ANALYSES OF ELECTRON SWARMS IN GASES UNDER STEADY-STATE TOWNSEND CONDITIONS

A new simulation technique for obtaining the equilibrium electron ener gy distributions of electron swarms in gases under steady-state Townse nd conditions is proposed based on a propagator method. The electron e nergy distribution function could be obtained from calculations in onl y one slab in real space, assuming exponential spatial growth of an el ectron swarm and similarity of the electron energy distribution at any position. The electron energy distributions were analysed in argon at E/N = 1414 Td for a case of a positive large value of the effective i onization coefficient alpha and in an argon (90%)/fluorine (10%) mixtu re at E/N = 56.6, 84.8, 113.1 and 141.1 Td for a case of values of alp haBAR crossing zero. The results agreed excellently with those of a Mo nte Carlo simulation and a Boltzmann equation analysis. This propagato r method was found to deduce stably proper solutions for both positive and negative values of alphaBAR. A relation between the present metho d for a steady-state Townsend condition and a similar method for a pul sed Townsend condition is discussed.