A Possible modification of ceramic chambers in the injection area at the RCS in J-PARC

Shobuda, Yoshihiro   ; Kamiya, Junichiro   ; Takayanagi, Tomohiro   ; Horino, Koki*; Ueno, Tomoaki*; Yanagibashi, Toru*; Kotoku, Hirofumi*

At the injection area of the RCS in J-PARC, the interaction between the copper stripes (RF-shields) on the ceramic chambers and the external magnetic fields modulatesthe magnetic fields in the chamber, causing beam losses for a special tune. A ceramic chamber spirally covered by the stripes is a candidate to mitigate the modulations. In this report, we numerically and experimentally investigate how the interaction is suppressed, while sustaining the beam impedance enhancement within tolerable at the RCS.