Simulation of High-Voltage DC Breakdown for Angled Dielectric Insulators Including Space-Charge and Gas-Collision Effects

We report on 2D Particle-In-Cell (PIC) simulations of a Bergeron geometry with steady-state fields in a semi-infinite, two-electrode system separated by an angled dielectric with a background gas at various pressures. The often-neglected effects of space charge, dielectric surface charging, spatial and temporal distributions of particles, and the shape of the secondary-emission curve are included. For pressures below a few-hundred mTorr, discharges are dominated by multipactor breakdown initiated by a triple-point source; the breakdown condition is well-characterized by an average secondary-emission coefficient greater than unity at the onset of anodic current, otherwise a dark-current develops due to space-charge saturation. Additional avalanche phenomena occur with increased pressure >= 1 Torr, where space-charge coupling leads to oscillations in an otherwise DC discharge.