Transport coefficients defined by arrival-time spectra of electron swarms in methane gas

An analysis of the swarm parameters defined by the arrival time spectra (ATS) of electron swarms in gases, using a multi-term expansion technique of calculation for solving the Boltzmann equation, is presented. The ATS method is important since it enables one to calculate directly important swarm parameters such as the ionization coefficient and the mean arrival-time drift-velocity. This method is applied to methane gas, which has extremely large inelastic electron collision cross-sections, not only in the high electron-energy region but also in the low electron-energy region, and the ATS swarm parameters and energy distributions are calculated by means of a multi-term technique for the first time. The multi-term technique utilizes an amalgamated procedure of the conventional two-term expansion and the Galerkin method. The results by this technique are compared with those by a Monte Carlo simulation, to show good agreement for both relatively high and low E/p 0 conditions.