Crossed-beam intermodulated fluorescence spectroscopy as a spatially resolved temperature diagnostic for supersonic nozzles.

A variant of laser saturation spectroscopy has been applied to the determination of spatially resolved temperature in low-pressure supersonic flows. By copropagating a pump and probe beam with a small crossing angle, the full Doppler profile is retained, but the signal is limited to the volume where both beams are overlapped. The technique was demonstrated on several rovibrational lines of the I2X1Sigma(0g+)-->B3Pi(0u+) transition in a Mach 2 Laval nozzle. A temperature of 146 K+/-1.5 K was extracted from measurements of the I2P(46) 17-1 spectral line with a spatial resolution of 2.4 mm3. Application of the technique to the turbulent gain medium of a chemical oxygen-iodine laser is discussed.