• M. Kawase, M. Kinsho, O. Takeda, Y. Yamazaki, M. Yoshimoto
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken

The charge exchange device for 3GeV RCS in J-PARC, which require that a broken foil is exchanged for a new foil by remote control and automatically in vacuum. The control system's important task will be to control under the unified management of the vacuum system and foil driving system and to support EPICS. This device consists of the vacuum system using PLC (Programmable Logic Controller) and the foil driving system using MCU (Multi Control Unit). A workstation (WS) was required, and we developed control system which control under the unified management of 2 different type of system. The uniform management control system became complex system. In fact, therefore control system was unfinished system, it did not protect trouble such as the vacuum gate valve closed while transfer rod insert in the ring. Each algorithm of PLC, MCU and WS was reviewed, and the control system that was able to do the unified management was restructured. Each algorithm of PLC, MCU and WS was debugged so that this control system is made remote control using EPICS. We introduce the reconstruction of the control system for the charge exchange system at the RCS in J-PARC.

• Y. Yamazaki, M. Kinsho, O. Takeda, M. Yoshimoto
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• I. Sugai
  KEK, Ibaraki

J-PARC requires thick carbon stripper foils to strip electrons from the H^- beam supplied by the linac before injection into the Rapid Cycling Synchrotron (RCS). Foil thickness is about 200 μg/cm² corresponding to conversion efficiency of 99.7% from the primary H^- beams of 181MeV energy to H⁺. For this purpose, we have successfully developed hybrid type thick boron-doped carbon (HBC) stripper foils, which showed a drastic improvement not only with respect to the lifetime, but also with respect to thickness reduction and shrinkage at high temperature during long beam irradiation. We started to study carbon stripper foils microscopically why carbon foils have considerable endurance for the beam impact by boron-doped. At first, we made a comparison between nominal carbon and HBC by the electric microscope and ion-induced analysis. In this paper, we will introduce some results for characteristics of HBC foils.

• M. Yoshimoto, M. Kawase, M. Kinsho, O. Takeda, Y. Yamazaki
  JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
• Z. Kabeya
  MHI, Nagoya
• Y. Saito
  KEK, Ibaraki

At the 3GeV RCS (Rapid Cycling Synchrotron) in J-PARC (Japan Proton Accelerator Research Complex), the scheme of H^- charge exchange injection using stripping foils is adopted. The charge exchange system is composed of three stripping foil devices. The first stripping foil device, which converts the H^- beam from the 181MeV LINAC into the H⁺ beam, can replace the broken foil with new one in vacuum remotely and automatically. In September 2007, mechanical trouble with the first stripping foil device had occurred just before the RCS beam commissioning was started. The magnetic coupling of the transfer rod had been decoupled and the transfer rod had been broken which was caught in the vacuum gate valve. We studied the trouble cause, re-examined the structural design and the selection for the material, and then verified the specification from endurance tests with sample pieces. Then the improved device was installed in the ring in September 2008. In this presentation, we report the mechanical trouble and that countermeasure, including the improvements of the charge exchange system.