Experimental study of the initiation mechanism of laser-supported absorption waves

Mechanisms for prompt initiation of laser supported absorption waves are identified with their experimental consequences. A phenomenological theory of electron emission from metals under intense laser irradiation is discussed. A recent model for initiation of laser supported detonation waves which requires exceeding both irradiation and fluence thresholds is summarized. Experiments with 0.1 ns pulses of 1.06 micrometers laser light with irradiance from 8 to 250 Mw/sq cm on various aluminum targets in vacuum are described. Data are given for the time dependence and peak current density of electron emission as a function of laser irradiance and for the dependence of electron emission on laser polarization. The implications of the data for initiation mechanisms is discussed.