Electron kinetics in dc argon microplasmas

Abstract

We carried out one-dimensional particle-in-cell and Monte Carlo collisional simulations of argon dc microplasmas. It is found that argon dc microplasmas have quite different electron kinetics from those of conventional low-pressure argon dc plasmas or helium dc microplasmas. The electron energy probability functions (EEPFs) of the argon dc microplasma are bi-Maxwellian for pressures exceeding 100 Torr, whereas it shows a convex-shaped profile for 10 Torr. The different EEPFs at high pressures come from the fact that, as the pressure is increased, elastic and inelastic electron–neutral collisions increase, because the cathode fall length decreases more slowly than the electron–neutral collisional mean free paths.