Continuous wave and pulsed microwave resonant cavity produced discharges.

The basic properties of continuous wave and pulsed microwave discharges and their application to laser pump sources are both theoretically and experimentally investigated. This dissertation includes three perturbation diagnostics applicable to microwave resonant cavity discharges. First, the classical microwave perturbation technique examines the shift in the resonant frequency and cavity quality factor of the resonant cavity caused by low electron density discharges. However, modifications presented here allow the analysis to be applied to discharges with electron densities beyond the limit predicted by perturbation theory. Second, a so-called exact perturbation analysis is presented which models the discharge as a separate dielectric, thereby removing the restrictions on electron density imposed by the classical technique. The exact method also utilizes measurements of the shifts in the resonant conditions of the cavity. Third, an electromagnetic analysis is presented which uses a characteristic equation, based upon Maxwell's laws, and predicts the discharge conductivity based upon measurements of a complex axial wavenumber. By allowing the axial wavenumber of the electromagnetic fields to be complex, the fields are experimentally and theoretically shown to be spatially attenuated. The diagnostics are applied to continuous wave microwave (2.45 GHz) discharges produced in an Asmussen resonant cavity. Double Langmuir probes, placed directly in the discharge at the point where the radial electric field is zero, function as a comparison with the analytic diagnostics. The double Langmuir probe diagnostic is also applied to pulsed discharges. The potential application of resonant cavity discharges in laser systems is studied. Applications to copper chloride and helium neon discharges are considered. Results presented suggest that a microwave pumped copper chloride laser should be realized by use of a high power pulsed magnetron discharge. Population inversion in a pulsed helium neon discharge was also observed, yet the inversion was insufficient to overcome losses inherent in the use of an optical cavity, thereby preventing the occurrence of lasing.PhDNuclear ScienceUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/103814/1/9409762.pdfDescription of 9409762.pdf : Restricted to UM users only