Solid-State Power Switches for HPM Modulators

Power modulators for pulsed microwave applications, generally utilizing a thyratron-switched PFN, typically produce 50-120 kV, 1-2 kA microsecond timescale pulses with sub-microsecond 100-200 nsec risetimes. This paper will review an investigation into the feasibility of utilizing certain solid-state power switches at the relatively fast speeds required for HPM modulators. Two very different thyristor switches, an ABB HCT and ann-type MCT, were investigated in a fast 136 nsec, low-impedance 1.4 microsec PFN. Limited success was obtained, as both switches demonstrated sub-microsecond switching times. The ABB HCT switched a bias of 3840V with a risetime of 524 nsec. The N-MCT was faster, switching a bias of 944V in 220 nsec. These results indicate that thyristor switches may be fast enough for some HPM modulator applications.