Keyword: HOM
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TUCOZBS06 Cryomodules for the Mainz Energy-Recovering Superconducting Accelerator (MESA) cavity, cryomodule, operation, radiation 56
 
  • T. Stengler, K. Aulenbacher, F. Hug, D. Simon, C.P. Stoll, S.D.W. Thomas
    KPH, Mainz, Germany
  • K. Aulenbacher
    HIM, Mainz, Germany
  • K. Aulenbacher
    GSI, Darmstadt, Germany
 
  Funding: This work is supported by the German Research Foundation (DFG) under the Cluster of Excellence "PRISMA+" EXC 2118/2019}
The Mainz Energy-recovering Superconducting Accelerator (MESA) will be an electron accelerator allowing c.w. operation in energy-recovery (ER) mode. The energy gain of 50 MeV will be provided by two modified ELBE/Rossendorf-type cryomodules. The MESA-cryomodules are delivered and tested. The test results will be discussed.
 
slides icon Slides TUCOZBS06 [10.644 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-TUCOZBS06  
About • paper received ※ 16 September 2019       paper accepted ※ 11 November 2019       issue date ※ 24 June 2020  
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WEPNEC22 Beam Impedance Study on a Harmonic Kicker for the CCR of JLEIC impedance, cavity, kicker, simulation 116
 
  • G.-T. Park, J. Guo, F. Marhauser, R.A. Rimmer, H. Wang, S. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: Work supported by Jefferson Science Associates, LLC under U.S DOE Contract No. DE-AC05-06OR23177
In this report, we present the development of a fast harmonic kicker, a normal conducting deflecting cavity that kicks electron bunches from ERL ring to circulator cooler ring (CCR) in Jefferson Lab Electron Ion Collider (JLEIC). This cavity utilizes 5 harmonic modes to generate a sharp kick to the electron bunch at high frequency of 86.6MHz, which is injection frequency into the CCR. The beam dynamics study and RF design of the hardware was reported in [1],[2]. In this report we present further progress including impedance by higher order mode (HOM) study and mechanical design for fabrication.
[1] G. Park, et. al TUPAL068, Proc. of IPAC 2018, Apr 2018, Vancouver, BC Canada
[2] G. Park, et. al, Proc. of IPAC2019, May 2019, Melbourne, Australia
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-WEPNEC22  
About • paper received ※ 30 September 2019       paper accepted ※ 04 November 2019       issue date ※ 24 June 2020  
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THCOWBS06 Beam Breakup Limit Estimations and Higher Order Mode Characterisation for MESA cavity, dipole, cryomodule, simulation 134
 
  • C.P. Stoll, F. Hug
    KPH, Mainz, Germany
 
  Funding: Work supported by the German Research Foundation (DFG) under the Cluster of Excellence "PRISMA+" EXC 2118/2019, through RTG2128 Accelence and by ARIES.
MESA is a two pass energy recovery linac (ERL) currently under construction at the Johannes Gutenberg-University in Mainz. MESA uses two 1.3 GHz TESLA type cavities with 12.5 MV/m of accelerating gradient in a modified ELBE type cryomodule in c.w. operation. One potential limit to maximum beam current in ERLs is the transverse beam breakup (BBU) instability induced by dipole 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. To measure the quality factors and frequencies for the dressed as well as undressed cavities improves the validity of any current limit estimation done.
 
slides icon Slides THCOWBS06 [3.256 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-THCOWBS06  
About • paper received ※ 18 September 2019       paper accepted ※ 04 November 2019       issue date ※ 24 June 2020  
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THCOXBS02 Development of HOM Coupler with C-Shaped Waveguide for ERL Operation cavity, insertion, GUI, cryomodule 138
 
  • M. Sawamura, R. Hajima
    QST, Tokai, Japan
  • M. Egi, K. Enami, T. Furuya, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
 
  HOM damping in the superconducting cavities has been becoming increasingly important for high current beam acceleration. Though some HOM damping devices have already been used with success at moderate currents, they have some inherent disadvantages for high current in principle. We have proposed the new type of the HOM coupler using the C-shaped wave guide (CSWG). The CSWG is structured by topologically transforming a rectangular waveguide into coaxial-like structure whose inner and outer conductors are connected with a plate. Similar to the rectangular waveguide, the CSWG has cutoff frequency whose half wave length is approximately equal to the mean circumference. This enables a smaller low-pass filter than the rectangular waveguide. Since the inner conductor can be easily cooled through the plate and the outer conductor, this prevents the connector for HOM power extraction from temperature rising. These characteristics of the CSWG-type HOM coupler can solve the disadvantages of the conventional damping devices. The properties of sufficient HOM damping were confirmed by the measurements with the CSWG-type HOM couplers equipped to the cavity models.  
slides icon Slides THCOXBS02 [7.418 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-THCOXBS02  
About • paper received ※ 13 September 2019       paper accepted ※ 01 November 2019       issue date ※ 24 June 2020  
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FRCOYBS04 Working Group Summary: Superconducting RF cavity, controls, operation, cryomodule 177
 
  • F. Gerigk
    CERN, Meyrin, Switzerland
  • P.A. McIntosh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  To be added  
slides icon Slides FRCOYBS04 [17.955 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ERL2019-FRCOYBS04  
About • paper received ※ 20 September 2019       paper accepted ※ 01 November 2019       issue date ※ 24 June 2020  
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