XFEL diffraction measurements of shocked Fe and Fe alloys for planetary science*

Earth's core is composed of Fe mixed with small amounts of light elements like Si, O, and C. Determining the properties of high-pressure liquids, the melting curve, and solid phase relations of Fe and derivative alloys is important for understanding the cores of Earth and terrestrial exoplanets. High pressure and temperature conditions can be achieved with high power lasers, but the states are highly transient, and the inherently high strain rate introduces physics not expected to occur in planetary interiors. The recent advance of facilities with high-power lasers coupled to XFELs enables characterization of shocked states with the powerful suite of X-ray techniques used by the static community. Here we present results from recent ultrafast X-ray diffraction measurements of shocked Fe alloys at the coupled XFEL-optical laser facilities using the EH5 end station at the SACLA facility (Japan) and the LCLS end station MEC at SLAC National Accelerator Laboratory (USA).