Kinetics of Higher Lying Potassium States after Excitation of the D2 Transition in the Presence of Helium
AIR FORCE INSTITUTE OF TECHNOLOGY WRIGHT-PATTERSON AFB OH WRIGHT-PATTERSON AFB United States
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A kinetic model for the performance of a potassium Diode Pumped Alkali Laser DPAL, including the role of higher lying states is developed to assess the impact on device efficiency and performance. A rate package for a nine level kinetic model including recommended rate parameters is solved under steady-state conditions. The fraction of the population removed from the basic three levels associated with the standard model is less than 10 percent for all reasonable laser conditions, including pump intensities up to 100 kWcm2 and K densities as high as 10exp 16 cm-3. To benchmark this new model, fluorescence emitted by a high power, transverse flow potassium DPAL was collected to characterize the highly excited state population. The population in these states was found to be less than 5 percent for all cases. The additional heat loading due to the quenching of the higher states is minimal, 1 percent of the spin-orbit mixing heat load. This extra heat has a small effect on both Strehl and efficiency in the static system, but these can be recovered with flow velocities commensurate with transit times across the pump volume 0.1 s.
- Inorganic Chemistry
- Lasers and Masers