Simulation of helium discharge ignition and dynamics in thin tubes at atmospheric pressure

Simulations of the influence of electrode geometries on helium discharge ignition and dynamics in thin dielectric tubes are presented. In all studied cases, as observed in experiments, the discharge ignition occurs at the outer edges of the high voltage ring and the influence of the width of the grounded ring on the discharge dynamics is shown. Taking into account the change of permittivity encountered by the discharge as it exits from the tube, the velocity of the discharge front is shown to increase at the tube exit before decreasing downstream similarly to experimental observations.