High-Capacity Capacitor Charging Power Supply for a Pulse Modulator

Abstract

The Shanghai Institute of Applied Physics China Academy of Science (SINAP) has been operating a Soft X-ray LINAC with an energy of 1.5 GeV at accelerator specifications of X-Band 20 MW, S- Band 110 MW, and C-Band 110 MW. The pulse modulator of the SINAP is a pulse forming network (PFN) type with its total capacitance divided as 511 nF, 508 nF, and 540 nF. The operating voltage of the PFN is 45.6 kV (maximum), and the repetition frequency during the operation is up to 50 Hz. In this study, a highly precise capacitor charging power supply (CCPS) capable of charging the PFN capacitors in the pulse modulator is designed and the specifications are verified by comparing the simulation results with the test results of the manufactured products. The maximum output voltage of the CCPS is +50 kV, and the average power is 37.5 kJ/s. A pulse modulator is installed for performance verification in the Dawonsys Company, which demonstrates a satisfactory PFN voltage stability of less than 30 ppm for each PFN capacitance condition at a pulse repetition frequency of 50 Hz. In addition, the master controller and the precision controller are designed to achieve precise control.