Flame-Sheet Analysis of C. W. Diffusion-Type Chemical Lasers, I. Uncoupled Radiation
An analytical treatment of diffusion-type chemical lasers is presented. Chemical formation of the lasing molecule by laminar mixing and combustion of parallel streams of fuel and oxidizer is assumed to be diffusion controlled, and subsequent collisional deactivation of each vibrational level of the lasing molecule by nonreactive V — Kand V — T energy transfer is found by a successive-approximation scheme. Radiative processes are considered only for a downstream optical cavity of infinitesimal streamwise length. A laser employing the reaction H2 + F -> HF(f) + H is considered in detail with the use of a single-boundary-layer, flame-sheet model. Expressions for integrated zero-power gain, laser power, and efficiency are obtained. It is found that the efficiency of conversion of chemical power (i.e., 3.15 Mw/lbm of F/sec) to laser radiant power is approximately 30 % when collisional deactivation is neglected in comparison with radiative deactivation. The effect of collisional deactivation is reduction of the efficiency to levels of 10 to 20 % for cases in which H2 diffusion times are of the order of HF collisional deactivation times. In the latter regime, the efficiency varies approximately as [A>w(j;6>_e)1 /2]~1. (pe is gas pressure, w is semiheight of the oxidizer channel, and y6 _ e is the initial mass fraction of atomic fluorine.)