Electron and vibrational kinetics in an N₂-H₂ glow discharge with application to surface processes

The electron and vibrational kinetics in an N₂-H₂ glow discharge have been analysed using a self-consistent theoretical approach valid in the conditions of a low-pressure moderate current, positive column. This model is based on the solutions to the homogeneous Boltzmann equation and the two systems of rate balance equations for the vibrational levels N₂(X¹ Sigma _g⁺, v) and H₂(X¹ Sigma _g⁺, v'), which take into account e-V, V-V, and V-T processes for the N₂-N₂ and H₂-H₂ systems as well as those involving N₂-H₂ collisions. The paper presents a large amount of calculated data on the vibrational distribution functions of N₂(X,v) and H₂(X,v') molecules, electron energy distribution function, rate of dissociation and electron rate coefficients for excitation. This formulation provides a relationship between the characteristic vibrational temperatures T_v(N₂) and T_v(H₂) and a dependence of T_v(N₂) on the fractional H₂ concentration, which are in satisfactory agreement with measurements by emission spectroscopy and by CARS. The model also predicts the strong decrease of the rate of dissociation of N₂ as it is observed in flowing discharges when a few per cent of H₂ is added to N₂.