The electron swarm behaviour in nitrogen is studied for E/ rho 0 from 20 to 200 V cm-1 Torr-1 by a Boltzmann equation method. A set of electron collision cross sections is determined using newly published data. The modification of these cross sections when necessary is kept to within experimental error. Moreover, the validity of the vibrational excitation cross sections obtained theoretically by Hazi and co-workers (1981) is examined. The results show that the calculated swarm parameters are in close agreement with those obtained by a photon flux experiment of Wedding and co-workers (1985). This suggests that the set of electron collision cross sections determined in the present work is an appropriate one as far as the swarm parameter analysis is concerned. The electron energy distribution and electronic excitation coefficients and frequencies to various excited states are also calculated and discussed.
Three important transport coefficients, namely the ratio of the Townsend first ionization coefficient to the gas number density , the mean-arrival-time drift velocity and the product of the longitudinal diffusion coefficient and the gas number density , in methane have been experimentally determined over a wide range of E/N, E being the electric field and N the gas number density, from 0.2 to 2000 Td by a double-shutter drift tube method analysed by an arrival-time-spectrum (ATS) technique. Equilibrium of the electron energy at high values of E/N in the present experiment is confirmed by a Monte Carlo simulation for the same gas. The present values of and as a function of E/N agree well with those in the literature which were obtained by using techniques such as the steady-state Townsend experiment, time-of-flight analysis and a pulse experiment. This demonstrates the validity of the present drift tube method and ATS analysis. The present result for , however, agrees with that in the literature in the rough shape of variation with E/N only; it is found that there are differences of a few tens of percentage in the present values against the values in an earlier paper and that a local maximum and minimum found in the previous article do not exist.
The electron swarm behaviour in monosilane is studied for E/p0 from 0.2 to 300 V cm-1 Torr-1 by a Boltzmann equation method. A set of electron collision cross sections is determined by fitting the calculated values of the drift velocity, characteristic energy and effective ionisation coefficient to experimental values. The swarm parameters are calculated for the pulsed Townsend, steady-state Townsend and time-of-flight experiments. Moreover, the accuracy of the two-term approximation is checked by a Monte Carlo simulation. The results show that the calculated values of the effective ionisation coefficient, electron drift velocity and characteristic energy agree well with experimental ones and this suggests that the set of electron collision cross sections determined in the present analysis is an appropriate one, though no unique. It is also found that the electron energy distribution obtained in the present work is represented by a simple Druyvesteyn formula. The excitation frequencies for vibration and dissociation are also calculated and discussed.
The electron swarm behaviour in methane is studied for E/p0 from 0.2 to 200 V cm-1 Torr-1 by a Boltzmann equation method. The alteration of cross sections from the literature is avoided as much as possible in the analysis. The swarm parameters are calculated for the pulsed Townsend, steady-state Townsend and time-of-flight experiments. Moreover, the accuracy of the two-term approximation is checked by a Monte Carlo simulation. The values of the ionisation coefficient, electron drift velocity and characteristic energy calculated are found to agree well with the experimental ones if these values are properly interpreted. This result suggests that the set of electron collision cross sections tailored in the present analysis is an appropriate one. The electron energy distribution, and the excitation frequencies for vibration and dissociation are also calculated and discussed.
Electron swarm behaviour in SF6 and nitrogen mixtures is analysed over the E/N range from 141 to 707 Td by a three-term Boltzmann equation method. A set of electron collision cross sections, which was determined consistently with measurements for the respective pure gases by the authors ((SF,, ltoh et a/ (1988); N2, Ohmori et a/ (1988)), is used. The calculation is carried out for the steady-state Townsend (SST), pulsed Townsend (PT) and time-of-flight (TOF) experiments. In particular the TOF parameters of these mixtures are deduced for the first time as far as the authors are aware. It is found that the calculated values of the effective ionisation coefficient E shows a monotonic variation with percentage of SF, at a fixed E/N, the same as previous measurements. The E/N value at which E = 0, i.e. the limiting E/N, is also deduced and in close agreement with measurements. The variations of the electron energy distribution and other transport coefficients with the partial SF6 pressure are calculated and discussed in detail.
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