Simulation of the Processes of Formation and Dissociation of Neutral Particles in Air Plasma: Vibrational Kinetics of Ground States of Molecules

The results are given of the calculations of populations of vibrational levels of $\text{N}_2(X^1\Sigma^+_g)$, $\text{O}_2(X^3\Sigma^-_g)$, and $\text{NO}(X^2\Pi)$ molecules in an air plasma whose parameters correspond to the positive column of a DC discharge at pressures of $30$–$300$ Pa and currents of $20$–$110$ mA. Different processes are analyzed that form the distribution of molecules over levels, including the electron impact, $V$–$V$ and $V$–$T$ exchange, chemical reactions, and heterogeneous deactivation. The calculation results for $\text{N}_2(X^1\Sigma^+_g)$ are compared with experiment. It is found that the values of the effective vibrational temperature characterizing the populations of $\text{N}_2(X^1\Sigma^+_g)$ are close to the values realized in a nitrogen plasma, and the difference of the vibrational temperatures of $\text{O}_2(X^3\Sigma^-_g)$ and $\text{NO}(X^2\Pi)$ from the gas temperatures is not significant, which is due to high frequencies of $V$–$T$ relaxation of vibrational states of these molecules in collisions with $\text{O}(^3P)$ atoms.