Semiconductor submicrosecond power commutator switches

Increasing the capacity of existing pulse thyristors capable of commutating currents up to 100 A under a voltage of 1 kV to 1 MW of pulse power at a pulse rise time of 100 ns or shorter involves either decreasing the load resistance, although below 1 ohm the switching time increases excessively because of the finite parasitic circuit inductance, or increasing the initial applied voltage. In the latter case maximum switching speed is attained by preventing localization of the current during the turn-on transient period. Turn-on by a momentary overvoltage (in the statistical sense) pulse is preferable. In this case, impact ionization and the conductive component of the current provide the necessary action, while the capacitive current component is ineffective. Experiments confirm that combining such an overvoltage pulse with suppression of dynamic current localization can raise the current capacity of submicrosecond switching thyristor series chains by at least two orders of magnitude.