Author: Kinsho, M.
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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MOPRI108 Transverse H− Beam Halo Scraper System in the J-PARC L3BT 876
 
  • K. Okabe, M. Kinsho, K. Yamamoto, M. Yoshimoto
    JAEA/J-PARC, Tokai-mura, Japan
  
  In the Japan Proton Accelerator Research Complex (J-PARC) 3-GeV rapid cycle synchrotron (RCS), transverse beam halo scraping for the injection beam is required to increase the output beam power. The transverse collimation system at the Linac-RCS beam transport line (L3BT) was utilized in a nominal beam operation because the area of the scraper section was contaminated when scrapers were working. In the summer-autumn period of 2013, we installed a new beam-halo scraper which had optimized scraper heads for mitigation of the radiation around the scraper system. In this poster, we report a preliminary result for a halo scraper at the L3BT.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI108  
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WEPME035 Beam Loss Suppression by Improvement of Vacuum System in J-PARC RCS 2338
 
  • J. Kamiya, M. Kinsho, S. Noshiroya, K. Yamamoto
    JAEA/J-PARC, Tokai-mura, Japan
  
  In high power beam accelerators, pressure of the beam line directly affects the amount of the beam loss. For example, in the early 1970’s in CERN’s Intersecting Storage Ring (ISR), the ion-induced pressure bump produced the fall-off of the beam current. 3GeV synchrotron (RCS) in J-PARC is no exception. RCS is one of the most high power beam accelerators in the world. It aims the 1 MW beam power, which corresponds to the average and peak beam current of 333 uA and about 10 A, respectively. In the present stage, the injection line called L3BT line (Linac to 3GeV Beam Transport line), is the section, where the pressure notably produces the beam loss. In this line, H− beam from Linac was converted to H0 by charge stripping due to the interaction between H− beam and the residual gas molecules. Such H0 was not bended by the injection septum magnets and directly hit the vacuum wall. We decided to add the vacuum pumps in this line to reduce the residual gas molecules. We will present the effectivity of the additional pumps on the basis of the measured results of the pressure improvement and the beam loss suppression.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME035  
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THPME063 Residual Dose with 400 MeV Injection Energy at J-PARC Rapid Cycling Synchrotron 3379
 
  • K. Yamamoto, N. Hayashi, M. Kinsho
    JAEA/J-PARC, Tokai-mura, Japan
  
  Last summer shutdown J-PARC RCS injection energy was upgraded from 181 MeV to 400 MeV. We report the effect of the injection energy upgrade on the residual dose in the RCS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME063  
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THPME064 Progress and Status of the J-PARC 3GeV RCS 3382
 
  • M. Kinsho
    JAEA/J-PARC, Tokai-mura, Japan
  
  Big issue for the J-PARC 3GeV RCS was displacement of main magnets caused by last big earthquake because this made beam loss more than 400 kW beam power. Since realignment of main magnet and other components was essential to realize higher beam power and stable operation, this work has been done last maintenance period. To minimize amount of realignment work, we decided that not all components moved to designed regular potions but also minimum components moved to the position which was secured design acceptance 486 π mm mrad. Almost all components which are main magnets, rf cavities, and extraction magnets had to be moved in the range of 10 mm for horizontal, 3 mm for vertical and 9 mm for longitudinal, respectively. It was not necessary for the components installed in injection straight line to move because displacement of these components was less than ± 0.2 mm. At same time 400 MeV injection upgrade work should be done. Beam commissioning is planned from the middle of January 2014. The progress and status of the RCS in J-PARC are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME064  
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