High action thyristors for pulsed applications

High energy pulsers for various applications have been constructed by utilizing several different classes of high action switches. Most commonly used switches are high-pressure spark gaps, vacuum switches of varying architectures and solid state thyristors with different gate structures. All these categories of switches are capable of switching large number of coulombs. Spark gaps and vacuum switches have life time dependent on accumulated total coulomb transfer as a dominant rating factor. For the solid state thyristors, the action (current squared times pulse width) is the most significant parameter. Thyristors hold potential for applications in rugged duty, long life high-energy pulsers. Thyristors with different gate structures have been investigated. These thyristors have been designed for commercial low frequency applications. To use them for intended pulsed applications, the gate structure must be optimized, so that the rate of plasma spreading across the wafer is increased to switch maximum peak current at desired di/dt. 125 mm thyristors with different gate structures were tested on a 3.7 mF capacitor bank that had a resistance of 9 m/spl Omega/ and an inductance of 800 nH. Measurements of the current through the thyristor and the voltage drop across it show that power dissipated by the device could be reduced if the plasma-spreading rate could be increased.