Reduction of outgassing for suppressing electrical breakdown in the kicker magnet of J-PARC RCS

Kamiya, Junichiro   ; Kinsho, Michikazu  ; Ogiwara, Norio; Kuramochi, Masaya; Ueno, Tomoaki; Takayanagi, Tomohiro   ; Takeda, Osamu; Watanabe, Masao  ; Yamazaki, Yoshio ; Yoshimoto, Masahiro  

Kicker magnets in Rapid Cycling Synchrotron (RCS) of Japan Proton Accelerator Research Complex (J-PARC) are now under construction. The kicker magnets are short pulse magnets with high charging voltage of 60 kV or more which is installing in vacuum chambers. The kicker magnet mainly consists of aluminum alloy as electric plates and ferrite as magnetic cores. The outgas reduction from those components is very important to prevent not only electrical discharge but also interaction between the proton beam and residual gas in the vacuum. We thoroughly reduced the outgas from the components. Surface of the aluminum alloy was finished by pit-free electropolishing. Aluminum and ferrites were baked in vacuum before construction of the magnet. They were baked each other until water, which was the main component of outgas, was reduced. We will discuss the effects of above processes on the discharge in the vacuum.