Initiation Phenomena in Pulsed Chemical Lasers

It has been proposed that trace addition of ClF3 to conventional gas mixtures in photo-initiated HF/DF pulsed lasers might substantially improve chain reaction initiation and consequently, system electrical efficiency. It has further been proposed that steady flow of a spatially tailored trace addition of ClF3 might improve uniformity of initiation and, hence, cavity homogeneity in reptitively pulsed devices by providing enhanced initiation (F-atom production) in regions of diminished lamp illumination. An argon filled flash lamp with pulse duration (FWHM) of approximately 40 microsec was observed to radiate 3.5% of its initial electrical energy in the absorption band of ClF3 (1750A to 2400A) and 13% of its energy in the absorption band of F2 (2400A to 3400A). Theoretical modeling of flash lamp radiation indicates that short lamp pulses appropriate to pulsed chemical lasers would show equal or better radiation distribution of lamp electrical energy in these absorption bands. The flash lamp was used in photolysis studies which show that absorption of radiation by ClF3 results in dissociation with efficiency of order unity. Photolytic production of F-atoms could not be determined in the present UV attenuation studies due to the occurrence of a strongly absorbing unidentified photolysis product or products.