Author: Futatsukawa, K.
Paper Title Page
WEPPD050 Upgrade of the RF Reference Distribution System for 400 MeV LINAC at J-PARC 2630
 
  • K. Futatsukawa, Z. Fang, Y. Fukui, T. Kobayashi, S. Michizono
    KEK, Ibaraki, Japan
  • F. Sato, S. Shinozaki
    JAEA/J-PARC, Tokai-mura, Japan
 
  In J-PARC, the accelerator systems are controlled using the 12 MHz master clock in center control building. In the present J-PARC Linac, the negative hydrogen is accelerated by 181 MeV using the RFQ, DTLs, and SDTLs which have the resonance frequency of 324 MHz. The low-level radio frequency (LLRF) system is based on the reference signal of 312 MHz (LO) synchronized with the master clock. We are planning to upgrade Linac by the accelerated energy to 400 MeV by the installation of ACS cavities with the resonance frequency of 972 MHz. Then, not only 312 MHz but also 960 MHz reference signals are necessary. Therefore, a new RF reference signal oscillator was installed at J-PARC LINAC. The phase noise of the output signal in this module was measured by the signal source analyzer. The jitter of the output signal, which was estimated from the integration of phase noise from 10 Hz to 1 MHz, becomes about 40 fs and was two order smaller than that of the old system (about 1700 fs) by the installation of new oscillator and the optimization of the path of the master clock. It can be expected to improve the operating ratio in J-PARC LINAC.  
 
THPPC009 Investigation of the Approaches to Measure the RF Cable Attenuation 3290
 
  • K. Futatsukawa, Z. Fang, Y. Fukui, T. Kobayashi, S. Michizono
    KEK, Ibaraki, Japan
  • F. Sato, S. Shinozaki
    JAEA/J-PARC, Tokai-mura, Japan
 
  In the accelerator facilities, many RF cables are used for the various purposes such as the transmission system and the cavity monitor. The knowledge of the power attenuation in those cables is important role to control RF. In general, the cable attenuation is measured from S parameters to use a network analyzer. However, the control system is located far from the place of the cavities, and it difficult to measure by a network analyzer. Then we investigated other methods to measure the RF cable attenuation.  
 
THPPC010 Beam Start-up of J-PARC Linac after the Tohoku Earthquake 3293
 
  • M. Ikegami, Z. Fang, K. Futatsukawa, T. Miyao
    KEK, Ibaraki, Japan
  • T. Maruta, A. Miura, H. Sako, J. Tamura, G.H. Wei
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  The beam operation of J-PARC linac was interrupted by the Tohoku earthquake in March 2011. After significant recovering effort including the realignment of most linac components, we have resumed the beam operation of J-PARC linac in December 2011. In this paper, we present the experience in the beam start-up tuning after the earthquake and the status of the linac operation thereafter.