Author: Fang, Z.
Paper Title Page
WEPFI016 Upgrade of Power Supply System for RF-Chopper At J-PARC Linac 2735
 
  • K. Futatsukawa, Z. Fang, Y. Fukui, M. Ikegami, T. Miyao
    KEK, Ibaraki, Japan
  • E. Chishiro, K. Hirano, Y. Ito, N. Kikuzawa, A. Miura, F. Sato, S. Shinozaki
    JAEA/J-PARC, Tokai-mura, Japan
  • T. Hori
    JAEA, Ibaraki-ken, Japan
  • Y. Liu, T. Maruta
    KEK/JAEA, Ibaraki-Ken, Japan
  • T. Suzuki
    Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
 
  In the J-PARC Linac, the radio frequency deflector was adopted as a chopper to capture the particles into the RF-bucket in the next synchrotron. The chopper, consists of two deflectors, was installed on the medium-energy beam-transport line. In the operation of the RF-chopper, the fast rise/fall time of the pulse is a fundamental requirement to minimize the beam loss due to insufficient deflection to some beam bunches. In the previous system, the two series-connected chopper deflectors were driven by one solid- state amplifier. However, the fall time indicated a poor result to effect the ringing into each cavity. Therefore, the additional solid-state amplifier and low level RF system were installed in the summer 2012 and the connection changed to the parallel system from the series using two amplifiers. The rise/fall time of the chopped beam, is defined as the step height of 10% and 90%, was about 20 nsec in the beam current of 15 mA and the effect of the ringing was decreased. We would like to introduce the performance of the new chopper system.  
 
WEPFI017 Performance of Cavity Phase Monitor at J-PARC Linac 2738
 
  • K. Futatsukawa, S. Anami, Z. Fang, Y. Fukui, T. Kobayashi, S. Michizono
    KEK, Ibaraki, Japan
  • F. Sato, S. Shinozaki
    JAEA/J-PARC, Tokai-mura, Japan
 
  The amplitude and the phase stabilities of the RF system play an important role for the cavity of a high intensity proton accelerator. For the J-PARC Linac, the accelerating field ambiguity must be maintained within ±1% in amplitude and ±1 degree in phase due to the momentum acceptance of the next synchrotron. To realize the requirement, a digital feedback (FB) control is used in the low level RF (LLRF) control system, and a feed-forward (FF) technique is combined with the FB control for the beam loading compensation. The stability of ±0.2% in amplitude and ±0.2 degree in phase of the cavity was achieved including the beam loading in a macro pulse. Additionally, the cavity phase monitors, which can measure the phase difference between any two cavities, were installed in summer, 2011. The monitor has the three different types, which are for the present 324-MHz RF system, the 972-MHz RF system and the combined system of 324-MHz RF and 972-MHz RF. The phase monitor for the 324-MHz RF has been in operated since Dec. 2011. We would like to introduce the phase monitor and indicate the phase stability at the J-PARC linac.  
 
THPWO028 Commissioning Plan for Energy Upgrade of J-PARC Linac 3821
 
  • M. Ikegami, Z. Fang, K. Futatsukawa, T. Miyao
    KEK, Ibaraki, Japan
  • Y. Liu
    KEK/JAEA, Ibaraki-Ken, Japan
  • T. Maruta
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • A. Miura, J. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
 
  In J-PARC linac, we plan to have an energy and intensity upgrade in summer 2013. The upgrade involves replacement of the ion source and RFQ (Radio Frequency Quadrupole linac), and addition of ACS (Annular Coupled Structure linac) cavities after existing SDTL (Separate Drift Tube Linac) section. With this upgrade, the design peak current will be increased from the present 30 mA to 50 mA, and the energy from 181 MeV to 400 MeV. This significant upgrade will be followed by a full-scale beam commissioning campaign. In this paper, we present the plan for the commissioning with outlining the assumed commissioning schemes.  
 
THPWO030 Recent Progress in Beam Commissioning of J-PARC Linac 3827
 
  • M. Ikegami, Z. Fang, K. Futatsukawa, T. Miyao
    KEK, Ibaraki, Japan
  • Y. Liu
    KEK/JAEA, Ibaraki-Ken, Japan
  • T. Maruta
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • A. Miura, J. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
 
  The beam operation of J-PARC linac has been restored from the earthquake, and started to pursue higher beam power operation. We have also started to prepare for coming energy and intensity upgrade. In this paper, we review recent progress in beam commissioning of J-PARC linac with emphasis on the beam loss mitigation and preparation for the upgrade.