Particle-in-Cell Model of a Laser-Triggered Spark Gap

A particle-in-cell simulation of the streamer formation process in a laser-triggered spark gap has been developed to estimate streamer radius and conductivity under a variety of conditions. The motivation for developing the model was to understand the initial conditions of the switching arc in a laser-triggered spark gap, with the goal of accelerating the resistive decay of the arc. In a parallel plate switch configuration with dimensions of 0.6 mm times 0.3 mm, the electric field was varied from 2 to 5 MV/m, the gas pressure was varied from 1 to 1.5 atm, and the gas type was varied between Ar and Ne. The laser triggering parameters, including the laser ionization rate (from 5 to 20middot10¹⁸ s^-1), laser spot area (from 1200 to 4800 mum²), and laser spot orientation relative to the electric field, were also varied. The electric field had a large influence on radius, increasing it by 19% with increasing field, and on conductivity, resulting in a 285% increase with increasing field. Among the laser triggering parameters, a linear focal spot-oriented transverse relative to the electric field direction was observed to produce a very large increase in streamer radius