Troubleshooting of new injection shift-bump power supply of J-PARC RCS

Takayanagi, Tomohiro   ; Hayashi, Naoki  ; Kinsho, Michikazu  ; Ueno, Tomoaki*; Horino, Koki; Okabe, Kota  ; Irie, Yoshiro*

New injection shift-bump (SB) power supply of the 3-GeV Rapid-Cycling Synchrotron (RCS) at Japan Proton Accelerator Research Complex (J-PARC) has been developed and manufactured. The power supply adopted a capacitor commutation method to form the trapezoid waveform pattern (bump waveform) at 32 kA peak by the Insulated Gate Bipolar transistor (IGBT) switch. However, in the test operation, the diodes of the DC charger for the capacitor in the Flat-top unit (Ft-unit) were frequently damaged. It is found the delay of the risetime for the current feedback loop is the cause of the overvoltage across the diodes. This paper reports the characteristic and troubleshooting of the SB power supply.