryogenic temperatures. This work will provide some preliminary results on NEG properties at low temperatures, e.g. pumping speed and capacity, as well as its behaviour under electron bombardment, where electron stimulated desorption (ESD) yields will be calculated. The ternary Ti-Zr-V coating, deposited with dense and columnar structure, will be the first material to be tested at cryogenic temperatures in ASTeC Daresbury laboratory. The results were compared with the ones obtained at room temperature, offering an insight into the behaviour of NEG-coated cryogenic chambers when beam-induced effects are present.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS114  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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TUPTS115 The Progress in Physical Start-Up of the NSC KIPT Subcritical Neutron Source Facility Driven by an Electron Linear Accelerator neutron, target, detector, vacuum 2197
 
  • P. Gladkikh, O.V. Bykhun, I.M. Karnaukhov, A. Mytsykov, V. Stomin, I. Ushakov, A.Y. Zelinsky
    NSC/KIPT, Kharkov, Ukraine
 
  National Science Center ’Kharkov Institute of Physics &Technology’ (NSC KIPT), Kharkov, Ukraine and Argonne National Laboratory (ANL), Chicago, USA are jointly constructing and commissioning the Ukraine Neutron Source facility. The facility consists of a subcritical assembly driven by a 100MeV/100kW electron linear accelerator. The electron beam will be used for generating the neutrons for operating the subcritical assembly using tungsten or natural uranium target. The facility is planned to support the Ukraine nuclear industry, and provide a capability for performing reactor physics, material research, and basic science experiments, to produce medical isotopes, train young nuclear professionals. The integrating facility tests were completed at the end of 2018, and physical start-up operation began in 2019. The facility commissioning and current start-up results are presented and discussed in the paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS115  
About • paper received ※ 10 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS116 Adjustment and Improvement of 100 MeV/100 kW Electron Linear Accelerator Parameters for the NSC KIPT SCA Neutron Source neutron, gun, operation, MMI 2200
 
  • P. Gladkikh, V.P. Androsov, O. Bezditko, O.V. Bykhun, V.V. Gevtsev, A.N. Gordienko, A. Gvozd, V.E. Ivashchenko, D.A. Kapliy, I.I. Karhaukhov, I.M. Karnaukhov, V.P. Lyashchenko, M. Moisieienko, A. Mytsykov, A.V. Reuzayev, A.B. Shevtsov, D.V. Tarasov, V.I. Trotsenko, A.Y. Zelinsky
    NSC/KIPT, Kharkov, Ukraine
 
  The NSC KIPT SCA Neutron Source uses 100 MeV/ 100 kW electron linear accelerator as a driver for the generation of the initial neutrons. The electron linear accelerator was designed and manufactured by the Institute of High Energy Physics (IHEP) of China. At present, the accelerator was assembled at NSC KIPT, all the components were tested, and the first beam commissioning results are obtained. The pilot operation of the accelerator was started in 2018. The progress in the accelerator system operations and electron beam performance improvement are described in the paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS116  
About • paper received ※ 10 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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TUPTS117 Photocathode Activities at INFN LASA cathode, operation, laser, gun 2203
 
  • D. Sertore, G. Guerini Rocco, P. Michelato, L. Monaco
    INFN/LASA, Segrate (MI), Italy
  • S.K. Mohanty
    DESY Zeuthen, Zeuthen, Germany
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
 
  We present the activity on alkali antimonide photocathodes at INFN LASA. The long term goal is to transfer to these photocathodes the know-how acquired in the successful development of cesium telluride photocathodes, nowadays used in many leading FEL facilities and accelerator complex. In this paper we present and discuss the results so far obtained on alkali antimonide films grown in our R&D system and the status of the new preparation system specifically designed for these sensitive materials.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS117  
About • paper received ※ 16 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEXPLM1 XFEL Operational Flexibility due to the Dechirper System undulator, FEL, controls, laser 2219
 
  • A.A. Lutman, K.L.F. Bane, Y. Ding, C. Emma, M.W. Guetg, E. Hemsing, Z. Huang, J. Krzywiński, J.P. MacArthur, G. Marcus, A. Marinelli, T.J. Maxwell, A. Novokhatski
    SLAC, Menlo Park, California, USA
  • G. Guo
    Stanford University, Stanford, California, USA
 
  Funding: U.S.Department of Energy, Office of Science, Laboratory Directed Research and Development (LDRD) program at SLAC National Accelerator Laboratory, under Contract No. DE-AC02-76SF00515.
The RadiaBeam/SLAC dechirper was installed to demonstrate the concept of using wakefields from a corrugated structure to change the energy profile along an electron bunch. Since installation, the system has allowed a large number of additional XFEL operating modes including fresh-slice two-color or three color operation, fresh-slice seeding, passive streaking, etc. This talk will discuss the results from using the dechirper system and possible implementation issues related to the high-rate LCLS-II.
Lutman, A. A. et al. Nat. Photon. 10, 745-750 (2016).; Nat. Photon. 10, 695-696 (2016); other papers in submission.
 
slides icon Slides WEXPLM1 [5.744 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEXPLM1  
About • paper received ※ 10 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEXPLS1 High Performance ECR Sources for Next-Generation Nuclear Science Facilities ECR, plasma, ion-source, ECRIS 2224
 
  • D. Leitner
    LBNL, Berkeley, California, USA
 
  Modern heavy-ion accelerators require intense heavy-ion beams with high charge state. Electron Cyclotron Resonance (ECR) sources are the primary tool for generating such beams. Advances in magnet technology and an improved understanding of the ECR ion source plasma physics have led to significant improvements in ECR source performance over the last several decades. The current state of the art is represented by third-generation sources operating at frequencies around 28 GHz and peak coil fields of about 7 T using NbTi conductor. Fourth-generation ECR ion sources with an operating frequency above 40 GHz have the potential to quadruple the source output beam current. These sources will need to incorporate advanced conductor technologies and/or novel coil configurations in order to exceed the limitations of the present structures. This talk will present worldwide efforts currently underway to develop high-performance ECR sources using new design approaches in support of next-generation nuclear physics facilities.  
slides icon Slides WEXPLS1 [8.012 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEXPLS1  
About • paper received ※ 16 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEXXPLM1 Amplified Emission of a Soft-X Ray Free-Electron Laser Based on Echo-Enabled Harmonic Generation FEL, laser, experiment, free-electron-laser 2230
 
  • E. Allaria, L. Badano, G. De Ninno, S. Di Mitri, B. Diviacco, W.M. Fawley, N.S. Mirian, G. Penco, P. Rebernik Ribič, S. Spampinati, C. Spezzani, M. Trovò
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • G. De Ninno
    University of Nova Gorica, Nova Gorica, Slovenia
  • E. Ferrari, E. Prat
    PSI, Villigen PSI, Switzerland
  • D. Garzella
    CEA, Gif-sur-Yvette, France
  • V. Grattoni
    DESY, Hamburg, Germany
  • E. Hemsing
    SLAC, Menlo Park, California, USA
  • M.A. Pop
    MAX IV Laboratory, Lund University, Lund, Sweden
  • E. Roussel
    PhLAM/CERLA, Villeneuve d’Ascq, France
  • D. Xiang
    Shanghai Jiao Tong University, Shanghai, People’s Republic of China
 
  We report the first evidence of substantial gain in a soft-X ray Free Electron Laser (FEL) based on Echo-Enabled Harmonic Generation (EEHG). The experiment was focused on harmonics 36 (~7.3nm) and 45 (5.8 nm) and clearly demonstrated the expected EEHG capability of generating powerful and coherent FEL pulses, with strongly reduced sensitivity to electron-beam fluctuations. The experiment was carried out at FERMI, the seeded FEL user facility at Elettra-Sincrotrone Trieste.  
slides icon Slides WEXXPLM1 [11.410 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEXXPLM1  
About • paper received ※ 17 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEXXPLS1 Magnetron R&D for High Efficiency CW RF Sources of Particle Accelerators injection, cavity, controls, klystron 2233
 
  • H. Wang, R.M. Nelson, R.A. Rimmer
    JLab, Newport News, Virginia, USA
  • B.R.L. Coriton, C.P. Moeller
    GA, San Diego, California, USA
  • A. Dudas, M.L. Neubauer
    Muons, Inc, Illinois, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, DOE OS/NP STTR Grant DE-SC0013203 and DOE OS/HEP Accelerator Stewardship award 2019-2021.
The scheme of using a high efficiency magnetron to drive a superconducting or normal conducting radio frequency accelerator cavity needs not only injection phase locking but also amplitude modulation to compensate for the cavity’s microphonics, frequency change, variations of cavity voltage and beam current. To be able to do a fast and efficient modulation and to compensate the frequency pushing effect due to the anode current change, the magnetron’s magnetic field has to be trimmed by an external coil*. To facilitate this, a low eddy current magnetron body has been designed and built**. This paper will present the experimental results of such modulation on a conventional 2.45 GHz magnetron at the R&D test stand. In addition, the progresses on the injection lock test to a new 1497 MHz, 13kW magnetron prototype aimed for the CEBAF klystron replacement with newly built low level RF (LLRF) controller for the amplitude modulation will be reported. Based on these R&D results, a 915MHz, 2×75kW CW industrial heating type magnetron system is being developed to be used for the high efficiency (>80%) RF source to the electron accelerator for industrial applications.
* H. Wang, et al,THPAL145, proceedings of IPAC 2018.
** M. Neubauer, et al,THPAL042, proceedings of IPAC 2018.
 
slides icon Slides WEXXPLS1 [8.033 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEXXPLS1  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEXXPLS3 Is it Possible to Use Additive Manufacturing for Accelerator UHV Beam Pipes? vacuum, laser, ECR, experiment 2240
 
  • G. Sattonnay, M. Alves, S. Bilgen, B.J. Bonnis, A. Gonnin, D. Grasset, S. Jenzer, F. Letellier-Cohen, B. Mercier, E. Mistretta
    LAL, Orsay, France
  • F. Brisset
    ICMMO, Orsay, France
 
  Funding: Work supported by a grant from IN2P3/CNRS, program I3D metal
Recently, additive manufacturing (AM) has revolutionized mechanical engineering by allowing the quick production of mechanical components with complex shapes. AM by selective laser melting (SLM) is an advanced manufacturing process which uses lasers to melt metal powders one layer at a time to produce final 3D components. This technology could be also used to make Ultra High Vacuum components. Therefore, we investigated in this work the reproducibility of AM 316L stainless steel properties for different specimen supplied by several manufacturers with the same SLM process. Clearly, the microstructure and therefore the mechanical properties of the investigated AM samples are different as a function of manufacturers: indeed, they are largely influenced by processing parameters, which produces heterogeneous and anisotropic microstructures that differ from traditional wrought counterparts. Samples were also submitted to bake cycles at high temperature, in order to check the structural stability of material properties after heat treatments. The outgassing rates and the secondary emission yield of vacuum components constructed from AM 316L were also measured. Finally, the possibility to use AM for accelerator beam pipes will be discussed.
 
slides icon Slides WEXXPLS3 [9.009 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEXXPLS3  
About • paper received ※ 01 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEYYPLS2 First Experimental Measurements of the Caustic Nature of Trajectories in Bunch Compressors linac, FEL, experiment, sextupole 2270
 
  • T.K. Charles
    The University of Melbourne, Melbourne, Victoria, Australia
  • J. Björklund Svensson
    Lund University, Lund, Sweden
  • A. Latina
    CERN, Geneva, Switzerland
  • S. Thorin
    MAX IV Laboratory, Lund University, Lund, Sweden
 
  Theoretical advancements describing density perturbations in accelerated charge particle beams, known as caustics, has been recently developed * This proceeding describes the first experimental measurements of the caustic nature of charged particle trajectories in a particle accelerator. Caustics by their nature are discontinuities that result from small continuous perturbations of an input. Under certain conditions, small density modulations will reliably produce striking changes in the corresponding output current profile. These current modulations can shift alone the bunch with varying higher-order longitudinal dispersion. The MAX IV linac double-bend achromats provide the perfect test bed for experimentally verifying how the caustic lines evolve. The natural amplification of small perturbations makes caustics an attractive diagnostic tool, and effective tool for characterise the bunch compressors. This approach also allows us to modify and improve the longitudinal charge profile, removing current spikes or creating tailor shaped current profiles.
* T.K.Charles et. al. Phys. Rev. Accel. Beams 19, 104402
 
slides icon Slides WEYYPLS2 [5.402 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLS2  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEZPLS1 Control of Laser Plasma Accelerated Electrons: A Route for Compact Free Electron Lasers laser, undulator, radiation, FEL 2280
 
  • M.-E. Couprie, T. André, F. Blache, F. Bouvet, F. Briquez, Y. Dietrich, J.P. Duval, M. El Ajjouri, A. Ghaith, C. Herbeaux, N. Hubert, C.A. Kitegi, M. Labat, N. Leclercq, A. Lestrade, A. Loulergue, O. Marcouillé, F. Marteau, D. Oumbarek Espinos, P. Rommeluère, M. Sebdaoui, K.T. Tavakoli, M. Valléau
    SOLEIL, Gif-sur-Yvette, France
  • I.A. Andriyash, S. Corde, J. Gautier, J.-P. Goddet, O. S. Kononenko, G. Lambert, K. Ta Phuoc, A. Tafzi, C. Thaury
    LOA, Palaiseau, France
  • S. Bielawski, C. Evain, E. Roussel, C. Szwaj
    PhLAM/CERLA, Villeneuve d’Ascq, France
  • V. Malka
    Weizmann Institute of Science, Physics, Rehovot, Israel
 
  The recent spectacular development of laser plasma ac- celerators that now can deliver GeV electron beams in an extremelyshortdistancemakesthemverypromising. Ap- plications for light sources based on undulator radiation and free electron laser appear as an intermediate step to move from an acceleration concept to an accelerator qual- ification. However, the presently achieved divergence and energy spread require some electron beam manipulations. The COXINEL test line was designed for enabling Free Elec- tron Laser operation with baseline reference parameters. It comprises variable permanent magnet quadrupoles for di- vergence handling, a magnetic chicane for electron energy sorting, a second set of quadrupole for chromatic focusing and an undulator for synchrotron radiation emission and/or free electron laser gain medium. The transport along the line is controlled [1]. The synchrotron radiation emitted by the undulator radiation is studied under different conditions of detection (CCD camera, spectrometer), electron beam manipulation and undulator parameters. These observations pave the way towards Laser Plasma Acceleration based Free Electron Laser.

[1] T. André et al., Control of laser plasma accelerated electrons for light sources, accepted in Nature Comm.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEZPLS1  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEZZPLS3 Longitudinal-Phase-Space Manipulation for Efficient Beam-Driven Structure Wakefield Acceleration wakefield, linac, simulation, acceleration 2296
 
  • W.H. Tan, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
  • A. Zholents, A. Zholents
    ANL, Argonne, Illinois, USA
 
  Funding: This work is funded by the United States Department of Energy awards DE-SC0018656 with Northern Illinois University and DE-AC02-06CH11357 with Argonne National Laboratory.
Collinear beam-driven structure wakefield acceleration (SWFA) is an advanced acceleration technique that could support the compact generation of high-energy beams for future multi-user x-ray free-electron-laser facilities*. Producing an ideal shaped drive beam through phase space manipulation is crucial for an efficient SWFA. Controlling the final longitudinal-phase space of the drive beam necessitate staged beam manipulations during acceleration. This paper describes the preliminary design of an accelerator beamline capable of producing drive beam with tailored current distribution and longitudinal-phase-space correlation. The proposed design is based on simple analytical models combined in a 1-D longitudinal beam-dynamics simulation tracking program supporting forward and backward (time reversal) tracking.
* A. Zholents, et al., Dielectric wakefield accelerator to drive the future FEL light source
 
slides icon Slides WEZZPLS3 [2.869 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEZZPLS3  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPMP010 8 Gev Slow Extraction Beam Test for Muon to Electron Conversion Search Experiment at J-PARC kicker, extraction, timing, injection 2322
 
  • M. Tomizawa, Y. Arakaki, Y. Fukao, Y. Hashimoto, Y. Igarashi, T. Kimura, S. Mihara, M. Moritsu, S. Murasugi, R. Muto, H. Nishiguchi, K. Okamura, Y. Shirakabe, K. Ueno, E. Yanaoka
    KEK, Ibaraki, Japan
  • Y. Fujii
    Monash University, Faculty of Science, Clayton, Victoria, Australia
  • F. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
 
  A muon to electron conversion search experiment (COMET) planned at J-PARC needs 8 GeV bunched proton beams with a continuous 1 MHz pulse structure. In this experiment, an intensity ratio of the residual to the main pulsed beam, which is expressed as extinction, should be less than the level of 10-10. In RUN78 (Jan. to Feb., 2018), we have succeeded in slow extraction of 8 GeV protons with 7.3×1012 ppp, satisfies the COMET phase-I requirement, and the extinction derived from a timing measurement of secondary particles from the target shows a promising result. A mechanism to explain the measured extinction will be also described in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP010  
About • paper received ※ 01 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPMP029 Systematic Optics Studies for the Commissioning of the AWAKE Beamline optics, plasma, experiment, quadrupole 2383
 
  • C. Bracco, B. Goddard, I. Gorgisyan, M. Turner, F.M. Velotti, L. Verra
    CERN, Geneva, Switzerland
  • M. Aiba
    PSI, Villigen PSI, Switzerland
 
  The commissioning of the AWAKE electron beam line was successfully completed in 2018. Despite a modest length of about 15 m, this low-energy line is quite complex and several iterations were needed before finding satisfactory agreement between the model and the measurements. The work allowed to precisely predict the size and positioning of the electron beam at the merging point with the protons inside the plasma cell, where no direct measurement is possible. All the key aspects and corrections which had to be included in the model, precautions and systematic checks to apply for the correct setup of the line are presented. The sensitivity of the ~18 MeV electron beam to various perturbations, like different initial optics parameters and beam conditions, energy jitter and drifts, earth’s magnetic field etc., is described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP029  
About • paper received ※ 10 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPMP049 Simulations of Beam Shaping for Dark Matter Experiments at LCLS-II experiment, FEL, optics, quadrupole 2443
 
  • Y.M. Nosochkov, C. Hast, T.W. Markiewicz, L.Y. Nicolas, T.O. Raubenheimer, M. Santana-Leitner
    SLAC, Menlo Park, California, USA
 
  Funding: * Work supported by the U.S. DOE Contract DE-AC02-76SF00515.
A new transfer beamline, called S30XL, and an experimental facility are proposed to be built at SLAC, taking advantage of the LCLS-II free electron laser (FEL) under construction. The S30XL will operate parasitically to the FEL by extracting the unused low intensity 4-GeV LCLS-II bunches into the existing A-line and the End Station-A (ESA). This provides a unique capability of multi-GeV nearly continuous electron beam for a variety of HEP experiments, in particular the dark matter search experiments. The latter require a very low beam current ranging from pA to micro-A, as well as a large beam spot at the detector. The necessary beam shaping will be performed using spoilers and collimators in the A-line, and by optimizing the optics. FLUKA and elegant codes are used to generate and track the beam into the ESA.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP049  
About • paper received ※ 16 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPGW004 Wire Scanner for High Intensity Ion Beam* quadrupole, focusing, LEBT, vacuum 2466
 
  • A. Beller, D. Bondoux, F. Bouly
    LPSC, Grenoble Cedex, France
 
  Funding: Part of this work supported by the European Atomic Energy Community (EURATOM) H2020 Program under grant agreement n°662186 (MYRTE project).
The goal of the project is to develop a Wire-Scanner compatible with low energy - high intensity ion beams and adaptable to various beam chamber diameters. The purpose is to obtain the 2D beam profile by passing measurement wires through the beam. Thanks to a high speed passage of measurement wires, it allows to avoid "disrupting" the beam passage, and can be considered as a non-destructive diagnosis. Wires heating and measuring issues have been solved by using tungsten wires kept in tension by a mechanical system. All driving and signal measurements are performed by a PXI based system. The synchronization of the measurements is guaranteed by an analog input board recovering the wires current and the translator position, the latter being carried out by a laser sensor. Besides this technological aspect, an optimization algorithm for beam profile reconstruction from measured data under Gaussian hypothesis has been developed. The standalone system and first experimental results are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW004  
About • paper received ※ 13 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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WEPGW008 Fiber Beam Loss Monitors at MAMI beam-losses, experiment, detector, FPGA 2477
 
  • M. Dehn, P. Achenbach, I. Beltschikow, O. Corell, P. Gülker, W. Lauth, M. Mauch
    IKP, Mainz, Germany
 
  Funding: Work supported by DFG (CRC 1044) and the German federal state of Rhineland-Palatinate
At the 14 MeV stage of the 1508 MeV cascaded racetrack microtron accelerator Mainz Microtron (MAMI) fiber beam loss monitors with multi-anode photomultipliers (ma-PMTs) have been successfully tested. The combination of individual fibers for each recirculation beam pipe with ma-PMTs allows to detect beam losses turn by turn in the order of 10-4 or even lower which cannot be accomplished with the already existing beam diagnostics. This kind of beam loss monitor might be an alternative to ionisation chambers for the new Mainz Energy Recovering Superconducting Accelerator (MESA).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW008  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW009 DEVELOPMENT OF THE ELECTRON BEAM PROBE FOR HADRON SYNCHROTRONS. simulation, hadron, proton, experiment 2480
 
  • M. Droba, C. Hübinger, O. Meusel, H. Podlech, K.I. Thoma
    IAP, Frankfurt am Main, Germany
  • O.R. Jones, M. Wendt, F. Zimmermann
    CERN, Meyrin, Switzerland
 
  Funding: BMBF 05P18RFRB2
Non-invasive diagnostics is essential to get important information about intense hadron beams, e.g. the transverse beam profile, which is indispensable in order to attain high brilliance and luminosity for upgrades on present machines and for future projects. Furthermore, it can be used to optimise parameter settings in environment of the running machine. An electron beam probe (EBP) is a beam diagnostics instrument which scans a low energy, low current electron beam through a hadron beam and obtains information from the detected response. The electrons are shot perpendicular through the hadron beam to be examined, which causes deflection in the beam potential of the intense hadron bunch, that needs to be detected and further analysed. We propose to build the EBP scanning apparatus for synchrotrons under ultra-high vacuum condition. The results of multi particle simulations evaluating limitations the expected measurement potential and limitations are presented. This work will be performed in collaboration with CERN.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW009  
About • paper received ※ 11 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPGW010 Diagnostics and First Beam Measurements at FLUTE laser, cathode, diagnostics, experiment 2484
 
  • T. Schmelzer, A. Bernhard, E. Bründermann, A. Böhm, S. Funkner, B. Härer, I. Križnar, A. Malygin, S. Marsching, W. Mexner, A.-S. Müller, M.J. Nasse, G. Niehues, R. Ruprecht, M. Schuh, N.J. Smale, P. Wesolowski, M. Yan
    KIT, Karlsruhe, Germany
 
  FLUTE (Ferninfrarot Linac- Und Test-Experiment) is a compact versatile linear accelerator at the Karlsruhe Institute of Technology (KIT). It serves as a platform for a variety of accelerator studies as well as a source of strong ultra-short THz pulses for photon science. In the commissioning phase of the 7 MeV low energy section the electron bunches are used to test the different diagnostics systems installed in this section. An example is the split-ring-resonator-experiment. In this contribution we report on the commissioning status of the beam diagnostics and present first beam measurements at FLUTE.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW010  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPGW011 Development of a Silicon Strip Detector for Novel Accelerators at Sinbad detector, simulation, acceleration, linac 2487
 
  • S. Jaster-Merz, R.W. Aßmann, F. Burkart, U. Dorda, U. Kraemer, E. Panofski, M. Stanitzki
    DESY, Hamburg, Germany
 
  At the SINBAD facility (DESY Hamburg), novel particle acceleration techniques like dielectric laser acceleration (DLA) structures will be tested using the ARES linac. Due to the small size of these structures, the accelerated electron beams only have a very low (sub-pC) charge. To determine the energy distribution of these beams, a silicon strip detector for the ARES linac spectrometer is currently under development. This detector fulfils the requirements of high spatial resolution for low charge density beams. The detector consists of two 1 cm x 1 cm silicon strip sensors and readout components. The design of the detector, its components and an estimate of its behaviour for a specific electron beam distribution are presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW011  
About • paper received ※ 17 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPGW012 Vertical Beam Size Measurement Methods at the BESSY II Storage Ring and their Resolution Limits diagnostics, storage-ring, polarization, detector 2491
 
  • M. Koopmans, F. Armborst, J.G. Hwang, A. Jankowiak, P. Kuske, M. Ries, G. Schiwietz
    HZB, Berlin, Germany
 
  With the VSR upgrade for the BESSY II electron storage ring* bunch resolved diagnostics are required for machine commissioning and to ensure the long-term quality and stability of operation. For transverse beam size measurements we are going to use an interferometric method, which will be combined with a fast gated intensified CCD camera at a subsequent stage. A double-slit interferometer method has already been verified successfully at BESSY II**. In addition first 2D bunch resolved measurement tests have been performed at the dedicated diagnostics beamline for bunch length measurements. Measurements of the interferometer and X-ray pinholes as function of a vertical electron beam excitation are compared in this paper.
* A. Jankowiak et al., Germany, June 2015. DOI: 10.5442/R0001
** M. Koopmans et al., in Proc. IPAC’17, paper MOPAB032, 2017
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW012  
About • paper received ※ 09 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPGW014 A Non-Invasive THz Spectrometer for Bunch Length Characterization at European XFEL FEL, radiation, diagnostics, factory 2495
 
  • N.M. Lockmann, C. Gerth, P. Peier, B. Schmidt, S. Wesch
    DESY, Hamburg, Germany
 
  The European X-ray Free-Electron Laser provides one of the most powerful X-ray laser pulses to a wide range of experiments. These experiments strongly benefit from the exact knowledge of the electron bunch current profile and demand for stable and shortest-possible pulse lengths. During the 2018 summer shutdown, the 4-staged grating spectrometer CRISP* has been installed at a diffraction radiation (DR) beamline just upstream of the undulator beamline switchyard. The DR at final electron beam energies of up to 17.5 GeV enables non-invasive bunch length characterization based on form factor measurements down to a few micrometers. Fast detectors and electronics allow for the characterization of the whole bunch train with repetition rates above 1 MHz. This contribution will present commissioning results of the THz beamline as well as first measured form factors and reconstructed electron current profiles.
* S. Wesch et al., Nuclear Instruments and Methods in Physics Research Section A 665 (2011) pp. 40-47
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW014  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPGW018 An Ultra-Fast and Wide-Spectrum Linear Array Detector for High Repetition Rate and Pulsed Experiments detector, experiment, radiation, synchrotron 2504
 
  • M.M. Patil, E. Bründermann, M. Caselle, S. Funkner, B. Kehrer, A.-S. Müller, G. Niehues, W. Wang, M. Weber
    KIT, Karlsruhe, Germany
  • C. Gerth
    DESY, Hamburg, Germany
  • D.R. Makowski, A. Mielczarek
    TUL-DMCS, Łódź, Poland
 
  Funding: "BMBF: is funded by the BMBF contract number: 05K16VKA" (2016-2018) ("NeoDyn")
Photon science research at accelerators is influenced radically by the developments of sensor and readout technologies for imaging. These technologies enable a wide range of applications in beam diagnostics, tomography and spectroscopy. The repetition rate of commercially available linear array detectors is a limiting factor for the emerging synchrotron applications. To overcome these limitations, KALYPSO(Karlsruhe Linear arraY detector for MHz rePetition rateSpectrOscopy), an ultra-fast and wide-field of view linear array detector operating at several mega-frames per second(Mfps), has been developed. A silicon micro-strip sensor is connected to custom cutting-edge front end ASICs to achieve unprecedented frame rate in continuous readout mode. In this contribution, the third generation of KALYPSO will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW018  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW022 A Numerical Analysis to Choose the Most Performing Optical Transition Radiation Screen target, radiation, brightness, site 2518
 
  • F. Cioeta, D. Alesini, A. Variola
    INFN/LNF, Frascati (Roma), Italy
  • M. Ciambrella, A. Mostacci
    Sapienza University of Rome, Rome, Italy
  • D. Cortis, M. Marongiu, V. Pettinacci
    INFN-Roma, Roma, Italy
 
  Optical Transition Radiation (OTR) screen represents the most appropriate instrument to measure and verify the characteristics of a beam spot size produced by a particle accelerator. In order to measure such beam properties, OTR screens have to sustain thermal and mechanical stresses due to the energy that several bunches deposit. Owing to these requirements, it is essential to identify the more suitable material to optimize the OTR dimensions and to get reliable measures from the diagnostic system. In this paper, we describe a numerical procedure to choose the most performing material taking into account the physical requirements of a multi-bunch high brightness. The procedure is based on a dedicated ANSYS script able to evaluate the fatigue life time of the material considering a high number of thermal cycles generated by several bunches. The main characteristic of this script is the capability to simulate the real thermal and mechanical effect on the target that the hitting particle beam produces. The numerical procedure has been applied to compare the performance of three relevant materials-Aluminium, Silicon and Graphite simulating a beam hitting with well-known parameters.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW022  
About • paper received ※ 13 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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WEPGW027 Evaluation and Reduction of Influence of Filling Pattern on X-Ray Beam Position Monitors for SPring-8 space-charge, storage-ring, operation, undulator 2526
 
  • H. Aoyagi, Y. Furukawa, S. Takahashi
    JASRI/SPring-8, Hyogo, Japan
 
  SPring-8 constantly provides various several-bunch mode operations, which combine single bunches and train bunches. Recently, influence of filling pattern on the accuracy of the XBPMs became apparent, so that we started a systematic evaluation. It was found that the influence was caused by suppression of current signal due to space charge effect, which could be quantified by observing a behaviour of the current signal while changing the voltage of photoelectron collecting electrodes. In order to mitigate the space charge effect, we examined some methods, such as, changing operation parameters of the XBPMs and the undulators. As a result, we successfully reduced the influence of filling pattern.
* H. Aoyagi et al., Proc. of PASJ2018 WEOL06
http://www.pasj.jp/webpublish/pasj2018/proceedings/PDF/WEOL/WEOL06.pdf
http://www.pasj.jp/webpublish/pasj2018/proceedings/PDF/WEOL/WEOL06oral.pdf
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW027  
About • paper received ※ 10 May 2019       paper accepted ※ 17 May 2019       issue date ※ 21 June 2019  
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WEPGW030 Beam Profile Monitor for Slow Extracted Beam Using Multi-Layered Graphene at J-PARC target, extraction, proton, real-time 2532
 
  • Y. Hashimoto, Y. Hori, R. Muto, M. Tomizawa, T. Toyama, M. Uota
    KEK, Tokai, Ibaraki, Japan
  • M. Endo, H. Sakai
    Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
  • M. Murakami, K. Murashima, M. Tachibana, A. Tatami
    KANEKA, Osaka, Japan
 
  Extracted-beam profiles in slow extraction at J-PARC has been measured by using secondary electrons emitted from a target array made by multi-layered graphen, in real time during spill time of around 2 seconds. The target array consists of 20 ribbons with width of 1 mm, pitch of 2 mm, and thickness of 1.1 micron. Secondary-electron current at each channel is measured by a current amplifier having sensitivity more than 1 pA. These configuration produces useful information for beam dynamics in slow extraction. We have set this monitor at the entrance of a septum magnet, then we can also measure the last few-turns beam with the extracted beam simultaneously. We will discuss about features of this instrument and recent beam study with 51 kW extracted-beams.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW030  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW031 Measurement of Cherenkov Diffraction Radiation from a Short Electron Bunches at t-ACTS radiation, experiment, photon, detector 2536
 
  • S. Ninomiya, H. Hama, F. Hinode, K. Kanomata, S. Kashiwagi, S. Miura, N. M. Morita, T. Muto, I. Nagasawa, K. Nanbu, H. Saito, K. Takahashi, H. Yamada
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
 
  Cherenkov Diffraction Radiation (ChDR) can be considered as a tool of non-destructive beam diagnostics. It also has the feature that the photon flux of ChDR is proportional to the thickness of the dielectric used as the radiator and can be much larger than ordinary diffraction radiation. An experimental set-up for the measurement of coherent ChDR from short electron bunches of about 100 fs is being prepared at t-ACTS, Tohoku University. Results of a basic experimental study about coherent ChDR will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW031  
About • paper received ※ 16 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPGW033 Development of the Bunch Shape Monitor Using the Carbon-Nano Tube Wire high-voltage, vacuum, operation, DTL 2543
 
  • R. Kitamura, N. Hayashi, K. Hirano, Y. Kondo, K. Moriya, H. Oguri
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • K. Futatsukawa, T. Miyao, M. Otani
    KEK, Ibaraki, Japan
  • S. Kosaka, Y. Nemoto
    Nippon Advanced Technology Co., Ltd., Tokai, Japan
 
  A bunch shape monitor (BSM) is one of the important instruments to measure the longitudinal phase space distribution. The information of the bunch length measured by the BSM is useful to tune phases of the accelerating cavities in the linear accelerator. For example, in the J-PARC linac, three BSM’s using the tungsten wire are installed and tested at the ACS section to measure the bunch shapes between the accelerating cavities. However, this conventional BSM is hard to measure the bunch shape of H beam with 3 MeV at the beam transport between the RFQ and DTL sections, because the wire is broken around the center region of the beam. The new BSM using the carbon-nano-tube (CNT) wire is being developed to be able to measure the bunch shape of the H beam with 3 MeV. One challenge to introduce the CNT wire for the BSM is the measure to the discharge. The careful attention should be paid to apply the high voltage of 10 kV to the CNT wire. The several measures are taken to suppress the discharge from the wire and operate the CNT-BSM. This presentation reports the current status of the development and future prospective for the CNT-BSM.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW033  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPGW034 Development of L-band Cavity BPM for STF cavity, electronics, linac, simulation 2547
 
  • S.W. Jang, E.-S. Kim
    KUS, Sejong, Republic of Korea
  • H. Hayano
    KEK, Ibaraki, Japan
 
  We developed a L-band beam position monitor with position resolution of few hundred nano meter for Superconducting Test Faciliy(STF) in KEK. The L-band BPM was developed to install inside the superconducting cryomodule of STF in KEK and it’s test was performed at Accelerator Test Facility in KEK. The three L-band BPM are fabricated and installed at the end of Linac of ATF. The position resolution measurement was performed with new L-band BPM electronics. In this talk, we will describe about the development of L-band BPM and its beam test results of nano meter level beam position resolution with new electronics system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW034  
About • paper received ※ 15 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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WEPGW037 Development of a Dense Gas Sheet Target for a 2D Beam Profile Monitor experiment, simulation, vacuum, target 2554
 
  • N. Ogiwara, Y. Hori
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • Y. Hikichi, J. Kamiya, M. Kinsho
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • I. Yamada
    Doshisha University, Graduate School of Engineering, Kyoto, Japan
 
  We have been developing a dense gas sheet target to realize a non-destructive and fast-response beam profile monitor for the accelerators in J-PARC. The beaming effect in vacuum science and technology has been employed for making a gas sheet. The gas sheet with a thickness of ~ 1 mm and the density of 2 x 10-4 Pa was successfully obtained. Then, we have successfully measured the profiles of the 400 MeV H ion beam in J-PARC linac by detecting the ions generated through the collision of this gas sheet to the H beam. This time, we have developed the gas sheet with the density of more than 10-3 Pa using a circular slit. The details of the new gas sheet generator will be shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW037  
About • paper received ※ 20 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPGW038 Beam Control and Monitors for the Spiral Injection Test Experiment injection, experiment, solenoid, site 2557
 
  • M.A. Rehman
    Sokendai, Ibaraki, Japan
  • K. Furukawa, H. Hisamatsu, T. Mibe, H. Nakayama, S. Ohsawa
    KEK, Ibaraki, Japan
  • H. Iinuma
    Ibaraki University, Hitachi, Ibaraki, Japan
 
  A new experiment at J-PARC (E34) is under construction in order to measure the muon’s g-2 to unprecedented precision of 0.1 ppm and electric dipole moment up to the sensitivity of 10-21 e.cm in order to explore new physics beyond the standard model. A novel three-dimensional spiral injection scheme has been devised to inject and store the beam into a small diameter MRI-type storage magnet for E34. The new injection scheme features smooth injection with high storage efficiency for the compact storage magnet. However, spiral injection scheme is an unproven idea, therefore, a Spiral Injection Test Experiment (SITE) is underway to establish this injection scheme. The SITE is consist of 80 keV thermionic electron gun, two-meter-long beamline, and a solenoidal storage magnet. In order to match the beam with the solenoidal field, several optical elements have been placed on the beamline to control the beam phase space. The DC electron beam spiral track has been confirmed by the de-excitation of the nitrogen gas in the vacuum chamber of the storage magnet. A current monitor system has been developed in order to extract the beam current and geometrical information of three-dimensional trajectory. An electric chopper system to produce the pulsed beam and beam monitors to detect the pulsed beam will also be discussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW038  
About • paper received ※ 01 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW039 Multi-Ribbon Profile Monitor for High Power Proton Beam at J-PARC MR Abort Line target, proton, extraction, emittance 2561
 
  • K. Sato
    The University of Tokyo, Graduate School of Science, Tokyo, Japan
  • E. Hamada, Y. Hashimoto, S. Igarashi, T. Koseki, Y. Sato
    KEK, Tsukuba, Japan
 
  Japan Proton Accelerator Research Complex (J-PARC) Main Ring (MR), the world-class high intensity proton synchrotron, provides proton beam to two experimental facilities with two extraction modes: Fast extraction (FX) and Slow extraction (SX). The number of protons per pulse (ppp) in MR recorded the world highest value of 2.6×1014 in the FX mode. Now we are planning to increase the ppp further up to 3.3×1014 in near future. The beam profile is one of the most important parameters to discuss the high intensity beam dynamics in MR. Monitors using multi-wires / ribbons are effective to measure the beam profile with good accuracy and wide dynamic range. However, they cause significant beam losses by interactions with high-intensity circulating beam in synchrotrons. Recently, we installed new multi-ribbon profile monitor (MRPM) in an abort line in MR. The abort line is one of the extracted beam lines of the FX system. It has a quadrupole doublet which is called Abort Q and transports extracted beam to a beam dump. The FX system can extract the circulating beam in MR with an arbitrary energy. Performing the single-pass measurement with MRPM and changing the transfer matrix by sweeping field strength of Abort Q, the emittance of the extracted beam can be measured. In this paper, we present the design, manufacturing, and results of the first beam test of newly installed MRPM system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW039  
About • paper received ※ 01 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPGW041 Development of a Gas Distribution Measuring System for Gas Sheet Beam Profile Monitor injection, experiment, detector, simulation 2567
 
  • I. Yamada
    Doshisha University, Graduate School of Engineering, Kyoto, Japan
  • Y. Hikichi, J. Kamiya, M. Kinsho
    JAEA/J-PARC, Tokai-mura, Japan
  • N. Ogiwara
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
 
  The beam profile monitor is needed for measuring one of the beam parameters of high intensity accelerator to avoid radioactivating the systems. A monitor with sheet-shaped gas that can measure the beam profile nondestructively in two dimensions is developing. One of issues to introduce the monitor in accelerator is that the gas distribution is not uniform. Obtaining correct beam profile data needs to measure the gas distribution data because signal from the monitor is in proportion to beam intensity and gas distribution. A system analyzing distribution of ions produced from the gas using electron beam to measuring gas distribution in three dimensions is developing. An electron gun that produces ideal narrow beam, electrodes that forms parallel electric field toward micro-channel plate(MCP), and phosphor constitute the system. The electron beam that ionizes the gas which needs to be measured, produced ions are induced to MCP, and image on phosphor gives gas distribution data. In preliminary experiment for inspecting the measuring principle, experimental results agreed with simulation. The details of this system and the results of gas measuring experiment are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW041  
About • paper received ※ 28 April 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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WEPGW044 Study on the Influence of Beam Transverse Position on the Cavity Bunch Length Measurement cavity, simulation, dipole, laser 2578
 
  • Q. Wang, S.M. Jiang, Q. Luo, B.G. Sun
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  Funding: Work supported by National Key R&D Program of China (Grant No. 2016YFA0401900 and No. 2016YFA0401903) and The National Natural Science Foundation of China (Grant No. U1832169 and No. 11575181).
Monopole modes in the resonant cavity are wildly used to obtain the beam current and the bunch length, while dipole modes are used to measure the beam transverse position. It is generally recognized that the monopole modes are independent of the beam transverse offset. In this paper, the influence of beam transverse offset on the bunch length measurement using monopole modes is analyzed. The simulation results show that the relative error of the bunch length measurement is less than 1 % when the beam offset is within 1 mm.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW044  
About • paper received ※ 25 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPGW045 Application of Clustering by Fast Search and Find of Density Peaks to Beam Diagnostics at SSRF SRF, GUI, storage-ring, diagnostics 2581
 
  • R. Jiang, Y.B. Leng
    SSRF, Shanghai, People’s Republic of China
 
  With the increased technological complexity of accelera-tors, meeting the demand of beam diagnostics and opera-tion need more powerful and faster methods. And detect-ing the accuracy and stability of beam position moni-tors(BPMs) are important for all kinds of measurement systems and feedback systems in particle accelerator field. As an effective tool for data analysis and automa-tion, the machine learning methods had been used in accelerator physics field, recently. Among machine learn-ing methods, the clustering by fast search and find of density peaks as a typical unsupervised learning algo-rithms could be performed directly without training in arbitrary accelerator systems and could discover un-known patterns in the data. This paper used clustering by fast search and find of density peaks to detect faulty beam position monitor or monitoring beam orbit stability by analysis five typical parameters, that is beta oscilla-tion of X and Y direction(BetaX and BetaY), transverse oscillation of X and Y direction(AmpX and AmpY) and energy oscillation(AmpE). The results showed that cluster-ing by fast search and find of density peaks could classi-fy beam data into different clusters on the basis of their similarity. And that, aberrant run data points could be detected by decision graph. Morever, analysis results demonstrate the characteristic parameters AmpE, AmpX and BetaX amplitude have the same effect to distinguish the faulty BPMs and the AmpY and the BetaY amplitude are also.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW045  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW051 Designing of a Solenoid Lens for the Application to a Compact Electron Beam Testing Bench solenoid, gun, space-charge, cathode 2591
 
  • S.Y. Lu, G. Feng, T. Hu, X.D. Tu, Y.Q. Xiong, P. Yang
    HUST, Wuhan, People’s Republic of China
 
  To calculate beams transport is vital for designing vacuum pipe and arranging focusing elements for each electron beam line system. Space charge effects of a low-energy, high-intensity DC electron beam focused by a solenoid lens with bucking coil are investigated theoretically in this paper. A second-order equation is numerical solved for the beam envelope focused by a short solenoid lens. In addition, a conventional transfer matrix of solenoid is not applicable to low-energy, high-intensity electron beams because the strong space charge effects are ignored. By cutting a solenoid into several segments, we have derived a micro-transfer matrix which takes space charge fields into account, and a complete beam envelope for a transport system. A simulation is used to verify our theoretical calculation results, and corresponding discussions are given in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW051  
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPGW053 Study with Wire Scanner and Beam Loss Monitor at CSNS-LINAC MEBT, experiment, linac, neutron 2598
 
  • J.L. Sun, R.Y. Qiu, T. Yang
    IHEP CSNS, Guangdong Province, People’s Republic of China
  • J.M. Tian, T.G. Xu, Zh.H. Xu, L. Zeng
    IHEP, Beijing, People’s Republic of China
 
  China Spallation Neutron Source (CSNS) consists of 80 MeV H LINAC, 1.6 GeV RCS, RTBT line and one target. Many wire scanners and beam loss monitors (BLM) distributed along the LINAC and the RTBT for the profile and beam loss measurement. For the wire scanner, signal on the wire induced by the secondary electron is used for the profile measurement. Signal lost may happen when the wire or the signal chain shorted, thus a backup readout chain is required for the accident condition. As for the BLM, it is difficult to do the online calibration to see how sensitive the monitor is. Based on the two requests above, a crosscheck study was carried out recently, one wire scanner and the BLM next to it were chose at LINAC and RTBT. Both wire signal and BLM signal were recorded while the wire scanner crossing the beam. We found these two type of signals have the same accuracy for the profile measurement, and ~ 1 μA beam loss induced by the wire disturbance can be detected. Also thermal electron emission suspected happening during the measurement. More detailed experiment will be carried out in December. Secondary electron emission efficiency of the tungsten wire and thermal electron emission rate will be verified then.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW053  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW055 Beam Longitudinal Distribution Reconstructed by GESPAR Method at CAEP THz FEL radiation, FEL, laser, experiment 2602
 
  • D. Wu, T.H. He, P. Li, J. Liu, X. Luo, Q. Pan, L.J. Shan, X. Shen, J. Wang, D.X. Xiao, L.G. Yan, P. Zhang, K. Zhou
    CAEP/IAE, Mianyang, Sichuan, People’s Republic of China
 
  Funding: Work supported by National Natural Science Foundation of China with grant (11505173, 11505174, 11575264, and 11605190)
Coherent radiation can be used to measure the longitudinal distribution of the electron beam bunch of any length, as long as the coherent radiation spectrum can be measured. In many cases, the Kramers-Krönig relationship is used to reconstruct the temporal distribution of the beam from the coherent radiation spectrum. However, the extrapolation of the low frequency will introduce the uncertainty of the reconstruction. In this paper, GrEedy Sparse PhAse Retrieval (GESPAR) method was used to reconstruct the beam longitudinal distribution measured by coherent transition radiation on the THz FEL facility of China Academy of Engineering Physics. The results indicate that the GESPAR method works well for the complex and ultrashort distribution. It will be an effective tool to accurately measure the femtosecond bunch temporal structure.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW055  
About • paper received ※ 14 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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WEPGW060 Theoretical Analysis and Experimental Design of Terahertz Single-Pulse Picking based on Plasma Mirror plasma, laser, target, FEL 2613
 
  • S.Y. Zhao, M. Li, P. Li, J. Wang, D. Wu, X. Yang
    CAEP/IAE, Mianyang, Sichuan, People’s Republic of China
 
  Funding: Work supported by National Natural Science Foundation of China with grant (11505173, 11505174, 11575264, and 11605190)
China Academy of Engineering Physics terahertz free electron laser (CTFEL) facility needs a terahertz switch for picking of single-pulse, which can facilitate the experiments that require high peak power but low average power. At present, many researches mainly focus on resonant tunneling effects, tunable metamaterials such as graphene and vanadium dioxide, nonlinear modulation based on the principle of all-optical switching, etc. However, the frequency range of these terahertz switches is generally not applicable to CTFEL(1.87-2.3THz). In this paper, self-induced plasma switching technology is applied to CTFEL. Single-pulse is reflected by a dense plasma in a Ge, Al or fused quartz slab that is photoexcited by laser system. Theoretical analysis and numerical simulation demonstrate the feasibility of the experiment. In addition, schematic layout of the experiment setup and specifications of the major instruments are given.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW060  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPGW063 Fiber-based Cherenkov Beam Loss and Beam Profile Monitor at BEPC II linac, operation, instrumentation, beam-losses 2622
 
  • L. Yu, Y.F. Sui, L. Wang, D.C. Zhu
    IHEP, Beijing, People’s Republic of China
 
  A fiber-based Cherenkov beam loss monitor (CBLM) consisting of large core (400μm), long (50 m) multimode fibers, has been developed as an long-range detection tool for the BEPCII: primarily designed for radiation safety in order to limit the dose outside the shielding of the machine, this monitor also serves as an tool to measure beam profile with the wire sccaner. In this paper, principal of operation, instrumentation and programming of these CBLMs are discussed. Some results of beam loss and beam profile measurement with these CBLMs are also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW063  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPGW067 The Study of Beam-Beam Effects on BINP Electron-Positron Colliders injection, positron, detector, luminosity 2629
 
  • V.M. Borin, G.V. Karpov, O.I. Meshkov, D.N. Shatilov, D.B. Shwartz, M.V. Timoshenko
    BINP SB RAS, Novosibirsk, Russia
  • V.L. Dorokhov
    BINP, Novosibirsk, Russia
 
  The beam-beam effects depending on the beams current and energy were studied at electron-positron colliders VEPP-2000 and VEPP-4M by the set of different diagnostics: the streak camera, optical dissector, BPM. The beam transverse profiles as well as longitudinal motion were acquired from the moment of a first collision of the beams in the interaction point up to the establishment of an equilibrium state. The spectra of the beams oscillation during this process as well as influence of the transverse feedback were studied. The obtained results are compared with a numerical simulations and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW067  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW068 Measurements of Beam Parameters at the Last Track of the ERL-Based Novosibirsk Free Electron Laser FEL, radiation, diagnostics, undulator 2632
 
  • V.M. Borin, Ya.V. Getmanov, A.S. Matveev, O.I. Meshkov, O.A. Shevchenko, N.A. Vinokurov
    BINP SB RAS, Novosibirsk, Russia
  • V.L. Dorokhov
    BINP, Novosibirsk, Russia
  • Ya.V. Getmanov
    NSU, Novosibirsk, Russia
  • A.I. Mickailov
    Budker INP & NSU, Novosibirsk, Russia
 
  Parameters and dynamics of the electron beam of the Novosibirsk infrared Free Electron Laser are studied. The Novosibirsk FEL is based on the multi-turn energy recovery linac (ERL). The ERL operate in CW mode with an average beam current about 5 mA. Therefore non-destructive beam diagnostic methods are preferable. The beam energy at the last track of the ERL is 42 MeV. As a result, significant part of synchrotron radiation from bending magnets is in the visible range and can be used for diagnostic purposes. The transverse beam dimensions were measured with the optical diagnostics before (transition radiation) and after (synchrotron radiation from a bending magnet) the undulator applied for generation of middle-infrared coherent radiation. The obtained data are used to calculate the beam energy distribution and emittance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW068  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW072 Evaluation of Pilot-Tone Calibration Based BPM System at Elettra Sincrotrone Trieste electronics, FPGA, injection, diagnostics 2638
 
  • P. Leban, M. Žnidarčič
    I-Tech, Solkan, Slovenia
  • G. Brajnik, R. De Monte
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  Stable and reliable beam position measurement is of paramount importance for the present and future light sources. Stabilization with a pilot-tone technique was developed by Elettra Sincrotrone Trieste and supported in the commercial BPM electronics Libera Spark. Both system components (the pilot-tone front-end and BPM electronics) are controlled through a common software interface which is compatible with TANGO, EPICS and LabVIEW/MATLAB clients. The system provides a reliable self-diagnostics, cable and button diagnostics and drift compensation. This paper presents results from beam measurements under different environmental and beam conditions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW072  
About • paper received ※ 13 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW080 Design of Resonant Stripline BPM for an IR-FEL Project at NSRL FEL, dipole, vacuum, emittance 2665
 
  • X.Y. Liu, B.G. Sun
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  • M. Bopp, M.M. Dehler, X.Y. Liu, A. Scherer
    PSI, Villigen PSI, Switzerland
 
  Funding: Work supported by the National Science Foundation of China (11575181, 21327901, 11705203); X. Y. Liu was supported by the China Scholarship Council for a 2-year study at PSI (Grant No. 201706340057).
This paper presents the design of a 476MHz resonant stripline beam position monitor (BPM) for an IR-FEL machine at NSRL. This type of BPM was developed based on stripline BPM by moving the coupling feedthrough closer to the short end downstream. This modification introduces a resonance that gives this BPM a better capability to detect lower beam currents compared to broadband devices like button and stripline BPM. Meanwhile, the change is small enough to use the same type of electronics [1-3]. In the following sections, the basic principle, nonlinear effect, sensitivity, the filtered sum and difference signals, and the mechanical design of this BPM will be mainly discussed.
Email address: xiaoyu.liu@psi.ch
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW080  
About • paper received ※ 10 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPGW087 Control System Studio to Monitor Front End and Beamlines Status as well as Light Source Stability status, operation, controls, photon 2687
 
  • W.Y. Lin, B.Y. Chen, C.S. Huang, C.H. Kuo, T.Y. Lee
    NSRRC, Hsinchu, Taiwan
 
  The primary task during a shift change at the Taiwan Photon Source Accelerator Operations team is to know the exact status of the machine, so that problems can be discovered immediately and solved when the machine behaves abnormal. To provide a stable beam during top-up operation, it is necessary to monitor closely the stability of the light source, of front end areas and beamlines. Should any abnormality occur, the operator would initiate initial troubleshooting and adjustments, inform users and sub-system staff members and perform subsequent first anal-yses and system optimizations. In this article, we describe how to sort through the nec-essary information with the Control System Studio (CSS) design page. There are currently seven beamlines in operation at the Taiwan Photon Source (05, 09, 21, 23, 25, 41, 45) and more new beamlines will be added in the future. Com-pared with other tools, CSS is intuitive and easy to revise. No matter weather adding new parameters or changing settings, the operation team can quickly get familiar with the machine status and perform an interface upgrade.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW087  
About • paper received ※ 27 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW089 Calibration of the AWAKE Electron Spectrometer with Electrons Derived from a Partially Stripped Ion Beam proton, quadrupole, plasma, experiment 2694
 
  • D. A. Cooke, M. Cascella, J. Chappell, S. Jolly, F. Keeble, M. Wing
    UCL, London, United Kingdom
  • R. Alemany-Fernández, J. Bauche, I. Gorgisyan, E. Gschwendtner, V. Kain, M.W. Krasny, S. Mazzoni, A.V. Petrenko
    CERN, Meyrin, Switzerland
  • P. La Penna, M. Quattri
    ESO, Garching bei Muenchen, Germany
 
  The energy distribution of electrons accelerated in the wake of a self-modulated proton beam is measured using a magnetic spectrometer at AWAKE. The spectrometer was commissioned in 2017 and ran successfully throughout 2018. Imaging properties of the spectrometer system are studied via a combination of simulations and linear optics models and validated using mono-energetic electrons stripped from the partially stripped ion beam in the AWAKE beamline at CERN. These and other details of the calibration and performance will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW089  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPGW090 Emittance Evolution of Low Energy Antiproton Beams in the Presence of Deceleration and Cooling emittance, proton, antiproton, closed-orbit 2697
 
  • J.R. Hunt, J. Resta-López, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • C. Carli, B. Dupuy, D. Gamba
    CERN, Geneva, Switzerland
  • J.R. Hunt, J. Resta-López, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  The commissioning of the Extra Low Energy Antiproton (ELENA) ring has been completed before the start of the second long shutdown (LS2) at CERN. First beams to an experiment in a new experimental zone have as well already been delivered. ELENA will begin distributing 100 keV cooled antiproton beams to all antimatter experiments in 2021. This contribution presents measurements made using a novel scraping algorithm capable of determining the emittance of non-Gaussian beams in the presence of dispersive effects. The emittance is sampled during various sections of the ELENA deceleration cycle, investigating the efficiency of the electron cooler and extracting additional information from the beam. The electron cooler is shown to effectively reduce the transverse phase space after blow-up during deceleration. The beam is characterised before extraction for the purpose of tracking and optimisation of the new electrostatic transfer lines currently being installed. Finally, the application of the scraping algorithm to other machines with a scraper located in a dispersive region is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW090  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPGW093 Commissioning of the Prototype for a New Gas Curtain Beam Profile Monitor Using Beam Induced Fluorescence for HL-LHC photon, gun, background, experiment 2709
 
  • A. Salehilashkajani, C.P. Welsch, H.D. Zhang
    The University of Liverpool, Liverpool, United Kingdom
  • M. Ady, N. Chritin, J. Glutting, O.R. Jones, R. Kersevan, T. Marriott-Dodington, S. Mazzoni, A. Rossi, G. Schneider, R. Veness
    CERN, Geneva, Switzerland
  • P. Forck, S. Udrea
    GSI, Darmstadt, Germany
  • C.P. Welsch, H.D. Zhang
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: This work is supported by the HLLHCUK project and the STFC Cockcroft Institute core grant No. ST/G008248/1.
A new supersonic gas-jet curtain based beam profile monitor is under development for minimally invasive simultaneous transverse profile diagnostics of proton and electron beams, at pressures compatible with LHC. The monitor makes use of a thin gas-jet curtain angled at 45 degrees with respect to the charged particle beams. The fluorescence caused by the interaction between the curtain and the beam can then be detected using a dedicated imaging system to determine its transverse profile. This contribution details design features of the monitor, discusses the gas-jet curtain formation and presents various experimental tests, including profile measurements of an electron beam using nitrogen and neon curtains. The gas-jet density was estimated by correlating it with the number of photons detected by the camera. These measurements are then compared with results obtained using a movable pressure gauge. This monitor has been commissioned in collaboration with CERN, GSI and the University of Liverpool. It serves as a first prototype of a final design that will be placed in the LHC beam line to measure the profile of the proton beam.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW093  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPGW095 Coherent Transition Radiation Spatial Imaging as a Bunch Length Monitor radiation, detector, simulation, focusing 2713
 
  • J. Wolfenden, R.B. Fiorito, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • M. Brandin, E. Mansten, S. Thorin
    MAX IV Laboratory, Lund University, Lund, Sweden
  • R.B. Fiorito, C.P. Welsch, J. Wolfenden
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • B.S. Kyle, T.H. Pacey, T.H. Pacey
    UMAN, Manchester, United Kingdom
  • B.S. Kyle
    University of Manchester, Manchester, United Kingdom
  • E. Mansten
    Lund University, Division of Atomic Physics, Lund, Sweden
  • T.H. Pacey
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • A.G. Shkvarunets
    UMD, College Park, Maryland, USA
 
  Funding: This work was supported by the EU under Grant Agreement No. 624890 and the STFC Cockcroft Institute core Grant No. ST/G008248/1.
High-resolution bunch length measurement is a key component in the optimisation of beam quality in FELs, storage rings, and plasma-based accelerators. Simulations have shown that the profile of a coherent transition radiation (CTR) image produced by a charged particle beam is sensitive to bunch length and can thus be used as a diagnostic. This contribution presents the development progress of a novel bunch length monitor based on imaging the spatial distribution of CTR. Due to the bunch lengths studied, 10fs-100fs FWHM, the radiation of interest was in the THz range. This led to the development of a THz imaging system, which can be applied to both high and low energy electron beams. The associated benefits of this imaging distribution methodology over the typical angular distribution measurement are discussed. Building upon preliminary multi-shot proof of concept results last year, a new series of experiments have been conducted in the short pulse facility (SPF) at MAX IV. Single-shot measurements have been used to measure the exact point of maximum compression. Analysis from the proof of concept results last year, and initial results from the new measurements this year are discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW095  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW096 Development of Supersonic Gas-Sheet-Based Beam Profile Monitors photon, background, radiation, monitoring 2717
 
  • H.D. Zhang, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • M. Ady, J. Glutting, O.R. Jones, T. Marriott-Dodington, S. Mazzoni, A. Rossi, G. Schneider, R. Veness
    CERN, Geneva, Switzerland
  • P. Forck, S. Udrea
    GSI, Darmstadt, Germany
  • A. Salehilashkajani, C.P. Welsch, H.D. Zhang
    The University of Liverpool, Liverpool, United Kingdom
 
  Funding: HL-LHC project funded by STFC and CERN, and the STFC Cockcroft core grant No. ST/G008248/1.
Non-destructive beam profile monitoring is very desirable, essentially for any particle accelerator but particularly for high-energy and high-intensity machines. Supersonic gas jet-based monitors, detecting either the ionization or fluorescence of a gas sheet interacting with the primary beam to be characterized, allow for minimally invasive measurements. They can also be used over a wide energy range, from keV to TeV beams. This contribution gives an overview of the jet-based ionization and fluorescence beam profile monitors which have been developed, built and tested at the Cockcroft Institute. It discusses gas sheet generation, vacuum considerations, choice of gas species and detection methods.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW096  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW099 Development of a Beam Halo Monitor radiation, synchrotron-radiation, synchrotron, optics 2721
 
  • V.G. Dudnikov, R.P. Johnson, M. Popovic
    Muons, Inc, Illinois, USA
  • M.A. Cummings
    Northern Illinois University, DeKalb, Illinois, USA
  • R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
 
  Our innovative approach is to design the Beam Halo Monitor, where beam induced synchrotron radiation will be used to monitor the beam Halo. This involves an original scheme of light collection using a coronograph for measuring beam halo.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW099  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW103 Synchrotron Radiation Beam Diagnostics at IOTA - Commissioning Performance and Upgrade Efforts optics, radiation, experiment, detector 2732
 
  • N. Kuklev, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
  • J.D. Jarvis, A.L. Romanov, J.K. Santucci, G. Stancari
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work supported by National Science Foundation award PHY-1549132, the Center for Bright Beams. Fermi Research Alliance operates Fermilab under Contract DE-AC02-07CH11359 with the US Dept. of Energy.
The Integrable Optics Test Accelerator is a research electron and proton storage ring recently commissioned at the Fermilab Accelerator Science and Technology facility. A key part of its beam diagnostics suite are synchrotron radiation monitors, used for measuring transverse beam profile, position, and intensity. In this paper, we report on the performance and uses of this system during the year 1 run. We demonstrate sub-100nm statistical beam position uncertainty and high dynamic range from 109 electrons down to a single electron. Commissioning challenges and operational issues are discussed. We conclude by outlining current upgrade efforts, including improved modularity, small emittance measurements, and a multi-anode photomultiplier system for turn-by-turn acquisition.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW103  
About • paper received ※ 15 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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WEPGW104 The CBETA Beam Position Monitor (BPM) System Design and Strategy for Measuring Multiple Simultaneous Beams in the Common Beam Pipe timing, injection, hardware, MMI 2736
 
  • R.J. Michnoff, R.L. Hulsart
    BNL, Upton, Long Island, New York, USA
  • J. Dobbins
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
CBETA, a 4-pass electron Energy Recovery Linac (ERL) is presently under construction at Cornell University and is a collaboration between Brookhaven National Laboratory (BNL) and Cornell University. Beam commissioning began in March 2019 with a single pass ERL configuration. Commissioning of the complete 4-pass machine is scheduled to begin in fall 2019. The fixed field alternating gradient (FFA) return loop for CBETA uses Halbach permanent magnets with a common beam pipe for seven different energy beams (4 accelerating energies and 3 decelerating energies). One of the most challenging requirements for the CBETA BPM system is to independently measure the position of each of these beams. The overall design of the CBETA BPM system and the techniques planned to measure the position of each energy beam will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW104  
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPGW108 Transverse Uncorrelated Emittance Diagnostic for Magnetized Electron Beams emittance, diagnostics, simulation, cathode 2745
 
  • M.S. Stefani
    ODU, Norfolk, Virginia, USA
  • F.E. Hannon
    JLab, Newport News, Virginia, USA
 
  Funding: This manuscript has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy.
The study of magnetized electron beam has become a high priority for its use in ion beam cooling as part of Electron Ion Colliders and the potential of easily forming flat beams for various applications. In this paper, a new diagnostic is described with the purpose of studying transverse magnetized beam properties. The device is a modification to the classic pepper-pot, used in this novel context to measure the uncorrelated components of transverse emittance in addition to the typical effective emittance. The limitations of traditional methods are discussed, and simulated demonstrations of the new technique shown.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW108  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW110 Feasibility Study of Beam Profile Measurements Using Interferometer and Diffractometer Techniques for ALS-U synchrotron, storage-ring, radiation, lattice 2752
 
  • C. Sun, S. De Santis, D. Filippetto, F. Sannibale, C. Steier
    LBNL, Berkeley, California, USA
 
  Funding: Work supported by the Director Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
ALS-U is an ongoing upgrade of Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. The upgraded ALS will replace the existing Triple-Bend Achromat (TBA) storage ring lattice with a compact Multi-Bend Achromat (MBA) lattice. This MBA technology allows us to tightly focus electron beams down to about 10 μm to reach diffraction limit in a soft x-ray region. The beam size measurement is a challenging task for this tightly focused beam. The interferometer technique with visible light from synchrotron radiation has been developed in many facilities to measure their beam size at a micrometer-level accuracy. In this paper, we will present the feasibility study of this technique for the ALS-U storage ring beam size measurement.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW110  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW112 Energy Calibration of the Rea3 Accelerator by Time-of-Flight Technique* dipole, cyclotron, linac, detector 2760
 
  • A.C.C. Villari, D.B. Crisp, A. Lapierre, S. Nash, T. Summers, Q. Zhao
    NSCL, East Lansing, Michigan, USA
 
  Funding: * This material is based upon work supported by the National Science Foundation under Grant No. PHY15-65546.
We report on a simple method to perform an absolute calibration of the magnetic beam analyser of the reaccelerator ReA3 at the National Superconducting Cyclotron Laboratory. The method is based on the time of flight between two beam stoppers 7.65 m apart. Based on two independent time-of-flight measurements at three different beam energies, the beam analyser magnet is calibrated with an accuracy of 0.12 %, corresponding to a beam energy accuracy of 0.24 %.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW112  
About • paper received ※ 25 April 2019       paper accepted ※ 28 May 2019       issue date ※ 21 June 2019  
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WEPGW113 Propose a Non-Destructive Stern-Gerlach Apparatus for Measuring the Spin Polarization of Electron Beam quadrupole, polarization, simulation, software 2763
 
  • W. Liu, E. Wang
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Mott polarimeter is used for measuring the spin polarization of <10 MeV electron beam destructively. We propose a nondestructive spin polarization measurement device for electron beam based on Stern-Gerlach effect, which include a magnetic quadrupole, Lorenz force compensated electric quadrupole and Beam position monitor. The magnetic quadrupole provides a spin-magnetic interaction force (or Stern-Gerlach force) for the spin polarized electrons. The electric quadrupole provides an electric field force for electrons to offset the Lorentz force induced by the magnetic quadrupole. So that the polarized electron beam only experience the gradient force in the device, which has ability to split the spin polarized electron beam. By measuring the split spin polarized electrons using high resolution beam position monitor, the polarization of electron beam can be calculated. We will present the theoretical analysis and calculation of electron motion in this device.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW113  
About • paper received ※ 01 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPGW114 Interferometric Measurement of Bunch Length of a 3Mev Picocoulomb Electron Beam laser, cathode, experiment, space-charge 2766
 
  • X. Yang, M. Babzien, B. Bacha, G.L. Carr, W.X. Cheng, L. Doom, M.G. Fedurin, B.N. Kosciuk, J.J. Li, D. Padrazo Jr, T.V. Shaftan, V.V. Smaluk, C. Swinson, L.-H. Yu, Y. Zhu
    BNL, Upton, Long Island, New York, USA
 
  Funding: BNL LDRD
We report the bunch length measurement of low-energy 3 MeV electron beams in picosecond regime with the charge from 1.0 to 14 pC. It is the first time that we demonstrate single-cycle nano-joule coherent terahertz (THz) radiation from 3MeV electron beam can be meas-ured via a far-infrared Michelson interferometer using a QOD. At this low energy range, when charge is about 1 pC, the signal from the conventional helium-cooled sili-con composite bolometer is too low. Compared to the bunch length measurement via the ultrafast-laser-pump and electron-beam-probe in the timescale 10-14 to 10-12 s which is determined by the phase-transition dynamics in solids, the advantages are: there are no needs of pump laser and probe sample, greatly simplifying the experi-ment; the timing jitter between laser and electron beams contributes no error to the bunch length measurement; furthermore, the method can be extended to sub-picosecond regime enabling bunch length measurement in a much broader timescale 10-14 to 10-11 s for low-energy electron beams. In the current experiment the bunch length is limited to 1 ps only because the setup of driving laser to cathode with a large 70° incident angle, effective-ly lengthening the laser pulse to ≥1 ps.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW114  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPGW115 Radiation Robust RF Gas Beam Detector R&D for Intensity Frontier Experiments detector, cavity, GUI, plasma 2770
 
  • K. Yonehara, A. Moretti
    Fermilab, Batavia, Illinois, USA
  • M.A. Cummings, R.P. Johnson, G.M. Kazakevich
    Muons, Inc, Illinois, USA
 
  A novel radiation robust RF gas beam detector has been demonstrated by using the Main Injector beam at Fermilab. The detector demonstrated a stable signal gain, fast response time, and high radiation resistivity with intense proton beams. The plasma process in the detector is studied to validate the plasma physics model. The result suggests that the detector is applicable for Long Baseline Neutrino Facility at Fermilab. To prepare for the LBNF, a proto type detector will be made and applied for the Neutrino at Main Injector target system. Progress of the project will be given in the presentation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW115  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW121 Update on the JLEIC Electron Collider Ring Design collider, optics, quadrupole, solenoid 2780
 
  • F. Lin, V.S. Morozov, Y. Zhang
    JLab, Newport News, Virginia, USA
  • Y. Cai, Y.M. Nosochkov
    SLAC, Menlo Park, California, USA
 
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, and Office of Nuclear Physics under Contracts DE-AC05-06OR23177 and DE-AC02-76SF00515.
The design concept of electron collider ring in the Jefferson Lab Electron-Ion Collider (JLEIC) is based on a small beam size at the interaction point (IP) to boost the luminosity. With a chosen beta-star at the IP, electron beam size is determined by the equilibrium emittance obtained from the linear optics design. In this paper, we present an update on the lattice design of the electron ring considering not only preservation of low beam emittance, but also optimization of geometric arrangement. In particular, recent development of the lattice design has been focused on incorporating the vertical dogleg, which brings the electron beam to the ion beam plane for collisions, in the spin rotator design. The vertical dogleg is designed with no horizontal emittance growth, controlled vertical emittance and no first-order effect on the electron polarization.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW121  
About • paper received ※ 21 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPGW123 Full Acceptance Interaction Region Design of JLEIC detector, dipole, coupling, interaction-region 2787
 
  • V.S. Morozov, R. Ent, Y. Furletova, F. Lin, T.J. Michalski, R. Rajput-Ghoshal, M. Wiseman, R. Yoshida, Y. Zhang
    JLab, Newport News, Virginia, USA
  • Y. Cai, Y.M. Nosochkov, M.K. Sullivan
    SLAC, Menlo Park, California, USA
  • G.L. Sabbi
    LBNL, Berkeley, California, USA
 
  Funding: This material is based upon work supported by the U.S. DoE under Contracts No. DE-AC05-06OR23177, DE-AC02-76SF00515, and DE-AC03-76SF00098.
Nuclear physics experiments envisioned at a proposed future Electron-Ion Collider (EIC) require high luminosity of 1033-1034 cm-2s-1 and a full-acceptance detector capable of reconstruction of a whole electron-ion collision event. Due to a large asymmetry in the electron and ion momenta in an EIC, the particles associated with the initial ion tend to go at very small angles and have small rigidity offsets with respect to the initial ion beam. They are detected after they pass through the apertures of the final focusing quadrupoles. Therefore, the apertures must be sufficiently large to provide the acceptance required by experiments. In addition, to maximize the luminosity, the final focusing quadrupoles must be placed as close to the interaction point as possible. A combination of these requirements presents serious detection, optics and engineering design challenges. We present a design of a full-acceptance interaction region of Jefferson Lab Electron-Ion Collider (JLEIC). The paper presents how this design addresses the above requirements up to an ion momentum of 200 GeV/c. We summarize the magnet parameters, which are kept consistent with the Nb-Ti superconducting magnet technology.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW123  
About • paper received ※ 23 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB008 Design Study of High Gradient Compact S-band TW Accelerating Structure for the ThomX LINAC Upgrade linac, HOM, vacuum, emittance 2807
 
  • M. El Khaldi, M. Alkadi, C. Bruni, L. Garolfi, A. Gonnin, H. Monard
    LAL, Orsay, France
 
  ThomX is a Compton source project in the range of the hard X rays (45/90 keV). The machine is composed of a 50/70 MeV injector Linac and a storage ring where an electron bunch collides with a laser pulse accumulated in a Fabry-Perot resonator. The final goal is to provide an X-rays average flux of 1012-1013 ph/s. A demonstrator was funded and is being built on the Orsay university campus. The S-band injector Linac consists of 2.5 cell photocathode RF gun and a TW accelerating section. During the commissioning phase, a standard LIL S-band accelerating section is able to achieve around 50 MeV corresponding to around 45 keV X-rays energy. Since the maximum targeted X-ray energy is 90 keV, the development of a new S-band accelerating section, intended to replace the LIL structure, will provide an electron beam energy of 70 MeV. This requires essentially the development of more reliable high gradient compact S band accelerating section. Such design is tailored for high gradient operation, low breakdown rates. We present here the RF design of the LINAC upgrade and the performances obtained in terms of beam dynamics.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB008  
About • paper received ※ 02 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB020 Compact Ultra High-Gradient Ka-Band Accelerating Structure for Research, Medical and Industrial Applications linac, accelerating-gradient, operation, gun 2842
 
  • L. Faillace
    INFN-Milano, Milano, Italy
  • M. Behtouei
    Sapienza University of Rome, Rome, Italy
  • V.A. Dolgashev
    SLAC, Menlo Park, California, USA
  • B. Spataro, A. Variola
    INFN/LNF, Frascati, Italy
  • G. Torrisi
    INFN/LNS, Catania, Italy
 
  Technological advancements are strongly required to fulfil demands for new accelerators devices from the compact or portable devices for radiotherapy to mo-bile cargo inspections and security, biology, energy and environmental applications, and ultimately for the next generation of colliders. In the frame of the collab-oration with INFN-LNF, SLAC (USA) we are working closely on design studies, fabrication and high-power operation of Ka-band accelerating structures. In par-ticular, new manufacturing techniques for hard-copper structures are being investigated in order to determine the maximum sustainable gradients above 150 MV/m and extremely low probability of RF breakdown. In this paper, the preliminary RF and mechanical design as well as beam dynamics estimations for a Ka-Band accelerating structure at 35 GHz are presented together with discussions on practical accelerating gradients and maximum average beam current throughput.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB020  
About • paper received ※ 08 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPRB024 Low Power RF Test of a Quadrupole-free X-Band Mode Launcher for High Brightness Applications GUI, brightness, quadrupole, simulation 2856
 
  • G. Torrisi, L. Celona, S. Gammino, O. Leonardi, G. Sorbello
    INFN/LNS, Catania, Italy
  • G. Castorina
    Sapienza University of Rome, Rome, Italy
  • V.A. Dolgashev
    SLAC, Menlo Park, California, USA
  • L. Faillace
    INFN-Milano, Milano, Italy
  • G.S. Mauro
    INFN/LNL, Legnaro (PD), Italy
  • G. Sorbello
    University of Catania, Catania, Italy
  • B. Spataro
    INFN/LNF, Frascati, Italy
 
  In this work we present the low power RF characterization of a novel TM01 X-band mode launcher for the new generation of high brightness RF photo-injectors. The proposed mode launcher exploits a fourfold symmetry which minimizes both the dipole and the quadrupole fields in order to mitigate the emittance growth in the early stages of the acceleration process. Two identical aluminum mode launchers have been assembled and measured in back-to-back configurations for three different central waveguide lengths. From the back-to-back results we infer the performance of each mode launcher. The low power RF test, performed at the Istituto Nazionale di Fisica Nucleare Laboratori Nazionali del Sud (INFN-LNS), validate both the numerical simulations and the quality of fabrication. An oxygen-free high-conductivity copper version of the device is being manufactured for high power and ultra high vacuum tests that are planned to be conducted at SLAC  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB024  
About • paper received ※ 09 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPRB027 Electromagnetic Design and Characterization of an S-band 3-Cell RF Accelerating Cavity cavity, emittance, simulation, acceleration 2867
 
  • G.R. Montoya Soto
    Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
  • C. Duarte Galván, C.A. Valerio
    ECFM-UAS, Culiacan, Sinaloa, Mexico
  • B. Yee-Rendón
    JAEA/J-PARC, Tokai-mura, Japan
 
  An S-Band (2998 MHz) RF cavity to accelerate electrons was developed taking into account the beam space charge, the relativistic change in velocity of the low energy beam particle distribution through the cavity and the emittance growth. The electromagnetic design and geometry optimization were done using the codes Poisson Superfish and CST Studio. In addition, beam dynamics simulations were done using the program Travel to optimize the emittance and take into account the space charge effect. The machining was done in a CNC machining center. Measurements of the cavity resonance frequencies were carried out and compared with the obtained by the simulations with good agreement between them.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB027  
About • paper received ※ 30 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPRB031 SRF Trip Caused by the Tuner in BEPCII SRF, cavity, operation, collider 2880
 
  • J.P. Dai, Z.H. Mi, P. Sha, Y. Sun, Q.Y. Wang, L.G. Xiao
    IHEP, Beijing, People’s Republic of China
 
  Funding: Work support by Natural Science Foundation of China (11575216)
The stability and reliability of the Superconducting RF system (SRF) is generally a key issue in a large scale accelerator such as Beijing Electron Positron Collider II (BEPCII). In the past several years, SRF is one of the main factors limiting the availability of BEPCII, and many efforts have been made to fix the SCRF troubles. This paper focuses on the details of the SCRF trip caused by the tuner, which is one of the most persistent troubles and figured out till the summer of 2018.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB031  
About • paper received ※ 08 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB042 High Power Test of the First C-band Spherical Pulse Compressor Prototype GUI, cavity, FEL, linac 2896
 
  • Z.B. Li
    SINAP, Shanghai, People’s Republic of China
  • W. Fang, Q. Gu, X.X. Huang, J.H. Tan, Z.T. Zhao
    SSRF, Shanghai, People’s Republic of China
 
  Funding: National Natural Science Foundation of China (No. 11675249)
Recently, a new C-band (5712 MHz) compact spherical radio frequency (RF) pulse compressor was designed and tested for Shanghai Soft X-ray Free Electron Laser Facili-ty (SXFEL). This pulse compressor utilizes one high Q0 spherical RF resonant cavity that works with two TE1, 1,3 modes and a dual-mode polarized coupler. The peak power multiply factor is 6.1 and average power gain 3.8 in theory. During the high power test, a peak power mul-tiply factor of 5.74 and average power gain of 3.77 was achieved. This paper presents the RF measurement of the C-band spherical pulse compressor and the high power test results.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB042  
About • paper received ※ 19 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB045 Suppression of Secondary Electron Yield Effect in the 650MHz/800kW Klystron for CEPC cavity, klystron, simulation, multipactoring 2906
 
  • X. He, C. Meng, S. Pei, J.L. Wang, O. Xiao, N. Zhou
    IHEP, Beijing, People’s Republic of China
 
  The circular electron positron collider (CEPC) is in pre-research, it will need more than two hundred 650MHz/800kW klystrons. The secondary electron yield (SEY) effect suppression is very important for the klystron working stable. The simulation uses an incident primary electron source and considers all the phases and power levels of the input microwave. Two methods are simulated for the SEY suppression. The groove cutting on the nose of cavities is much simple while the TiN coating can suppress better. The effect after groove cutting on nose is also simulated and the corresponding compensations are adopted. For simplify the fabrication progress as well as some experience that can be referenced, the groove cutting method is adopted finally for the first klystron prototype, which is expected to be available in the summer of 2019.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB045  
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB048 Design, Fabricate, and Tuning of X-Band Deflecting Structure for CERN simulation, cavity, GUI, free-electron-laser 2915
 
  • J.H. Tan, W. Fang, Q. Gu, X.X. Huang, Z.T. Zhao
    SSRF, Shanghai, People’s Republic of China
 
  A 20-cell x-band deflecting structure for CERN has been finished, and now is under high power conditioning at XBOX of CERN.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB048  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPRB049 HOM Analysis of the 4-cell Superconducting Cavity on CTFEL Facility HOM, cavity, FEL, simulation 2918
 
  • X. Luo, T.H. He, C.L. Lao, L.J. Shan, X.M. Shen, D. Wu, K. Zhou
    CAEP/IAE, Mianyang, Sichuan, People’s Republic of China
  • F. Wang
    PKU, Beijing, People’s Republic of China
 
  The higher order modes (HOMs) of the 1.3GHz 4-cell cavity on CTFEL facility is analyzed in this paper. The passbands of the HOMs in the 4-cell cavity were simulat-ed, and the most harmful modes were determined. The power of the wakefields was estimated. By microwave test at room temperature, the frequencies of the HOMs were measured, as well as the external Q’s of the HOM cou-plers. Besides, a frequency distribution measurement system was built. The HOM signal excited by beam at 2 K temperature is measured, and some preliminary results are obtained. The measurement techniques and results of the HOM damping performance are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB049  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB054 Design of the Multiplexing Optical Measurement System for a Pre-bunched THz Free Electron Laser laser, radiation, detector, FEL 2931
 
  • Y.K. Zhao, W. Li, B.G. Sun, Y.G. Tang, F.F. Wu, T.Y. Zhou
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  Funding: Work supported by the the Fundamental Research Funds for the Central Universities (WK2310000080, WK2310000057), and the National Science Foundation of China (11705203, 11575181)
A new and compact a pre-bunched terahertz (THz) free electron laser (FEL) at the National Synchrotron Radiation Laboratory, University of Science and Technology of China is being constructed and aims to generate the tunable radiation frequency ranges from 0.5 THz to 5 THz at 11-18 Mev electron energy. This system is expected to use for imaging, basic researches as well as industrial applications as a result of the significant merits of simple, compact and cost-effective. Due to the THz laser measurement system plays an important part in the pre-bunched THz FEL facility. Therefore, a multiplexing THz laser sensing measurement system model is developed for measuring the output laser power and the optical spectrum of THz radiation with the excellent advantages of robustness, high sensitivity and low-cost in this paper.
Corresponding author (email: tiany86@ustc.edu.cn)
Corresponding author (email: wufangfa@ustc.edu.cn)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB054  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB055 Design of 3 MeV S-band Electron Linac Structure With 2.5 Bunching Cells bunching, linac, coupling, simulation 2934
 
  • Y. Joo, P. Buaphad, H.R. Lee
    University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
  • Y. Kim
    KAERI, Daejon, Republic of Korea
  • J.Y. Lee, S. Lee
    Korea Atomic Energy Research Institute (KAERI), Daejeon, Republic of Korea
 
  Funding: UST (University of Science and Technology), KAERI (Korea Atomic Energy Research Institute)
The Korea Atomic Energy Research Institute (KAERI) has been designing several 3 MeV S-band RF electron linear accelerators (linacs) for non-destructive testing. Until now, the bunching cell of the linac has a full-cell geometry. However, to maximize the acceleration of electrons after emission from the electron gun, the geometry of the first bunching cell is modified from a full-cell to a half cell. To accelerate electron beams more gently, recently, we increased the total number of bunching cells from 1.5 to 2.5. In this paper, we describe design concepts and detailed optimization processes of a 3 MeV linac with the 2.5 bunching cells to optimize RF parameters such as the quality factor, resonance frequency, and uniformity of electric field distribution along the linac. Lastly, we will discuss the application of 3 MeV linac.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB055  
About • paper received ※ 04 June 2019       paper accepted ※ 16 June 2019       issue date ※ 21 June 2019  
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WEPRB058 Combined Field Emission and Multipactor Simulation in High Gradient RF Accelerating Structures multipactoring, simulation, cavity, GUI 2940
 
  • D. Banon-Caballero
    IFIC, Valencia, Spain
  • N. Catalán Lasheras, K. T. Szypula, W. Wuensch
    CERN, Geneva, Switzerland
  • A. Faus-Golfe
    LAL, Orsay, France
  • B. Gimeno
    UVEG, Burjasot (Valencia), Spain
 
  Field emitted electrons have important consequences in the operation of high-gradient RF accelerating structures both by generating so-called dark currents and initiating RF breakdown. The latter is an important limitation of the performance in such devices. Another kind of vacuum discharge that primarily affects the operation of lower-field RF components, for example those used in space applications, is multipactor. Theoretical simulations using CST Particle Studio, show that field emitted electrons generated in the high field regions of high-gradient accelerating cavities migrate to low field regions under ponderomotive forces potentially triggering multipactor there. This phenomenon is an interplay between high field and low field processes which may have as a consequence that multipactor actually affects to the performance of high-gradient cavities because field emitted electrons might reduce the timescales for the onset of multipactor.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB058  
About • paper received ※ 27 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPRB059 Dark Current Analysis at CERN’s X-band Facility radiation, operation, ECR, linac 2944
 
  • D. Banon-Caballero, M. Boronat, V. Sánchez Sebastián, A. Vnuchenko
    IFIC, Valencia, Spain
  • N. Catalán Lasheras, S. Pitman, M. Widorski, W. Wuensch, V. del Pozo Romano
    CERN, Meyrin, Switzerland
  • A. Faus-Golfe
    LAL, Orsay, France
  • B. Gimeno
    UVEG, Burjasot (Valencia), Spain
  • T.G. Lucas, M. Volpi
    The University of Melbourne, Melbourne, Victoria, Australia
  • W.L. Millar
    Lancaster University, Lancaster, United Kingdom
  • J. Paszkiewicz
    University of Oxford, Oxford, United Kingdom
 
  Dark current is particularly relevant during operation in high-gradient linear accelerators. Resulting from the capture of field emitted electrons, dark current produces additional radiation that needs to be accounted for in experiments. In this paper, an analysis of dark current is presented for four accelerating structures that were tested and conditioned in CERN’s X-band test facility for CLIC. The dependence on power, and therefore on accelerating gradient, of the dark current signals is presented. The Fowler-Nordheim equation for field emission seems to be in accordance with the experimental data. Moreover, the analysis shows that the current intensity decreases as a function of time due to conditioning, but discrete jumps in the dark current signals are present, probably caused by breakdown events that change the emitters’ location and intensity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB059  
About • paper received ※ 10 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB062 Spatially Resolved Dark Current in High Gradient Traveling Wave Structures linac, diagnostics, site, collider 2956
 
  • J. Paszkiewicz, W. Wuensch
    CERN, Meyrin, Switzerland
  • P. Burrows
    JAI, Oxford, United Kingdom
  • P. Burrows
    Oxford University, Physics Department, Oxford, Oxon, United Kingdom
 
  High-gradient accelerating structures are known to produce field-emitted current from regions of high surface field, which are captured and accelerated by the fields within the structure. This current is routinely measured in structures under test in the CLIC high-gradient test stands using Faraday cups. This paper presents a novel technique to spatially resolve the longitudinal distribution of field emitted current by analysing downstream Faraday cup signals when the structure is fed with RF pulses much shorter than its filling time. Results from this method applied to X-band cavities operating at 100 MV/m are presented, and are compared to breakdown position distributions. A decay in emitted current as conditioning progressed in regions with a low breakdown rate and large jumps in regions with a large breakdown rate are observed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB062  
About • paper received ※ 29 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPRB063 Connection of 12 GHz High Power RF from the XBOX 1 High Gradient Test Stand to the CLEAR Electron LINAC LLRF, klystron, linac, software 2960
 
  • A.V. Edwards
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • N. Catalán Lasheras, S. Gonzalez Anton, G. McMonagle, S. Pitman, B.J. Woolley, V. del Pozo Romano
    CERN, Meyrin, Switzerland
 
  A new RF system is being established at XBOX1 to drive two §I{100}{MV/m} CLIC structures in the CLEAR electron linac. In the past, these structures had been powered by RF from PET structures excited by a drive beam. This drive beam is no longer available. The upgrade will reroute power from the §I{50}{MW} klystron and pulse compressor which was previously used to power the structure in XBOX1. During the upgrade, the LLRF system will be optimised to improve the modulation of the output signals and down-mixing of the returning signals to obtain accurate phase and amplitude information. The design of the improved LLRF and software, along with phase noise measurements and comparisons with the old system are made in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB063  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB072 Ultra-High Gradient Short RF Pulse Gun gun, cathode, emittance, brightness 2987
 
  • S.P. Antipov, P.V. Avrakhov, S.V. Kuzikov, A. Liu
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • G. Ha, J.G. Power
    ANL, Argonne, Illinois, USA
 
  Funding: DOE SBIR DE-SC0018709
High brightness beams enable novel applications like x-ray free electron lasers and ultrafast electron microscopes. High brightness beams essentially consist of a large number of electrons in a small phase space volume, i.e. a high peak current. When such beams are generated from the cathode, there is a strong space charge force, which elongates the bunch and reduces its brightness. An optimal solution is to raise the accelerating voltage in the gun. However, the maximum gradient is limited by the effects of RF breakdown. The probability of RF breakdown is reduced as the RF pulse length decreases. We present a development of an electron photoinjector operating with short RF pulse, 10 ns scale. We have designed an X-band gun including the RF design, beam quality optimization, and engineering. The gun will be fed by 10 ns, 300 MW RF pulse generated at the Argonne Wakefield Accelerator Facility for two-beam acceleration experiments. We also manufactured an aluminum prototype and measured its microwave properties, most importantly, fill time. The proposed high brightness beam source can be used as the main beam in wakefield accelerators. It will find commercial applications in ultrafast electron diffraction and microscopy systems.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB072  
About • paper received ※ 21 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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WEPRB073 CW Room Temperature Accelerating Structures impedance, operation, radiation, SRF 2990
 
  • S.P. Antipov, P.V. Avrakhov, E. Gomez, S.V. Kuzikov
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • A.A. Vikharev
    IAP/RAS, Nizhny Novgorod, Russia
 
  To this day CW linear electron accelerators were based only on expensive and bulky (embedded in a cryostat) superconducting accelerating structures. CW regime can in principle be realized with normal conducting structures provided the shunt impedance is high. Such structures can be designed using dielectrics (ultra-pure ceramics in C-band and diamond in mm-waves) with ultra-low loss tangent (~10-6). The use of dielectrics allows to concentrate the electromagnetic energy density in the dielectric region and thus minimize fields and ohmic loss on metallic walls. The thermal loss in dielectric can be relatively low given the loss tangent is small. We report here the design of structures with shunt impedance on the order of 104 MOhm/m, which is several orders of magnitude higher than shut impedance in copper structures in GHz and THz range. High shunt impedance makes it possible to accelerate electrons to 1 MeV using kW-level CW RF sources like magnetrons in C-band and gyrotrons in THz range. Such CW accelerators will find applications in sterilization, food irradiation, industrial radiography and cargo inspection.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB073  
About • paper received ※ 21 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB076 Analysis of Higher Order Multipoles of the 952.6 Mhz RF-Dipole Crabbing Cavity for the Jefferson Lab Electron-Ion Collider cavity, multipole, dipole, HOM 2996
 
  • S.U. De Silva, J.R. Delayen, S. Sosa
    ODU, Norfolk, Virginia, USA
  • V.S. Morozov, H. Park
    JLab, Newport News, Virginia, USA
 
  The crabbing system is a key feature in the Jefferson Lab Electron-Ion Collider (JLEIC) required to increase the luminosity of the colliding bunches. A local crabbing system will be installed with superconducting rf-dipole crabbing cavities operating at 952.6 MHz. The field non-uniformity across the beam aperture in the crabbing cavities produces higher order multipole components, similar to that which are present in magnets. Knowledge of higher order mode multipole field effects is important for accurate beam dynamics study for the crabbing system. In this paper, we quantify the multipole components and analyse their effects on the beam dynamics.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB076  
About • paper received ※ 20 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB084 Mechanical Design and Analysis of the Proposed APEX2 VHF CW Electron Gun cavity, gun, vacuum, cathode 3014
 
  • A.R. Lambert, H.Q. Feng, D. Filippetto, M.J. Johnson, D. Li, T.H. Luo, C.E. Mitchell, F. Sannibale, J.W. Staples, S.P. Virostek, R.P. Wells
    LBNL, Berkeley, California, USA
 
  Funding: Work supported by the Office of Science, U.S. Department of Energy under DOE contract number DEAC02-05CH11231
Normal conducting radio-frequency (RF) guns resonating in the very high frequency (VHF) range (30-300 MHz) and operating in continuous wave (CW) mode have successfully achieved the targeted brightness and reliability necessary for upgrading the performance of current lower repetition rate accelerator-based instruments such as X-ray free electron lasers (FELs), and ultra-fast electron diffraction (UED) and microscopy (UEM). The APEX2 (Advanced Photo-injector Experiment 2) electron gun is a proposed upgrade for the current LCLS-II injector, which was based on the original APEX design. In contrast, APEX2 is designed as a two-cell cavity operating at 162.5 MHz with a launching field at the cathode equal to 34 MV/m, producing a beam energy of 1.5 to 2 MeV, more than double APEX. Operation of the gun in this condition will require upwards of 200 kW of RF power, thus proper thermal management is crucial to achieve target performance. This paper describes the current design, thermal performance and tuning methods.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB084  
About • paper received ※ 13 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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WEPRB089 Theoretical Analysis of Quasiparticle Overheating, Positive Q-Slope, and Vortex Losses in SRF Cavities cavity, SRF, niobium, experiment 3020
 
  • J.T. Maniscalco, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • T. Arias, D. Liarte, J.P. Sethna, N. Sitaraman
    Cornell University, Ithaca, New York, USA
 
  The surface resistance of an SRF cavity is an important measure of its performance and utility: lower resistance leads directly to lower cryogenic losses and power consumption. This surface resistance comprises two components, namely the ‘‘BCS resistance’’, which depends strongly on the quasiparticle temperature, and a temperature-independent ‘‘residual resistance’’, which is often dominated by losses due to trapped magnetic vortices. Both components are generally dependent on the RF field strength. Here we present a summary of recent theoretical advances in understanding the microscopic mechanisms of the surface resistance, in particular addressing niobium hydride formation and quasiparticle overheating (using the tools of density functional theory) and discussing issues with existing models of the positive Q-slope, a field-dependent decrease in the BCS resistance, and possible paths for improvement of these models. We also discuss trapped flux losses using ideas from collective weak pinning theory.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB089  
About • paper received ※ 20 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB093 Design of a Proof-of-principle Crabbing Cavity for the Jefferson Lab Electron-ion Collider cavity, HOM, collider, luminosity 3027
 
  • H. Park, S.U. De Silva, J.R. Delayen, S.I. Sosa Guitron
    ODU, Norfolk, Virginia, USA
  • J.R. Delayen, H. Park
    JLab, Newport News, Virginia, USA
 
  The Jefferson Lab design for an electron-ion collider (JLEIC) requires crabbing of the electron and ion beams in order to achieve the design luminosity. A number of options for the crabbing cavities have been explored, and the one which has been selected for the proof-of-principle is a 952 MHz, 2-cell rf-dipole (RFD) cavity. This paper summarizes the electromagnetic design of the cavity and its HOM characteristics.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB093  
About • paper received ※ 22 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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WEPRB094 Measurements of the Electrical Axes of the CeC PoP RF Cavities cavity, cathode, gun, SRF 3031
 
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • Y.C. Jing, V. Litvinenko, J. Ma, I. Pinayev, K. Shih, G. Wang
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  • K. Shih
    SBU, Stony Brook, New York, USA
 
  It is common knowledge that every mode in an SRF cavity has a so-called electrical axis, and only in an ideal cavity would this axis align exactly with the geometrical axis of the device. The misalignment of the electrical axis creates an additional undesirable transverse kick to the beam, which has to be corrected to achieve the designed beam parameters. In this paper we present the two methods which have been used in order to determine the electrical axes in the RF cavities of the Coherent electron Cooling (CeC) Proof of Principle (PoP) accelerator. The electron accelerator for the CeC PoP consists of the three main RF components: the 113 MHz SRF gun, the two normal-conducting 500 MHz bunching cavities, and the 704 MHz SRF 5-cell elliptical cavity. We discuss, in detail, the specifics of the measurement for each cavity and provide the corresponding results. In addition, we describe the influence of the field asymmetry in the 500 MHz bunchers on the beam dynamics, which was observed experimentally and confirmed by simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB094  
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPRB095 Microbunching Plasma-Cascade Instability plasma, simulation, bunching, focusing 3035
 
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  • T. Hayes, Y.C. Jing, D. Kayran, J. Ma, T.A. Miller, G. Narayan, I. Pinayev, F. Severino, G. Wang
    BNL, Upton, Long Island, New York, USA
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • K. Shih
    SBU, Stony Brook, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy and NSF Grant No. PHY-141525
We present a new type of longitudinal microbunching instability entitled ’Plasma-Cascade Instability’. This instability could occur in beams propagating along a straight section with external focusing elements. We present a theoretical description of this instability as well as self-consistent 3D simulations. Finally, we present results of experimental observation of Plasma-Cascade Instability at frequencies up to 10 THz using SRF linear accelerator built for Coherent electron Cooling experiment *.
* Commissioning of FEL-based Coherent electron Cooling system, V.N. Litvinenko et al., In proc. of 38th Int. Free Electron Laser Conf.(FEL’17), Santa Fe, NM, USA, August 20-25, 2017, p. 132
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB095  
About • paper received ※ 18 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB102 Correction of Crosstalk Effect in the LEReC Booster Cavity cavity, booster, resonance, HOM 3051
 
  • B. P. Xiao, K. Mernick, F. Severino, K.S. Smith, T. Xin, W. Xu
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
The Linac of Low Energy RHIC electron Cooler (LEReC) is designed to deliver a 1.6 MeV to 2.6 MeV electron beam, with peak-to-peak dp/p less than 7·10-4. The booster cavity is the major accelerating component in LEReC, which is a 0.4 cell cavity operating at 2 K, with a maximum energy gain of 2.2 MeV. It is modified from the Energy Recovery Linac (ERL) photocathode gun, with fundamental power coupler (FPC), pickup coupler (PU) and higher order mode (HOM) coupler close to each other. The direct coupling between FPC and PU induced crosstalk effect in this cavity. This effect is simulated and measured, and is further corrected using low level RF (LLRF) to meet the energy spread requirement.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB102  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB106 Simulation of the Transition Radiation Transport Through an Optic System radiation, simulation, optics, diagnostics 3059
 
  • M. Marongiu, A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
  • F.G. Bisesto, E. Chiadroni, G. Di Pirro, G. Franzini, A. Giribono, V. Shpakov, A. Stella, A. Variola
    INFN/LNF, Frascati, Italy
  • A. Cianchi
    Università di Roma II Tor Vergata, Roma, Italy
  • A. Mostacci, L. Palumbo
    INFN-Roma, Roma, Italy
 
  Optical Transition Radiation (OTR) screens are widely used for beam profile measurements. The radiation is emitted when a charged particle beam crosses the boundary between two media with different optical properties. The main advantages of OTR are the instantaneous emission process allowing fast single shot measurements (i.e. bunch by bunch measurements in a multi bunch machine), and the good linearity with the beam charge (if coherent effects can be neglected). Furthermore, OTR angular distribution strongly depends on beam energy. Since OTR screens are typically placed in several positions along the Linac to monitor beam envelope, one may perform a distributed energy measurement along the machine: this will be useful, for instance, during the commissioning phase of a machine. This paper deals with the studies of an algorithm to optimize the generation and the transport of the transition radiation through an optic system using the simulation tool Zemax. The algorithm, in combination with a particle tracking code (i.e. Elegant), will allow to simulate the radiation generated by a beam and, so, to take into account beam divergence and energy spread or chromatic effects in the optic system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB106  
About • paper received ※ 08 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPRB107 The New 1-18 MHz Wideband RF System for the CERN PS Booster cavity, vacuum, electronics, impedance 3063
 
  • M.M. Paoluzzi, L. Arnaudon, V. Bretin, Y. Cuvet, J. Daricou, S. Energico, M. Haase, A.J. Jones, D. Landré, C. Rossi
    CERN, Meyrin, Switzerland
  • C. Ohmori
    KEK/JAEA, Ibaraki-Ken, Japan
 
  The LHC Injector Upgrade (LIU) project at CERN prepares the injectors to meet the requirements of the High Luminosity LHC. For protons, it includes the new Linac4, PS Booster (PSB), PS and SPS. Among the major changes concerning the PSB, the extraction energy increase from 1.4 GeV to 2 GeV and the higher beam intensity, made possible by the Linac4 together with the new charge exchange injection system into the PSB (2·1013 protons) strongly affect the RF system requirements. To deal with this more demanding beam operation, a new RF system was designed. It is based on modern magnetic alloy loaded cavities driven by solid-state amplifiers. Its wideband frequency response (1 MHz to 18 MHz) covers all the required frequency schemes. This new RF system has been produced in 2017 and 2018; installation is planned during 2019, the first year of Long Shutdown 2 (LS2) and commissioning foreseen in 2020. Most of the production and testing was outsourced to industry; parts acceptance, cavities assembly and pre-testing was done in-house. A quality assurance plan was established to achieve the required high reliability. This paper describes the procurement, production and testing strategies and methodologies. It also reports the achieved results, system performances and relevant statistics.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB107  
About • paper received ※ 26 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPTS007 Short Bunch Experiment at EXALT Facility laser, cathode, experiment, gun 3100
 
  • C. Bruni, J-N. Cayla, S. Chancé, V. Chaumat, N. Delerue, N. ElKamchi, P. Lepercq, H. Purwar
    LAL, Orsay, France
  • E. Baynard, M. Pittman
    CLUPS, Orsay, France
  • B. Lucas, O. Neveu
    CNRS LPGP Univ Paris Sud, Orsay, France
  • T. Vinatier
    DESY, Hamburg, Germany
 
  Nowdays, different applications required short bunches, with low energy spread and low emittances. On EXALT facility, we perform an experiment with a short (few100 femtosecond) laser pulse on a photocathode in a 3 GHz RF gun. We perform the measurement of the single photon emission process with a copper cathode. We show that the longitudinal photoinjector model via transfer matrix is suitable for the reconstruction of the bunch duration even in short pulse mode with an increased accurracy charge below 20 pC. We clearly measure the parabolic profile in the energy spectrum resulting from blow out phenomena at the cathode due to strong space charge forces. Measurements are also compared with the Astra simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS007  
About • paper received ※ 21 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPTS013 The Cooling Effect of Beam Self-Fields on the Photocathode Surface in High Gradient RF Injectors cathode, emittance, laser, space-charge 3112
 
  • Y. Chen, M. Krasilnikov, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
 
  The intrinsic slice emittance of the emitted electrons on the photocathode surface at each moment during the transient photoemission process depends on the transverse size of the slice and the mean kinetic energy of the electrons within the slice. The latter relies on the surface barrier potentials of the cathode material at a fixed wavelength of the incident light, and is thus significantly influenced by the presence of strong rf and beam self-fields at / close to the cathode surface. This is, in particular, the case in high brightness injectors for modern free electron lasers. In this article, the beam self-fields are determined in a self-consistent approach, based on which improved transverse and temporal emission distributions are obtained. The nonlinear correlations of the intrinsic surface slice emittance within the bunch are shown for multiple bunch charges. A peak to peak variation of the intrinsic surface emittance is estimated as 30\% for the highest charge-density case considered in this paper. An overall reduction of the average intrinsic emittance is computed as 10\% accordingly. The cooling effect on the cathode surface is enhanced as the local space-charge density rises. Furthermore, the impacts of the cooling effect on downstream beam qualities are demonstrated through particle tracking simulations based on the injector setup at the Photo Injector Test Facility at DESY in Zeuthen (PITZ).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS013  
About • paper received ※ 27 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPTS017 Synchrotron Radiation Module in OCELOT Toolkit undulator, radiation, simulation, FEL 3127
 
  • S. Tomin, G. Geloni
    EuXFEL, Hamburg, Germany
 
  Synchrotron radiation (SR) sources based on single-pass accelerators (e.g. linacs, plasma accelerators) have to cope with electron beams with a rather complicated phase space distribution. In this case, the convolution method usually employed to calculate radiation properties can give poor accuracy or be not applicable at all. Moreover, dynamical effects can also play a role in the emission mechanism. This happens when the beam parameters (e.g. beam current) significantly change during the passage through the undulator. In this work, we present a dedicated SR module of the OCELOT toolkit, which is well suited to deal with these situations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS017  
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPTS034 Generation of Sub-Femtosecond Electron Beams and Electron Bunch Trains With High Form Factor Using Wake Field Structures wakefield, bunching, space-charge, simulation 3174
 
  • Z. Dong, H. Chen, X.J. Deng, Y. C. Du, Z. Zhou
    TUB, Beijing, People’s Republic of China
 
  In this paper, we propose two beam manipulation methods with wakefield structures in a photo-injector. First, we propose a simple scheme to compensate non-linear effects during ballistic bunching by using a wakefield structure. Simulations have shown beams of 1 pC charge can be compressed to 1.56 fs rms, and even shorter beams (a few hundred attoseconds) can be obtained with bunch charge well below 1 pC. In the second part, a method of producing bunch trains with high form factor is proposed by using multiple wake-field structures. Simulation results have shown the production of a train with a form factor of 0.5 using a 1 nC beam at few-MeV energy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS034  
About • paper received ※ 11 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPTS043 SixTrack Version 5: Status and New Developments simulation, scattering, collimation, HOM 3200
 
  • R. De Maria, J. Andersson, L. Field, M. Giovannozzi, P.D. Hermes, N. Hoimyr, G. Iadarola, S. Kostoglou, E.H. Maclean, E. McIntosh, A. Mereghetti, J. Molson, V.K.B. Olsen, D. Pellegrini, T. Persson, M. Schwinzerl
    CERN, Geneva, Switzerland
  • B. Dalena, T. Pugnat
    CEA-IRFU, Gif-sur-Yvette, France
  • K.N. Sjobak
    University of Oslo, Oslo, Norway
  • I. Zacharov
    EPFL, Lausanne, Switzerland
 
  SixTrack Version 5 is a major SixTrack release that introduces new features, with improved integration of the existing ones, and extensive code restructuring. New features include dynamic-memory management, scattering-routine integration, a new initial-condition module, and reviewed post-processing methods. Existing features like on-line aperture checking and Fluka-coupling are now enabled by default. Extensive performance regression tests have been developed and deployed as part of the new-release generation. The new features of the tracking environment developed for the massive numerical simulations will be discussed as well.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS043  
About • paper received ※ 17 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPTS048 Electron Beam Dynamics Simulation for Electron Lenses gun, simulation, cathode, experiment 3220
 
  • S. Sadovich, A. Rossi
    CERN, Meyrin, Switzerland
  • G. Stancari
    Fermilab, Batavia, Illinois, USA
 
  A test stand is under construction at CERN to study high perveance electron guns, electron beam dynamics, and electron beam diagnostics for electron lenses. It will be used to test electron guns for the Hollow Electron Lenses under consideration for beam halo control for High Luminosity LHC (CERN), and for the Space Charge Compensation at SIS18 (GSI) in the frame of the EU funded ARIES project. In order to prepare for this test stand, simulations will be presented and compared with experiments undertaken at the Fermilab (FNAL) electron lens test stand. These were conducted using a hollow electron gun, with the magnetic field configuration and beam current varied to study their effect. The impact of imperfections on the beam dynamics and overall quality of the electron beam will be discussed. A method for comparing experimental data with simulation is also presented to allow bench-marking of the computer models and simulation tools that will later be applied to the analysis of measurements performed at CERN.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS048  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPTS050 Multi-Species Electron-Ion Simulations and their Application to the LHC simulation, operation, beam-losses, space-charge 3228
 
  • L. Mether, G. Iadarola, K.L. Poland, G. Rumolo, G. Skripka
    CERN, Meyrin, Switzerland
 
  During operation in 2017 and 2018, the LHC suffered from recurrent beam aborts associated with beam losses in one of its arc cells in correlation with quickly developing transverse coherent oscillations. The events are thought to have been caused by a localised high gas density resulting from the phase transition of a macro-particle that has entered the beam. In order to model the observed coherent effects through the interaction of the beam with the induced pressure bump, novel modelling capabilities have been implemented that allow for the simulation of multiple clouds of different particle species and their interaction with the beam. In this contribution the simulation model and its application are described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS050  
About • paper received ※ 13 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPTS051 Comparison of Electron Cloud Build-Up Simulations Against Heat Load Measurements for the LHC Arcs With Different Beam Configurations simulation, operation, synchrotron-radiation, radiation 3232
 
  • G. Skripka, G. Iadarola, L. Mether, G. Rumolo, E.G.T. Wulff
    CERN, Meyrin, Switzerland
  • P. Dijkstal
    PSI, Villigen PSI, Switzerland
 
  Electron cloud effects are among the main performance limitations for the operation of the Large Hadron Collider (LHC) with 25 ns bunch spacing. A large number of electrons impacting on the beam screens of the cold magnets induces significant heat load, reaching values close to the full cooling capacity available from the cryogenic system. Interestingly, it is observed that parts of the machine that are by design identical show very different heat loads. We used numerical simulations to investigate the possibility that these differences are induced by different surface properties, in particular maximum Secondary Electron Yield (SEY) for the different cryomagnets. Using the PyECLOUD code, the electron cloud build-up was simulated assuming different values of SEY in the LHC cold magnets. Comparing the measured heat loads to the simulation results for the 25 ns beams at 450 GeV we have identified the SEY values that match the observations in these conditions. These SEY values were found to be in good agreement with the heat loads measured with different beam configurations (changing the bunch pattern, the bunch intensity and the beam energy).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS051  
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPTS052 Electron Cloud Build-Up Simulations in the Two-Beam Common Chamber of the HL-LHC TDIS With Nonuniform Surface Properties simulation, injection, vacuum, operation 3236
 
  • G. Skripka, C. Bracco, G. Iadarola, A. Perillo-Marcone
    CERN, Meyrin, Switzerland
 
  The segmented injection protection absorber (TDIS) foreseen for the High-Luminosity Large Hadron Collider (HL-LHC) project is designed to protect the machine in case of injection kicker malfunctioning. Since the current LHC injection protection absorber has suffered from vacuum issues possibly induced by electron multipacting, numerical studies were done to estimate the electron flux expected on the internal surfaces of the TDIS. This device will consist of three pairs of movable absorbing blocks above and below one beam and a beam screen surrounding the second circulating beam. The build-up of electron cloud in the TDIS was simulated accounting for the presence of two counter-rotating beams, for the configuration of the jaws and for the different materials used for the different surfaces in the device. The simulation studies have also investigated the possibility of coating the most critical surfaces with amorphous carbon in order to mitigate the multipacting.  
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