Research of high-power repetitive spark-gap switch under adverse conditions

With rapid development of pulse power technology, two-electrode gas spark switch has broadened its application in industrial fields, such as the extraction of unconventional gas resources. Thus, the repetitive switch requests high current capability, low breakdown voltage dispersancy, and long lifetime in an airtight chamber without gas blowing system or electrode cooling system. The purpose of this paper was to study the switch´s operating characteristics under adverse conditions and to analyze the failure cause. A test stand was established to research the Cu-W (70% mass percent of W) two-electrode spark-gap switch working in an airtight chamber (1.2L) filled with dry air and without gas blowing system. The switch was tested with frequency of 0.1Hz, self-breakdown voltage of 30kV for 5800 shots. The self-breakdown voltages of the switch followed the mixed Normal distribution. The anode electrode erosion rate was 5.4691 × 10^-6 cm³/C and the cathode electrode erosion rate was 6.3434 × 10^-6 cm³/C. By analyzing PTFE insulator surfaces´ compositions, the chemical reactions between electrodes and insulators which produced electronegative gas was speculated as the main reason leading to the switch´s failure.