Influence of liquid electrical conductivity on the dynamic process of the cavitation bubble induced by corona discharge

Currently, experimental studies on cavitation bubble dynamics typically employ one of several established methods for bubble generation, including underwater explosions, underwater electrical discharges, tube arrest, and laser focusing. However, differences among these methods result in significant variation in experimental precision and repeatability. In this study, we propose a novel cavitation bubble generation approach based on underwater corona discharge induced by a high-voltage single-electrode system. The aim is to investigate the key factors influencing the bubble dynamics associated with this unique discharge method. Experiments conducted in saline solutions with different electrical conductivities reveal that the conductivity markedly affects the corona discharge process and the associated plasma morphology, thereby altering the dynamic behavior of the cavitation bubbles. For instance, as conductivity increases, the maximum radius of bubble expansion in free field decreases, the normalized oscillation period becomes longer, and the minimum radius increases. These changes in bubble behavior are expected to influence the development of micro-jets and the intensity of shock waves under various boundary conditions. Focusing on cavitation bubbles generated beneath a free liquid surface, the results show that with increasing conductivity, the velocity of the micro-jet increases, then decreases, and increases again. Similarly, the peak pressure of the shock wave shows an initial rise followed by a decline. These new findings not only provide important support for improving the experimental accuracy of bubble dynamics and for future investigations into scale effects, but also offer theoretical insights into the cavitation intensity relevant to underwater discharge-based sterilization applications.