Table 1 - uploaded by Yosuke Sakai
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Sets of the cross-sections?.
Source publication
Electron swarm development in nitrogen is studied for E/N=85-1131 Td by a Boltzmann equation method using eighteen recently published electronic excitation cross-sections (those given by Cartwright et al. (1977) and Chutjian et al. (1977), summarised in Cartwright (1978)). The results show that the ionisation coefficient and the electron drift velo...
Similar publications
Momentum transfer cross-section, rotational cross-sections, vibrational
cross-sections, and electronic excitation cross-sections for
H2 molecule for plasma discharge simulation have been
determined from measured and calculated electron transport coefficients
in H2--Ar mixtures and in pure H2 gas at 293 K
using the electron swarm study and the two-t...
Citations
The behavior of a group of electrons moving in a neutral gas under the influence of a space-time dependent force can be described by the velocity distribution function f(v,r,t). In the following discussion it will be assumed that space-charge fields are negligible and only an external electric field E(r,t) is considered. The distribution function can be obtained from the Boltzmann equation $$
\frac{{\partial f}}{{\partial f}} + {\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{v} ^.}{\nabla _r}f + \frac{q}{m}{\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{E} ^.}{\nabla _v}f = (\frac{{\partial f}}{{\partial f}})coll.
$$ (1)
Knowledge of the cross-sections for inelastic scattering of electrons by atoms and molecules is essential in the investigation of low temperature plasma physics, chemistry and optics. As follows from Chap. 4, the totality of scattering cross-sections determines the form of the electron energy distribution function (EEDF) and the rate coefficients for the various processes involving free electrons. There is now an extensive literature in this area (for example [1–8]). We will accordingly present here only the data on integral scattering cross-sections that is required for studying and modelling the kinetic processes in low-temperature plasmas of N2 and O2 and their mixtures.
Free electrons are the most important component of a plasma, the energy balance and electrical conductivity of which are determined solely by these particles. Collisions of free electrons with heavy particles are the principal mechanism for excitation of internal degrees of freedom (for example, electronic and vibrational levels), ionization and dissociation. The kinetics of free electrons is closely connected with the vibrational and chemical kinetics, and the optical and electrical characteristics of the plasma.
A spectroscopic technique is described to investigate the transport processes of electrons and the quenching processes of excited metastable molecules under the condition of non-self-sustained Townsend discharges. The technique is applied to pure N//2, and N//2 including NO as an impurity at E/N equals 282. 5 Td and currents less than 10** minus **9 A. The results give a quantitative explanation for the rapid decrease of the secondary ionization coefficient in N//2 in the presence of small amounts of the impurity. Also the radiative lifetime and the self-queching rate coefficient are estimated in the present experimental conditions.
Relative differential cross sections, at 0°, for electron-impact
excitation of the E 3Σ+g state of
the nitrogen molecule have been measured in the near-threshold energy
region. A high-resolution crossed-beam double trochoidal electron
spectrometer is used and the cross section is measured directly, by
inelastically scattered electrons detection. Measurements are placed on
the absolute scale by simultaneous measurement of this process and
vibrational excitation of the v=8 level of the ground state of
N2, via the 2Πg resonance. Integral
cross sections are obtained by using relative angular distributions from
previous measurements, for energies of 11.94 and 12.14 eV. Obtained
results are compared with other available data.
Differential cross sections for electron impact excitation of the optically forbidden C 3Piu, E 3Sigmag+ and a" 1Sigmag+ states of N2 have been measured at incident energies of 17.5 and 20 eV and over the angular range 10 to 100 degrees . Cross sections for vibrational and electronic transitions have been obtained. Integral electronic cross sections for the C 3Piu and E 3Sigmag+ states have also been determined. The present results are compared with previous experimental and theoretical studies.
The drift velocity, mean energy and ionization coefficients in nitrogen are re-evaluated using the Monte Carlo technique over the range of 50 ⩽ E/N ⩽ 560 Td. Recently published data on cross-sections, including ten vibrational levels and eighteen excitation levels, are used in the simulation for the first time. The theoretical swarm parameters agree very well with experimental and other theoretical results with only a slight modification of the cross-sections. New data on collision frequencies for ionization, dissociation and various excitation states are reported.
The Townsend first ionisation coefficient alpha /p20 and the total secondary coefficient gamma T have been measured for nitrogen and methane mixtures by the steady-state Townsend method for 40<or approximately=E/p20<or approximately=500 V cm-1 Torr-1 (121<or approximately=E/N<or approximately=1520 Td). The results show that the alpha /p20 of the mixtures lies between the alpha /p20 values of the respective pure gases and that the alpha /p20 of the mixture may be represented by a linear function of the fractional methane partial pressure k for E/p20<or approximately=100 V cm-1 Torr-1, but a linear relationship tends to break down at higher E/p20. The results also show that the gamma T of the 90% nitrogen and 10% methane mixture increases with E/p20 and that the gamma T decreases rapidly with k at a fixed E/p20. A possible explanation of this rapid decrease in terms of quenching of the excited states of the nitrogen molecule by the methane molecule is given.
