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Proceedings Paper

Short Pulse X-Ray Diffraction Studies Of Shocked And Annealed Crystals Using The Janus Research Laser
Author(s): R. W. Lee; M. J. Eckart; J. D. Kilkenny; R. R. Whitlock; A. Hauer; J. S. Wark
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Paper Abstract

When a crystal is annealed or shocked the spacing of the interatomic planes is altered, and a measurement of the lattice spacing can yield information on the temperature or compression respectively. We have used the JANUS research laser at LLNL to perform such measurements of transiently strained crystals. JANUS is a two beam laser system, with separate synchronized oscillators for each beam. One beam of the laser, containing ~10 -100 J of 1.06pm light in a pulse of 1 ns FWHM, was focused to a 3.9 cm diameter spot on the surface of a silicon crystal; the crystal was either annealed or shock-compressed, depending on the absence or presence of a variety of thin coatings applied to the crystal surface. At some time during or after the perturbing pulse, the second synchronous but delayed laser beam, containing ~10 J of 0.53pm light in a pulse of 100 ps (FWHM), was focused to a 40pm diameter spot onto a separate target containing calcium, potassium, and chlorine. Thus, a short pulse of the helium-like line radiation of these atoms was produced, and this radiation was Bragg diffracted from the surface of the strained crystal. Measurements of the change in Bragg angle, caused by thermal expansion or shock compression, gives a direct measurement of one component of the strain within the crystal. A single laser shot gives recordable x-ray levels. A number of shots at different irradiances and delay times gave information about the lattice spacing as a function of time. The potential applications of such results is discussed.

Paper Details

Date Published: 4 February 1988
PDF: 8 pages
Proc. SPIE 0831, X-Rays from Laser Plasmas, (4 February 1988); doi: 10.1117/12.965044
Show Author Affiliations
R. W. Lee, Lawrence Livermore National Laboratory (United States)
M. J. Eckart, Lawrence Livermore National Laboratory (United States)
J. D. Kilkenny, Lawrence Livermore National Laboratory (United States)
R. R. Whitlock, Naval Research Laboratory (United States)
A. Hauer, Los Alamos National Laboratory (United States)
J. S. Wark, University of Rochester (United States)

Published in SPIE Proceedings Vol. 0831:
X-Rays from Laser Plasmas
Martin C. Richardson, Editor(s)

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