Time-of-Flight Investigations of Electron Transport in Some Atomic and Molecular Gases

Abstract

The time-of-flight (TOF) method for the determination of electron-diffusion coefficients D and drift velocities w described earlier could not be used to investigate a number of gases because a Gieger—Müller counter was used for an electron detector. A new experimental apparatus using differential pumping and an electron-multiplier detector was developed to remove this restriction. Using this new apparatus, D and w have been measured for He, Ar, H2, N2, CO, CO2, CH4, and C2H4. Considerable divergence of D values from published values by the Townsend method have been obtained, indicating a fundamental difference in the methods.

The Effect of Inelastic Collisions on Diffusion Coefficients for Electron Swarms

“…We would now like to apply these results to some real gases, in particular to explain some of the DL/fl data of Wagner et al (1967), and this is discussed in the next section.…”

“…Fig. 3 also shows the DL/fl results of Wagner et al (1967). When there are no inelastic collisions present we expect the DL/DT ratio to be 0·57; however, in Fig.…”

“…Even though the present results are only applicable to model gases with very simple inelastic energy dependences it is still interesting to try and use them to explain some of the DL/fl data of Wagner et al (1967). Hydrogen is a particularly good gas to consider first, as its elastic cross section is almost independent of energy.…”

“…Experimental values of DTIIl and DL/Il versus EIP for hydrogen. The DTIIl data are from Crompton et al (1967) and the DL/Il data from Wagner et al (1967).…”

“…The effect of varying both the strength of the inelastic effects and their energy dependence is examined and the results are used to discuss some of the DL/f.l data of Wagner et al (1967). …”