Characterization of Inverted Populations in Chemical Lasers by Temperaturelike Distributions: Gain Characteristics in the F+H_sub.2 - HF+H System

With the aid of the temperature parameters characterizing product state distributions in a number of chemical reactions, frequently used concepts in chemical laser studies can be expressed in a compact form. The assumption of a rotational‐translational microcanonical equilibrium in the product atom‐diatom system leads to simple expressions for population inversions and gain factors. (However, the equilibrium assumption is not necessary; the expressions will retain their simple form also when the vib‐rotational distributions are more specific.) The main advantage is that of using only one or two parameters instead of different vibrational and rotational temperatures for every transition. Two special situations are considered in detail: (a) a nonrelaxed initial product population and (b) a vibrationally nonrelaxed but rotationally thermal population. As a specific example, the HF laser with F + H2 → HF + H as the pumping reaction is studied. Rate equations governing the emission of different laser transitio...