Threshold of nonstationary laser supported detonation wave

Summary form only given, as follows. The threshold laser intensity required to support a laser induced detonation wave in air was measured for different laser pulse shapes. A TEA CO/sub 2/ laser used in the experiments generated pulses consisting of a leading high amplitude peak with 300 ns width on the half maximum and a tail with 5 /spl mu/s duration. A cell filled with SF/sub 6/ was used to change the amplitude of the leading peak. The separation of the shock wave from the plasma front, indicating the detonation wave decay, was detected using schlieren photography. The higher threshold intensity of laser supported detonation wave decay was measured for higher amplitude of the leading peak in the laser pulse shape. An explanation for the effect is given on the basis of the earlier proposed mechanism of nondimensional laser supported detonation wave decay.