Electron transport coefficients in gas mixtures.
2015-11-19T09:17:48Z (GMT) by
Experimental and theoretical approaches to the quantification of electron lateral and longitudinal diffusion coefficients and drift velocity in gases are reviewed. The development and arrangement of the experiments to measure transport coefficients are discussed. The procedures used for measuring these in counter gases at low electric field strength to pressure ratios are given. Lateral diffusion coefficient to mobility ratios were determined for electrons in the following gases; 100% methane, argon + methane mixtures (in the proportions 25% / 75%, 50% / 50% and 90% / 10%), 100% carbon dioxide, argon + carbon dioxide mixtures (in the proportions 50% / 50%, 75% / 25% and 90% / 10%), argon + 5% carbon dioxide + 3% acetylene, argon + 25% isobutane and neon + 10% methane. Drift velocities and longitudinal diffusion coefficient to mobility ratios were determined in 100% methane, argon + 50% methane and argon + 10% methane. The experimental results for the lateral diffusion coefficient to mobility ratio and the drift velocity are presented as functions of the ratio of the electric field strength to gas pressure and are compared with predictions made by solution of the Boltzmann equation and by Monte-Carlo simulation. Less reliable are the results for the longitudinal diffusion coefficient to mobility ratio, these are given as functions of the electric field strength to pressure ratio and compared with predictions made by Monte-Carlo simulation. The inadequacy of the arrangement to measure longitudinal diffusion is considered together with its value for the determination of the other coefficients.