Energy Transfer Efficiency Improvement of Liquid Pulsed Current Discharge by Plasma Channel Length Regulation Method

Dynamic shock waves induced by high-pulsed current discharge in liquid have wide potential applications in industrial and civil fields, such as rock fragmentation, electrohydraulic cleaning, and oil stimulation. Normally, the interelectrode gap distance is small due to the high electrical breakdown field of the liquid. Most of the electrical energy is consumed by the external circuit due to the low impedance of the plasma channel, and the energy transfer efficiency from the electrical energy to the mechanical energy is very low. In this paper, the optimal interelectrode distance and the effect of the plasma channel length on the intensity of the shock wave are investigated. The voltage across the liquid gap, main discharge current through the gap and the pressure wave, as well as the time-resolved images of the plasma channel development and the bubble formation are observed and presented. Results show that the optimal interelectrode distance can generate the strongest intensity of the shock waves. The plasma channel length can be extended by the plasma channel length regulation (PCLR) method, and the deposited energy into the plasma channel is increased. Besides, the energy transfer efficiency can be improved effectively by the PCLR method, and the requirement of the capacitor and switch can be reduced to obtain the same shock wave intensities. Based on the PCLR method, the induced shock wave was applied to increase the permeability of the specimen. It shows that the energy transfer efficiency can be improved effectively based on the presented method, and the shock wave can increase the permeability effectively.