中文摘要：

水下高压脉冲放电过程中的瞬态物理现象非常复杂，放电通道等效电阻从放电初期的kΩ量级到中期的mΩ量级，为一时变参数。若在仿真计算中将它看作常数，则计算得到的放电电流在峰值和振荡周期上均与实验结果相差较大。为尽可能真实地反映放电特性，建立了放电水间隙时变等效电阻R（t），推导了等效放电回路方程，利用有限差分法进行求解，得出放电电流和放电电压的表达式，并将仿真波形与实验测量得到的放电电流和放电电压的波形进行了对比分析。结果表明，在放电电极时变等效模型基础得到的仿真结果相对于常数等效电阻的仿真结果，更接近实验结果，同时显示出有限差分方法在求解放电回路变系数微分方程时的有效性。

英文摘要：

If two electrodes are stressed with a high voltage which creates a sufficiently strong electric field between the electrodes, the water between the electrodes is breakdown and a highly conductive discharge channel is formed, then discharge happens and sophisticated physical phenomena is involved in this process. Because of the discharge, the resistance of the channel changes from a few kilohms at the beginning of the discharge to only a few milliohms at the metaphase Therefore, it is not suitable to calculate the discharge current and voltage on the assumption that the resistance of the channel is invariable, although the calculation will be easy by treating it as a constant. Consequently, a time-varying model of the equivalent resistance of the electrodes was established, and the equivalent equation of the discharge circuit was established and solved with the finite difference method. The numerical expression of the discharge current was obtained. Furthermore, the experimental discharge current and voltage waveforms were meas ured. The comparison of calculations with the experimental results shows that good agreement is achieved when modification of the resistance of the channel is introduced.