Probing Crystal Structural Transitions in High Energy Density Materials Using Time-Resolved X-Ray Diffraction on the OMEGA EP Laser

A method of measuring multiple temporally resolved powder x-ray diffraction (XRD) measurements during a single laser experiment has been demonstrated on shock-compressed iron and ramp-compressed Zr at the Omega EP Laser Facility. Using a variation of the time-integrating powder XRD image-plate configuration, up to four temporally resolved snapshots of the XRD pattern are collected on an x-ray framing camera with a 2θ scattering angle coverage of 48° to 65° with a 400-ps temporal resolution.[1] The experimental configuration allows for simultaneous velocimetry, time-integrated image-plate XRD, and time-resolved XRD. Time resolution on a single sample affords the opportunity to probe transitions under evolving hydrodynamic conditions, time-dependent properties such as elastic and plastic deformation, stochastic processes such as phase nucleation and growth, and the temporal evolution of kinetically hindered transitions. X ray diffraction snapshots capture the transformation to a high-pressure β phase in ramp-compressed Zr, constraining the atomic structure evolution in a single shot.

[1] J. R. Rygg et al., Rev. Sci. Instrum. 83, 113904 (2012).