Diffusion tensor of electron swarm in electric field in gases. II. The influence of the conservative inelastic collisions

Abstract

For pt.I see ibid., vol.17, p.699 (1984). An investigation of the deep structure of the electron diffusion tensor D in an isolated swarm has been developed from the Boltzmann equation as applied to the electron conservative case including inelastic collisions. It is shown that D consists of three components. They are the weighted ensemble average in the velocity space, and the two-additional terms which represent both the curvature effect due to the electric field and the scattering effect at collision. Numerical calculations in Ar have been executed to emphasise the importance of the last two terms. A difference of over 5% appears between the transverse diffusion coefficient DT and the conventional expression DV with E/N subject purely to elastic collisions due to the curvature effect. As is expected, the discrepancy between DT and DV grows with E/N where the recycling effect due to the excitation-energy barrier is included.

An analysis of transverse evolution of electron swarms in gases using moment equations and a propagator method

“…D T = D L . Many references quoted in the present paper show D T > D L except under particular conditions such as strong anisotropic scattering and low electric field as found in Kr and Xe (Dutton 1975), Ar (Braglia andBaiocchi 1978, Makabe andShimoyama 1986) and CH 4 (Segur et al 1984). It is noted that these gases have the Ramsauer-Townsend minimum in their momentum transfer cross sections.…”

“…Values of D T in real gases were calculated using Boltzmann equation analyses, Monte Carlo simulations, and other numerical methods by Lowke et al (1973) for a CO 2 /N 2 /He mixture, Pitchford and Phelps (1982) and Phelps and Pitchford (1985) for N 2 , Makabe and Shimoyama (1986) and Koura (1987) for Ar or an Ar-like gas, Yachi et al (1991) and Date et al (1993) for CH 4 , etc. D T was also calculated for Ba + ions in Ar by Viehland (1994).…”

“…On the other hand, mathematical descriptions relating D T with other transport parameters were given by Tagashira et al (1977Tagashira et al ( , 1978, Kitamori et al (1980), Kumar et al (1980), Ikuta and Nakajima (1993) and Robson (1995). Values of D T in real gases were calculated using Boltzmann equation analyses, Monte Carlo simulations and other numerical methods by Lowke et al (1973) for a CO 2 /N 2 /He mixture, Pitchford and Phelps (1982) and Phelps and Pitchford (1985) for N 2 , Makabe and Shimoyama (1986) and Koura (1987) for Ar or an Ar-like gas, Yachi et al (1991) and Date et al (1993) for CH 4 , etc. D T was also calculated for Ba + ions in Ar by Viehland (1994).…”

Modeling and diagnostics of the structure of rf glow discharges in Ar at 13.56 MHz

“…Realistic models are possible because of the work devoted to measuring both the microscopic collision cross sections between the charged particle and Ar [4][5][6][7][8][9][10][11][12], and the macroscopic swarm parameters in Ar [4,[13][14][15][16][17][18][19][20][21][22][23][24]. Reliable radiative lifetimes and deactivation rate constants for the excited states in Ar have been also reported [25 -35].…”

Evaluation of the viscosity cross sections for elastic electron-atom collisions in krypton and xenon at low electron energies

“…(1) Q~=2~r S e, 0 This quantity is important in determining both the transport properties of plasmas, gas discharges and electron swarms [2,3], and the spectral characteristics of electromagnetic waves propagated in weakly ionized plasmas placed in external electric fields [4,5]. More specifically, the viscosity cross section (1) appears whenever the classical problem of evaluation of the electron distribution function in weakly ionized plasmas and/or electron swarms is reduced to solving the Boltzmann equation by way of spherical-harmonics expansion, and more than two terms are envisaged (see e.g.…”