Date of Award


Document Type


Degree Name

Master of Science


Department of Engineering Physics

First Advisor

Brian A. Tom, PhD.


A tunable diode laser absorption spectroscopy system, capable of collecting data at a 10 kHz repetition rate near 4.5 microns. This system was made feasible in recent years due to the development of quantum cascade lasers active in the 4.5 microns region of the spectrum. Reaching into the mid-IR region of the electromagnetic spectrum allowed for an analysis of the fundamental absorption bands for both CO and CO2. The spectral absorption was measured for ethylene, methane, ethane, and propane across a variety of equivalence ratios, at various heights above a Hencken Burner surface. For each fuel, the concentration of CO2 was found to agree with chemical equilibrium analysis (CEA) calculations within approximately 8%. The concentration for CO agreed with CEA but with larger error bounds at approximately 20%. It is believed that such large error can be attributed to taking measurements on a hot band, as well as large amounts of H2O and CO2 absorption in the area. This ultimately resulted the measurement of combustion efficiency, which agreed with expected results with approximately 10% error bounds. With this system's proof of concept, it will be possible to analyze real combustors as well as detonation events.

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