Author: Naito, F.
Paper Title Page
TUPB042 Progress on RFQIII Fabrication in J-PARC Linac 570
 
  • T. Morishita
    JAEA/LINAC, Ibaraki-ken, Japan
  • K. Hasegawa, Y. Kondo
    JAEA, Ibaraki-ken, Japan
  • H. Kawamata, F. Naito, T. Sugimura
    KEK, Ibaraki, Japan
 
  The J-PARC accelerator comprises an injector linac, a 3 GeV Rapid-Cycling Synchrotron and a 50 GeV Main Ring. The J-PARC linac has been operating for users with the beam energy of 181 MeV. The energy (to 400 MeV) and current (to 50 mA) upgrade of the linac is scheduled for 1MW operation at RCS. For the current upgrade, the fabrication of a new RFQ, which is designed for 50 mA acceleration, has been started. The engineering design and the fabrication technologies were carefully chosen to reduce the discharge risk during the operation. For good vacuum pumping, vanes and ports are brazed for the direct pumping through slits at the tuners. Also, we tried a chemical polishing to improve the smoothness of the vane surface. In this paper, we present the fabrication progress of a new RFQ in J-PARC linac.  
 
TUPB099 Input Coupler of the J-PARC DTL 690
 
  • F. Naito, K. Nanmo, H. Tanaka
    KEK, Ibaraki, Japan
  • K. Hirano, T. Ito
    JAEA/J-PARC, Tokai-mura, Japan
 
  Each tank of J-PARC DTL has two input couplers. The coupler has a movable coupling loop with an capacitive element which increase the coupling with the tank. The loop position is the outside of the tank, where is the atmosphere. The tank vacuum is kept by the ceramic window on the wall for the coupler port. The ceramic is made of Aluminum oxide of 99.7 % purity. RF properties and the mechanical structure of the coupler were designed adequately in order to achieve the desired performance. We will report the design of the coupler in detail and the experiences for the practical operation of the DTL.  
 
TUPB100 Recovery and Status Report of DTL/SDTL for the J-PARC After Earthquake 693
 
  • T. Ito, K. Hirano
    JAEA/LINAC, Ibaraki-ken, Japan
  • F. Naito, K. Nanmo
    KEK, Ibaraki, Japan
 
  The J-PARC facilities had big damages because of the earthquake on March 11, 2011. The J-PARC linac in the tunnel had also damages. For instance the alignment of the cavity was deformed more than 40 mm and there had been observed about 0.2 mm in horizontal direction for a few DTs in the DTL. However, as the result of the recovery work which includes the re-alignment and re-conditioning of whole cavities, we were able to restart the beam acceleration of the linac. The stability of the DTL and SDTL has returned to the state before the earthquake except for a few tanks of SDTL. In this paper, we will present the recovery works from the earthquake and the operating status of the DTL and the SDTL.  
 
TUPB101 Beam Loss Occurred at DTL Cavity in J-PARC Linac 696
 
  • A. Miura, K. Hirano, T. Ito, T. Maruta
    JAEA/J-PARC, Tokai-mura, Japan
  • M. Ikegami
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • T. Miyao, F. Naito, K. Nanmo
    KEK, Ibaraki, Japan
 
  The beam operation of J-PARC linac was suspended until December 2011 due to the damage by the Tohoku earthquake in March 2011. After resumed the operations, we measured the residual radiation along with the beam line during a short interval. Because the higher residual radiation was detected at the surface of drift tube linac (DTL) cavity by radiation survey, we installed the scintillation beam loss monitors (BLM) at the points where the higher radiation was detected to understand the cause of the radiation. Even the DTL section is low energy part of the linac, fine structure of the beam loss was observed by the scintillation BLM. And we measured the beam loss occurred at the DTL with the parameters of beam orbit and cavity settings. Also, the BLM is employed for the linac tuning. In this paper, the result of the radiation measurement and beam loss signals obtained by the scintillation BLMs are presented.  
 
THPB020 Annular-ring Coupled Structure for the Energy Upgrade of the J-PARC Linac 888
 
  • H. Ao, H. Asano, N. Ouchi, J. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  • F. Naito, K. Takata
    KEK, Ibaraki, Japan
 
  The linac of Japan Proton Accelerator Research Complex (J-PARC), which is an injector to the synchrotron, comprises a 3-MeV RFQ, 50-MeV DTLs and the 181-MeV Separated-type DTLs. In order to increase the beam power of the synchrotron, the task of the 400-MeV energy upgrade of the linac started from March 2009. The tanks of the Annular-ring Coupled Structure (ACS) linac, RF sources, beam monitors and utilities are in production. Although some peripheral components of the ACS linac are prepared previously, the all ACS tanks will be installed and conditioned for 4 months from July 2013. Beam commissioning of the 400-MeV linac is scheduled to begin in October and expected to finish at the end of November 2013. In this paper, we present the current status of the energy upgrade and some R&D results for new equipment for ACS linac.  
 
THPB052 Recent Progress with the J-PARC RFQs 972
 
  • Y. Kondo, K. Hasegawa, T. Morishita
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • H. Kawamata, F. Naito, T. Sugimura
    KEK, Ibaraki, Japan
 
  In this paper, we will report recent topics about J-PARC RFQs. First, the operating RFQ (RFQ I) have been recovered from the long shutdown due to the earthquake. This RFQ have been suffered from breakdown problem since 2008, therefore we have been developing a back-up RFQ (RFQ II). In April 2012, the high power test was successfully performed. Finally, we are fabricating a new RFQ for the beam-current upgrade of the J-PARC linac (RFQ III). The status of these RFQs are described.