Impedance measurements of RF cavities in J-PARC synchrotrons

Nomura, Masahiro  ; Tamura, Fumihiko   ; Schnase, A.; Yamamoto, Masanobu   ; Hasegawa, Katsushi*; Shimada, Taihei ; Hara, Keigo*; Toda, Makoto*; Omori, Chihiro*; Yoshii, Masahito*

J-PARC 3 GeV RCS and 50 GeV MR employ Magnetic Alloy (MA) loaded RF cavities to achieve a high accelerating voltage. RCS RF cavities employ MA un-cut cores and MR use MA cut cores. We report the impedance measurement results of the RCS RF cavities loaded MA cores without epoxy resin and effectiveness of coating of MR cutting core surface to prevent rusting. We also report the RF systems affected by the great East Japan earthquake.