Short pulse x-ray diffraction studies of shocked and annealed crystals using the JANUS research laser
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 1.06..mu..m light in a pulse of 1 ns FWHM, was found to a 3.9 cm diameter spot on the surface of 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 /approximately/10 J of 0.53..mu..m light in a pulse of 100 ps (FWHM), was focused to a 40..mu..m 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. 10 refs., 6 figs.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA); Naval Research Lab., Washington, DC (USA); Los Alamos National Lab., NM (USA); Rochester Univ., NY (USA). Lab. for Laser Energetics
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5121340
- Report Number(s):
- UCRL-97218; CONF-8708110-38; ON: DE88011329
- Resource Relation:
- Conference: 31. SPIE annual international technical symposium on optical and optoelectronic applied science and engineering, San Diego, CA, USA, 16 Aug 1987
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CRYSTALS
STRUCTURAL CHEMICAL ANALYSIS
BRAGG REFLECTION
COMPRESSION
IRRADIATION
LASER RADIATION
NEODYMIUM LASERS
SILICON
STRAINS
THERMAL EXPANSION
X-RAY DIFFRACTION
COHERENT SCATTERING
DIFFRACTION
ELECTROMAGNETIC RADIATION
ELEMENTS
EXPANSION
LASERS
RADIATIONS
REFLECTION
SCATTERING
SEMIMETALS
SOLID STATE LASERS
656002* - Condensed Matter Physics- General Techniques in Condensed Matter- (1987-)