| Pulsed power technology has an extensive usage in the fields of national defense and industrial application, such as high power microwave generator, X-ray generation and gas lasers generation, and so on. In these applications, it is very important to improve the high pulse repetition rate. But the switch is the key obstacle for development of high pulse repetition rate. So high power, high current, long life-time, repetitive spark gap switch is researched widely in the world. Also for the high current gas switch, they have one main disadvantage, they have a finite lifetime. Hereby, the research on gas spark switch in the paper will focus on the improvement of its lifetime.In this paper, the recovery characteristics of insulation gas is analyzed in theory, also the electrode cooling is analyzed by electromagnetic soft. And a three electrodes gas spark switch with high current and long life-time is designed. The results provide a theoretical and experimental basis to design the repetitive spark switch with high power, high current and long lifetime.For the theoretical analysis and simulation research, at first, the breakdown mechanism of gas spark gap and the main parameters of the spark switch are analyzed. Then, a kind of structure of high voltage and high current switch is designed based on the results of comparing two kinds of high current switch. For anti-pollution design of switch, the outer housing of the switch is made of brass and a metal baffle is used to protect the pollution of top insulating plate from molten metal droplets of the electrode and plasma jets during the close of gas switch. This design is beneficial to increasing the lifetime of the switch. At the same time, the electric field of spark gap switch has been researched using the CST-EM-STUDIO software,and the main dimensions of the switch are optimized. At last, the electrode cooling of the switch is simulated with the help of the ANSYS-THERMAL software. The simulation results show that it is effectively to cool the electrode with the refrigerant and to improve the lifetime and stability of the switch.At the same time, according to the results of theoretical analysis and software simulation, a high power, high current, long life-time and repetitive spark gap switch is designed. The gas blowing system and electrode cooling system are also designed for the switch.Finally, a series of experiments are performed for the switch: (1) the self breakdown experiments show that operating voltage is 33～45kV when the gas pressure is 0.10～0.25MPa in the switch, and the self breakdown voltage is linear increase with the gas pressure. (2) During the single trigger experiment, the operating ranges of the switch are 25～94%,38～86%,40～88% and 44～88% when the gas pressure are 0.10, 0.15, 0.20 and 0.25MPa respectively and the trigger voltage is 80kV. And when the gas pressure is 0.25MPa, the experimental results indicate that the operating voltage is 40kV which is about eighty eight percent of self-breakdown voltage; delay time 50ns; jitter 1.28ns; deviation less than 3%.(3) In the repetitive experiments, the parameters of the switch are related to the pulse repetitive rate, i.e. pulses per second (pps).They are 10kV, 10kA for 30Hz and 20kV, 20kA for 10Hz. The switch works stably and reliably.
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