Transport of Air Plasma.

Abstract

Abstract : This report describes research results on the Transport of Air Plasmas obtained in the High Temperature Gasdynamics Laboratory at Stanford University. This research has emphasized studies of ionizational nonequilibrium and electron recombination in atmospheric pressure air plasmas. The present report discusses, in the first part, theoretical investigations of the mechanism for ionizational nonequilibrium and, in the second part, measurements of the rate of recombination of electrons in air, nitrogen, and air/argon plasmas. These investigations have shown the surprising result that ionizational nonequilibrium in air (or nitrogen) plasmas results from and is controlled by the chemistry of neutral species. It was also found that very large discrepancies exist between the rates proposed in the literature for the controlling reactions. The experimental results have confirmed the proposed recombination mechanism and have provided an assessment of the rates of the controlling reactions, namely N + 0 + M in equilibrium with NO + M in air plasmas, and N + N + M in equilibrium with N2 + M in nitrogen plasmas. Novel diagnostic techniques were developed for this work, in particular for the measurement of electron number densities between 10 to the 11th power and 10 to the 13th power/cc using the optical radiation emitted by the predissociative delta (C-X) bands of NO.