A THEORETICAL AND EXPERIMENTAL EXAMINATION OF PULSED 16 MICRONS CARBON-DIOXIDE TRANSFER CHEMICAL LASERS.

摘要

An experimental and theoretical investigation of hydrogen-halide CO(,2) 16 (mu)m laser systems was made. The experiments employed a pulsed hydrogen-halide chemical laser to optically pump a cell containing a mixture of HX, CO(,2), and diluent. Similar experiments using deuterium instead of hydrogen were also performed.; Initially a computer model was developed simulating laser oscillation in a DF/CO(,2) and HBr/CO(,2) device. The model used a rate equation approach to compute the time histories of the concentrations of both the lasing and non-lasing species. Rotational non-equilibrium of both CO(,2) and HX molecules was permitted. Non-equilibrium of the rotational population could be the result of lasing or preferential pumping.; Kinetic mechanisms important to 16 (mu)m lasing were identified using the results of the computer simulation. The predictions of the HBr/CO(,2) model were compared to the experimental results of Osgood {lcub}7, 8{rcub}, who reported 16 (mu)m laser output from an optically pumped HBr/CO(,2)/Ar gas mixture.; The model predictions compared favorably with the experimental results of Osgood in all but one instance. Experimental results demonstrated that increasing Ar partial pressure increased 16 (mu)m pulse power while the computer simulations predicted the opposite trend.; The computer program was subsequently modified to more accurately simulate the absorption of the optical input pulse.; The results of the computer calculations were again compared to the experimental observations of R. M. Osgood and also to the experimental observations of N. Barnes {lcub}22{rcub}. In both instances the model predictions agreed with experimental results. The model correctly predicted that increasing the partial pressure of Ar raised 16 (mu)m pulse power while lowering pulse energy.; Because of the potential for higher output powers and energies from HF lasers compared to HBr and HF pumped HF/CO(,2) 16 (mu)m laser would be desirable. To demonstrate the feasibility of such a device experiments were performed using an HF laser to optically pump an HF/CO(,2)/He gas mixture. Due to HF polymerization at low temperatures it was necessary to maintain the gas mixture above 260(DEGREES)K contrast to the HBr device of Osgood that could operate at 193(DEGREES)K. No evidence of laser output from the HF/CO(,2) device was ever observed.; To attempt to explain these reults the computer model was modified to simulate the chemical kinetics in an HF/CO(,2) gas mixture. The results of the computer calculations predicted very weak 9.4 (mu)m lasing (approximately 2% of HBr output at 9.4 (mu)m) and no 16 (mu)m laser output. A combination of slower energy transfer between HF and CO(,2) compared to HBr and a vibrational self-deactivation rate two orders of magnitude greater for HF than for HBr appeared to be responsible for these results.