Development of PIC-DSMC air breakdown model in the presence of a dielectric: Breakdown time sensitivity to self-absorption and photoemission

摘要

Summary form only given. Electrical breakdown between electrodes in the presence of a dielectric cylinder is simulated using an electrostatic particle-in-cell (PIC) code that models particle-particle collisions using the direct simulation Monte Carlo (DSMC) method. In this talk we will present recent work on sensitivity of the breakdown time delay to the dielectric photoemission yield and to inclusion of self-absorption of photons by the background gas. Validation of the simulation model is being performed against prior experimental data on breakdown across a 13mm rod-to-plane gap with a 10mm dielectric cylinder in the middle1. The dielectric cylinder provides both an electron source by photoemission from low energy photons and enhances the reduced field (thus changing the plasma radiation spectrum)2.The model includes electron-neutral elastic, excitation, ionization, and attachment collision chemistry; ion and photon induced electron emission from surfaces; ion-neutral collisions; and self-absorption, photoionization, and photodissociation. The model tracks excited state neutrals which can be quenched through collisions with the background gas and surfaces or spontaneously emit a photon (isotropically) and transition to a lower state. Each simulated photon from an emission event is given a wavelength based on the transition that includes natural and Doppler broadening3. Emitted photons have an energy dependent probability of causing photoemission from the dielectric or electrode surfaces, as pre-computed by a separate electron Monte Carlo transport code4.