Effect of small impurities in molecular gases on deviation from thermodynamic equilibrium in low-current electric arcs. The dissociation of nitrogen

Results are presented of an experimental investigation of the populations of excited levels of nitrogen atoms, molecules, and molecular ions in the nonequilibrium plasma ($T_e$ greater than $T_a$) of an electric arc carrying a current of $5$ A; the arc burns at atmospheric pressure in argon having small nitrogen impurities ( less than equivalent to $1\%$). The mechanisms for the excitation of these levels are analyzed along with the mechanism of nitrogen dissociation. It is shown that the most probable dissociation mechanism under these conditions is stepped excitation of the molecules due to the action of electron impact followed by dissociation from the electron-excited states.