Abstract

With a first application of semiconductor lasers to absorption measurements of seeded atomic Rb in high-enthalpy flow fields, a diagnostic technique for time-resolved determination of flow velocity and gas temperature with a line-shape analysis was developed. In our measurements a GaAlAs diode laser was used to scan repetitively at 15 kHz over 1.3 cm^-1 across the D₂ resonance transition (5S _1/2 → 5P _3/2, 780.2 nm) of seeded atomic Rb to obtain multiple absorption line shapes. The time-dependent signal contains highly resolved spectral line-shape information, which we interpret by fitting the spectrally resolved line shapes to Voigt profiles. Kinetic temperatures in the range 900–1400 K and gas velocities in the range 3900–6200 ms^-1 were obtained from the Doppler-broadened component of the line shape and from the Doppler shift, respectively, of the absorption frequency.

© 1998 Optical Society of America

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