Modeling the plasma kinetics in a kinetically enhanced copper vapor laser utilizing HCl+H2 admixtures

A detailed computer model has been used to simulate the plasma kinetics and lasing characteristics in a kinetically enhanced copper vapor laser (KE-CVL) which utilizes Ne-H-2-HCl buffer gas mixtures, The model reproduces key features of the observed operating characteristics of the KE-CVL-in particular, relating to the electrical characteristics of the plasma tube, time evolution of Cu 4s(2)S(1/2) ground state density (c.f, hook measurements), and formation of the laser output. It is shown that the principal role of the HCl additive is to increase the electron loss rate during the interpulse period via dissociative attachment reactions between free electrons and vibrationally excited HCl(upsilon = 1, 2) molecules. This leads to a reduction of the prepulse electron density, establishing more favorable prepulse conditions for laser action during the subsequent excitation phase. In the KE-CVL, the plasma skin effect governing the development of the radial electric field is greatly reduced compared to conventional CVL's, altering the spatio-temporal evolution of the optical gain and laser field intensities to substantially enhance high-beam-quality output. Comparisons between model results and experimental data for the decay rate of the Cu4s(2) D-2(3/2) metastable lower laser level in the early afterglow suggest that there may be an additional de-excitation mechanism for the D-2(3/2,5/2) levels in the KE-CVL plasma which has yet to be identified.