Time-dependent behaviour of electron transport in methane-argon mixtures

The Boltzmann transport equation is solved to determine the time-dependent electron velocity distribution function in various mixtures of methane and argon subjected to an external electric field, E. In the solution of the equation no expansion of the distribution function is made. The concentration of methane in the mixture is varied systematically. The distribution function is used to calculate several time-dependent electron swarm parameters in these gas mixtures. For each gas mixture a wide range of E/N values, from 0.1 to 1000 Td, is investigated. Steady-state values of various calculated swarm parameters (drift velocity, Townsend ionization coefficient and characteristic energy) agree quite well with the corresponding experimental values.