Keyword: beam-loading
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TUPRI023 Simulation of Debunching for Slow Extraction in J-PARC MR cavity, resonance, simulation, impedance 1606
 
  • M. Yamamoto, M. Nomura, T. Shimada, F. Tamura
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda, M. Yoshii
    KEK, Ibaraki, Japan
  • A. Schnase
    GSI, Darmstadt, Germany
 
  The J-PARC MR delivers a proton beam for nuclear physics experiments with slow extraction. The beam is debunched at flat top to obtain a coasting beam by turning off the rf voltage. The controlled emittance blow-up before the flat top has been investigated to mitigate the microwave instability. Beam loading effect can disturb the uniformity of the debunching at the flat top. We describe the results of the particle tracking simulation whole acceleration cycle including the controlled emittance blow-up and the beam loading effect.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI023  
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TUPRI072 Status and Performance of Bunch-by-bunch Feedback at BESSY II and MLS feedback, synchrotron, operation, diagnostics 1733
 
  • A. Schälicke, P. Goslawski, M. Ries, M. Ruprecht
    HZB, Berlin, Germany
 
  Funding: Work supported by German Bundesministerium für Bildung und Forschung and Land Berlin.
Bunch-by-bunch feedback systems provide an important component in the reliable operation of electron storage rings. Modern digital bunch-by-bunch feedback systems allow efficient mitigation of multi-bunch instabilities, and at the same time offer valuable beam diagnostics. In this contribution, setup and performance of the bunch-by-bunch feedback systems at BESSY II and the MLS are presented. Longitudinal and transverse instabilities are studied under different machine conditions. The developed data analysis techniques and experimental measurements are discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI072  
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TUPRI073 Impact of Simplified Stationary Cavity Beam Loading on the Longitudinal Feedback System for SIS100 feedback, synchrotron, cavity, controls 1736
 
  • K. Groß, H. Klingbeil, D.E.M. Lens
    TEMF, TU Darmstadt, Darmstadt, Germany
  • H. Klingbeil
    GSI, Darmstadt, Germany
  • D.E.M. Lens
    TU Darmstadt, RTR, Darmstadt, Germany
 
  Funding: Work supported by the German Federal Ministry of Education and Research (BMBF) under the project 05P12RDRBF.
The main synchrotron SIS100 of the Facility for Antiproton and Ion Research (FAIR) will be equipped with a bunch-by-bunch feedback system to damp longitudinal beam oscillations. In the basic layout, one three-tap finite impulse response (FIR) filter will be used for each single bunch and oscillation mode. The detected oscillations are used to generate a correction voltage in dedicated broadband radio frequency (RF) cavities. The digital filter is completely described by two parameters, the feedback gain and the passband center frequency, which have to be defined depending on the longitudinal beam dynamics. In earlier works*, the performance of the closed loop control with such an FIR-filter was analyzed and compared to simulations and measurements with respect to the damping of coherent dipole and quadrupole modes, the first modes of oscillation. This contribution analyzes the influence of cavity beam loading on the closed loop performance and the choice of the feedback gain and passband center frequency to verify future high current operation at FAIR.
* H. Klingbeil et al., IEEE Trans. Nuc. Sci., Vol. 54, No. 6, 2007 and D. Lens et al., Phys. Rev. STAB 16, 032801, 2013.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI073  
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WEPRO018 Theoretical Maximum Current of the NSLS-II Linac linac, simulation, cavity, gun 1980
 
  • R.P. Fliller, F. Gao, G.M. Wang
    BNL, Upton, Long Island, New York, USA
 
  Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
An analysis of the maximum available NSLS-II linac current was performed as part of the preparation for NSLS-II Booster commissioning. The analysis was necessary in order to establish the maximum beam current available from the linac and the maximum current that would be available to the booster accelerator. In this paper we discuss the assumptions that were used in determining the maximum linac current, the model of the linac and comparison to operational conditions.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO018  
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THPME065 Beam Test of the CERN PSB Wide-band RF System Prototype in the J-PARC MR feedback, cavity, impedance, extraction 3385
 
  • F. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  • K. Hasegawa, C. Ohmori, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
  • M.M. Paoluzzi
    CERN, Geneva, Switzerland
 
  In the framework of the LHC Injectors Upgrade project (LIU), a complete replacement of the existing narrow-band rf systems of CERN PSB with wide-band magnetic alloy (MA) loaded rf systems is in progress. A single gap MA loaded rf system prototype, which uses solid-state power amplifier and includes fast rf feedback for beam loading compensation, has been installed in the J-PARC MR to investigate the system behavior with high intensity proton beams. We report the wake voltage measurement results with and without fast rf feedback. In addition to the fast feedback, the rf feedforward method is under consideration to compensate the heavy beam loading more effectively. Preliminary beam test results with feedforward are also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME065  
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THPRI065 Effects of Beam Loading and Higher-order Modes in RF Cavities for Muon Ionization Cooling cavity, plasma, space-charge, higher-order-mode 3921
 
  • M. Chung, A.V. Tollestrup, K. Yonehara
    Fermilab, Batavia, Illinois, USA
  • B.T. Freemire
    IIT, Chicago, Illinois, USA
  • F. Marhauser
    Muons, Inc, Illinois, USA
 
  Envisioned muon ionization cooling channel is based on vaccum and/or gas-filled RF cavities of frequencies of 325 and 650 MHz. In particular, to meet the luminosity requirement for a muon collider, the muon beam intensity should be on the order of 1012 muons per bunch. In this high beam intensity, transient beam loading can significantly reduce the accelerating gradients and deteriorate the beam quality. We estimate this beam loading effect using an equivalent circuit model. For gas-filled cavity case, the beam loading is compared with plasma loading. We also investigate the excitation of higher-order modes and their effects on the performance of the cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI065  
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