Dynamic x-ray diffraction of shock compressed carbon phase transformations on Sandia’s Z Pulsed Power Facility*

Experiments on the Z Pulsed Power Facility at Sandia National Laboratories are able to produce dynamically compressed high-pressure states of matter with unprecedented uniformity, duration, and size, which are ideal for investigations of fundamental material properties. X-ray diffraction (XRD) is a key material science measurement since it provides direct observation of the compression and strain of the crystal lattice, and is used to detect and identify phase transitions. Several unique challenges of dynamic compression experiments on Z preclude using XRD schemes that have worked at other dynamic compression facilities, thus a novel imaging-fiber XRD diagnostic has been designed and implemented. We performed experiments on Z to shock compress carbon (pyrolytic graphite) samples to pressures of 150 – 320 GPa. The Z-Beamlet laser generated Mn-He_α 6.2 keV x-rays to probe the shock-compressed carbon sample, and the new XRD diagnostic measured changes in the diffraction pattern as the carbon transformed into its high-pressure phases.