Author: Hayashi, N.
Paper Title Page
MOPF15 Advanced uses of a Current Transformer and a Multi-Wire Profile Monitor for Online Monitoring of the Stripper Foil Degradation in the 3-GeV RCS of J-PARC 239
  • P.K. Saha, H. Harada, S. Hatakeyama, N. Hayashi, H. Hotchi, M. Kinsho, K. Okabe, R. Saeki, K. Yamamoto, Y. Yamazaki, M. Yoshimoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  We have established advanced and sophisticated uses of a Current Transformer (CT) and a Multi-Wire Profile Monitor (MWPM) for measuring as well as online monitoring of the stripper foil degradation during user operation of the 3-GeV Rapid Cycling Synchrotron (RCS) in Japan Proton Accelerator Research Complex (J-PARC). An incoming negative hydrogen beam from the Linac is stripped to a proton beam by using a stripper foil placed in the RCS injection area. Foil degradation such as, foil thinning and pinhole formation are believed to be signs of a foil breaking. A sudden foil breaking is not only a load on the accelerator downtime but also raises maintenance issues. In a high intensity accelerator like RCS, a proper monitoring system of the foil is thus important in order to avoid such above issues by replacing the foil with a new one in the scheduled maintenance day. The thickness of the stipper foil used for the present 181 MeV injection energy is 200 ug/cm2, where a change of foil thickness as low as 1% or even less has already been successfully monitored by utilizing the presented method. Measured data for the last 6 months operation of the RCS will be presented.  
poster icon Poster MOPF15 [1.591 MB]  
WEPC19 Performance of Injection Beam Position Monitors in the J-PARC RCS 716
  • N. Hayashi, P.K. Saha
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • T. Toyama
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  It is important to monitor the injected beam trajectory and position into a synchrotron ring. In the J-PARC RCS, there are two specialized beam position monitors (BPM) in the first arc section in order to perform continuous monitoring. They detect the linac RF frequency 324 MHz or its second harmonics, these contributions quickly decrease after a few turns in the ring. Therefore, they are sensitive only just injected beam. The RCS adopts the multi-turn injection and transverse painting. These monitors are useful to check the beam behavior on-line.