Population Inversions in an Expanding Gas: Theory and Experiment

Abstract

It is well established that population inversions between the (001) and (100) vibrational energy levels of CO1 can be created by rapid expansions of CO2-N2-H2O or He mixtures through supersonic nozzles. New experimental results are presented for such inversions. These experiments were conducted in both the 3-MW arc tunnel and the 12.7-cm shock tunnel at the Naval Ordnance Laboratory. The results support previously published theoretical predictions obtained with a numerical, time-dependent, nonequilibrium nozzle flow analysis employing a simplified vibrational kinetic model. This theory is also compared with experimental data obtained by other investigators.