Keyword: focusing
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MOPGW005 Space-Charge Potential for Elliptical Beams space-charge, beam-beam-effects, proton 69
 
  • S.R. Koscielniak
    TRIUMF, Vancouver, Canada
 
  This work is motivated by the weak-strong beam-beam effect as occurs in colliding charged-particle beams. We consider beams with elliptical cross section and power law binomial forms for the density distribution. We demonstrate explicitly how to construct analytically the space-charge potential inside the ’strong’ beam. This is essential to the program of calculating beam-beam effects for non-gaussian beams.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW005  
About • paper received ※ 19 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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MOPGW016 Straightness Correction of Ballistic Trajectories FEL, alignment, undulator, quadrupole 101
 
  • V. Balandin, W. Decking, N. Golubeva, M. Scholz
    DESY, Hamburg, Germany
 
  We describe procedure for straightness correction of ballistic trajectories in the presence of BPM noise and unknown BPM offsets. We also discuss applicability of this method to the beam based alignment of the European XFEL undulators.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW016  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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MOPGW023 An Algorithm for Automated Lattice Design of Transfer Lines quadrupole, lattice, dipole, target 127
 
  • S. Reimann, M. Droba, O. Meusel, H. Podlech
    IAP, Frankfurt am Main, Germany
 
  Since the last 20 years, modern heuristic algorithms and machine learning have been increasingly used for several purposes in accelerator technology and physics. Since computing power has become less and less of a limiting factor, these tools have become part of the physicist community’s standard toolkit. This paper describes the construction of an algorithm that can be used to generate an optimised lattice design for transfer lines under the consideration of restrictions that usually limit design options in reality. The developed algorithm has been applied to the existing SIS18 to HADES transfer line in GSI.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW023  
About • paper received ※ 28 April 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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MOPGW054 Study on Spherical Aberration Correction of Solenoid Lens in Ultrafast Electron Diffraction electron, induction, solenoid, emittance 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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MOPGW104 Equilibria and Synchrotron Stability in Two Energy Storage Rings electron, storage-ring, damping, simulation 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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MOPGW107 Study of Integrable and Quasi-Integrable Sextupole Lattice sextupole, resonance, lattice, optics 371
 
  • L. Gupta, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
  • S. Baturin
    Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
  • S. Nagaitsev
    Fermilab, Batavia, Illinois, USA
 
  Funding: Funded through Center for Bright Beams, NSF award PHY-1549132
In order to maximize beam lifetime in circular particle accelerators, the nonlinear beam optics are optimized to maximize the dynamic aperture of the beam. The dynamic aperture (DA), which is a 6-D phase space volume of stable trajectories, depends on the strength of the nonlinearities in the machine, and is calculated via particle tracking. Current DA optimization processes include multi-objective genetic algorithm optimizers, and relies on minimizing the magnitudes of resonance driving terms (RDT), which are calculated from the nonlinear contribution to the one-turn-map. The process of searching through the parameter space for an ideal combination that maximizes DA is computationally strenuous. By setting up the sextupole channel such that it is resembles a symplectic integrator of a smooth Hamiltonian, with only a few sextupoles we are able to closely reproduce phase space trajectories of a smooth Hamiltonian up to the hyperbolic point. No chaos and resonances are observed if phase advance per one sextupole magnet in the channel does not exceed ~0.12x2 pi. Therefore, an important property of the suggested approach is the intrinsic elimination of the resonances, and minimization of corresponding RDTs.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW107  
About • paper received ※ 13 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPGW123 Electromagnetic Study and Measurements of the iRCMS Cell optics, quadrupole, proton, extraction 403
 
  • N. Tsoupas, P.N. Joshi, F. Méot, D. Trbojevic
    BNL, Upton, Long Island, New York, USA
  • D.T. Abell
    RadiaSoft LLC, Boulder, Colorado, USA
  • V.L. Bailey, J.P. Lidestri
    Best Medical International, Springfield, USA
  • M. Sinnott
    Everson Tesla Inc., Nazareth, Pennsylvania, USA
 
  Funding: BNL Contract TSA-NF-18-80
The ion Rapid Cycle Medical Synchrotron (iRCMS) * will provide proton and C ion bunches with maximum energy 270 MeV and 450 MeV/u respectively at a frequency of 15 Hz for treating cancerous tumors. One of the six cells of the iRCMS has been designed, built and magnetic field measurements have been performed. We will present results from the static and AC electromagnetic study of the iRCMS cell and compare the measured magnetic fields with those calculated using the OPERA computer code **. In addition the beam optics of the cell will be calculated based on the experimental fields using the zgoubi computer code *** and compared with the designed beam optics.
* D. Trbojevic, iRCMS Magnet Review, BNL, Sept. 6, 2012 (unpublished)
** OPERA computer code https://operafea.com/
*** The zgoubi computer code https://www.bnl.gov/isd/documents/79375.pdf
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW123  
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, electron, 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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MOPRB021 Remodeling of 150 MeV FFAG Main Ring at KURNS to Pion Production Ring FFAG, proton, target, resonance 616
 
  • K. Suga, Y. Fuwa, Y. Ishi, Y. Kuriyama, Y. Mori, H. Okita, T. Uesugi
    Kyoto University, Research Reactor Institute, Osaka, Japan
 
  A possibility of remodeling main ring of 150 MeV FFAG accelerator at Kyoto University, Institute for Integrated Radiation and Nuclear Science (KURNS) to Pion Production Ring (PPR) for muon transmutation study has been discussed. Design was made on the assumption that 400 MeV proton beams circulate and hit a target in the ring to generate pions. Optimizations of lattice parameters and 3D magnet modeling are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB021  
About • paper received ※ 30 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPRB075 Radiation Limits on Permanent Magnets in CBETA radiation, electron, vacuum, permanent-magnet 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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MOPTS079 Design of 1.5 GeV Compact Storage Ring for the EUV and Soft X-rays storage-ring, quadrupole, synchrotron, resonance 1028
 
  • J.Y. Lee, I.G. Jeong
    Korea Atomic Energy Research Institute (KAERI), Daejeon, Republic of Korea
  • P. Buaphad, Y.J. Joo, H.R. Lee
    University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
  • P. Buaphad, Y.J. Joo, Y. Kim, H.R. Lee, S. Lee
    KAERI, Jeongeup-si, Republic of Korea
 
  Recently, there has been discussions about the need for the next-generation synchrotron light source facility in Korea. The facility in consideration is composed of a super-conducting linear accelerator for the injector, a storage ring for the EUV and soft X-rays, and a main storage ring for hard X-rays. In this study, design concepts of the soft X-ray storage ring is presented. To effectively utilize the small space allocated for the soft X-ray storage ring, a compact storage ring is taken into account. The compact storage ring is a synchrotron accelerator of which diameter is shorter than the length of injector beamline. In this paper, we report design concepts and optimization of the compact storage ring for the EUV and soft X-ray users. The lattice of the storage ring is modelled by utilizing ELEGANT simulation code to optimize beam parameters and performance of the ring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS079  
About • paper received ※ 24 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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MOPTS095 Optimization of the Alba Linac Operation Modes linac, gun, simulation, solenoid 1086
 
  • E. Marín, D. Lanaia, R. Muñoz Horta, F. Pérez
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
 
  ALBA is a third generation synchrotron light source that consists on a linac, booster and storage ring. The linac is capable of operating in single (SBM) and multi-bunch injection mode (MBM). Since 2016 the Single Bunch Bucket Selection algorithm which runs in SBM, permits to inject on a selected bucket keeping the charge uniformity along the ring below 4\%. However when running in SBM a significantly lower transmission along the linac is observed, with respect to the one when running in MBM. Simulation efforts have been deployed in order to build up a reliable model of the ALBA linac which can reproduce the experimental measurements. In this paper we present the new simulation model that renders the experimental observations, and the new optimization procedure developed in simulations and tested in the real machine.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS095  
About • paper received ※ 12 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS111 Primary Beam Dynamics Design of a Heavy-Ion IH-DTL With Electromagnetic Quadrupoles DTL, quadrupole, rfq, cavity 1140
 
  • P.F. Ma, X. Guan, R. Tang, X.W. Wang, Q.Z. Xing, X.D. Yu, S.X. Zheng
    TUB, Beijing, People’s Republic of China
 
  A new IH-DTL beam dynamics scheme, IH-EMQ (ElectroMagnetic Quadrupole) is presented to obtain a large longitudinal acceptance. In this scheme, electromagnetic quadrupoles are installed inside the drift tubes of IH-DTL. A large-longitudinal-acceptance heavy-ion IH-DTL design is described in this paper. With the limit current of 25 mA, the 90% normalized longitudinal acceptance reaches 87.8 pi.deg. MeV for the 60 MeV 107Au30+, which is 8 times of the input emittance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS111  
About • paper received ※ 09 April 2019       paper accepted ※ 17 May 2019       issue date ※ 21 June 2019  
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TUPMP029 Establishing a Laser Treatment to Suppress the Secondary Electron Emission laser, electron, experiment, synchrotron 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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TUPGW084 Multi-pass ERL in a ’Dogbone’ Topology linac, optics, cavity, dipole 1601
 
  • S.A. Bogacz
    JLab, Newport News, Virginia, USA
 
  Funding: Work has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy.
The main thrust of a multi-pass RLA is its very efficient usage of expensive linac structures. That efficiency can be further enhanced by configuring an RLA in a ’dogbone’ topology, which further boosts the RF efficiency by factor of two (compare to a corresponding racetrack). However, the ’dogbone’ configuration requires the beam to traverse the linac in both directions, while being accelerated. This can be facilitated by a special ’bisected’ linac Optics. Here, the quadrupole gradients scale up with momentum to maintain periodic FODO structure for the lowest energy pass in the first half of the linac and then the quadrupole strengths are mirror reflected in the second linac half. The virtue of this optics is the appearance of distinct nodes in the beta beat-wave at the ends of each pass (where the droplet arcs begin), which limits the growth of initial betas at the beginning of each subsequent droplet arc. Furthermore, ‘bisected’ linac optics naturally supports energy recovery in the ’dogbone’ topology. In this paper, we present a-proof-of-principle lattice design of a multi-pass ’dogbone’ ERL.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW084  
About • paper received ※ 08 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, experiment, simulation, electron 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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TUPTS080 Beam Dynamics Studies of an APEX2-Based Photoinjector solenoid, gun, emittance, cathode 2109
 
  • C.E. Mitchell, H.Q. Feng, D. Filippetto, M.J. Johnson, A.R. Lambert, D. Li, T.H. Luo, F. Sannibale, J.W. Staples, S.P. Virostek, R.P. Wells
    LBNL, Berkeley, California, USA
 
  APEX2 is a proposed normal conducting radio-frequency (RF) electron gun operating in the very high frequency (VHF) range in continuous wave (CW) mode, designed to drive applications that require both high beam brightness and high repetition rate, such as free electron lasers (such as LCLS-II-HE), ultra-fast electron diffraction, and microscopy. The gun consists of a two-cell RF cavity operating at 162.5 MHz with a cathode field of 34 MV/m, together with an embedded focusing solenoid. We study the beam dynamics in an APEX-II-based photoinjector (up to ~20 MeV), targeting a transverse 95% beam emittance of 0.1 um at 12.5 A peak current for the case of 100 pC charge for FEL applications. The high cathode field leads to enhanced beam brightness, while the increased gun exit energy of ~1.5 MeV reduces the effects of space charge, and possibly eliminates the need for an RF buncher. The embedded solenoid is designed to control the transverse beam size while minimizing emittance growth due to geometric aberrations. As a result, the transverse beam performance targets are achieved, and ongoing work will further optimize longitudinal beam quality for downstream FEL transport.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS080  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEYYPLS3 Development of Methods for Calculation of Bunch Radiation in Presence of Dielectric Objects radiation, target, simulation, vacuum 2274
 
  • A.V. Tyukhtin, E.S. Belonogaya, S.N. Galyamin, V.V. Vorobev
    Saint Petersburg State University, Saint Petersburg, Russia
 
  Funding: This work was supported by the Russian Science Foundation (Grant # 18-72-10137).
Radiation of charged particles moving in presence of dielectric targets is of interests for various applications in accelerator and beam physics*. Typically, the size of the target is much larger than the wavelengths under consideration. This fact gives us an obvious small parameter of the problem and allows developing approximate methods of analysis. We develop two methods: "ray-optical method" and "aperture method"**. These methods can be very effective for all situations where we can find the tangential field components on the "aperture" which is an object boundary illuminated by Cherenkov radiation. We apply the aperture method to different dielectric objects including a prism, a cone, and a ball. Electromagnetic field is analyzed on different distances from the objects. The special attention is given to investigation of the field in the far-field (Fraunhofer) area having large importance for various applications. We obtain analytical results for different objects, demonstrate typical radiation patterns and discuss new physical effects, in particular, the phenomenon of concentration of radiation and effect of "Cherenkov spotlight". Prospects of use of aperture method and ray-optical one for other objects are discussed as well.
* R.Kieffer et al, PRL, 121, 054802 (2018).
** E.S.Belonogaya et al, JOSA B, 32, 649 (2015); S.N.Galyamin, A.V.Tyukhtin, PRL, 113, 064802 (2014); A.V.Tyukhtin et al, J. Instrum., 13, C02033 (2018).
 
slides icon Slides WEYYPLS3 [4.063 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLS3  
About • paper received ※ 14 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, electron, 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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WEPGW095 Coherent Transition Radiation Spatial Imaging as a Bunch Length Monitor radiation, electron, detector, simulation 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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WEPGW105 Measuring Beam Parameters with Solenoid solenoid, cathode, experiment, emittance 2739
 
  • I. Pinayev, Y.C. Jing, D. Kayran, V. Litvinenko, K. Shih, G. Wang
    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.
We have developed methods of measuring electron beam energy and trajectory including angle and position based on the analysis of beam steering by a solenoid. Beam energy measurement is performed in the straight beamline and is suitable for the beams with substantial energy spread. In this paper, we describe the experimental set-up and the obtained results.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW105  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB095 Microbunching Plasma-Cascade Instability plasma, simulation, electron, bunching 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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WEPTS014 Coherent vs Incoherent Effects and Debye Length space-charge, plasma, lattice, vacuum 3116
 
  • G. Franchetti
    GSI, Darmstadt, Germany
 
  In this proceeding it is discussed the effect of coherent vs. incoherent effect and discussing the validity of frozen models of space charge according to the Debye length and beam radius. This in view of discussing the relation of IBS and space charge  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS014  
About • paper received ※ 15 April 2019       paper accepted ※ 28 May 2019       issue date ※ 21 June 2019  
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WEPTS023 Hamiltonian Formalism of Intense Beams in Drift-Tube Linear Accelerators DTL, quadrupole, space-charge, acceleration 3145
 
  • H. Okamoto
    HU/AdSM, Higashi-Hiroshima, Japan
 
  Starting from the principle of least action, we construct a general Hamiltonian formalism for beam dynamics in drift-tube linear accelerators (DTLs). The Alvarez-type structure is considered here as an example, but the present theory can readily be extended to other types of conventional linacs. The three-dimensional Hamiltonian derived includes the third-order chromatic term as well as the effects from acceleration and space charge. A clear dynamical analogy between the DTL system and compact Paul ion-trap system is pointed out, which indicates that we can conduct a fundamental design study of high-intensity hadron linacs experimentally in a local tabletop environment instead of relying on large-scale machines.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS023  
About • paper received ※ 09 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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WEPTS075 Effect of Beam-Beam Kick on Electron Beam Quality in First Bunched Electron Cooler electron, solenoid, alignment, simulation 3297
 
  • S. Seletskiy, M. Blaskiewicz, A.V. Fedotov, D. Kayran, J. Kewisch
    BNL, Upton, Long Island, New York, USA
 
  The low energy RHIC electron cooler (LEReC) currently under commissioning at BNL is going to be the first non-magnetized bunched electron cooler (EC). For successful cooling LEReC requires that the electrons in the cooling section (CS) have small angles with respect to co-propagating ions. Since there is no strong magnetic field in the CS, the effects of ions on both the trajectory and focusing of the e-bunches is critical. In this paper we consider the ion beam kick on the electron bunches and derive requirements to the respective alignment of electron and ion beams in non-magnetized coolers.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS075  
About • paper received ※ 08 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPTS079 Analysis of Particle Noise in a Gridless Spectral Poisson Solver for Symplectic Multiparticle Tracking space-charge, emittance, plasma, simulation 3304
 
  • C.E. Mitchell, J. Qiang
    LBNL, Berkeley, California, USA
 
  Funding: This work was was supported by the Director, Office of Science, Office of High Energy Physics, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Gridless symplectic methods for self-consistent modeling of space charge in intense beams possess several advantages over traditional momentum-conserving particle-in-cell methods, including the absence of numerical grid heating and the presence of an underlying multi-particle Hamiltonian. Despite these advantages, there remains evidence of irreversible emittance growth due to numerical particle noise. For a class of such algorithms, a first-principles kinetic model of the numerical particle noise is obtained and applied to gain insight into noise-induced entropy growth and thermal relaxation.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS079  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPMP014 2D TRACKING CODE FOR DRIFT TUBE LINAC DTL, linac, simulation, drift-tube-linac 3482
 
  • A. Yamaguchi, K. Nakayama, K. Okaya, K. Sato
    Toshiba, Yokohama, Japan
  • N. Hayashizaki
    RLNR, Tokyo, Japan
  • Y. Iwata, S. Yamada
    NIRS, Chiba-shi, Japan
  • T. Takeuchi
    Toshiba Energy Systems & Solutions Corporation, Keihin Product Operations, Yokohama, Japan
 
  A 2D tracking code has been developed for Alternating-Phase-Focusing drift tube linacs (APF-DTL). This code can design DTLs with a 2D electric field simulation and particle tracking by approximate equations. In this paper, we describe an outline of the 2D tracking code and a comparison of 2D tracking results and 3D simulation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP014  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPMP029 Design Study of a Compact Superconducting Cyclotron SC240 for Proton Therapy cyclotron, proton, extraction, superconducting-magnet 3506
 
  • F. Jiang, G. Chen, Y. Chen, K.Z. Ding, J. Li, Y. Song, Z. Wu, J. Zhou
    ASIPP, Hefei, People’s Republic of China
  • Z. Zhong
    HFCIM, HeFei, People’s Republic of China
 
  Funding: National Natural Science Foundation of China under grant No. 11775258 & 11575237; International Scientific and Technological Co-operation Project of Anhui (grant No. 1704e1002207).
A compact AVF cyclotron of 240 MeV is under-designed for proton therapy. In order to reduce the size, the weight and operation cost, two superconducting coils are designed to implement the 2.35T central field. And the magnet weight is about 90 tons. The constant gap between the sectors is considered without deteriorating the beam stability. A dedicated design on extraction zone is performed to make the average field to close the isochronous field. The extraction efficiency is expected higher than 80%, by regulating the 1st harmonic field and arranging the extraction elements properly. In order to avoid the large scale of volume helium explosion in the quench, the low temperature superconducting coil using NbTi/Cu wire is cooled by 4K GM Cryocooler in a helium volume limiting design. The paper will present the physical design of this cyclotron.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP029  
About • paper received ※ 17 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPMP050 Progress on the Optics Modeling of BMI’s Ion Rapid-Cycling Medical Synchrotron at BNL dipole, optics, GUI, simulation 3561
 
  • F. Méot, P.N. Joshi, N. Tsoupas
    BNL, Upton, Long Island, New York, USA
  • J.P. Lidestri
    Best Medical International, Springfield, USA
 
  Funding: A project funded by Best Medical International, in the framework of a Technical Services Agreement (No. TSA-NF-18-50) with Brookhaven National Laboratory.
The Brookhaven National Laboratory continues to provide technical support and guidance to Best Medical International to build and test a 60 degree magnetic arc of a rapid-cycling ion synchrotron for cancer treatment. The 60 degree magnetic sector on its guirder has undergone field measurements, including the production of partial 3D field maps. Concurrently, OPERA field map computations as well as lattice and beam dynamics simulations have been performed, aimed at both preparing and analyzing the field measurements. Contingency responses aimed at adapting to non-ideal orbit and optics have been devised. These works and their outcomes are summarized here.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP050  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPMP053 Tuning Quadrupoles for Brighter and Sharper Ultra-fast Electron Diffraction Imaging quadrupole, electron, experiment, solenoid 3571
 
  • X. Yang, L. Doom, M.G. Fedurin, Y. Hidaka, J.J. Li, D. Padrazo Jr, T.V. Shaftan, V.V. Smaluk, G.M. Wang, L.-H. Yu, Y. Zhu
    BNL, Upton, Long Island, New York, USA
  • W. Wan
    ShanghaiTech University, Shanghai, People’s Republic of China
 
  Funding: BNL LDRD
We report our proof-of-principle design and experi-mental commissioning of broadly tunable and low-cost transverse focusing lens system for MeV-energy electron beams at the ultra-fast electron diffraction (UED) beam-line of the Accelerator Test Facility II of BNL. We exper-imentally demonstrate the independent control over the size and divergence of the electron beam at the sample via tunable quadrupoles. By applying online optimiza-tion, we achieve minimum beam sizes 75 µm from 1 to 13 pC, two orders of magnitude higher charge density than previously achieved using conventional solenoid tech-nique. Finally, we experimentally demonstrate Bragg-diffraction image (BDI) with significant improvement up to 3 times brighter and 2 times sharper BDI peaks via the optimized quadrupoles, improvement larger with higher charge. The result could be crucial for the future single-shot ultra-fast electron microscope development.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP053  
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPGW001 Design of LhARA - Laser Hybrid Accelerator for Radiobiological Applications proton, laser, target, experiment 3578
 
  • J. Pasternak
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  • O. Ettlinger, C. Hunt, A. Kurup, K.R. Long, Z. Najmudin, J.K. Pozimski
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  • H.T. Lau
    EBG MedAustron, Wr. Neustadt, Austria
 
  Recent developments of using lasers interacting with targets for the creation of ion beams offer a possibility to provide beams for radiobiology research. This research aims to precisely study the radiobiological effectiveness of charged particles on various cultures of cells, which is essential to inform next generation hadron therapy treat-ment plans. The Laser hybrid Accelerator for Radiobio-logical Applications (LhARA) has been proposed to use a laser driven beam, which will be captured and focused using Gabor Lenses. The beam will be then energy and momentum selected to create a beam for in-vitro cells studies or sent to a post-accelerator ring to create beam for in-vivo studies. The optical design of LhARA is pre-sented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW001  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPGW004 The Use of an RF Undulator in the Design of an Accelerating Structure proton, acceleration, undulator, simulation 3587
 
  • N.V. Avreline
    TRIUMF, Vancouver, Canada
  • P.G. Alexey, S.M. Polozov
    MEPhI, Moscow, Russia
 
  The idea of accelerating a beam in the accelerating structures based on an RF undulator poses great advantages in high current proton and ions accelerators. The accelerating structure based on an RF undulator uses a combinational wave that consists of the zeroth and the first harmonics for acceleration and focusing. This paper presents the development of this accelerating structure for acceleration of a beam. In particular, we show that this structure is an H-type resonator composed from five coupled sections.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW004  
About • paper received ※ 01 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPGW006 Avoiding Emittance Degradation When Transferring the Beam From and to a Plasma-Wakefield Stage emittance, plasma, acceleration, quadrupole 3594
 
  • A. Chancé, P.A.P. Nghiem
    CEA-IRFU, Gif-sur-Yvette, France
  • X. Li
    DESY Zeuthen, Zeuthen, Germany
 
  Funding: European Union’s Horizon 2020 research and innovation programme under grant agreement No. 653782.
The plasma-wakefield acceleration technique is known to provide a very strong accelerating gradient (GV/m), up to three orders of magnitude higher than the conventional RF acceleration technique. The drawback is a relatively higher energy spread and especially a huge beam divergence at the plasma exit, leading to an irremediable and strong emittance degradation right after its extraction from the plasma for transferring it to an application or another plasma stage. In this article, we determine the criteria to be achieved so as to minimize this emittance growth after pointing out all the parameters involved in its mechanism. Then the plasma down ramp profile is studied in a typical configuration of the EuPRAXIA project at 5 GeV. It turns out that no specific profile is needed. For minimizing emittance growth at beam extraction, it is enough to optimize the ramp length so that the Twiss parameter γ is minimized. Finally the design of an optimal transfer line allows showing that the emittance growth can be contained to less than 10% in realistic conditions when transferring the beam to a free electron laser.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW006  
About • paper received ※ 09 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPGW019 FLASHforward Findings for the EuPRAXIA Design Study and the Next-Generation of Compact Accelerator Facilities plasma, wakefield, electron, laser 3619
 
  • P. Niknejadi, R.T.P. D’Arcy, J.M. Garland, J. Osterhoff, L. Schaper, B. Schmidt, G.E. Tauscher
    DESY, Hamburg, Germany
  • M. Ferrario, S. Romeo
    INFN/LNF, Frascati, Italy
  • C.A. Lindstrøm
    University of Oslo, Oslo, Norway
  • T.J. Mehrling
    LBNL, Berkeley, USA
 
  FLASHForward, the exploratory FLASH beamline for Future-ORiented Wakefield Accelerator Research and Development, is a European pilot test bed facility for accelerating electron beams to GeV-levels in a few centimeters of ionized gas. The main focus is on the advancement of plasma-based particle acceleration technology through investigation of injection schemes, novel concepts and diagnostics, as well as benchmarking theoretical studies and simulations. Since the plasma wakefield will be driven by the optimal high-current-density electron beams extracted from the FLASH L-band Superconducting RF accelerator, FLASHForward has been in a unique position for studying and providing insight for the design study of next-generation light source and high energy physics facilities such as EuPRAXIA*. Summary of these findings and their broader impact is discussed here.
*P. A. Walker, et. al., "Horizon 2020 EuPRAXIA design study," Journal of Physics Conference Series 874(1):012029, July 2017.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW019  
About • paper received ※ 15 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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THPGW072 Seeded Self-Modulation of Transversely Asymmetric Long Proton Beams in Plasma plasma, wakefield, proton, simulation 3757
 
  • T. A. Perera, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • P. Muggli
    MPI-P, München, Germany
  • T. A. Perera, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: This work is supported by Science and Technology Facilities Council grant ST/P006752/1.
The AWAKE experiment at CERN recently demonstrated the world’s first acceleration of electrons in a proton-driven plasma wakefield accelerator*. Such accelerators show great promise for a new generation of linear e-p colliders using ~1-10 GV/m accelerating fields. Effectively driving a wakefield requires 100-fold self-modulation of the 12 cm Super Proton Synchrotron (SPS) proton beam using a plasma-driven process which must be care-fully controlled to saturation. Previous works have modelled this process assuming azimuthal symmetry of the transverse spatial and momentum profiles **, ***. In this work, 3D particle-in-cell simulations are used to model the self-modulation of such non-round beams. Implications of such effects for efficiently sustaining resonant wakefields are examined.
* Adli, E., et. al. (2018). Nature, 561(7723), 363-367.
** Lotov, K. V. (2015). Physics of Plasmas, 22(10), 103110.
*** Schroeder, C. B., et. al. (2011). Phys. Rev. Lett., 107(14).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW072  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPGW079 THz-Based Femtosecond MeV Electron Bunch Compression electron, FEM, GUI, experiment 3766
 
  • M. A. K. Othman, M.C. Hoffmann, M.E. Kozina, R.K. Li, E.A. Nanni, X. Shen, E.J. Snively, X.J. Wang
    SLAC, Menlo Park, California, USA
 
  Funding: This work was supported by Department of Energy contract DE-AC02-76SF00515.
Probing structural dynamics at atomic spatial and ultrashort temporal scales reveals unprecedented details of fundamental behavior of nature, allowing for better understanding of intricate energy-matter interaction occurring at such scales. Developing state-of-the-art technology to access these details entails utilizing X-ray free-electron lasers (XFELs), ultrafast electron diffraction (UED), and advanced electron microscopes. In particular, ultrafast diffraction science received growing attention thanks to innovation in sources, detectors and instrumentation in general. Within this context, interest in laser-generated THz wave-matter interaction has recently emerged as a new regime for controlling electrons with high temporal precision. Previously, the SLAC UED team has demonstrated attosecond electron metrology using laser-generated single-cycle THz radiation, which is intrinsically phase locked to the optical drive pulses, to manipulate multi-MeV relativistic electron beams. Here we demonstrate further steps towards achieving ultrafast timing resolution that utilizes femtosecond electron bunches. The proposed setup allows for compressing electron beam bunches down to a femtosecond using interaction with high field single-cycle THz pulses. We demonstrate a novel design of a dispersion-free parallel-plate tapered waveguide that provides focusing of THz pulses achieving >100 MV/m field strength at the interaction point as measured by electro-optical sampling for ~7 μJ of incoming THz pulse energy. The structure is being designed and built for bunch compression experiments using the SLAC UED facility.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW079  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPTS044 Parameter Design of a Rotating Coil Measurement System for Quadrupoles quadrupole, dipole, multipole, synchrotron-radiation 4207
 
  • Y. Xie, W. Chen
    Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People’s Republic of China
  • H. Liang, B. Qin, J. Yang
    HUST, Wuhan, People’s Republic of China
 
  Funding: This work was supported by The National Key Research and Development Program of China; and by National Natural Science Foundation of China (11375068).
HUST-PTF is a 5-year National Key Research and Development Program of China which is composed of cyclotron, beamline system, treatment chambers, etc. The beamline system connects the cyclotron and treatment chambers, provides proton beams in adequate size and shape and is crucial to the whole program. Vast dipoles and quadrupoles are employed in the beamline. Aimed at the quadrupoles used in the beamline, this article carried out the research on the high-precision rotating coil magnetic measurements for quadrupoles, including the quadrupole parameters, the principle and structure of the measuring system, measuring procedures and data processing method. Design of the rotating coils and analysis of the main errors are also contained.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS044  
About • paper received ※ 13 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPTS094 High Gradient Quadrupoles for Low Emittance Synchrtrons quadrupole, dipole, vacuum, lattice 4332
 
  • S.K. Sharma, T.V. Shaftan, V.V. Smaluk, C.J. Spataro, T. Tanabe, G.M. Wang
    BNL, Upton, Long Island, New York, USA
  • N.A. Mezentsev
    BINP SB RAS, Novosibirsk, Russia
 
  A new lattice design has been proposed recently based on a Complex-Bend concept [1,2] for low emittance syn-chrotrons. The dipoles of a standard DBA lattice are replaced in the Complex Bend by high-gradient (~ 450 T/m) quadrupoles interleaved between discrete dipoles. In another version of the Complex Bend [3] the high gradient quadrupoles are displaced transversely along the beam trajectory to generate the required dipole field. In the latter version the quadrupole strength is reduced to ~ 250 T/m for a lattice that will conform to the layout of the existing NSLS-II 3-GeV storage ring. In this paper we present conceptual designs of a Halbach permanent-magnet (PM) quadrupole, a hybrid PM quadrupole, and a superconducting quadrupole, that can produce the de-sired quadrupole strengths for the Complex Bend appli-cation. REFERENCES [1] T. Shaftan, V. Smaluk and G. Wang, ’The Concept of Com-plex Bend’, NSLS-II Tech note No. 276, Jan 2018. [2] G. Wang et al., ’Complex Bend: Strong-focusing magnet for low emittance synchrotrons’, Physical Review Accelerators and Beams, 21, 100703 (2018). [3] G. Wang et al., ’Complex Bend II’, paper submitted to Physi-cal Review Accelerators and Beams.

 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS094  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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