A Novel Application of GaAs Photoconductive Semiconductor Switch in Triggering Spark Gap

Based on the characteristics of the GaAs photoconductive semiconductor switch (PCSS) and the spark gap, a new combined switch is developed. The combined switch integrates a traditional GaAs PCSS and a normal spark gap, which could offer two to three times of self-breakdown voltage for the spark gap in nanoseconds. Compared with the traditional single GaAs PCSS, a higher peak current at the output terminal was observed in the experiments when the combined switch was used. Based on the transferred electron effect and the runaway fast electron model, the turn-on process of the GaAs PCSS and the mechanism for the formation of plasma channel in the spark gap are discussed. In addition, due to the interaction between the GaAs PCSS and the spark gap, lock-on effect is avoided in a bulk GaAs PCSS when the bias electric field is larger than the lock-on threshold, which indicates that this combined switch could improve the longevity of the GaAs PCSS under high applied voltage.