Explosion in atmospheric air initiated by an electric discharge and associated with the growth of the concentrations of electronically excited species and free charges

Abstract

Under certain conditions, the plasma of a discharge in atmospheric air exhibits an avalanche-like growth of the electric current and NO(B ²Π) emission intensity. The kinetics of the radiation features two stages. In the first of them (preexplosion stage), the gas in the discharge gap emits violet and ultraviolet radiation, after which, 0.03–0.04 s later, the explosion occurs, during which most of the radiation comes from the blue-green region of the spectrum, with its brightness being much higher than in the previous stage. The mechanism of the development of the explosion involves the formation of N(² P) atoms in the chain reaction of oxidation of atmospheric nitrogen. These atoms lead to increase the conductivity of the plasma due to the occurrence of the associative ionization N(² P) + O → NO⁺ + e⁻. The growth of the concentration of electrons produces, in turn, an increase in the rate of the formation of metastable nitrogen N₂(A ³Σ ⁺ _u ), which initiate a chain oxidation reaction.