First measurement and online monitoring of the stripper foil thinning and pinhole formation to achieve a longer foil lifetime in high-intensity accelerators

Saha, P. K.   ; Yoshimoto, Masahiro  ; Hatakeyama, Shuichiro; Hotchi, Hideaki  ; Harada, Hiroyuki  ; Tamura, Fumihiko   ; Yamamoto, Kazami   ; Yamazaki, Yoshio ; Kinsho, Michikazu  ; Irie, Yoshiro*

We have established and implemented a nondestructive online monitoring system for the first time for measuring stripper foil thinning and pinhole formation, which are believed to the foil breaking signals caused by high-intensity beam irradiation. A longer foil lifetime is desired, while a foil failure during operation not only reduces the accelerator availability but also has serious issues for regular accelerator maintenances. The present research has been carried out at the RCS of J-PARC, where we aimed to ensure proper uses of foil and to achieve a longer foil lifetime without any failure. We have precisely measured a foil thinning and pinhole outbreak information to obtain a detail of foil degradation to determine a realistic foil lifetime by achieving a record of nearly 2 years of operation with a single foil and without any failures.