Date of Award

Fall 2016

Document Type


Degree Name

Doctor of Philosophy (PhD)



Committee Director

Charles I. Sukenik

Committee Director

R. Jeffery Balla

Committee Member

Lepsha Vuskovic

Committee Member

Ted Rogers

Committee Member

Gordon Melrose


Non-intrusive flow diagnostics are essential for studying the physics of hypersonic flow wake regions. To advance the development of next generation hypersonic vehicles and to improve computational fluid dynamics techniques in the hypersonic regime, NASA needs a suitable non-intrusive diagnostic technique to measure velocity, density, and temperature. We will present our work on developing a seedless, non-intrusive diagnostic technique using excited state argon atoms, prepared via multi-photon excitation. In this dissertation, we report results on the first phase of this hypersonic wake measurement project. In particular, we have redesigned and characterized the performance of a high energy, nanosecond pulsed Ti:Sapphire laser. Using this laser, we have studied in argon, a three-photon excitation that yields a long-lived metastable state via radiative decay. Our measurements were conducted over a range of pressures both with and without a krypton buffer gas. We compare our measured results to detailed calculations of the excitation pathway and describe the physical processes that govern the excitation and decay processes. Finally, we provide a roadmap for the next phase of the project.


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