We derive a general formalism for the inversion of the Boltzmann high-energy operator in any particle-beam-sustained molecular or atomic plasma discharge, including all excitation transitions: ionisation, electronic, vibrational and rotational with the possibility of de-excitation from molecules excited in the first vibrational state. The final formulation predicts strong departures from Maxwellian in the 'tail' of the electron distribution function. Use of the present analysis together with measurements of the high-energy distribution provides a means for obtaining information about cross sections for vibrational excitations in molecules. Essential scaling laws are also derived from this formalism. Applications are made in the case of low-pressure molecular nitrogen lasers and to long-distance energy transport in a nitrogen atmosphere.

A molecular plasma generated by a particle beam generally departs strongly from a Maxwellian distribution and exhibits a pronounced depletion of electrons as soon as cold electrons cross the first vibrational barrier. We show that this situation produces screened Coulomb interactions that enlarge the Coulomb cross-section in the neighbourhood of this first vibrational threshold. Including these screened interactions through the Balescu–Lenard operator with all excitation transitions leads to a modification of the distribution at the first vibrational barrier. An application is given to the case of low-pressure nitrogen lasers.

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This paper gives a complete kinetic theory of atomic discharges whatever their parameters. Very high-frequency discharges and high-pressure continuous discharges were studied in an earlier paper by the same authors [J. Plasma Phys. 54, 309 (1995)]; in the present paper we study low-pressure continuous discharges or high-frequency discharges whose parameters satisfy different conditions and therefore cannot be described by the earlier model. Analytical results are applied to a high-frequency argon discharge and to a low-pressure continuous argon discharge. The results are in good agreement with the numerical results of Ferreira and co-workers.

This paper is the third of three papers on the kinetics of particle-beam-generated molecular plasmas. In the first paper we derived a general formalism for the inversion of the Boltzmann high-energy operator in this kind of molecular plasma. In the second paper we applied and modified this general formalism to the interesting particular case of 0,, taking into account the low threshold excitation of metastable modes. In this third paper we complete this kinetic investigation by an analysis of the Boltzmann low-and mediumenergy equation available for any stationary particle-beam-generated molecular (or atomic) plasma, including all inelastic processes. Use of this analysis together with the moment conservation equations provides a means to obtain analytically the electron density and 'temperature' in the plasma. Theoretical results are compared with experimental parameters measured in 0, by Pointu and Zeller at Orsay, with gun jet electrons, and orders of magnitude are in good agreement when diffusion is taken into account.