Nuclear-induced xenon monobromide fluorescence pumping of the atomic iodine laser
Williams, Wade Henry
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https://hdl.handle.net/2142/19247
Description
Title
Nuclear-induced xenon monobromide fluorescence pumping of the atomic iodine laser
Author(s)
Williams, Wade Henry
Issue Date
1992
Doctoral Committee Chair(s)
Miley, George H.
Department of Study
Nuclear, Plasma, and Radiological Engineering
Discipline
Nuclear Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Electronics and Electrical
Engineering, Nuclear
Language
eng
Abstract
This thesis reports on a study of the atomic iodine laser pumped with nuclear-excited XeBr fluorescence. These results represent the first demonstration of a nuclear flashlamp pumped laser.
Preliminary experiments, conducted in the TRIGA reactor on the campus of the University of Illinois at Urbana-Champaign, investigated the fluorescence of the excimer XeBr under nuclear pumping with $\sp{10}$B and $\sp3$He, for use as a flashlamp gas to stimulate the laser. These measurements included a determination of the fluorescence efficiency (light emitted in the wavelength region of interest, divided by energy deposited in the gas) of XeBr under nuclear pumping, with varying excimer mixtures. Maximum fluorescence efficiencies were approximately 1%.
In order to better understand XeBr under nuclear excitation, a kinetics model of the system was prepared. The model generated the time-dependant concentrations of 20 reaction species for three pulse sizes, a TRIGA pulse, a fast burst reactor pulse, and an e-beam pulse. The modeling results predicted fluorescence efficiencies significantly higher (peak efficiencies of approximately 10%) than recorded in the fluorescence experiments. The cause of this discrepancy was not fully determined; several possibilities were considered.
A ray tracing computer model was also prepared to evaluate the efficiency with which nuclear-induced fluorescence generated in one cavity of a laser could be coupled into another cavity containing an iodine lasant. Several simple geometries were considered, aiding in design and evaluation of a test laser.
Finally, an experimental laser cell was constructed to verify that nuclear-induced XeBr fluorescence could be used to stimulate a laser. Lasing was achieved at 1.31 micron in the TRIGA using C$\sb3$F$\sb7$I, a common iodine lasant. Peak laser powers were approximately 20 mW. Measured flashlamp pump powers at threshold agreed well with literature values, as did lasant pressure dependency on laser operation, indicating that the laser was operating as anticipated. Outside of the use of radiation-resistant glass in the laser, no special considerations were found necessary in applying the iodine laser to the intense radiation environment of nuclear pumping. It is hoped that these results will encourage further studies into this, as well as other nuclear flashlamp pumped laser systems.
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