A test preparation of thick carbon stripper foils for RCS of J-PARC

Japan-Proton Accelerator Research Complex requires thick carbon stripper foils (300–500 μg/cm2) to strip electrons from the H− beam supplied by the linac before injection into the Rapid Cyclic Synchrotron. The 400 MeV H− beam from the linac has a pulse length of 0.5 ms with a repetition rate of 25 Hz and an average beam current of 335 μA. For this high-energy and high-intensity beam, the conventional carbon stripper foils will be ruptured in a very short time. Thus, long-lived thick carbon stripper foils are indispensable to this next-generation accelerator. For this purpose, we prepared carbon stripper foils of 130 μg/cm2 by means of a controlled AC–DC arc discharge method. eparation procedure is described and lifetime tests with a 3.2 MeV Ne+ beam of 3–4 μA are reported.