Exploiting the European-XFEL for a New Generation of Static Compression Research

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This project proposes to study the transformation dynamics of materials shocked using X-ray pulses in a diamond anvil cell (DAC) at the European-XFEL (X-ray free electron laser) facility in Hamburg. This project aims to study the response of materials to extreme strain rates, pressures and temperatures. Currently, AWE can access extreme conditions statically using standard DACs and toroidal DACs (currently under development), and dynamically using laser shocking (and to a lesser extent, gas guns). Fielding a DAC at XFEL, in essence, combines both techniques and should enable, through different thermodynamic pathways, access to new phase space for materials.Experiments will be carried out at the European XFEL facility in Hamburg using the High Energy Density (HED) beamline. Only XFEL can provide the high repetition rate of hard X-ray pulses required for these experiments. The initial objective is to send a train of energetic femtosecond X-ray pulses into the sample (already loaded into a DAC) to simultaneously, and rapidly, compress and heat the sample. Extremely fast detectors will be used to collect diffraction patterns during compression. Temperatures will be measured optically using streak spectro-radiometry technology. The ultimate goal is to develop a means of tuning the high strain rates, and consequently the pressures and temperatures induced in samples, through control of the X-ray pulse train. Understanding kinetic effects is critical to understanding phase transformations in materials under extreme conditions.