Further Investigations on a Modified Avalanche Transistor-Based Marx Bank Circuit

Abstract

Avalanche transistor-based Marx bank circuit (MBC) is widely used to generate nanosecond pulses with high amplitude, high repetition rate, fast rise time, and low jitter. Recently, the problem that avalanche transistors in the first several stages of $M \times N$ -stage MBC fail frequently has been alleviated by adopting auxiliary triggering topology (ATT). However, the reasons for improvement and the optimal design method have not been fully understood. In this article, a flexible $4\,\,\times10$ -stage MBC is developed to further investigate the output characteristics under different modified stages, capacitors, and loads through both experiments and simulations. The results show that on the one hand, adopting ATT will cause energy loss of the main capacitors to auxiliary triggering capacitors, which can decrease the output voltage; and on the other hand, transistors operating in the auxiliary triggering switching-ON mode have lower residual voltage than in the lower overvoltage switching-ON mode, which can increase the output voltage. This implies that there exists an optimal value of modified stages, which is 5 for the $4\,\,\times10$ -stage MBC. Besides, by adopting ATT, the waveform of output pulse changes, and the rising edge becomes faster. Finally, a repetitive nanosecond pulse generator is developed based on the optimized parameters, which can produce pulses with an amplitude of 9.04 kV, a rise time of 3.4 ns, a pulse width of 18.8 ns, and a maximum repetition rate of 1 kHz at the 75- $\Omega $ open-ended cable. Also, the feasibility of this modified MBC is validated by the preliminary experiments of driving atmospheric pressure plasma jet (APPJ).