Non-equilibrium dissociation of nitrogen

Capitelli, M.; Dilonardo, M.

doi:10.1051/rphysap:01978001303011500

Cited by 56 publications

(15 citation statements)

References 16 publications

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“…v ¡ w coef cients. 17 In this case, at high T e and T v , the relaxation time is less than the one obtained for a = 0.15, and the discrepancy decreases with decreasing T v and T e . Figure 6 also shows for these two temperatures the evolution of s HO e (T e , T v )/ s HO e, Tv !…”

Section: A Harmonic Casementioning

confidence: 57%

Analytical Models for Electron-Vibration Coupling in Nitrogen Plasma Flows

Bourdon

Vervisch

2000

Journal of Thermophysics and Heat Transfer

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A model for the electron-vibration energy exchange in nitrogen based on a Landau-Teller-type rate equation is presented. Analytical expressions of relaxation times are derived for cutoff harmonic oscillator and Morse oscillator approximations, assuming that the relaxation proceeds by way of a continuous series of Boltzmann distributions over the vibrational states. Comparisons with the direct numerical integration of the master equation have shown that the use of a two-temperature relaxation time allows accurate modeling of the nitrogen vibrational energy relaxation rate for various conditions encountered in high-enthalpy ows with electron and vibrational temperatures up to 40,000 K. Nomenclature a = constant in the analytical expression of rate coef cients for v > 0 ! w > v transitions dE n v / dt = nondimensionalvibrational energy relaxation rate E v = vibrational energy per unit volume, J/m 3 E ¤ v = vibrational energy calculated with vibrational levels in Boltzmann equilibrium at the electron temperature T e , J/m 3 E v, init = vibrational energy at 0-s time, J/m 3 J = rotational quantum number k B = Boltzmann constant, J/K k v,w = electron-vibration(E-V) rate coef cient of the v ! w transition, m 3 /s N t = total N 2 number density, N v , m ¡ 3 N v = number density of the vibrational level v of N 2 , m ¡ 3 n e = electron number density, m ¡ 3 p e = electron partial pressure, n e k B T e , atm T e = electron temperature, K T v , T exci = vibrational temperature, K t = time, s t n = nondimensionaltime v m = total number of excited vibrational levels D ² = constant of the Morse oscillator, cm ¡ 1 ²(v) = energy of the vibrational level v of N 2 , J ² 1 = energy of the rst vibrational level of N 2 , J r v, w = E-V cross section of the v ! w transition, m 2 s e = E-V relaxation time, s Supercripts HO = truncated harmonic oscillator MO = Morse oscillator

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Section: A Harmonic Casementioning

confidence: 57%

Analytical Models for Electron-Vibration Coupling in Nitrogen Plasma Flows

Bourdon

Vervisch

2000

Journal of Thermophysics and Heat Transfer

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“…are not exactly resonant and, for v < w, have a larger coefficient for the forward process than for the backward one. This originates a climbing in the vibrational ladder as the e-V collisions cease to be effective [28,168]. The V-V up-pumping in the vibrational relaxation of anharmonic oscillators also exists for other diatomic molecules, such as CO(X 1 Σ + ) [169,170] and NO(X 2 Π r ) [171].…”

Section: Vibrational Kineticsmentioning

confidence: 95%

Kinetic modeling of low-pressure nitrogen discharges and post-discharges

Guerra¹,

Sá

Loureiro³

2004

Eur. Phys. J. Appl. Phys.

223

251

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The kinetic modeling of low-pressure (p ∼ 1−10 torr) stationary nitrogen discharges and the corresponding afterglows is reviewed. It is shown that a good description of the overall behavior of nitrogen plasmas requires a deep understanding of the coupling between different kinetics. The central role is played by ground-state vibrationally excited molecules, N2(X 1 Σ + g , v), which have a strong influence on the shape of the electron energy distribution function, on the creation and destruction of electronically excited states, on the gas heating, dissociation and on afterglow emissions. N2(X 1 Σ + g , v) molecules are actually the hinge ensuring a strong link between the various kinetics. The noticeable task done by electronically excited metastable molecules, in particular N2(A 3 Σ + u) and N2(a 1 Σ − u), is also pointed out. Besides contributing to the same phenomena as vibrationally excited molecules, these electronic metastable states play also a categorical role in ionization. Furthermore, vibrationally excited molecules in high v levels are in the origin of the peaks observed in the flowing afterglow for the concentrations of several species, such as N2(A 3 Σ + g), N2(B 3 Πg), N + 2 (B 2 Σ + u) and electrons, which occur downstream from the discharge after a dark zone as a consequence of the V-V up-pumping mechanism.

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“…For majority species in the mixture, diffusion should be treated in the generalized formalism of Stefan-Maxwell equations [83]. In principle, all the above-mentionned formulas should be used with caution since they ignore collisions of neutrals with ions and electrons, and cannot give good results in highly dissociating and ionizing regimes [88]. However in usual SiH4 discharge conditions the ionized fraction of the gas remains small enough to ignore these effects.…”

Section: Neutral Collisions and Reactionsmentioning

confidence: 99%

Cross‐Sections, Rate Constants and Transport Coefficients in Silane Plasma Chemistry

Perrin

Leroy

Bordage

1996

Contrib. Plasma Phys.

342

260

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This paper presents a critical review of the basic data concerning the physics and chemistry of low pressure SiH4 glow discharges used to deposit hydrogenated amorphous silicon films (a&: H). Starting with an updated table of thermochemical data, we analyze the gas-phase elementary processes consisting of i) electron-molecule collisions, ii) ion-molecule collisions, iii) neutral-neutral collisions, iv) other electron and ion collisions involving electron-ion and ion-ion recombination, electron attachment on radicals and detachment of anions, and v) cluster growth kinetics in dusty plasmas. Experimental data or theoretical estimates are given and discussed in terms of cross-sections, collision and reaction rate constants, and transport coefficients. We also analyze the surface processes and reaction probabilities of ions, radicals and molecules.

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Non-equilibrium dissociation of nitrogen

Abstract: Résumé. -

Cited by 56 publications

References 16 publications

Analytical Models for Electron-Vibration Coupling in Nitrogen Plasma Flows

Analytical Models for Electron-Vibration Coupling in Nitrogen Plasma Flows

Kinetic modeling of low-pressure nitrogen discharges and post-discharges

Cross‐Sections, Rate Constants and Transport Coefficients in Silane Plasma Chemistry

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