Detailed temporal behavior of laser-excited sodium tracer in nitrogen and application to nitrogen number density measurements at low densities

Detailed rate equation modeling of the laser-excited sodium-molecular nitrogen system was conducted to investigate the applicability of the steady-state three-level model to prediction of sodium laser-induced fluorescence intensities. Redistribution of vibrational population in the nitrogen molecules can, under some conditions, produce a transition to a second-state condition not predicted by the simple three-level model. The feasibility of a major species number density measurement using tracer gas impurity laser-induced fluorescence is discussed in light of the sodium-nitrogen modeling results.