Measurement of continuous degradation of a stripper foil during ths operation with 300 kW beam power in the 3-GeV RCS of J-PARC

J-PARC 3GeVシンクロトロンにおける半年間にわたる300kW出力時での荷電変換フォイルの劣化過程の計測

Saha, P. K.   ; 吉本 政弘  ; 發知 英明  ; 原田 寛之  ; 岡部 晃大  ; 山崎 良雄 ; 金正 倫計  ; 入江 吉郎*

Saha, P. K.; Yoshimoto, Masahiro; Hotchi, Hideaki; Harada, Hiroyuki; Okabe, Kota; Yamazaki, Yoshio; Kinsho, Michikazu; Irie, Yoshiro*

In the 3-GeV RCS, we have clearly measured a continuous degradation of the stripper foil used for charge exchange injection. The measurement was carried out during six months operation with 300 kW. The foil at the injection beam spot was measured to be continuously thickening and it was more than 10% thicker as compared to its initial thickness indicating that a strong wrinkling or curling occurred at the foil edge even with present beam intensity. The missing H was also measured to be gradually increased due to the curling. It is thus a big issue for 1 MW operation as a missing H would increase the heat load on the waste beam dump. A foil thickening on the other hand increases the foil scattering beam loss. A foil thinning and pinhole formation caused by the radiation due to radiation are believed to signals for foil breaking and is also one big concern as beam intensity is increased. The present high precession measurement technique is believed to play an important role for determining a proper timing for foil replacement in order to ensure a stable operation of the RCS.