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Tomizawa, M.

Paper Title Page
TUPAN051 Design of Dynamic Collimator for J-PARC Main Ring 1505
  • M. Tomizawa, A. Y. Molodozhentsev, M. J. Shirakata
    KEK, Ibaraki
  The J-PARC main ring has a beam collimator section downstream of the injection area. The allowed beam loss is about 500 W. The beam halo during injection can be scraped by a standard collimator scheme. The beam halo can grow during the acceleration. Such a halo may cause a serious beam loss for extracted beam. A collimation during acceleration (dynamic collimator) is usefull to reduce the uncontrolable beam loss at the extraction. We will report the design and simulation of the dynamic collimation.  
TUPAN052 New Beam Optics Design of Injection/Fast Extraction/Abort Lines of J-PARC Main Ring 1508
  • M. Tomizawa, A. Y. Molodozhentsev, E. Nakamura, I. Sakai, M. Uota
    KEK, Ibaraki
  J-PARC Main Ring has three straight sections for injection, slow extraction and fast extraction. Injection line has been redesigned so as to give a higher reliability for the thin septa. The magnetic field can be reduced by adding an extra kicker. New optics for the fast extraction with a larger acceptance has been proposed. In this design, the thin septa are replaced by kickers with a large aperture. Beam with an arbitrary energy can be aborted from opposite side from the fast extraction. An external abort line has been designed to deliver the beam aborted with an arbitrary energy to a dump just by using a static quadrupole doublet for the focus.  
THPAN039 Space Charge Effects for JPARC Main Ring 3315
  • A. Y. Molodozhentsev, T. Koseki, M. Tomizawa
    KEK, Ibaraki
  The JPARC Main Ring should provide the beam power up to 0.8MW at the maximum energy of 50GeV. According to the basic operation scenario during the injection period 8 bunches with the maximum bunch power up to 100kW should be created around the ring. In frame of this report we present the space charge effects in combination with the nonlinear resonances, caused by the machine imperfection, for different beam intensities and different machine operation scenario, including the Main Ring RF system, the collimator system of the RCS-MR beam line and the MR collimation system. The measured field data for main magnets of the ring has been taken into account for this study.  
FRPMN036 Resonance Correction systems for JPARC Main Ring 4024
  • A. Y. Molodozhentsev, T. Koseki, M. Tomizawa
    KEK, Ibaraki
  • S. Machida
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  The injection time for the JPARC Main Ring for the basic scenario is about 120ms, which corresponds to about 20,000 turns. The particle losses at the Main Ring collimator should be less than 1% from the expected maximum beam power at the injection energy. To keep the particle losses for the Main Ring operation below the limit, the correction systems have been suggested to eliminate possible resonance excitation. The proposed correction schemes allow us to suppress linear and nonlinear resonances. The calculated and/or measured field data for main magnets of the ring has been taken into account for this study.