A Time-dependent Quasi-one-dimensional Analysis of Population Inversions in an Expanding Gas

A time-dependent technique for the numerical solution of convergent-divergent, nonequilibrium nozzle flows was used to analyze the rapid, vibrational nonequlibrium, supersonic expansion of CO2-N2-H2O and CO2-N2-He mixtures, wherein the finite rate molecular energy transfer processes can result in a population inversion between the (001) and (100) vibrational energy levels of CO2. Results for such population inversions are presented. Among these, a comparison was made between the present results and the recent results of Basov et al; this comparison indicates that Basov's calculations overestimate the population inversion in an expanding mixture of CO2 and N2. In addition, results are presented from a series of numerical experiments conducted to assess the validity of several simplified methods for computing population inversions. (Author).