Development of semiconductor switches for high-power crowbar circuits

Many ignitrons are used in the clover device of the klystron power supply for RF acceleration in the J-PARC LINAC. However, these ignitrons contain mercury, of which use is restricted worldwide, and their production is expected to be discontinued in the future. Therefore, we designed a semiconductor clover switch for short-circuit protection of klystron using MOS gate thyristors. We have manufactured an oval-type board module that realizes an operating output of 3 kV, 40 kA, and 50 µs per board. For the control power supply to each board module assuming a high voltage of 120 kV, we adopted a self-power supply method that creates a control power supply with a high-voltage DCDC converter from the voltage shared and charged by each board module. It was possible to confirm the operating performance on a 1/2 scale (60 kV, 40 kA) against the voltage of the existing equipment (120 kV, 40 kA) by connecting twenty oval board modules in series. The output test result will be reported. (author)