Coupled electron energy and vibrational distribution functions in stationary N2 discharges

Abstract

The electron energy distribution function in N2 and the vibrational distribution function of N2 molecules in the electronic ground state were calculated self-consistently for steady state conditions by solving the Boltzmann equation coupled to a system of rate balance equations for the fibration levels including e-V, V-V, and V-T energy exchange processes. This formulation provides a relationship between the degree of vibrational excitation, as measured by a characteristic vibrational temperature theta , the ratio of the electric field to the gas density E/N, and the degree of ionisation ne/N. The values of theta have only a small dependence on E/N in the range 3*10-16-3*10-15 V cm2 and increase with ne/N from about 2*103K to 6*103K in the range 10-11<or=ne/N<or=10-5. The inclusion of superelastic e-V collisions in the Boltzmann equation strongly affects the electron energy distribution function and results in a significant increase in the electron rate coefficients for excitation especially at the lower E/N values. The authors present calculations of electron transport parameters and excitation rates, of the power transferred by the electrons through the various collisional mechanisms, of the rate of dissociation, and of the net power transferred to the gas translational mode by the V-T and the non-resonance V-V energy exchanges, and by electron collisions.