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MECHANISMS OF LASER-SURFACE INTERACTIONS
HONEYWELL INC HOPKINS MN CORPORATE RESEARCH CENTER
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This report describes extensions of measurements of particle emission produced in the interaction of high power laser radiation with absorbing surfaces. Most of the experimental work in this report period involved the use of a hemispherical interaction chamber with collectors around the periphery. A multiplier detector and a bipolar detector have been employed in addition to the ordinary disc collectors used previously. The experimental results for a tungsten target and a laser flux density of the order of 50 megawattssq. cm. indicate that the blowoff material consists of a mixture of neutral molecules and of a plasma containing approximately 10 to the 13th or 14th power electrons and ions. Secondary electron emission from the collector surfaces bombarded by the incident heavy particles is important in producing the observed signals. Temperature of the expanding material is of the order of 10 eV. Additional work has been devoted to measuring the optical emission from glass samples heated by a CO2 laser beam and also to an investigation of the possible presence of picosecond pulses in our laser output.
APPROVED FOR PUBLIC RELEASE