MHz pulsed power by semiconductor devices

Pulsed power generators with repetition rates on the order of MHz have been developed by using semiconductor opening switch (SOS), static induction thyristor (SIThy), and silicon carbide junction field-effect-transistor (SiC-JFET). A compact SOS circuit based on inductive energy storage has been developed. It uses semiconductor switches for forward and reverse current control of the SOS diodes, instead of commonly used magnetic switch. The repetition rate has reached 500 kHz (burst) for output voltage pulse of 10 kV and pulse width of 15 ns (FWHM). A full-bridge switching unit using SIThy has been developed and tested for bipolar square voltage pulse generation of plusmn 2 kV for a 100-Omega load, at repetition rate of 1 MHz (burst). A stacked SiC-JFET switching unit consists of 4 devices (2S x 2P) has been operated for 2 kV and 20 A at repetition rate up to 5 MHz (burst). Important issues on switching characteristics, such as rise- time, heat loading, and balance between devices have been studied. The MHz-repetitive power modulators are expected to have various applications in the future, especially for high- energy accelerators and biological treatment.