Exchange and observation systems for charge stripper foils at the J-PARC 3GeV-RCS

The Japan Proton Accelerator Research Complex (J-PARC) has been under construction in Tokai-mura, Ibaraki, Japan. Three independent charge stripper devices are set up at the injection line of the 3 GeV Rapid Cycling Synchrotron (RCS). The H− beam accelerated by a 181 MeV Linac is charge-exchanged to a H+ beam by the first stripper foil, and then injected into the RCS. The H0 and H− fractions of the beam, which are not stripped by the first stripper foil, are converted into a H+ beam by the second and the third stripper foils. e designed the charge exchange devices by adopting the transfer-rod system for moving the foils in a vacuum. We have fabricated a new type of transfer-rod, which can move over a distance of 1500 mm. e also developed a new telescope system to observe possible wrinkles and pinholes of the foil. The system withstands more than 1 MGy of radiation dose and has a resolution of 250 μm at a distance of 10 m from an object.