Non-equilibrium coupled kinetics in stationary N₂-O₂discharges

A detailed study of the coupled electron and heavy-particle kinetics in a low-pressure stationary N 2 -O 2 discharge is carried out. The model is based on the self-consistent solutions to the Boltzmann equation coupled to the rate balance equations for the vibrationally excited molecules N 2 (X 1 Sigma g + ,v) and O 2 (X 3 Sigma g - ,v'), NO(X 2 Pi r ) molecules and N( 4 S) and O( 3 P) atoms. It is shown that the vibrational distribution of N 2 (X,v) plays a central role in the whole problem, affecting considerably the predicted concentrations of NO molecules and N atoms, whereas the concentration of O atoms is practically independent of both vibrational distributions. In particular, it is shown that, in the case of a rate coefficient of about 10 -13 cm 3 s -1 for the reaction N 2 (X,v)+O to NO+N, the N 2 (X,v) molecules are strongly de-excited by vibrational-translational energy exchange processes associated with N 2 -N collisions. In contrast, in the case of a higher value for this rate coefficient, the N 2 (X,v) molecules are efficiently destroyed by this mechanism. The contributions of the different processes to the total production of NO, N and O are evaluated and compared.