Filtered Rayleigh scattering measurements using a MHz rate pulse-burst laser system

We present measurements of the spectral characteristics of a MHz rate, Nd:YAG pulse-burst laser system, with particular emphasis on data relevant to spectrally filtered scattering diagnostics which employ molecular iodine vapor filters. The time-averaged laser spectral profile is found to correspond quite well to that predicted from the Fourier transform of the observed temporal profile. The measured maximum extinction value of 5 x 10 exp -5 for the second harmonic output is in good agreement with modeling predictions, based on a 10 cm path length iodine cell under typical operating conditions. Filtered images of time sequences of supersonic flow over a 14-deg wedge are also presented. The images clearly illustrate the unsteadiness of the oblique shock wave and the correlation of its dynamic behavior with large-scale turbulent boundary layer structure. (Author)

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