Author: Ezura, E.
Paper Title Page
TUPME019 Simulation for Control of Longitudinal Beam Emittance in J-PARC MR 1610
  • M. Yamamoto, M. Nomura, A. Schnase, 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
  The J-PARC MR receives a high intensity beam from the RCS. The designed longitudinal emittance of the RCS is 5 eVs, whereas the MR rf bucket has enough margin to accept up to 10 eVs. Although the RCS emittance can be increased by using PM method and a large emittance is desirable to increase the bunching factor and to avoid instability, it is difficult to receive such large emittance beam in the MR because of the MR kicker performance. We have performed the particle tracking simulation of longitudinal emittance control for enlarging the beam emittance by PM method and for keeping the bunching factor high using 2nd harmonic rf during the MR injection period.  
WEPEA019 Status of the J-PARC MA Loaded RF Systems 2537
  • M. Yoshii, E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda
    KEK, Tokai, Ibaraki, Japan
  • M. Nomura, T. Shimada, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-mura, Japan
  • A. Schnase
    GSI, Darmstadt, Germany
  Japan proton accelerator complex operates two cascaded synchrotrons, 3GeV RCS and 50GeV MR. The high electric field gradient magnetic alloy (MA) loaded cavities are used in both synchrotrons. The RF systems have no tuning control loop and the direct digital synthesis based fully digital low level RF guarantees the stable and reproducible proton acceleration. The feed-forward systems using the circulating beam current signals works efficiently to compensate the heavy beam induced voltage. In RCS, 11 RF systems are operating in a dual harmonic mode since December 2008. The longitudinal RF control based on the particle tracking performed effectively and the equivalent beam power of 530 kW was successfully demonstrated. The 260kW operation for the neutron users started in October 2012. In MR synchrotron, the 9th RF system was newly installed and became available as a 2nd harmonic RF system in November 2012. A 30 GeV proton of 200 kW beam power has been delivered to the T2K neutrino beam experiment with 2.48 sec repetition cycle. This paper summarizes the operation details and the status and features of the J-PARC RF systems.