Development of DC‐1 MV Ultrahigh Voltage Generator for ITER

SUMMARY This paper presents development results of a five‐stage DC‐1MV Ultrahigh Voltage Generator for ITER. Each generator outputs −200 kV, and the total five generators are connected in series and outputs −1 MV. In order to realize the DC‐1MV output and 1‐h continuous operation, a feasibility of both gas insulation and gas cooling for semiconductor devices was validated. A simplified structure with stud‐type diodes and heatsinks resulted in the compatibility of enough insulation distance and wide cooling surface. Withstand voltage tests and a temperature rise test were performed for the actual equipment of the rectifier and the step‐up transformer. These test results verified the validity of the proposed design.