Longitudinal- and transversal-diffusion coefficients for electrons in CH4, Ar and CO2

Abstract

This paper reports the results of calculations of diffusion coefficients of electron swarms in an electric field, performed according to the modern transport theory. The results are compared with corresponding values obtained by Monte Carlo simulations as well as by calculations performed according to the conventional transport theory for the three gases CH4. Ar and CO2. For what concerns the calculation of the longitudinal- and transverse-diffusion coefficients, use is made of a new procedure we have recently developed. The procedure solves by Legendre and associated Legendre polynomial expansions the kinetic equations which are obtained for the hydrodynamic state gy expanding the electron velocity distribution function with respect to the gradient of the electron density in the Boltzmann equation. The solutions of the kinetic equations are obtained with increasing (even) approximation order of the Legendre and associated Legendre polynomial expansion up to convergence.