Keyword: beam-loading
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THPO004 Pulsed Operation of CEBAF for JLEIC Injection cavity, injection, electron, linac 682
 
  • J. Guo, J.M. Grames, R. Kazimi, F. Lin, T. E. Plawski, R.A. Rimmer, H. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
JLab Electron Ion Collider (JLEIC) is planning to use the recently upgraded 12 GeV CEBAF 1497 MHz SRF CW recirculating linac as a full-energy injector for the electron collider ring. The JLEIC electron injection requires 3-4µs long bunch trains with a 20-400ms spacing in between, resulting in uneven beam loading for the CW CEBAF. With the high beam current in JLEIC collider rings, the low duty factor of injection also requires to a very high pulsed beam current from CEBAF, exacerbating the transient beam loading issue. In this paper, we will present CEBAFs detailed pulsed operation scheme for JLEIC injection, as well as some experimental results at CEBAF.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO004  
About • paper received ※ 20 September 2018      issue date ※ 18 January 2019  
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THPO011 First Energy Recovery Operation at the S-DALINAC: RF Control Stability Measurements controls, operation, cavity, linac 706
 
  • M. Steinhorst, M. Arnold, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  • C. Burandt
    HIM, Mainz, Germany
 
  Funding: *Supported by the DFG through GRK 2128.
One of the main research instruments at the institute for nuclear physics at the TU Darmstadt is the recirculating superconducting linear accelerator S‑DALINAC. Many improvements were implemented since the first recirculated beam in 1991. One of the major enhancement is the upgrade from a twice to a thrice recirculating scheme in 2015/2016. With this upgrade the operation mode can be changed between a conventional accelerating operation and energy recovery linac (ERL) mode by an 180° rf phaseshift of the beam done via a path length variation of the arcs in the second recirculation. ERL operation was not possible when the rf control system for the superconducting structures was set up in 2010. Therefore the current rf control system is not optimized for this kind of operation and so it had to be tested during ERL operation in order to also demonstrate its capability of this operation mode. In August 2017 a first once recirculating ERL operation was achieved. During this operation measurements regarding the rf control stability and the demand of rf power were done. This contribution is discussing this measurements and possible improvements for future energy recovery beam times.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO011  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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THPO113 Design of 4 Ampere S-Band Linac Using Slotted Iris Structure for Hom Damping linac, HOM, damping, target 934
 
  • J. Pang, S. Chen, X. He
    CAEP/IFP, Mainyang, Sichuan, People’s Republic of China
  • S. Pei, H. Shi, J.R. Zhang
    IHEP, Beijing, People’s Republic of China
 
  An S-band LINAC with the operating frequency of 2856 MHz and beam current of 4 A was designed for flash X-ray radiography for hydrodynamic test. The optimization of the parameters of the LINAC was processed to obtain the minimum beam radius and the maximum energy efficiency. For the purpose of reducing the beam orbits offset at the exit of LINAC, a slotted iris accelerating structure would be employed to suppress the transverse Higher Order Modes (HOMs) by cutting four radial slots in the iris to couple the HOMs to SiC loads. In this paper, we present the design of the LINAC and the results of beam dynamic analysis.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO113  
About • paper received ※ 10 September 2018      issue date ※ 18 January 2019  
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THPO127 The Effect of Energy Fluctuation on the Multi-bunch Acceleration in E-driven ILC Positron Source positron, acceleration, cavity, booster 958
 
  • M. Kuriki, H. Nagoshi
    HU/AdSM, Higashi-Hiroshima, Japan
  • S. Kashiwagi
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  • K. Negishi
    Iwate University, Morioka, Iwate, Japan
  • T. Okugi, T. Omori, M. Satoh, Y. Seimiya, J. Urakawa, K. Yokoya
    KEK, Ibaraki, Japan
  • Y. Sumitomo
    LEBRA, Funabashi, Japan
  • T. Takahashi
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
 
  E-Driven method is a technical backup for positron source for ILC. In the positron source, the positron is generated and accelerated in a multi-bunch format with gaps in a macro-pulse. We employ AM (Amplitude Modulation) to suppress the transient beam-loading, but a small fluctuation is still expected, depending on the compensation accuracy. In this article, the positron yield which is ratio of numbers of positrons over electrons, is evaluated as a function of the compensation accuracy. With this result and the detail investigation of the beam loading compensation accuracy by AM, the positron yield of E-Driven Positron source for ILC is evaluated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2018-THPO127  
About • paper received ※ 12 September 2018      issue date ※ 18 January 2019  
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