Effects of Short Pulse on Lateral Current Spreading in Turn-on Process of Pulsed Thyristors under Inductive Load

Pulsed thyristors widely used in pulsed power generators are more easily confronted with damage problems in the turn-on process due to insufficient lateral current spreading under short pulses. This study aims to explore the spatial and temporal characteristics of the lateral current spreading under short pulses and reveal the relationship between the lateral current spreading and the external circuit with inductive load. Based on turn-on characteristics experiments of a thyristor with an amplifying gate and emitter shorts, mixed semiconductor device, and circuit simulations were carried out to compute the variation of current density in the thyristor under a ten-microsecond pulse. The results show that the current spreads incompletely under 17 $\mu \text{s}$ pulse due to the external circuit and the emitter short. For comparison, the current can continue spreading at the back of the first emitter short as the pulsewidth is 150 $\mu \text{s}$ . The relationship between the current lateral spreading and the external circuit with inductive load under short pulses is established, and a necessary condition for the current to spread at the back of the first emitter short is proposed.