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Anami, S.

Paper Title Page
MOPAN045 Longitudinal Particle Tracking of J-PARC RCS for Synchronization 260
 
  • M. Yamamoto, K. Hasegawa, M. Nomura, A. Schnase, F. Tamura
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Toda, M. Yoshii
    KEK, Ibaraki
 
  We have performed particle tracking simulation of J-PARC RCS to study the synchronization process. A frequency offset is added to the nominal RF frequency pattern to shift the center of the bunch, under the condition of the offset value should be 'adiabatic' with respect to the synchrotron motion. Since the synchrotron frequency of the J-PARC RCS is substantially changed during acceleration, the particle tracking simulation helps to decide upper limit of the frequency offset which can be employed.  
TUPAN055 Present Status of J-PARC Ring RF Ring RF Systems 1511
 
  • M. Yoshii, S. Anami, E. Ezura, K. Hara, Y. Hashimoto, C. Ohmori, A. Takagi, M. Toda
    KEK, Ibaraki
  • K. Haga, K. Hasegawa, M. Nomura, A. Schnase, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
 
  The RCS high frequency accelerating systems are prepared for beam commissioning in September 2007. Installations of cavities, power supplies and amplifiers have been carried out. The systems have been checked for operation and interoperability. For the MR high frequency accelerating system, the examination of the whole system and its final adjustment are done aiming at installation in October 2007. Here, we report on various issues which had been found and solved during the examination and installation period.

masahito.yoshii@kek.jp

 
TUPAN063 High Power Test of MA Cavity for J-PARC RCS 1532
 
  • M. Yamamoto, K. Hasegawa, M. Nomura, A. Schnase, F. Tamura
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Toda, M. Yoshii
    KEK, Ibaraki
 
  We have been testing the RF cavities for the J-PARC RCS, we can operate the cavities without sever problems. Before some MA cores were damaged, then we found such cores have low ribbon resistance. After that we have tested the cavities loaded with improved ribbon resistance.  
WEPMN024 RF Feedback Control Systems of the J-PARC Linac 2101
 
  • Z. Fang, S. Anami, S. Michizono, S. Yamaguchi
    KEK, Ibaraki
  • T. Kobayashi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • H. Suzuki
    JAEA, Ibaraki-ken
 
  The commissioning of the J-PARC 181MeV proton linac was started from October of 2006. The RF sources of the linac consist of 4 solid-state amplifiers and 20 klystrons. In each RF source, the RF fields are controlled by a digital RF feedback system installed in a compact PCI (cPCI) to realize the accelerating field stability of ±1% in amplitude and ±1 degree in phase. In this paper the performance of the RF feedback control systems will be reported in detail.  
WEPMN038 Development of the Beam Chopper Timing System for Multi-Turn Injection to the J-PARC RCS 2125
 
  • F. Tamura
    JAEA/LINAC, Ibaraki-ken
  • S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Toda, M. Yoshii
    KEK, Ibaraki
  • K. Hasegawa, M. Nomura, A. Schnase, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
 
  Multi-turn injection using charge exchange is employed for the J-PARC Rapid Cycling Synchrotron (RCS). To improve the bunching factor of the beam in the ring, the momentum offset injection scheme is used. In each turn, the bunch trains from the linac are injected into the RF buckets with a momentum offset. The bunch train is called the "intermediate pulse". The intermediate pulses are generated in the low energy section of the linac by the RF chopper and pre-chopper. Since the pulse must be synchronized to the RF voltage in the ring, the timing signals for the choppers are generated by the low-level RF (LLRF) system of the RCS and the signals are sent to the chopper control. The RF chopper and the pre-choppers require different pulse widths. Thanks to the direct digital synthesis (DDS) in the LLRF system, precise zero-cross signals for the reference of the chopper pulses are generated without difficulties. The cable route from the RCS LLRF system to the linac chopper control system is more than one kilometer. Thus, the chopper pulses are sent via optical cables. We developed the chopper timing module. We describe the details of the hardware and the preliminary test results.  
WEPMN039 Performance of J-PARC Linac RF System 2128
 
  • T. Kobayashi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • S. Anami, Z. Fang, Y. Fukui, M. Kawamura, S. Michizono, K. Nanmo, S. Yamaguchi
    KEK, Ibaraki
  • E. Chishiro, T. Hori, H. Suzuki, M. Yamazaki
    JAEA, Ibaraki-ken
 
  High power operation of all the RF systems of J-PARC linac was started for the cavity conditioning in October 2006. Twenty 324-MHz klystrons have powered the accelerating cavities successfully, and the beam commissioning was started in November 2006. The performance of the RF drive and control system will be presented.  
WEPMN040 MA Cavities for J-PARC with Controlled Q-value by External Inductor 2131
 
  • A. Schnase, M. Nomura, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • S. Anami, E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, M. Toda, M. Yoshii
    KEK, Ibaraki
 
  The original J-PARC RCS cavity design* used cut-cores to control the Q-value. Adjusting the distance between the C-shaped core parts the optimum Q=2 is reached. Because of problems related to the cut-core surfaces, the "hybrid cavity" was introduced, using tanks with uncut cores (Q=0.6) in parallel to tanks with cut cores with a wider gap (Q=4), resulting in total Q=2. This was successfully tested. The manufacturing procedure for cut-cores involves more steps than for uncut cores. To reduce risks for long-term operation, the RCS cavities will be loaded with uncut cores for day-1 operation. With uncut cores (Q=0.6) the maximum beam power is limited. Therefore we introduce a parallel inductor, placed in the push-pull tube amplifier driving the cavity, to adjust the Q-value to 2. Parallel vacuum capacitors shift the resonance near to 1.7 MHz. Each of the 10 cavity systems for RCS, necessary for day-1 operation, is tested for at least 300 hours to detect initial problems before installation into the RCS tunnel. We report the results of cavity performance tests with external inductor, which simulate 25Hz operation and the optimization of the combined system of cavity and amplifier.

* C. Ohmori at. al, "High Field-Gradient Cavity for J-PARC 3 GeV RCS", PAC 2004