Author: Toyama, T.
Paper Title Page
MOPPR028 Upgrade Plan of BLM System of J-PARC MR 837
  • K. Satou, T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  The upgrade plan of BLM system of J-PARC Main Ring synchrotron (MR) will be described. Existing proportional chamber beam loss monitors (P-BLMs) have fast signal rise time of about 100ns and high gas gain of about 2·104 at the maximum. These abilities were quite advantageous for the early beam commissioning stage. On the other hand, the gas gain is degraded with increasing output current. The P-BLM is suitable for a measurement of a low level beam loss event, however, vulnerable to a measurement of an accidental beam loss event (fast loss) causing high radiation. To enhance the dynamic range of the system, 1m long Air Ionization Chambers (AICs) will be installed and operated with the P-BLM. Experiments using the real beam loss at collimator area and at the Co60 radiation facility have demonstrated the stable operations up to the radiation level activated by the maximum beam loss power of the collimator area. A new data taking system is now under development, and its performances will also be presented.  
WEPPR008 Simulation of Controlled Longitudinal Emittance Blow-up in J-PARC RCS 2952
  • M. Yamamoto, M. Nomura, A. Schnase, 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, Tokai, Ibaraki, Japan
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  In the J-PARC RCS, a high intensity beam is prepared for the MR. The longitudinal beam emittance at the RCS extraction should be optimized to avoid beam loss during and after MR injection. In order to match the longitudinal emittance shape between the RCS and the MR, it is desirable to enlarge the longitudinal emittance during the RCS acceleration. We have performed the particle tracking simulation for the controlled longitudinal emittance blow up in the RCS.  
THPPD052 Operation and Current Status of Injection, Extraction, Kicker Magnet and the Power Supply for J-PARC 3 GeV RCS 3629
  • M. Watanabe, N. Hayashi, Y. Shobuda, K. Suganuma, T. Takayanagi, T. Togashi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  3-GeV RCS (Rapid Cycling Synchrotron) at High Intensity Proton Accelerator Facility (J-PARC) have started for 24-hour operation with repetition rate of 25 pps in February, 2009. Kicker power supply system which uses thyratrons switches is used for extraction of the proton beam. There were many troubles for unstable operation of the thyratrons just after beam commissioning started. Recently, however, the operations were improved and the failure rate was reduced to approximately 0.1 % in October 2010. After the earthquake on March 11, 2011, the injection and extraction magnets, power supplies, the cables and the bus-duct have been checked. Insulation resistance test, impedance test were performed. Reflected wave measurements by the low-level and high-power pulse of the kicker magnets were performed. Visual checks by a fiber endoscope were also performed in the kicker magnets. The results of the measurements and the checks were all not in the problem.  
THPPP081 Status of Injection Energy Upgrade for J-PARC RCS 3921
  • N. Hayashi, H. Harada, H. Hotchi, J. Kamiya, P.K. Saha, Y. Shobuda, T. Takayanagi, N. Tani, M. Watanabe, Y. Watanabe, K. Yamamoto, M. Yamamoto, Y. Yamazaki, M. Yoshimoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  The injection energy upgrade for J-PARC RCS is planed in 2013. This includes the power supplies upgrade of injection pulsed magnet system, suppression for leakage field, quadrupole correction magnets, reduction of kicker impedance effect and improvements of beam diagnostic instrumentation. The paper reports the present status.  
MOPPD051 Performance of Resonant Slow Extraction from J-PARC Main Ring 481
  • M. Tomizawa, Y. Arakaki, T. Kimura, S. Murasugi, R. Muto, H. Nakagawa, K. Okamura, H. Sato, Y. Shirakabe, T. Toyama, E. Yanaoka, M. Yoshii
    KEK, Ibaraki, Japan
  • D. Horikawa
    Sokendai, Ibaraki, Japan
  • K. Mochiki
    Tokyo City University, Tokyo, Japan
  • A. Schnase
    JAEA/J-PARC, Tokai-mura, Japan
  Proton beam accelerated by the J-PARC main ring (MR) with an imaginary transition lattice is slowly extracted by a third integer resonant extraction scheme and delivered to the hadron experimental hall. One of the critical issues in the slow extraction from a high intensity proton synchrotron is the inevitable beam loss caused by the extraction process at septum devices. A design with low beam loss (high extraction efficiency) is required to reduce machine damage and radiation exposure during hands-on maintenance. We have designed the slow extraction scheme to obtain high extraction efficiency for the MR lattice. The scheme has a large step size and a small angular spread enabling a hit rate of the beam on the developed thin septum device. Since the first 30 GeV proton beam was successfully delivered to the experimental hall in January 2009, an extremely high extraction efficiency of 99.5% has been achieved by an intensive beam tuning. In this paper, we report details of such performance. We will also describe some schemes to improve the serious spiky spill time structure due to large current ripples from the power supplies for the bending and quadrupole magnets.  
WEPPR052 Octupole Magnets for the Instability Damping at the J-PARC Main Ring 3045
  • S. Igarashi, T. Koseki, K. Ohmi, M.J. Shirakata, H. Someya, T. Toyama
    KEK, Ibaraki, Japan
  • A. Ando
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  Octupole magnets have been installed for the instability damping at the J-PARC main ring. The transverse instability was observed during the injection and acceleration periods and caused the beam losses. The chromaticity tuning and bunch-by-bunch feedback system have been applied to suppress the instability. Octupole magnets were considered to create a larger amplitude dependent betatron tune shift and to supply additional option for the instability damping. The side effects of the dynamic aperture reduction and the resonances have been studied.  
THPPP003 Coupling Impedance Study of the New Injection Kicker Magnets of the JPARC Main Ring 3725
  • K. Fan, S. Fukuoka, H. Matsumoto, T. Sugimoto, T. Toyama
    KEK, Ibaraki, Japan
  New lumped inductance kicker magnets have been developed for the J-PARC main ring injection system. For high intensity beam operation, the beam coupling impedance of the new kickers is a critical issue, which not only generates significant heating inside the ferrite impairing the performance of the kickers, but also drives beam instability. Numerical simulations based on CST studio have been studied during the design stage to optimize the kicker structure. Impedance measurements based on wire method have been carried out. The measured results agree well with the simulation results.  
THPPP004 Design and Test of Injection Kicker Magnets for the JPARC Main Ring 3728
  • K. Fan, S. Fukuoka, K. Ishii, H. Matsumoto, H. Someya, T. Sugimoto, T. Toyama
    KEK, Ibaraki, Japan
  The present injection kicker magnets of the JPARC main ring consists of three transmission type kickers. To overcome the operational problems, four lumped inductance kicker magnets have been developed for the simplicity and the high reliability. The tight requirements on the rise and fall time create difficulties for the new design. Magnetic field measurements, coupling impedance measurements and have been carried out. The measurement results show that the new kicker magnets can satisfy the requirements of beam injection.