Comprehensive analysis of the effect of atomic and molecular metastable state excitation on air plasma composition behind strong shock waves

Abstract

A detailed analysis of the processes of charged and neutral species formation in N2–O2–Ar system behind strong shock waves is conducted on the basis of an extended thermally non-equilibrium kinetic model with careful allowance of reactions with electronically excited atoms and molecules and vibration–electron–chemistry coupling. The model is validated against experimental data such as measurements of electron number density behind the strong shock wave front, temporal profile of O2 vibrational temperature, temporal evolution of NO(γ) radiation intensity in the post-shock region and values of time instants at which maximum quantities of radiation intensity of N2(1+) and bands are achieved. It is demonstrated that the model without the allowance of processes involving electronically excited atoms and molecules overestimates the concentrations of both charged and neutral species. For electron and NO concentrations the overestimation can come up to a factor of 2. The computations also indicate the existence of a strong vibration–electron–chemistry coupling in the air plasma produced by the strong shock wave. Only the model, which takes into account such an interaction, makes it possible to properly predict the variation of gas dynamic parameters and species concentrations in the post-shock region.