Pre-breakdown electron dynamics of a UV-light triggered spark gap

A simple spark gap can create a nanosecond-scale high voltage pulse, but applications are limited because of the inherent timing jitter. The conventional solution is to provide seed ionization in the gap with precise timing using a high-powered laser. Our work uses the photoelectric effect to produce free electrons at the cathode, which has several advantages. First, we can use lower power light sources–a UV-LED for instance–resulting in a more economical design. Additionally, the non-neutral nature of the photoelectric effect results in a negatively charged electron cloud which acts to boost the applied field; thus, if we hold the applied field just below the breakdown threshold, we can bundle our electron source and trigger into one mechanism. In this poster, we present work on computationally modelling the electron dynamics of our spark gap prior to breakdown by iteratively solving Poisson's equation and the electron drift-diffusion equation on a uniform grid. Specifically, we are interested in understanding how quickly and by how much the breakdown field can be exceeded with different UV light pulses in the hope that this will help us increase the consistency and decrease the timing jitter of our triggered spark gap.