A multi-term Boltzmann equation analysis of electron swarms in gases-the time-of-flight parameters

Abstract

An accurate and efficient method for solving the Boltzmann equation is presented. Using a multi-term expansion technique, the time-of-flight (TOF) electron swarm parameters (such as the centre-of-mass drift velocity Wr, the longitudinal DL and transverse DT diffusion coefficients) can be evaluated. The method utilizes an amalgamation of the conventional two-term expansion and the Galerkin method. The first two terms of the Legendre polynomial expansion of the electron energy distribution are obtained by the two-term method, while the third-order and higher-order terms are deduced by the Galerkin method. The present technique is applied to determine the electron energy distribution using Fourier components to solve the Boltzmann equation and TOF swarm parameters in methane gas. Good agreement with Monte Carlo simulation is obtained and the method is also applied to a previously described model gas.