Electrochemical Investigation of Plasma Channels During Hydraulic-Electric Pulsed Discharges

The hydraulic-electric pulsed discharge(HEPD) rock-breaking technology is a new high-efficiency technology that generates plasma shock waves to rupture rocks. Since the plasma channel formation mechanism involved in HEPD rock-breaking technology is difficult to describe, there are fewer theoretical models of this technology. This paper establishes a HEPD plasma model, which integrally considers the mutual coupling between five physical fields. The multi-physical field model realizes the whole process of plasma channels, breakdown channels, plasma shock waves, and plasma shock wave rock-breaking during the HEPD. The changes in mass fraction, density, and diffusion flux of relevant elements in the electrochemical reaction equation of the plasma channel are comprehensively analyzed. The obtained plasma multiphysics field model shows that the interpenetration of charged ions forms the breakdown channel and plasma channel. The anion number density is related to the H- number density, and the decrease in H- number density is due to the fact that the energy in the plasma channel is not sufficient to satisfy the relevant chemical equations to continue the collision reaction. The damage to the rock by the plasma shock wave takes the form of a gradual spreading of the plasma shock wave from the center of the rock to the edges, which leads to rock fragmentation. The model has the potential to establish a link between HEPD rock-breaking parameters and the efficiency of HEPD rock-breaking, which could provide a practical way for the development and parameter optimization of hydraulic-electric pulsed discharge rock-breaking tools.