Investigating Methods of Obtaining Electron Energy Distribution Functions in Plasma Simulations

Electron energy distribution function (EEDF) is one of the most fundamental properties that determines the behavior of a plasma. It illustrates the probability distribution of electron energy in a finite volume, which determines the local electron impact reaction rates. In computational low temperature plasma (LTP) simulations, three approaches are widely used to calculate the EEDFs. The first method assumes a single-temperature Maxwellian EEDF with tabulated reduced electric field (E/N) and electron temperature (T_e). The second method is to use a two-term approximation to solve the Boltzmann equation for EEDFs. The third method is to obtain EEDFs through a particle-based electron Monte Carlo (eMCS) approach.

In this work, the effect of EEDF calculation method on the properties of a low-pressure capacitively coupled plasma will be presented. The effects of pressure, power, chemistry and the role of elastic and inelastic collision processes on the plasma electronegativity will be covered. The importance of EEDFs in addressing non-local kinetics and the trade-offs in run time and accuracy associated with a method will be discussed.