Oscillation suppression for pulsed arc electrohydraulic discharges based on plasma impedance model

Abstract

The circuit oscillation generated during the process of pulsed arc electrohydraulic discharge can prolong the discharge time and pose potential hazards to the withstand voltage of the discharge equipment. To enhance the anti-oscillation performance of the equipment, the structure of the gas spark switch was analyzed and an improved pulse power switch for suppressing circuit oscillation was designed. Firstly, a two-dimensional axisymmetric simulation model of the gas spark switch was established by COMSOL software, and a theoretical model to express the impedance of the plasma channel through the series combination of resistance and inductance was put forward. Then, the correctness of the theoretical model was proved by the nonlinear regression method considering the capacitance effect of plasma discharge, and the results show that the theoretical model almost coincides with the actual discharge waveform, with a fitting rate of 99.73%. Finally, a thyristor-based pulse power switch was designed, and an electrohydraulic discharge experiment was carried out. The experimental results show that the designed switch can reliably control the output of the high-voltage pulses even if the repetitive discharge frequency is higher than 60 Hz under 8.5 kV voltage. Furthermore, the circuit oscillation process was suppressed, and the oscillation time was reduced from 242μs to 39 μs, with a decrease of 83.88 %. This study has potential application value in underwater high-voltage discharge applications.