Impedance Analysis of the Plasma Channel in Underwater Pulsed Power Discharge Process

The impedance characteristics of the plasma (PLAS) channel produced by pulsed power discharge in water play an important role in the estimation of shock wave energy. To study the impedance characteristics of the plasma channel, a reservoir improvement device based on high-voltage discharge was developed. First, the theoretical model of the quadruple voltage doubler rectifier circuit was built based on the state-space averaging method, the structure of the discharge electrode was introduced, and the discharge process was segmented. Then, the high-voltage discharge model was established by using COMSOL simulation software, and the breakdown process was simulated based on the bubble theory. The simulation experiment analyzed the discharge time, conductivity change, and thermal variation. The expression of the plasma channel radius changing with the current was obtained, and the simplified internal impedance of the plasma channel was estimated by using the principle of area equivalence. Finally, a pulsed power discharge experiment was carried out. The experimental results show that the actual charging waveform of the voltage-doubling rectifier circuit is consistent with the theoretical calculation. And the oscillation period remains constant despite fluctuations in discharge voltage, indicating that the theoretical impedance estimation satisfies the requirements of the area equivalence principle. Moreover, the actual discharge voltage waveform almost coincides with the waveform calculated using theoretical impedance estimation, verifying the accuracy of the theoretical analysis. The shock wave energy was also estimated based on the impedance model, providing a theoretical reference for energy consumption at each discharge stage.