Linear and Nonlinear Spectroscopy of Optically-Thick Argon and Argon-Helium Plasmas in Radio-Frequency Dielectric-Barrier Discharges

Ben Eshel

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An argon-helium plasma formed in a radio-frequency dielectric-barrier discharge has been studied for application to a diode-pumped rare gas laser using both linear and non-linear spectroscopic techniques. The pressure broadening and shift rates have been measured for four Ar s to p transitions in both pure Ar and Ar-He gas mixtures with improved precision over previously measured values. These broadening and shift rates are crucial to efficiently coupling the diode radiation into the gain medium. The Ar plasma was also studied under high-intensity laser fields to examine the saturation behavior and a numerical line shape was developed to qualitatively describe the observed trends. Additionally, the spin-orbit mixing rates of the alkali-metal rare-gas interaction was organized using adiabaticity with deviations correlated to the polarizability of the interacting pair. A time-dependent perturbation theory model was developed in order to predict the temperature dependence of these rates and was shown to be in good agreement with the full database of measured cross-sections.