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Cross sections and thermal rate coefficients are computed for electron-impact dissociative recombination and vibrational excitation/de-excitation of the N 2 + molecular ion in its lowest six vibrational levels, for collision energies/temperatures up to 2.3 eV/5000 K. [ABSTRACT FROM AUTHOR]

A theoretical investigation of electron-D2 resonant collisions—via the low-lying and the Rydberg states of D —is presented for vibrational excitation, dissociative electron attachment and dissociative excitation processes by using the local-complex-potential approach. Full sets of vibrationally resolved cross sections, involving the ground electronic state— —and the first two electronic excited states— and —of the D2 molecule, are given for fusion plasma applications in their technologically relevant partially dissociated, detached divertor regimes. In particular, transitions between electronic excited states are also considered. Comparisons are made with cross sections present in the literature, where available. [ABSTRACT FROM AUTHOR]

The relaxation of N2(X¹Σg+) molecules in a background gas composed of N(4Su) atoms and free electrons is studied by using an ideal isochoric and isothermic chemical reactor. A rovibrational state-to-state model is developed to study energy transfer process induced by free electron and atomic collisions. The required cross sections and the corresponding rate coefficients are taken from two well-known kinetic databases: NASA Ames kinetic mechanism for the description of the N2(X¹Σg+) - N(4Su) processes and the Phys4Entry database for the electron driven processes, N2(X¹Σg+) -e-. The evolution of the population densities of each individual rovibrational level is explicitly determined via the numerical solution of the master equation for temperatures ranging from 10000 to 30 000 K. It was found that the distribution of the rovibrational energy levels of N2(X¹Σg+) is strongly influenced by the electron driven collisional processes, which promote the excitation of the low lying vibrational levels. The macroscopic vibrational energy relaxation is governed by the molecule-atom collisions, when free electrons, initially cold are relaxing to the final heat-bath temperature. Thus, the main role of the free electrons is to ensure the equilibration of vibrational and free electron excitation, thus validating the existence of the local equilibrium TV-Te. However, if electrons and heavy particles are assumed to be in equilibrium at the heat bath temperature, electron driven processes dominate the vibrational relaxation. Finally, we have assessed the validity of the Landau-Teller model for the description of the inelastic energy transfer between molecules and free electrons. In the case of free-electron temperatures lower than 10 000 K, Landau-Teller relaxation model gives an accurate description of the vibrational relaxation, while at higher temperatures the error in the predictions can be significant and the model should not be used. [ABSTRACT FROM AUTHOR]

The physics of vibrational kinetics in nitrogen-containing plasma produced by collisions with electrons is studied on the basis of recently derived cross sections and rate coefficients for the resonant vibrational-excitation by electron-impact. The temporal relaxation of the vibrational energy and of the vibrational distribution function is analyzed in a state-to-state approach. The electron and vibrational temperatures are varied in the range [0-50 000] K. Conclusions are drawn with respect to the derivation of reduced models and to the accuracy of a relaxation time formalism. An analytical fit of the vibrational relaxation time is given. [ABSTRACT FROM AUTHOR]

Motivated by the huge need for data for non-equilibrium plasma modeling, a theoretical investigation of dissociative electron attachment to the NO molecule is performed. The calculations presented here are based on the local-complex-potential approach, taking into account five NO− resonances. Three specific channels of the process are studied, including the production of excited nitrogen atoms N(2D) and of its anions N−. Interpretation of the existing experimental data and their comparison with our theoretical result are given. A full set of ro-vibrationally-resolved cross sections and the corresponding rate coefficients are reported. In particular, a relatively large cross sections for N− ion formation at low energy of the incident electron and for vibrationally excited NO target are predicted. Finally, molecular rotation effects are discussed. [ABSTRACT FROM AUTHOR]

A theoretical investigation of the dissociative excitation by electron impact on the NO molecule is presented, aiming to make up for the lack of data for this process in the literature. A full set of vibrationally-resolved cross sections and corresponding rate coefficients are calculated using the local-complex-potential approach and five resonant states of NO−. [ABSTRACT FROM AUTHOR]

An ideal chemical reactor model is used to study the vibrational relaxation of oxygen molecules in their ground electronic state, X 3 Σ g - , in presence of free electrons. The model accounts for vibrational non-equilibrium between the translational energy mode of the gas and the vibrational energy mode of individual molecules. The vibrational levels of the molecules are treated as separate species, allowing for non-Boltzmann distributions of their population. The electron and vibrational temperatures are varied in the range [0–20,000] K. Numerical results show a fast energy transfer between oxygen molecules and free electron, which causes strong deviation of the vibrational distribution function from Boltzmann distribution, both in heating and cooling conditions. Comparison with Landau–Teller model is considered showing a good agreement for electron temperature range [2000–12,000] K. Finally analytical fit of the vibrational relaxation time is given. [ABSTRACT FROM AUTHOR]

A new set of electron-vibrational (e-V) processes linking the first 10 vibrational levels of the symmetric mode of CO2is derived by using a decoupled vibrational model and inserted in the Boltzmann equation for the electron energy distribution function (eedf). The new eedf and dissociation rates are in satisfactory agreement with the corresponding ones obtained by using the e-V cross sections reported in the database of Hake and Phelps (H-P). Large differences are, on the contrary, found when the experimental dissociation cross sections of Cosby and Helm are inserted in the Boltzman equation. Comparison of the corresponding rates with those obtained by using the low-energy threshold energy, reported in the H-P database, shows differences up to orders of magnitude, which decrease with the increasing of the reduced electric field. In all cases, we show the importance of superelastic vibrational collisions in affecting eedf and dissociation rates either in the direct electron impact mechanism or in the pure vibrational mechanism. [ABSTRACT FROM AUTHOR]