Development of ignitron alternative semiconductor switch and new kicker power supply for J-PARC accelerator

Ono, Ayato; Takayanagi, Tomohiro   ; Ueno, Tomoaki*; Horino, Koki*; Yamamoto, Kazami   ; Kinsho, Michikazu  

J-PARC uses an ignitron switch as the klystron power source clover device and a thyratron switch as the kicker power system. Ignitron uses mercury, which is of limited use worldwide, and is expected to be discontinued in the future. Therefore, a semiconductor switch for ignitron substitution using a MOS gate thyristor is designed. In order to be used as a crowbar device, a switch capable of resisting an operating output of 120 kV, 40 kA, 50 us is required. We have realized an oval type substrate module that achieves an operating output of 3 kV, 40 kA, 50 us per substrate. In addition, we adopted a LTD circuit using SiC-MOSFET as an alternative switch for thyratron, and produced a radially symmetric pulse power supply circuit to which this circuit was applied. This circuit board achieves a rise of 250 ns or less, and a flat top of 1.5 us or more necessary for the RCS kicker power supply system, with a pulse output of 800 V and 2 kA per circuit board. We report on the power test results at 20 kV.