Investigation on shock wave generated by underwater discharge due to different progress of plasma

This paper reports on the characteristics of shock waves generated by discharges with different electrode diameters. In the study, underwater discharges were generated by using a magnetic pulse compression (MPC) circuit. We used a pin-to-pin electrode to discharge between the electrodes and generate a shock wave. The electrode diameters used in the experiments were 0.8 mm, 1.2 mm and 1.5 mm and the gap distance were fixed at 0.2 mm. The shock waves were studied by pressure measurement through an elastic membrane using a fiber optic probe hydrophone (FOPH) pressure transducer. We describe the relationship between the peak voltage, the peak current and the discharge energy and the peak pressure of the shock waves. The discharge waveforms were changed under different experimental conditions. It was found that the maximum pressure of the shock wave became stronger as the current density increased. Also, we calculated the shock wave energy density from the obtained shock wave waveforms. As a result of examining the relationship between the maximum pressure and the shockwave energy density, it was found that the shock waves generated by the discharges with different electrode diameters had different shock wave energy density at the same peak pressures of the shock waves.