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Abstract: Advanced Diagnostics and Kinetics of Oxygen-Iodine Laser Systems
Wilson T. Rawlins, Seonkyung Lee, William J. Kessler, Lawrence G. Piper, Steven J. Davis,
"Advanced Diagnostics and Kinetics of Oxygen-Iodine Laser Systems
,"
presented at 36th AIAA Plasmadynamics and Lasers Conference
(Toronto, Ontario, Canada)
,
(6-9 June2005).
Copyright © 2005 Physical Sciences Inc.
Abstract
This paper describes a comprehensive, multispecies diagnostic suite for the characterization of chemical and electrical oxygen-iodine laser kinetics. Oxygen-iodine
lasers involve reactions and energy transfer among several key species, including electronically excited O2(a) and O2(b), the reagent I2, ground-state I, electronically excited I*, and, in the case of electric-discharge driven systems, atomic oxygen. We have implemented highly sensitive and accurate methods for the measurement of all of these species in a chemically reacting flow system. We have used quantitative near-infrared emission spectroscopy to detect O2(a), O2(b), and I*, ultra-high precision absorption spectroscopy to detect I2, ultra-high precision tunable diode laser absorption spectroscopy to detect I:I* small-signal gain, and a chemiluminescent titration method to detect O. All of these methods provide well-resolved species concentrations, and the spectral emission and laser absorption measurements also provide spectroscopic determinations of gas temperature. Multispecies
measurements of this type constrain reacting flow models so that gaps in our understanding of these systems can be identified and resolved. Through accurately calibrated spectral emission measurements, we have shown that high yields of O2(a) (>20%) can be attained via microwave discharge excitation of flowing dilute mixtures of O2 and Ar. For these conditions, we have observed positive small-signal gain on the I* - I transition, however the multispecies concentration data clearly show the existence of previously unknown kinetics limitations related to the presence of O. We discuss the calibration and accuracy of the diagnostic methods, and the implications of the results for the kinetics of discharge-driven oxygen-iodine laser systems.
sr-1229
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