Investigation of the mechanism for rapid heating of nitrogen and air in gas discharges

A rapid heating of nitrogen-oxygen mixtures excited by gas discharges is investigated numerically with allowance for the following main processes: the reactions of predissociation of highly excited electronic states of oxygen molecules (which are populated via electron impact or via the quenching of the excited states of N-2 molecules), the reactions of quenching of the excited atoms O(D-1) by nitrogen molecules, the VT relaxation reactions, etc. The calculated results adequately describe available experimental data on the dynamics of air heating in gas-discharge plasmas. It is shown that, over a broad range of values of the reduced electric field E/N, gas heating is maintained by a fixed fraction of the discharge power that is expended on the excitation of the electronic degrees of freedom of molecules (for discharges in air, eta (E) similar or equal to 28%). The lower the oxygen content of the mixture, the smaller the quantity eta (E). The question of a rapid heating of nitrogen with a small admixture of oxygen is discussed. (C) 2001 MAIK Nauka/Interperiodica.