SUMMARY

Understanding the optical properties of hypersonic flows and other high-enthalpy environments is essential for aero-optics and extreme flight dynamics. The strong shock waves generated around a vehicle causes significant changes in the flow properties behind the shock. In particular, the index of refraction of air at temperatures above 6000K deviates from known values due to the dissociation of nitrogen and oxygen and other reactions. Validation data is necessary to calculate and simulate these complex environments, however, little to no high fidelity experimental data exists due to several challenges. Experimental index-of-refraction data are limited since virtually no diagnostic methods are capable of measuring large density changes across high-velocity discrete boundaries.

To address this problem, this work proposes developing unique interferometric diagnostic techniques that can resolve large discrete optical changes across a shock front. The first objectives of this thesis are: 1.) to develop a high-resolution single-wavelength diagnostic capable of measuring across discrete large density gradients and 2.) implement it in a high-enthalpy shock tube to measure the high-temperature Gladstone-Dale coefficient of air. The next objectives are to: 3.) design and optimize a multi-wavelength diagnostic to extend capabilities and 4.) to demonstrate it under shock conditions.