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.