Development of a long-lifetime spark gap switch and its trigger generator for 2.0 MJ capacitive pulsed power supply module

Starting from the updated requirements of an advanced laser system, a switch-trigger system for a 2.0 MJ pulsed power supply module has been developed. This paper discusses the design, construction and testing of this switch-trigger system. The two-electrode construction for the spark gap switch was selected due to the superiority in long working life, high peak currents and fast rise-time of currents. The trigger generator based on resonant charging of pulse transformer was constructed. A magnetic isolator and a pressure controller were the auxiliary equipments of this system. In the section about the mathematical principles, the equations of the lifetime and stability of this spark gap switch with graphite electrodes are given. These expressions can be regarded as the design basis of the same type switch. As for the trigger generator, the analysis states that an appropriate ratio can be obtained when using the resonant charging based on core-type pulse transformer. The charging time is dependent on the leakage inductance and the capacitance of the primary and secondary capacitors. Extensive testing has proved the operating parameters of the switches and trigger generator. The measured discharge current waveform of 2.0 MJ capacitive pulsed power supply module is demonstrated to be over 500 kA peak-current and 500 μs pulse-width. And the life test has proved that the switch-trigger system can support more than 200 kC transfer charge. Via replacing the electrodes, the lifetime of this switch can be extended more.