Compact Design of 40 kV 100 A High-Voltage Pulsed-Power Modulator for Driving X-Band Magnetrons

This article describes the design of a very compact high-voltage pulsed power modulator for application in a medical linear accelerator. This modulator is manufactured with a modular cell structure based on a semiconductor switch, and the heat dissipation structure is minimized through a simple and efficient charge-and-discharge circuit design. In addition, an equalized charging strategy for multiple capacitors and a high-voltage electric field noise reduction strategy was applied. Thus, a high voltage pulsed-power modulator with a very compact size (310 (W) mm × 480 (H) mm × 230 (D) mm) and a high peak power density of 111 kW/L was realized without the use of an external cooling device such as a chiller. The modulator was built and experiments were conducted on high-voltage noninductive resistive load outputs. The results show that the modulator had a stable pulse voltage under various conditions, such as an output voltage of up to −40 kV, an output current of up to 100 A, a variable pulse width of 2–10 μs, and an output repetition rate of up to 1 kHz. In addition, the high-voltage insulation reliability of the proposed modulator and its applicability to magnetron loads were verified.