Fully kinetic particle-in-cell simulations of triggered three-electrode gas switches

We present the results of 2D and 3D fully-kinetic electromagnetic particle-in-cell Monte Carlo (PICMC) simulations of triggered three-electrode gas switches using dry air as a gas (at pressures greater than 1 atm). In such switches the AK gap voltage is set slightly below the breakdown threshold. A voltage pulse applied to a trigger needle placed in the AK gap allows breakdown to occur between, initially, the trigger and anode, followed by the trigger and cathode. We demonstrate that a fully-kinetic PICMC approach can be used to follow the entire evolution of the switch, from the initial avalanche and streamer formation up to the fully conducting phase. We utilize an 18-species air chemistry model which is shown to agree with swarm parameters (breakdown threshold, drift velocity) obtained by experiment. Photon transport and photo-ionization are also included to permit the modeling of cathode directed streamers. This computational model will be used to help design closing switches for pulsed-power systems.