Keyword: HOM
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MOPGW001 Design Review of Bellows RF-Shielding Types and New Concepts for Sirius shielding, storage-ring, wakefield, impedance 53
 
  • H.O.C. Duarte, P.P.S. Freitas, A.R.D. Rodrigues, R.M. Seraphim, T.M. da Rocha
    LNLS, Campinas, Brazil
 
  Large amounts of bellows in an accelerator justify the importance of simplifying the machining and assembling processes of their RF shield. Such quantity also makes this component one of the main contributors for a machine impedance budget. On the other hand, low impedance designs tend to complicate the mechanical aspects. Applied to Sirius round vacuum chamber of 24 mm inner diameter, the omega-strip and comb-type bellows concepts are compared with new proposed designs. In such comparison, the aforementioned aspects, wakefield losses and prototyping experiences are presented in this work.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW001  
About • paper received ※ 16 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW002 Longitudinal Kicker Design for Sirius Light Source cavity, kicker, GUI, feedback 57
 
  • H.O.C. Duarte, A. Barros
    LNLS, Campinas, Brazil
 
  An overloaded cavity kicker for the Sirius longitudinal bunch-by-bunch feedback system will be presented in this contribution. 4th generation light sources’ lower aperture of vacuum chambers lead to higher cutoff frequencies, jeopardizing the electromagnetic performance of cavities by trapping higher order modes (HOMs) inside the structure. With the objective of damping longitudinal and transverse HOMs without compromising the kicker shunt impedance, solutions as cavity radius reduction, tapered transitions and other geometry changes are discussed herein.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW002  
About • paper received ※ 15 May 2019       paper accepted ※ 17 May 2019       issue date ※ 21 June 2019  
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MOPGW025 Beam Breakup Simulations for the Mainz Energy Recovering Superconducting Accelerator MESA cavity, cryomodule, simulation, operation 135
 
  • C.P. Stoll, F. Hug
    KPH, Mainz, Germany
 
  Funding: This work is supported by DFG through PRISMA+ cluster of excellence EXC 2118/2019, RTG 2128 and by the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No 730871.
MESA is a two pass energy recovery linac (ERL) currently under construction at the Johannes Gutenberg-University in Mainz. MESA uses four 1.3 GHz TESLA type cavities with 12.5 MV/m of accelerating gradient in two modified ELBE type cryomodule with improved thermal connection of the HOM antennas and cw operation. In the first stage of MESA operation 1mA of beam current is foreseen, which will later be upgraded to 10mA. One potential limit to maximum beam current in ERLs is the transverse beam breakup (BBU) instability induced by dipole Higher Order Modes (HOMs). These modes can be excited by bunches passing through the cavities off axis. Following bunches are then deflected by the HOMs, which results in even larger offsets for recirculated bunches. This feedback can even lead to beam loss. Simulation results for HOM spectra of a single TESLA cavity are available for example in *. It was possible to measure the HOM spectra in the cold, not tuned cavities at DESY and in the cold string tuned to the 1.3 GHz fundamental mode at Mainz. Results for the maximum beam current for MESA, limited by BBU, for the various HOM spectra are presented.
* "Eigenmode Calculations for the TESLA Cavity Considering Wave-Propagation Losses through Fundamental and Higher-Order Mode Couplers", W. Ackermann, H. De Gersem, C. Liu, and T. Weiland
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW025  
About • paper received ※ 16 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW076 Verification by RF Measurements of New HOM Mitigation Scheme Developed for Future SPS 33-Cell Accelerating Structures damping, simulation, impedance, coupling 274
 
  • P. Kramer, A. Farricker, C. Vollinger
    CERN, Geneva, Switzerland
 
  Longitudinal higher-order modes (HOMs) at a frequency of around 630 MHz in the 200 MHz travelling wave RF structures currently limit the beam intensities in the CERN SPS to less than that required by the High Luminosity (HL-) LHC. In the framework of the LHC Injectors Upgrade (LIU) project, the performance of the already existing HOM damping scheme for these standing wave modes must be improved. This involves improving the existing HOM-couplers as well as the possible use of a new mitigation technique via the insertion of resonant posts in some cells of the multi-cell structures. The development of the new damping scheme has been performed using theoretical analysis of the cavity-coupler interaction in conjunction with full-wave electromagnetic (EM) field simulations. This contribution will show the verification of the improved HOM damping performance by measurements on a single section with 11 cells and on the future 33-cell structures. The parasitic impact of the damping scheme on the travelling wave fundamental passband (FPB) will also be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW076  
About • paper received ※ 11 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPGW083 Longitudinal Coupled-Bunch Instability Evaluation for FCC-hh impedance, emittance, cavity, synchrotron 297
 
  • I. Karpov, E.N. Shaposhnikova
    CERN, Meyrin, Switzerland
 
  High-order modes (HOM) of the accelerating rf structures and other machine elements, if not sufficiently damped, can drive longitudinal coupled-bunch instabilities (CBI). Their thresholds can be accurately obtained from macro-particle simulations using the detailed impedance model containing many different contributions. This method, however, is very difficult to apply for synchrotrons with a large number of bunches, as it is the case for the Future Circular hadron-hadron Collider (FCC-hh) with up to 10400 circulating bunches per beam. In this paper the semi-analytical approach is used for calculations of the instability thresholds during the acceleration cycle of the FCC-hh. As the result, we define requirements for the HOM damping that would be sufficient to prevent development of longitudinal CBI in the presence of weak synchrotron radiation damping.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW083  
About • paper received ※ 13 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPMP040 US Contributions to the High Luminosity LHC Upgrade - Focusing Quadrupoles and Crab Cavities cavity, luminosity, quadrupole, SRF 536
 
  • G. Apollinari, G. Ambrosio, R.H. Carcagno, SF. Feher, L. Ristori
    Fermilab, Batavia, Illinois, USA
 
  In the early 2000’s, the US High Energy Physics community contributing to the Large Hadron Collider (LHC) launched the LHC Accelerator R&D Program) (LARP), a long-vision focused R&D program, intended to bring the Nb3Sn and other technologies to a maturity level that would allow applications in HEP machines. Around 2015, the technologies developed by LARP were mature enough to allow the spin-off of a major upgrade project to the LHC complex, the High Luminosity LHC (HL-LHC). This paper will focus on the US contribution to HL-LHC, namely the large-aperture low-beta focusing Nb3Sn quadrupoles and the Radio Frequency Dipole (RFD) Crab Cavities, located in close proximity to the ATLAS and CMS experiments. This contribution, called the HL-LHC Accelerator Upgrade Project (HL-LHC AUP), focuses on production of these quadrupoles and cavities by sharing the work among a consortium of US Laboratories (FNAL, LBNL, BNL and SLAC) and Universities and in close connection with the CERN-led HL-LHC Collaboration. The collaboration achieved commonality of specifications and uniformity of performance. Final development of design, construction and first results from the prototypes are described to indi-cate the status of these critical components for HL-LHC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP040  
About • paper received ※ 30 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPMP051 56 MHz SRF System for SPHENIX Experiments at RHIC cavity, operation, SRF, detector 562
 
  • Q. Wu, M. Blaskiewicz, K. Mernick, S. Polizzo, F. Severino, K.S. Smith, T. Xin
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
The sPHENIX experiment is a proposal for a new detector at the Relativistic Heavy Ion Collider (RHIC), that plans to expand on discoveries made by RHIC’s existing STAR and PHENIX research groups. To minimize the luminosity outside the 20 cm vertex detector and keeping the radiation to other detector components as low as possible, a 56 MHz SRF system is added to the existing RHIC RF systems to compress the bunches with less beam loss. The existing 56 MHz SRF cavity was commissioned in previous RHIC runs, and contributed to the luminosity at a voltage of 300kV with thermal limitations from the Higher Order Mode coupler at high field, and at 1MV while using its fundamental damper for HOM damping. In this paper, we will analyze and compare the effect of different RF systems at various scenarios, and discuss possible solutions to the Higher Order Mode (HOM) damping scheme to bring the cavity to 2 MV.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP051  
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB006 HOM Damping Options for the Z-Pole Operating Scenario of FCC-ee cavity, damping, impedance, dipole 590
 
  • S. Gorgi Zadeh
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • R. Calaga
    CERN, Meyrin, Switzerland
  • T. Flisgen
    FBH, Berlin, Germany
  • U. van Rienen
    University of Rostock, Rostock, Germany
 
  The Z-pole option of FCC-ee is an Ampere class machine with a beam current of 1.39 A. Due to high HOM power and strong HOM damping requirements, the present baseline of FCC-ee considers a single cell cavity at 400 MHz. In this paper, different HOM damping schemes are compared for the Z-pole operating scenario with the aim of lowering the parasitic longitudinal and transverse impedance. The HOM power for each damping scheme is also calculated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB006  
About • paper received ※ 15 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPRB033 Preliminary Research of HOM for 100MHz Superconducting Cavity in the Pre-Research Project of HALS cavity, impedance, damping, simulation 649
 
  • Y.G. Tang, L. Wang, C.-F. Wu
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
 
  A 100MHz QWR superconducting cavity is researched in the pre-research project of Hefei Advanced Light Source (HALS). Higher order modes (HOM) damping is a big challenge for synchrotron radiation light source. In this paper, we first apply the novel choke mode structure to the 100MHz QWR (quarter wave resonator) cavity in order to damp the HOM. We identify the main harmful higher order modes. The HOMs in the QWR cavity are suppressed by optimizing the choke dimensions. The broadband HOM impedance spectrum of the cavity was also evaluated by calculating the beam induced wake potential in time domain. The results show that choke mode structure has a good HOM damping effect on the QWR cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB033  
About • paper received ※ 25 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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MOPTS063 Design and Low Power Test of a Prototype HOM LINAC DTL, cavity, linac, impedance 1001
 
  • L. Lu, T. He, C.C. Xing, L. Yang
    IMP/CAS, Lanzhou, People’s Republic of China
  • L. Yang
    University of Chinese Academy of Sciences, Beijing, People’s Republic of China
 
  A 325MHz HOM (higher order mode) type linac was proposed and studied for proton or heavy ion acceleration in medium energy region. The cavity was finished the fabrication already by using copper and aluminum material. We will report results of low power test of the HOM linac in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS063  
About • paper received ※ 29 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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MOPTS092 Numerical and Experimental Evaluation of the DQW Crab Cavity Cryomodule Thermal Budget cryomodule, cavity, radiation, experiment 1074
 
  • F. Carra, K. Brodzinski, E. Cano-Pleite, O. Capatina
    CERN, Meyrin, Switzerland
 
  Funding: Research supported by the HL-LHC project
One of the key devices of the HL-LHC project are SRF Crab Cavities. A cryomodule with two Double Quarter Wave (DQW) crab cavities has been fabricated at CERN in 2017 and successfully tested with beam in the Super Proton Synchrotron (SPS) in 2018. The aim of the present study is to present and compare the estimation of the thermal budget for the different components of the cryomodule, performed with numerical and semi-analytical methods, with the experimental measurements carried out on the cryomodule after installation in the SPS.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS092  
About • paper received ※ 12 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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TUPGW023 Incorporation of a MESA Linac Modules into BERLinPro linac, optics, operation, cavity 1449
 
  • B.C. Kuske, W. Anders, A. Jankowiak, A. Neumann
    HZB, Berlin, Germany
  • K. Aulenbacher
    IKP, Mainz, Germany
  • K. Aulenbacher
    HIM, Mainz, Germany
  • F. Hug, T. Stengler, C.P. Stoll
    KPH, Mainz, Germany
 
  Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin, grants of the Helmholtz Association and grants of Helmholtz Association and the DFG within GRK 2128
BERLinPro is an Energy Recovery Linac (ERL) project, currently being set up at the Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany. BERLinPro is designed as - and for - experiments in accelerator physics and as a test bed for novel ERL components. MESA is an ERL project under construction at the Johannes Gutenberg-Universität, Mainz, Germany. MESA is designed as a user facility to perform experiments in dark matter physics and precision measurements of natural constants. Despite the diverse goals, the main linac, providing the larger part of the particles energy, is fairly compatible. It is planned to test and run the MESA linac module in BERLinPro, prior to its usage in MESA. The goals and benefits of this unique cooperation for both projects are outlined in this paper. The necessary adaptions in BERLinPro, including hardware aspects, the new optics, and the scope of performance are described.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW023  
About • paper received ※ 30 April 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPGW099 Superconducting Crab Cavity Options for Short X-Ray Pulse Generation in SPEAR3 cavity, sextupole, GUI, impedance 1647
 
  • F. Toufexis, V.A. Dolgashev, X. Huang, Z. Li
    SLAC, Menlo Park, California, USA
 
  Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515.
We are exploring methods to generate short X-ray pulses in SPEAR3 on the order of 1 ps to enable studying ultrafast processes in materials. We are developing a 2-frequency crab cavity scheme with two sets of crab cavities* at the 6th and 6.5th harmonics of the 476 MHz ring RF frequency. In previous work we studied a normal conducting crab cavity for SPEAR3**. In this work we explored two superconducting cavity options: a traditional elliptical cavity and the Quasi-waveguide Resonator***. We found that the Quasi-waveguide Resonator cannot meet our field uniformity specifications due to higher order multipole fields. We then optimized a traditional elliptical cavity with the input, Lower Order Modes, and Higher Order Modes couplers following the Argonne Advanced Photon Source design.
* A. Zholents, et al, Nucl. Instrum. Methods Phys. Res., Sect. A, Vol. 425 (1999), p. 385.
** Z. Li, et al, Proceedings of IPAC17.
*** A. Lunin, et al, Proceedings of HOMSC14.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW099  
About • paper received ※ 11 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, simulation, electron, 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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TUPRB101 Damping Trapped Modes in an in-Vacuum Undulator at a Synchrotron Radiation Light Source simulation, vacuum, damping, impedance 1895
 
  • K. Tian, Z. Li, A. Ringwall, J.J. Sebek
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by US Department of Energy Contract DE-AC03-76SF00515.
In this paper, we report the efforts in solving the problem of coupled-bunch instabilities caused by an in-vacuum undulator in the SPEAR3 storage ring. After exploring several approaches to reduce the strength of the trapped modes, we found that ferrite dampers were the most effective and simplest way for mode damping in our SPEAR3 in-vacuum undulator. The results of the first RF cold measurement on an in-vacuum undulator equipped with these ferrite dampers agree well with numerical simulations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB101  
About • paper received ※ 13 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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TUPTS119 Status of the ESS Medium Beta Cavities at INFN - LASA cavity, status, controls, niobium 2211
 
  • P. Michelato, M. Bertucci, A. Bignami, A. Bosotti, M. Chiodini, A. D’Ambros, L. Monaco, R. Paparella, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • S. Aurnia, O. Leonardi, A. Miraglia, G. Vecchio
    INFN/LNS, Catania, Italy
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
  • L. Sagliano
    ESS, Lund, Sweden
 
  INFN-LASA contributes in-kind to the European Spallation Source ERIC with 36 6-cell cavities for the Medium Beta section of the Superconducting Linac. After having developed the electromagnetic and mechanical models, few prototypes have been produced and tested. Based on this experience, we are now supervisioning the cavity production at the industry, the resonators test at DESY and the delivery to CEA at Saclay. In this paper, we report on the status of the overall INFN-LASA contribution including also document handling, interface data exchange and QA/QC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS119  
About • paper received ※ 15 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, electron, 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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WEPRB011 PVD Depostion of Nb3Sn Thin Film on Copper Substrate from an Alloy Nb3Sn Target niobium, cavity, site, interface 2818
 
  • R. Valizadeh, S. Aliasghari, A.N. Hannah, O.B. Malyshev
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • K. Dawson, V. R. Dhanak
    The University of Liverpool, Liverpool, United Kingdom
  • G.B.G. Stenning
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • D. Turner
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • D. Turner
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
 
  In this study we report on the PVD deposition of Nb3Sn on Cu substrates with and without a thick Nb interlayer to produce Cu/Nb/Nb3Sn and Cu/Nb3Sn multilayer structures. The Nb3Sn was sputtered directly from an alloy target at room and elevated temperatures. The dependence of the superconducting properties of the total structure on deposition parameters has been determined. The films have been characterized via SEM, XRD, EDX and SQUID magnetometer measurements. Analysis showed that the composition at both room and elevated temperature was within the desired stoichiometry of 24’25 at%. However, superconductivity was only observed for deposition at elevated temperature or post annealing at 650 °C. The critical temperature was determined to be in the range of 16.8 to 17.4 K. In the case of bilayer deposition, copper segregation from the interface all the way to the surface was observed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB011  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB022 RF System Upgrade for Elettra 2.0 cavity, storage-ring, LLRF, klystron 2849
 
  • C. Pasotti, M. Bocciai, M. Rinaldi
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
 
  The Elettra 2.0 low emittance light source project has triggered the review of the installed RF system’s performances and the analyses of the new machine requirement. This study includes the imperative revamp of the RF power sources. The trade off between the best theoretical RF system design and the available room for installation and budget for Elettra 2.0 has been translated into the operational plan reported here. The first planned step is the installation of 100 kW 500 MHz solid state based transmitters.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB022  
About • paper received ※ 13 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019  
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WEPRB023 Vertical Test of ESS Medium Beta Cavities cavity, cryomodule, vacuum, linac 2852
 
  • A. Bosotti, M. Bertucci, A. Bignami, P. Michelato, L. Monaco, R. Paparella, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • D. Reschke, A.A. Sulimov, M. Wiencek
    DESY, Hamburg, Germany
 
  The Medium beta (β=0.67) section of the European Spallation Source (ESS) Linac is composed of 36 six-cell elliptical superconducting (SC) cavities. As a part to the in kind contribution of Italy to the ESS project, INFN-LASA is in charge of the development and of the industrial production of the whole set of 36 resonators plus two spares. The production activity is now ongoing at ZANON. To qualify the cavities power tests in vertical cryostat has been committed to DESY. During the qualification tests, where the cavities provided with He tanks are pushed to their electromagnetic limits, recording their main electromagnetics parameters such as quality factor Q0 vs Eacc. In this paper we report about the qualification tests performed on the first part of the quality production.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB023  
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPRB032 Superconducting Elliptical Cavities Developed in IMP for the CiADS cavity, multipactoring, operation, simulation 2883
 
  • Y.L. Huang, Y. He, R. Huang, T.C. Jiang, L.B. Liu, S.H. Liu, T. Tan, R.X. Wang, Z.J. Wang, S.H. Zhang, S.X. Zhang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  Multicell superconducting radio frequency (SRF) ellip-tical cavities are proposed for efficient acceleration of proton beam in the Chinese initiative Accelerator Driven Subcritical System (CiADS). Two families of such cavities will be used in the driver SRF Linac, the first family corresponding to βopt=0.62 cavities that will be used to accelerate the H+ beam from 175 MeV to 377 MeV and the second family corresponding to βopt=0.82 cavities that will accelerate the H+ beam from 377 MeV to 500 MeV, with the possibility to upgrade to 1 GeV and higher. The electromagnetic optimization of the cavities with the HOM, wakefield and multipacting analysis will be dis-cussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB032  
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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WEPRB034 Study on the Design of the X-band Waveguide-damped Structure wakefield, damping, GUI, simulation 2886
 
  • X.X. Huang, W. Fang, Z.T. Zhao
    SSRF, Shanghai, People’s Republic of China
  • A. Grudiev
    CERN, Meyrin, Switzerland
 
  The design of waveguide-damped structure is optimized to reduce the magnitudes of surface electromagnetic fields and strongly suppress long-range transverse wakefields of the 380 GeV Compact Linear Collider facility currently under study. The optimization is mainly discussed with the elliptical shape of the iris, the wall shape of the damping waveguides, the position of the high-order-mode damping loads and the widths of the waveguide openings of the entire sequence of damping waveguides.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB034  
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB043 Wakefield Suppression in the Main LINAC of the Klystron-Based First Stage of CLIC at 380 GeV wakefield, GUI, damping, linac 2899
 
  • J.Y. Liu, H.B. Chen, J. Shi, H. Zha
    TUB, Beijing, People’s Republic of China
  • A. Grudiev
    CERN, Meyrin, Switzerland
 
  An alternative klystron-based scenario for the first stage of Compact Linear Collider (CLIC) at 380 GeV centre-of-mass energy was proposed. To preserve the beam stability and luminosity of CLIC, the beam-induced transverse long-range wakefield in main linac must be suppressed to an acceptable value. The design of klystron-based accelerating structure is based on waveguide damping structure (WDS). The high-order modes (HOMs) propagating into four waveguides are absorbed by HOM damping loads. In this paper, the wakefield suppression in CLIC-K based on GdfidL code simulations are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB043  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB049 HOM Analysis of the 4-cell Superconducting Cavity on CTFEL Facility cavity, FEL, simulation, electron 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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WEPRB060 HOM Damped Normal Conducting 1.5 GHz Cavity Design Evolution for the 3rd Harmonic System of the ALBA Storage Ring cavity, GUI, simulation, insertion 2948
 
  • A. Salom, J.M. Alvarez, B. Bravo, F. Pérez
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
 
  In a collaboration framework with CERN, ALBA has designed a normal conducting active 1.5 GHz cavity which could serve as main RF system for the Damping Ring of CLIC and as an active third harmonic cavity for the ALBA Storage Ring. The third harmonic cavity at ALBA will be used to increase the bunch length in order to improve the beam lifetime and increase the beam stability thresholds. The main advantage of an active third harmonic cavity is that optimum conditions can be reached for any beam current. This paper presents the evolution of the preliminary design of this cavity and its trans-dampers: high order modes coaxial dampers with waveguide transitions to N, which allows extracting the power of the high order modes induced by the beam outside of the cavity and to dissipate it using standard loads. This approach has two main advantages: no ferrites brazing is needed and they provide a diagnostic to analyze the beam dynamics. The new features of the design, together with electromagnetic simulations, mechanical and thermal stress analysis will be presented in this paper as well as the first stages of the prototype production status.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB060  
About • paper received ※ 15 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, electron 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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WEPRB077 Simulation and Measurements of HOM Filter of the LARP Prototype RF-Dipole Crabbing Cavity Using an RF Test Box cavity, dipole, luminosity, damping 2999
 
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • Z. Li
    SLAC, Menlo Park, California, USA
 
  The RF-Dipole Crabbing Cavity designed for the LHC High Luminosity Upgrade includes two higher order mode (HOM) couplers. One of the HOM couplers is an rf filter, which is a high pass filter designed to couple to the horizontal dipole modes and accelerating modes up to 2 GHz, while rejecting the fundamental operating mode at 400 MHz. The coupler consists of a high pass filter circuit where the rejection of the operating mode and transmission of HOMs are sensitive to dimensional deviations. An rf test box has been designed to measure the transmission of the rf filter in order to qualify the fabricated HOM coupler and to tune the coupler. This paper presents the measurements of the HOM coupler with the rf test box.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB077  
About • paper received ※ 20 May 2019       paper accepted ※ 21 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, electron, 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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WEPRB098 Cryogenic RF Performance of Double-Quarter Wave Cavities Equipped with HOM Filters cavity, operation, cryogenics, SRF 3043
 
  • S. Verdú-Andrés, I. Ben-Zvi, Q. Wu, B. P. Xiao
    BNL, Upton, Long Island, New York, USA
  • I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
  • G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • G. Burt, J.A. Mitchell
    Lancaster University, Lancaster, United Kingdom
  • R. Calaga, O. Capatina
    CERN, Geneva, Switzerland
  • N.A. Huque, E.A. McEwen, H. Park, T. Powers
    JLab, Newport News, Virginia, USA
  • Z. Li, A. Ratti
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by US DOE through BSA LLC under contracts No. DE-AC02-98CH10886, No. DE-SC0012704, and the US LHC Accelerator Research Program (LARP) and by the EU HL-LHC Project.
Crab cavities are one of the several components included in the luminosity upgrade of the Large Hadron Collider (HL-LHC). The cavities have to provide a nominal deflecting kick of 3.4 MV per cavity while the cryogenic load per cavity stays below 5 W. Cold RF tests confirmed the required performances in bare cavities, with several cavities exceeding the required voltage by more than 50%. However, the first tests of a Double-Quarter Wave (DQW) cavity with one out of three HOM filters did not reach the required voltage. The present paper describes the studies and tests conducted on a DQW cavity with HOM filter to understand the limiting factor. The recipe to meet the performance specification and exceed the voltage requirement by more than 35% is discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB098  
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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WEPRB102 Correction of Crosstalk Effect in the LEReC Booster Cavity cavity, electron, booster, resonance 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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WEPRB111 Development of Nb3Sn Multicell Cavity Coatings cavity, niobium, factory, cryomodule 3070
 
  • G.V. Eremeev
    JLab, Newport News, Virginia, USA
  • U. Pudasaini
    The College of William and Mary, Williamsburg, Virginia, USA
 
  Funding: Co-Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics.
Nb3Sn films have the potential to augment niobium in SRF cavities. Besides single-cell cavity efforts to improve Nb3Sn films, we are working to replicate single-cell results onto the practical 5-cell CEBAF cavities. High quality factors (1011 at 2.0K and 10zEhNZeHn at 4.3 K) have been measured, but the cavities are typically limited by strong low-field Q-slopes and early quenches. Two of the cavities were selected to be assembled into a ’mock-up’ cavity pair unit, the standard step before installation into a cryomodule. Comparison of test results between VTA and pair test offered the first glimpse into post-processing effects on the cavity performance.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB111  
About • paper received ※ 16 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPTS043 SixTrack Version 5: Status and New Developments simulation, electron, scattering, collimation 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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WEPTS049 Flat-Bottom Instabilities in the CERN SPS simulation, impedance, feedback, LLRF 3224
 
  • M. Schwarz, K. Iliakis, A. Lasheen, G. Papotti, J. Repond, E.N. Shaposhnikova, H. Timko
    CERN, Meyrin, Switzerland
 
  At beam intensities of 2.6·1011 protons per bunch, required at SPS injection for the High Luminosity LHC beam, longitudinal instabilities can degrade the beam quality delivered by the SPS, the LHC injector at CERN. In this paper, we concentrate on beam instability at flat bottom. The dependence of the instability threshold on longitudinal emittance and LLRF system settings was measured, to help identify the impedance driving this instability. While reducing the longitudinal emittance reduces the losses at injection, it can drive the beam unstable. The LLRF system of the SPS (partially) compensates beam loading, but also affects the instability. The effect of the different LLRF systems (feedback, feedforward, phase loop and longitudinal damper) and fourth harmonic RF system on the instability was investigated. The measurements are compared with simulations performed with the longitudinal tracking code BLonD.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS049  
About • paper received ※ 10 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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THPMP046 Knowledge Exchange Within the Particle Accelerator Community via Cloud Computing simulation, GUI, software, electron 3548
 
  • D.L. Bruhwiler, D.T. Abell, N.M. Cook, C.C. Hall, M.V. Keilman, P. Moeller, R. Nagler, B. Nash
    RadiaSoft LLC, Boulder, Colorado, USA
 
  Funding: Work supported by US Department of Energy under Award Nos. DE-SC0011237, DE-SC0011340, DE-SC0018719, DE-SC0015212, DE-SC0017181 and DE-SC0017162.
The development, testing and use of particle accelerator modeling codes is a core competency of accelerator research laboratories around the world, and likewise for synchrotron radiation and X-ray optics codes at lightsource facilities. Such codes require time and training to learn a command-line workflow involving multiple input and configuration files, execution on a high-performance server or cluster, post-processing with specialized software and finally visualization. Such workflows are error prone an difficult to reproduce. Cloud computing and UI design are core competencies of RadiaSoft LLC, where the Sirepo* framework is being developed to make state of the art codes available in the browser of any desktop, laptop or tablet. We present our initial successes as real world examples of knowledge exchange (KE) between industry and the research community. This work is leading to broader knowledge exchange throughout the community by facilitating education of students and enabling instantaneous sharing of simulation details between colleagues. Sirepo design objectives include: seamless integration with legacy codes, low barrier to entry for new users, configuration transfer to command line mode, catalog of provenance to aid reproducibility, and simplified collaboration through multimodal sharing. The Sirepo Scientific Gateway** allows users to directly test the software. The combination of intuitive browser-based GUIs and Sirepo’s server-side application container technology enables simplified computational archiving and reproducibility. If embraced by the community, this could become an important asset for the design, commissioning and future upgrade of particle accelerator and X-ray beamline facilities.
* Sirepo cloud computing framework, https://github.com/radiasoft/sirepo
** Sirepo Scientific Gateway, https://sirepo.com
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP046  
About • paper received ※ 21 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPRB043 Design and Simulation of Thin Eddy-Current Septum for Injection of Diffraction Limited Storage Ring septum, injection, simulation, storage-ring 3908
 
  • J. Tong, M. Gu, B. Liu, Y.F. Liu, R. Wang
    SINAP, Shanghai, People’s Republic of China
 
  Funding: Work supported by the National Key Research and Development Program of China(Grant No.2016YFA0402002)
Ultra-low emittance in Diffraction Limited Storage Ring (DLSR) usually has small Dynamic Aperture (DA), which makes the traditional off-axis injection inadequate. Fast kickers together with thin septum magnets or direct current lambertsons could support on-axis injection for closely-spaced bunches with small DA. Thin eddy-current septum prototype had been designed for injection with laminated silicon steel sheets as magnet core. Theoretical analysis and transient simulation had been carried out within OPERA software. Due to the minimum thickness of the septa is only 1 mm , several optimization approaches had been applied, such as shielding with strongly paramagnetic material and exciting with full cycle driving pulse, to satisfy the requirement that the leakage field is less than 0.1% with respect to the main one.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB043  
About • paper received ※ 29 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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THPRB054 Design of a Ultrafast Stripline Kicker for Bunch-by-Bunch Feedback kicker, FEL, impedance, feedback 3931
 
  • J. Wang, P. Li, D. Wu, D.X. Xiao, L.G. Yan
    CAEP/IAE, Mianyang, Sichuan, People’s Republic of China
 
  Lorentz force detuning and beam loading effect of the rf cavities will induce a slope of the cavity gradient. Combed with the cavity misalignments, transverse position of subsequent bunches will differ from each other. The CAEP THz Free Electron Laser facility(CTFEL) will have a fast transverse bunch-by-bunch feedback system on its test beamline, which is used to correct the beam position differences of individual bunches in the macro-pulses. The time response of the kicker is rigid for the interval of the micro-pulses is 18.5ns and will upgrade to about 2 ns, requiring impedance matching of the kicker with the power source and transmission system in a high bandwidth. Also, the electromagnetic field must reach the requirements of the beam parameters. In this paper, the structure design and the optimization of the geometric parameters of the ultrafast stripline kicker is presented. The characteristic impedance, transmission characteristics, field consistency are analyzed and optimized. And the feedback signal generation scheme for continuous bunch trains was proposed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB054  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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THPTS013 Further Designs of HOM Couplers for Superconducting 400 MHz RF Cavities cavity, simulation, impedance, proton 4132
 
  • N.F. Petry, M. Busch, K. Kümpel, O. Meusel, H. Podlech
    IAP, Frankfurt am Main, Germany
 
  The Future Circular Collider (FCC) is one possible future successor of the Large Hadron Collider (LHC) at CERN. The proton-proton collider center-of-mass collision energy is set to 100 TeV with a beam current of 0.5 A. To achieve this energy a stable acceleration is critical and therefore higher order modes (HOM) need to be damped. HOM dampers, further characterized as couplers, need to fulfill several criteria to be efficient. As a first property the couplers should assure a longitudinal impedance of higher order modes of below 10 kW. Furthermore, the loaded Q-factor should be below 1000 and the corresponding R/Q value should be in the range of 10 Ω. Besides the Hook-type and Probe-type HOM coupler two additional designs were simulated. The recent results of the different couplers attached to a superconducting 400 MHz RF cavity will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS013  
About • paper received ※ 09 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPTS055 Design and Construction of 3D Helmholtz Coil System to Calibrate 3D Hall Probes alignment, controls, simulation, dipole 4228
 
  • J. Marcos, J. Campmany, A. Fontanet, V. Massana, L.R.M. Ribó
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
 
  In this paper we present the design of a system of 3D Helmholtz coils aimed to generate a magnetic field in any direction in a controlled way. The system is intended to be applied to the detailed characterisation of the response of 3D Hall probes as a function of the orientation of the measured field. The system will generate magnetic fields of up to 5 mT with an expected angular precision of 0.2 mrad.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS055  
About • paper received ※ 26 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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THPTS074 The Commission of Home-made 500MHz 80kW Solid-state Amplifier in NSRRC power-supply, ISOL, MMI, status 4288
 
  • T.-C. Yu, F.Y. Chang, L.-H. Chang, M.H. Chang, S.W. Chang, L.J. Chen, F.-T. Chung, Y.D. Li, M.-C. Lin, Z.K. Liu, C.H. Lo, Ch. Wang, M.-S. Yeh
    NSRRC, Hsinchu, Taiwan
 
  Solid-state for high power RF application is an attracting and interesting technology which is now become popular in accelerator field. To adopt and master such technique, a 500MHz, 80kW solid-state amplifier is thus developed in NSRRC. The amplifier is consisted of 100 900W amplifier modules which are driving by identical modules. Each module contains input and output directional couplers and status monitoring circuits. To have longer life time and better performance, the RF power transistors are integrated with water cooled heat sink directly. In such way, the transistors have higher output power and better efficiency. The RF power of each module is combined through coaxial combiner while its DC power is provided by parallel connected DC power supplies which can provide better redundancy and reliability. The home-made solid-state amplifier is demonstrated to have quite high quality RF power and reliability with acceptable power combination efficiency.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS074  
About • paper received ※ 29 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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