Author: Hara, K.
Paper Title Page
TUPRI023 Simulation of Debunching for Slow Extraction in J-PARC MR 1606
 
  • M. Yamamoto, M. Nomura, T. Shimada, F. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  • E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda, M. Yoshii
    KEK, Tokai, 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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THPME062 Status of the J-PARC Ring RF Systems 3376
 
  • M. Yoshii, M. Nomura, T. Shimada, F. Tamura, M. Yamamoto
    KEK/JAEA, Ibaraki-Ken, Japan
  • E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, K. Takata, M. Toda
    KEK, Tokai, Ibaraki, Japan
  • A. Schnase
    GSI, Darmstadt, Germany
 
  The high intensity proton accelerator complex (J-PARC) consists of the Linac, the 25Hz rapid cycling synchrotron (RCS) and the 50GeV main synchrotron (MR). During the long shutdown of 2013, the Linac energy was upgraded from 181MeV to the design value of 400MeV. In the RCS, we have installed the last 12th RF system. In operation from January 2014, beam commissioning aimed at 1 MW operation will be started. In the MR, the upgrade plan of the beam power, realizing by raising the repetition, has been started. For this reason the accelerating voltage must be increased, and all MR RF systems will be replaced with more efficient systems. A new magnetic alloy material (FT3L) has been developed. Manufacturing of the FT3L accelerating cavities has proceeded. It becomes possible to increase the accelerating voltage from 280 kV to 540 kV, using the new cavities in combination with the existing RF power supplies. We have started the developments of a 2nd harmonic system loaded with air-cooled FT3L cores and a high-Q VHF cavity system, too. Both systems are used for longitudinal dilution increase the bunching factor of the circulating high intensity proton beam.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME062  
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THPRI046 Air-cooled Magnetic Alloy Cavity for J-PARC Doubled Rep.-rate Scenario 3869
 
  • C. Ohmori, K. Hara, K. Hasegawa, K. Takata, M. Toda, M. Yoshii
    KEK, Tokai, Ibaraki, Japan
  • M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-mura, Japan
 
  The upgrade project of the J-PARC MR (Main Ring) is in progress to deliver the beam power of 750 kW based on doubled repetition-rate scenario. The present RF section will be occupied by 9 sets of new magnetic alloy, FT3L, cavity using the direct water cooling scheme. The direct water cooling requires dedicated high-quality cooling water. These cavities will be used for the fundamental RF for acceleration. The second harmonic RF is necessary to increase the bunch length. This allows to enlarge the beam current, and to relax the space charge effects during the injection. Thanks to the high impedance FT3L, the power loss in the second harmonic RF system becomes moderate. The air cooled cavity is designed to fit in any space in the MR where the dedicated water is not available. This paper reports the design of the second RF system, technical issues to produce the magnetic alloy cores to fit the air cooling, and construction of the system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI046  
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