Electrically Initiated HCl Chemical Laser and Threshold Excitation of XeF and KrF Lasers

Abstract

Abstract : The report describes the results of two separate experimental investigations. The first concerns the electrical excitation of the HCl chemical laser and was motivated by the potential improvement of the laser performance by the vibrational enhancement of the reaction Cl + H2(v=1) yields HCl(v=v,1) + H. Detailed kinetic modelling of the e-beam and e-beam sustained discharge experiments was used in the interpretation of the experimental data. The rate constant for the vibrationally enhanced reaction was 40 times larger than for the reaction with H2(v=0) at T = 300K. This enhanced rate is not fast enough to lead to efficient use of the H2(v=1) excited by electron impact. The maximum electrical to laser conversion efficiency obtained was 3 percent. The second part of the report describes measurements of the threshold pumping power density in e-beam sustained discharge excitation of KrF and XeF lasers. Stable discharges were obtained in Ar-Kr-F2 and Ar-Xe-NF3 mixtures at 1 atm for times greater than 0.5 microsecond and lasing pulse width as long as 0.5 microsecond. The threshold pump power densities varied inversely with the cavity build up time. Based on the present results it is evident that efficient laser operation in KrF and XeF could be achieved in a 1-m long sustained discharge with input power densities in the range of 50 to 100 kW/cu cm over a 1 microsecond time scale.