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 highpower 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 plasma distribution, enabling fast turn-on. This reduces commutation dissipation and permits high didt operation to be achieved. An 80mm diameter device was evaluated in a pulser using a 0.5 ms FWHM, 10 momega PFN with a matched load. Recent work with a 2.3 kA driver demonstrated operation at didt of 1.7 kAmus 26.6 percent to 70.7 percent and 177 kA. Differentiation of the current pulse gave a didt of 2.8 kAmus. These tests were performed using a two RSD stack in series with a diode to protect against voltage reversal. The devices were triggered by a common driver. The driver unit must be capable of holding off the PFN voltage and generating a high voltage reverse pulse for turn-on. A saturable reactor is required to isolate the main discharge circuit for a period of 2 ps. This technique can be extended to many devices in series, thus enabling a high voltage switch to be built using a single driver.