Author: Harada, H.
Paper Title Page
MOPRI107 The Mitigation System of the Large Angle Foil Scattering Beam Loss caused by the Multi-turn Charge-exchange Injection 873
 
  • S. Kato
    Tohoku University, Graduate School of Science, Sendai, Japan
  • H. Harada, H. Hotchi, M. Kinsho, K. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  Funding: Research Fellow of Japan Society for the Promotion of Science
In the J-PARC RCS, the significant losses were observed at the branch of H0 dump line and the Beam Position Monitor which was put at the downstream of the H0 dump branch duct. These losses were caused by the large angle scattering of the injection and the circulating beam at the charge exchange foil. To realize high power operation, we have to mitigate these losses. So, we developed a new collimation system in the H0 branch duct and installed in October 2011. In order to optimize this system efficiently, we focused on the relative angle of collimator block from scattering particles. We developed the beam based angler regulation method by the simulation and achieved the sufficient mitigation of the loss at 181 MeV injection energy. Since the injection energy will be upgraded to 400 MeV in this year, we will start to estimate again the collimator performance by the upgraded simulation set. We present this system as one of the mitigation methods of the large angle foil scattering beam loss caused by the multi-turn charge-exchange injection.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI107  
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TUPRI051 Comparison between Measurements and Orbit Code Simulations for Beam Instabilities due to Kicker Impedance in the 3-GeV RCS of J-PARC 1683
 
  • P.K. Saha, H. Harada, N. Hayashi, H. Hotchi, Y. Shobuda, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  The transverse impedance of the extraction kicker magnets is the most dominant beam instability source in the 3-GeV Rapid Cycling Synchrotron of J-PARC. The instability occurs when chromaticity is fully corrected during acceleration but on the other hand no instabilities are observed for a full chromatic correction only at the injection energy even for a beam power up to 500 kW. However, the situation may change for a beam power of 1 MW and also for the upgraded injection beam energy from the present 181 MeV to the 400 MeV, as space charge effect in the non-relativistic region is believed to suppress the growth rate of beam instability. In order to study the kicker impedance in detail, recently we have introduced measured time dependent impedance source in the ORBIT simulation code in a realistic manner. The ORBIT code itself has also been well upgraded and given realistic features for application to synchrotrons. We have also carried out a systematic experimental study for a maximum beam power of 500 kW. In this paper, a detail comparison between measurements and corresponding simulations including 1 MW simulation results are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRI051  
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