Experimental Study of the Initiation Mechanism of Laser Supported Absorption Waves.
Final rept. 1 Jan 75-30 Sep 77,
LOCKHEED MISSILES AND SPACE CO INC PALO ALTO CALIF PALO ALTO RESEARCH LAB
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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. Design, construction, and testing of an apparatus including a target to permit measurement of electron emission with fast time resolution and an electron energy spectrograph and detector system are described. Experiments with 0.3 microsec pulses of 10.6 micrometers laser light with peak irradiance from 0.5 to 10 Mwsq cm on stainless steel, titanium alloy, and aluminum targets in vacuum are reported. Data are given for the peak current density of electron emission as a function of laser irradiance. Roughening of the aluminum surface was found to increase electron emission and large emission currents were produced on an aluminum-coated multipoint microarray. Experiments with 0.1 ns pulses of 1.06 micrometers laser light with peak irradiance from 8 to 250 Mwsq 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.
- Lasers and Masers
- Radiofrequency Wave Propagation