Feasibility of non-intrusive optical diagnostic measurements in hypersonic boundary layers for flight experiments

The present investigation of possible methods for nonintrusive optical diagnostics of hypersonic vehicle boundary layers notes electron-beam fluorescence to be capable of obtaining measurements of density, temperature, and shock-front location, as well as of N2, O2, and NO concentrations. NO will be a key indicator of vehicle nose and leading edge chemistry. It is expected that laser-induced fluorescence will allow measurements of NO and O2 concentrations when compact and reliable UV lasers become available; the sensors and instrumentation for spectral resolution of fluorescence along a line emanating from the vehicle and passing through the shock front already exist.