X-ray diffraction from shock-loaded polycrystals

TL;DR

This paper demonstrates the use of X-ray diffraction to study the response of polycrystalline metals under shock compression on nanosecond timescales, revealing changes in diffraction angles related to pressure-induced lattice modifications.

Contribution

It introduces a novel experimental setup combining laser-induced shock waves with X-ray diffraction to observe real-time lattice changes in polycrystals.

Findings

Diffraction angles change with shock pressure

Diffraction consistent with elastic and plastic compression

Method enables real-time lattice response measurement

Abstract

X-ray diffraction was demonstrated from shock-compressed polycrystalline metal on nanosecond time scales. Laser ablation was used to induce shock waves in polycrystalline foils of Be, 25 to 125 microns thick. A second laser pulse was used to generate a plasma x-ray source by irradiation of a Ti foil. The x-ray source was collimated to produce a beam of controllable diameter, and the beam was directed at the Be sample. X-rays were diffracted from the sample, and detected using films and x-ray streak cameras. The diffraction angle was observed to change with shock pressure. The diffraction angles were consistent with the uniaxial (elastic) and isotropic (plastic) compressions expected for the loading conditions used. Polycrystalline diffraction will be used to measure the response of the crystal lattice to high shock pressures and through phase changes.