Sensitivities of 1-2D Paschen breakdown to scattering and energy partition models

Accurate simulations of breakdown depend on an inclusion of detailed collision models between electrons and neutral gas. For example, the left (low) pd branch of the Paschen curve is characterized by fewer collisions and is a regime where the effects of anisotropic electron scattering become important. Including a model for such scattering in particle simulations leads to better agreement with the analytic Paschen prediction. Here we use the Okhrimovskyy model for anisotropic scattering in 1D and 2D axi-symmetric PIC-DSMC models of Paschen breakdown. Furthermore, there are multiple models for partitioning energy between electrons after an ionization collision and several are explored in our simulations. Three models are considered: one-takes-all, uniform, and equal. We report on the effects these models have on the breakdown voltage and electron energy distributions.