Study on Characteristics of Surface Pulsed Discharge Over Carbon Foil in Water

In this paper, the phenomenon of liquid-solid interfacial discharge along a carbon foil immersed in water medium has been investigated. Based on the multi-physical diagnoses and high-speed photography, the pulsed discharges were performed under different charging voltages and electrode spacing. Compared with the traditional water-gap breakdown, it is found that introducing a carbon foil can significantly diminish the breakdown delay (less than 1 µs) and lower the requirement of applied voltage (kV/cm level). Charging voltage and electrode spacing affect the discharge load voltage, loop current and load power. When the charging voltage increases from 4.5 kV to 6.3 kV, the current peak increases from 2.352 kA to 3.583 kA, the voltage peak increases from 0.690 kV to 1.692 kV, and the power peak increases nearly two times. In addition, the discharge will produce light radiation, and an increase in charging voltage from 4.5 kV to 6.3 kV can increase the intensity of light radiation by 2.39 times. The discharge can also produce pressure waves lasting tens of microseconds and has a bubble effect. When the charging voltage increases from 4.5 kV to 8.9 kV, the maximum radial diameter of the bubble increases from 9.15 mm to 15.35 mm. This study not only enriches the fundamental research problems of liquid-solid interface discharge but also gives an alternative scheme of water gap discharge in technology, which improves the controllability and efficiency of underwater discharge.