Effect of laser ablation plasma on dynamics of a laser absorption wave in a gas

Experimental results indicate deceleration of the detonation wave under conditions of partial absorption of laser radiation when both plasmas--detonation wave and ablation plasma--are ignited simultaneously. The observed effect is attributed to a reduction of laser radiation intensity, reflected by the target surface and transmitted back to the detonation wave, due to the absorption in the dense ionized vapor of the target material. Also, we report results of studies on dynamics of axial and radial shock waves formed in a gas during propagation of the detonation wave. The observed differences between experimental results and self-similar computations are attributed to the effect of the hot gas transfer along the laser beam axis out of the zone of absorption of laser radiation. All the experiments were performed using carbon-dioxide laser with pulse width of a few microseconds and energy of 1 J. We employed streak camera, fast diodes, CCD camera imaging, and plasma transparency measurement techniques for data acquisition