Low Inductance High Current Characteristics Of The Gas Spark Switch

The gas-spark switch is the especial switch used in pulse- power equipment, and it has been widely used for its simple structure, very short switching time, high transmit-current and conveniently use. Because its performances directly influence the output parameters and the stability of equipment, in recent years, this kind of switch has been the research hotspot in the field of pulse- power technology in China and many other countries.The high-current gas-spark switch has been researched in this paper. It is a DC high-voltage close switch. Its peak current of discharge reaches 300kA～ 400kA, and the persistence time is about several microseconds. Its design methods have been made a summary based on researching the influenced factors of the switch such as the transmit-current capability, the performances in static and trigger state, and the material of electrode and insulator influenced on the natural life of switch. The key design factors that can improve the performance of switch have been made a summary, which based on contrast theory with result of experiment. They are:a) Desiring for low inductance of the switch, it should increase the outside-diameter of electrode and the diameter of spark-route, and reduce the length of spark-route as possible in mechanical design.b) Designed main electrode of the switch for well-distributed of electric field, which could enhance the self-breaking voltage of the switch, and gain high even electric field intensity in the path where streamers formed and transmitted when the trigger pulse arrived, decrease the delay time of the switch.c) The shape and location of the trigger electrode have a great influence on trigger performances of the switch. Therefore its parameters should be adjusted in physical design to make the maximal field aberration coefficient. The precise location in the axial and radial is importance in mechanical design.d) The electrode made use of the alloy of tungsten and copper can endure ablation, but it spatter to insulation rind badly. Some methods will be adoped such as shield structure and others safeguard structure could enhance natural life of switch in mechanical design.e) Organic glass has better insulation performances compared with nylon, so it is useful for the natural life of insulator.Using the research approaches and the conclusions presented in this paper, a high current gas-spark switch has been developed. Its peak current is 400kA, persistence time isl3.5μs. This switch has been used in DPF facility successfully.