Application of laser-induced thermal acoustics in air to measurement of shock-induced temperature changes

The laser-induced thermal acoustics (LITA) method was used to measure the temperature profiles induced behind spherical shock waves, generated by high-voltage discharge in air with an energy of 6 J. A Nd:YAG laser (wavelength 532 nm, energy 300 mJ, pulse duration 10 ns, line width 0.005 cm−1) and an Ar-ion laser (wavelength 488 nm, power 4 W) served as the pump and probe lasers, respectively for the LITA measurements. The peak temperatures were in good agreement with results calculated with the Euler equations. The temperature profiles behind the shock, however, differed in decay rates. The peak temperatures behind the shock wave were determined by reflected overpressure and agreed with those from the LITA measurements within a maximum error of 5%.