Transport Coefficients of Electron Swarms in Gases in the Presence of Nonconservative Collisions

Abstract

The moment method of solution of Boltzmann’s equation for electron swarms, as developed originally by Lin, Robson and Mason, has been extended to include various nonconservative processes (attachment, ionization), and the validity of the two-term approximation for calculation of transport and rate coefficients has been investigated. A second-order density gradient expansion is required. Improvements to the original LRM computer code have been made, enabling more accurate calculations for cases where cross-sections vary rapidly with energy. Velocity distribution functions are also found from the moment method, showing good agreement with finite element methods. Transport coefficients, as identified by various coefficients of ▽n in the equation of continuity, are argued to be universal constants, independent of the particular experimental arrangement used to extract them.