Time-resolved diagnostics of a pin-to-pin pulsed discharge in water: pre-breakdown and breakdown analysis

摘要

This paper presents an experimental study of an underwater pulsed plasma discharge in a pinto-pin electrode configuration. Time resolved refractive index-based techniques and electrical measurements have been performed in order to study the pre-breakdown and breakdown phenomena in water (sigma = 100 mu S cm(-1)). A single high voltage pulse with amplitude of a dozen of kV, rise time of 20 ns and duration of [0.1-1] ms is applied between two 100 mu m diameter platinum tips separated by 2 mm. This novel experimental work reports that different cases of electrical discharge in water occurs for a unique set of experimental conditions such as (i) bush-like channels from the cathode that do not span the electrode gap, (ii) bush-like channels from the cathode leading to breakdown and (iii) filamentary structures from the anode leading to a stronger breakdown. Two breakdown mechanisms, anode and cathode regimes, have been clearly identified and related to the two principal schools of thoughts to explain discharge propagation in liquid.