Analysis of the triggering behaviour of Marx generators using Spice simulations

Abstract

The basic operation of a Marx generator is well known and simple: capacitors are charged in parallel through high impedances and discharged in series, thus multiplying the output voltage compared to the charging voltage. As a basic explanation, in a Marx generator using spark gap switches, triggering the first stage is sufficient to double the voltage on the second stage's switch and so on. All the switches are then switched on in an avalanche mode. However, the behavior is often more complex. The parasitic impedances of the geometry play an important role for the creation of overvoltages. This can make the design and the development of Marx generators quite challenging, especially when aiming for good reproducibility and precise timing. The simulation method presented here has been developed to easily compare the effects and performances of different parameters on the Marx erection. Thus, the designers can readily optimize and compare different triggering schemes or other parameters influencing the erection process. Secondly, by coupling LTspice and Python, a statistical approach is presented to also study the effect of the triggering circuit and other parameters on the overall jitter of the machine.