Reverse switching dynistor pulsers

A unique type of thyristor, the reverse switching dynistor (RSD), has been studied in specially designed pulsers to evaluate their performance for several high-power applications. The dynistor is an asymmetric thyristor with an alternating p+ and n+ structure in its anode. It is a two-terminal device. Application of a reverse voltage across the dynistor makes the n+ regions inject electrons, the device operates like a transistor during turn-on and generates a uniform distribution, enabling fast turn-on. This commutation dissipation and permits high di/dt operation to be achieved. An 80 mm diameter device was evaluated in a pulser using a 0.5 ms (FWHM), 10 m/spl Omega/ PFN with a matched load. Two dynistor-based pulsers, the MPG-1 and the MPG-2, were tested. The MPG-1 used a stack of 24 mm devices and operated in bursts of 50 pulses, each 1 /spl mu/s (FWHM) wide, at a rate of 1 kHz. At 19.6 kV, peak current and di/dt were 6.9 kA and 24.5 kA/ps, respectively. The bursts were repeated at a rate of 2 Hz. The MPG-2 is a single pulse generator consisting of 80 mm devices. It was tested to 101.5 kA at 27 kV with a pulse width of 55 /spl mu/s (FWHM) and a di/dt of 8.2 kA//spl mu/s. The dynistors in the initial version of the MPG-2 pulser failed because of the high di/dt. The redesigned dynistor stack and a trigger circuit providing a 3 kA pulse current enabled successful operation. The dynistor study demonstrated that highly interdigitated gate structures combined with high trigger currents are essential to switch high peak currents and high di/dt.