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Proceedings Paper

Laser/matter interaction at intensities of 1012 W/cm2 and below
Author(s): S. Robert Goldman; Ronald S. Dingus; Ronald C. Kirkpatrick; Roger A. Kopp; Elmer K. Stover; Robert G. Watt
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Paper Abstract

For single pulsed laser-matter interactions at sufficiently high intensity, the electron density in the ablated vapor is large enough to absorb the laser radiation before it can reach the dense target material. The resulting interaction can be described in terms of energy flows: laser energy is absorbed in the plasma in front of the target and reappears as thermal electron energy and secondary radiation, part of which impinges upon and heats the dense target material at the dense material-vapor interface. This heating in turn drives ablation, thereby providing a selfconsistent mass source for the laser absorption, energy conversion, and transmission. Under typical conditions of laser intensity, pulse width and spot size, the flow patterns can be strongly two-dimensional. We have modified the inertial confinement fusion code LASNEX to simulate gaseous and some dense material aspects for the relatively low intensity, long pulse-length conditions of interest in many laser-related applications. The unique aspect of our treatment consists of an ablation model which defines a dense material-vapor interface and then calculates the mass flow across this interface. The model, at present, treats the dense material as a rigid, two-dimensional simulational mass and heat reservoir, suppressing all hydrodynamical motion in the dense material. The modeling is being developed and refined through simulation of experiments, as well as through the investigation of internal inconsistencies, and some simulation of model problems. The computer simulations and additional post-processors provide a wealth of predictions for possible measurements, including impulse given to the target, pressures at the target interface, electron temperatures and densities, and ion densities in the vapor-plasma plume region, transmission and emission of radiation along chords through the plume, total mass ablation from the target and burn-through of the target material at selected radial locations. We will present an analysis of some relatively well-diagnosed experimental behavior which has been useful in development of our modeling.

Paper Details

Date Published: 1 August 1990
PDF: 8 pages
Proc. SPIE 1279, Laser-Assisted Processing II, (1 August 1990); doi: 10.1117/12.20615
Show Author Affiliations
S. Robert Goldman, Los Alamos National Lab. (United States)
Ronald S. Dingus, Los Alamos National Lab. (United States)
Ronald C. Kirkpatrick, Los Alamos National Lab. (United States)
Roger A. Kopp, Los Alamos National Lab. (United States)
Elmer K. Stover, Los Alamos National Lab. (United States)
Robert G. Watt, Los Alamos National Lab. (United States)

Published in SPIE Proceedings Vol. 1279:
Laser-Assisted Processing II
Lucien Diego Laude, Editor(s)

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