A Coulomb collision model based on collision cross section and its effects on kinetic characteristics of atmospheric thermal microplasmas

Abstract

Coulomb collisions are important transport processes of charged particles and should not be neglected in atmospheric thermal microplasmas due to the high density of charged particles. However, there have been a few attempts at Coulomb collisions in atmospheric thermal microplasmas, and it is still unclear how to couple Coulomb collisions between different charged particles with collisions between charged particles and neutral atoms. This work proposes a Coulomb collision model based on the collision cross section, which is more computationally efficient than the typical Nanbu model and TA (Takizuka and Abebinary) model by reproducing the anisotropic electron–electron collision process. Then, the effects of Coulomb collision on the kinetic parameters and electron dynamics of atmospheric thermal microplasmas are investigated by coupling the implicit particle in cell and Monte Carlo collision (PIC MCC) method. It is found that the existence of electron–electron and electron–ion collisions reduces the particle number density in the bulk-plasma region. The electron–electron collisions are stronger than the electron–ion collisions and the ion–ion collisions can be ignored. The Coulomb collisions increase the dispersion of electron energy in the high-energy region.