Improvement of J-PARC klystron high voltage power supply

Chishiro, Etsuji; Kawamura, Masato*; Sagawa, Ryu*; Ogawa, Shinichi*

In J-PARC linac, six units of high voltage power supplies for 324 MHz klystrons have operated since 2006, and those running time exceed 35,000 hours. In addition, six units of power supplies for the 972 MHz klystrons have been operation since 2013. In the power supply, various troubles occur under the operation. In some anode modulators, arc discharge in the transformer oil had occurred due to the deterioration of the auxiliary solid insulator. In three modules combining a step-up transformer and a rectifier, the high voltage diode was breakdown because an unexpected overvoltage was applied. And by improving the voltage dividing resistor of the module, high stability cathode voltage was achieved. In this report, we describe the trouble and the improvement that occurred in the equipment.