Effect of stray capacitance on marx generator output voltage

In this paper effect of stray capacitance on output voltage of the Marx Generator is studied. Stray capacitances formed between high voltage metallic structures of Marx generator and its ground enclosure play a critical role in determining the voltage and rise time of the output pulse. With increase in enclosure diameter erected leakage inductance increases and stray capacitance reduces, with decrease and vice versa. Eventually in both the cases output voltage reduces and rise time increases. This effect is predominant in fast rising low energy MARX generators having low erected capacitances. In this paper effort has been made to quantify these effects. Simulations were carried out for different enclosure structures to find out their effect on output voltage and rise time with a fixed load. It was observed that conical enclosure helps in mitigating this problem in MARX generator. Simulations were also carried out to optimize the flaring angle of the conical enclosure to obtain maximum output voltage. Simulated results are experimentally validated using a 22 stage 450 kV MARX generator. Details of the analysis, simulations and experimental results are narrated thoroughly in this paper.