F2 absorption measurement in a combustion-driven chemical-laser nozzle

Abstract

A sensitive F2 absorption diagnostic technique was used to determine F2 densities in the flow of a 10.2-cm-long combustion-driven chemical-laser nozzle. The diagnostic device was demonstrated to be readily transportable and operable in a combustion-driven chemical-laser field environment. Cold- and hot-flow measurements up to 970 K plenum temperature (i.e., no F2 dissociation cases) were in agreement; hence, the measurement technique appears to be reliable. The use of C2H4 as a combustor fuel did not result in particulate absorption or scattering of sufficient magnitude to affect the measurement. The flow dissociation level (α) was ≳0.8 for this nozzle. The measurement sensitivity achieved in these tests was ΔI/I0=6×10−4, which corresponds to an F2 density of 6.76×10−6 mole/l (i.e., 0.127 Torr F2 at 300 K) for a 10.2-cm path length.

F-Atom Depletion in NF3 Combustor Laser Flows.

“…It will be noted that the yellow glow of the N 2 transition comes from the reactions involving N and NT, which are components of dissociated NF 3 . On the other hand, the green emission of NP comes from the reaction 4 of NF 2 and H and a subsequent reaction with HF(v-2) making HF(v=0), which degrades '-ser performance.…”