X-ray powder diffraction in reflection geometry on multi-beam kJ-type laser facilities
Résumé
An ultrafast x-ray powder diffraction setup for laser-driven dynamic compression has been developed at the LULI2000 laser facility. X-ray diffraction is performed in reflection geometry from a quasi-monochromatic laser-generated plasma x-ray source. In comparison to a transmission geometry setup, this configuration allows us to probe only a small portion of the compressed sample, as well as to shield the detectors against the x-rays generated by the laser-plasma interaction on the front side of the target. Thus, this new platform facilitates probing of spatially and temporarily uniform thermodynamic conditions and enables us to study samples of a large range of atomic numbers, thicknesses, and compression dynamics. As a proof-of-concept, we report direct structural measurements of the bcc-hcp transition both in shock and ramp-compressed polycrystalline iron with diffraction signals recorded between 2θ ∼30° and ∼150°. In parallel, the pressure and temperature history of probed samples is measured by rear-side visible diagnostics (velocimetry and pyrometry).
Mots clés
Atoms
Beam plasma interactions
Geometry
Laser beams
Laser produced plasmas
Plasma diagnostics
Ultrafast lasers
X ray lasers
X ray powder diffraction
Diffraction signals
Laser-plasma interactions
Polycrystalline iron
Pressure and temperature
Reflection geometry
Structural measurements
Thermodynamic conditions
Transmission geometries
X ray detectors
Domaines
Physique [physics]
Fichier principal
Denoeud et al - 2021 - X-ray powder diffraction in reflection geometry.pdf (9.21 Mo)
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