a Theoretical Study of the Kinetic Processes in a High-Power Xenon Chloride Excimer Laser Oscillator Driven by a Long Transmission Line Pulse Forming Network.

The avalanche/self-sustained discharge rare gas halide (RGH) excimer lasers driven by a transmission line type pulse forming network (PFN) belong to a novel class of discharge pumped gas lasers operating in the visible and ultraviolet wavelengths efficiently. The kinetics in this class of lasers, however, has not yet been fully understood. Therefore, it seems essential at this point to study the characteristics of the discharge plasma in such a device and determine the major energy flow paths in the active media before one attempts to optimize the operating conditions or deduce the scaling rules. The work presented here is the theoretical modeling of the discharge pumped XeCl laser driven by a long transmission line (two way transit time, 200 nsec). The mathematical formulation consisting of the rate equations, the temperature equation, the circuit equation, and the Boltzmann equation governing the velocity and energy distributions of the free electrons is developed under the assumptions that the applied electric field strength is spatially uniform and the number densities of all important chemical species are spatially homogeneous in the discharge volume. These coupled non-linear differential equations are solved numerically by using the GBS extrapolation method simultaneously with the time evolution of the electron mole fraction during the transient discharge. The time-dependent electron velocity and energy distribution functions are obtained from the numerical solutions of the Boltzmann equation, with all elastic (including electron-electron), inelastic, attachment, recombination, and ionization collisions included, by a self-consistent iteration technique. The kinetic reactions involved in the XeCl laser using Ne/Xe/HCl and He/Xe/HCl mixtures are comprehensively examined. The results of this study reveal that the new processes. e + XeCl('*) (--->) Xe('*) + Cl('-),. e + XeCl (--->) Xe + Cl('-) or Xe + Cl + e,. are important and have to be included in the model. In addition, the rate constants of the processes. e + HCl(v=1) (--->) H + Cl('-),. XeCl + Ne,He (--->) Xe + Cl + Ne,He, and. h(nu) + XeCl('*) (--->) XeC('**). should be revised from the earlier published values. They are discussed in detail. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of school.) UMI.