487 / 2017-05-10 13:25:10

Experiments on the pre-ionization of coaxial gas spark switch

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Gas spark switches are widely used in the application of pulse power for its short time delay, small jitter and many other advantages. To improve the working range, reduce the breakdown time delay and jitter of the switches, researchers employ ultraviolet light, plasma jet and other pre-ionization methods to assist the switch conduction. Based on coaxial gas spark switch, the pre-ionization on the overvoltage gap caused by the discharge arc of trigger gap’s conduction is studied in this paper. The trigger gap of the switch is parallel to the overvoltage gap, and the gap between the two gaps is completely transparent. To determine the specific influence range of the pre-ionization effect under certain trigger energy, the coaxial switch is equivalent with a column-type flat electrode with a smaller effective area. In this paper, the trigger characteristics of the swithch under different gas pressure and gap distance (vertical distance between two switch gaps) are tested in the case of three conditions, no baffle, JGS1 quartz glass baffle and opaque baffle. The test results prove that, under the case of opaque baffle, in other words, there is no pre-ionization, the switch can be conducted below 0.175Mpa, but the trigger characteristics are poor; in the case of no baffle, and the spacing is 2cm, gas pressure is 0.3Mpa, the switch can be stably conducted, as its breakdown time delay and jitter are better; when the gap distance ranges from 4cm to 10cm, and the gas pressure under 0.2Mpa, the trigger characteristics of the switch are stable.; in the case of JGS1 quartz glass baffle, which means only keeping the effect of the discharge arc’s ultraviolet light irradiation , the switching characteristic is improved compared to the case of opaque baffle, but the improvement is apparenetly reduced when the gap distance is longer than 4cm.