Textural evolution of dynamically compressed materials and the progress towards High Repetition Rate experiments

In this thesis, results from two laser shock compression and x-ray diffraction (XRD) experiments - #2740 and #6659 - at the High Energy Density (HED) instrument of the European XFEL (EuXFEL) are presented.
In #2740, the textural evolution of rolled iron foil shocked compressed through the α(BCC) - ϵ(HCP) phase transition has been studied, with the commissioning of the 1-10 Hz DiPOLE 100-X laser on HED providing pressures between 11 and 92 GPa. The textural evolution of the foils was analysed using a novel forward-modelling approach, with careful pre-characterisation of the initial texture and laser shock XRD simulation showing that the α(BCC) - ϵ(HCP) phase transition followed the Burgers mechanism. A Schmid factor based analysis was employed to provide a physical rationale for selecting which Burgers orientation relationships (ORs) were activated at different Euler angles along the fibre texture. This was validated through simulated XRD patterns that qualitatively matched the experimental results.
Additionally, a potential solution to the targetry demands of 10 Hz high-repetition rate
(HRR) laser shock experiments is presented: using the tape drive target system developed by the Central Laser Facility (CLF). A new deposition technique for producing isolated slurry targets (a mixture of powdered sample and epoxy) is described for silicon and copper targets with a mass ratio of 10:1 (epoxy to powder). Pre-characterisation with Scanning Electron Microscopy confirmed that the silicon and copper slurry targets had an average particle sizes of (2.66 ± 0.09) μm, or 0.5 to 1.5 μm, respectively. Interferometry shows respective average slurry thicknesses of (129 ± 4) μm, and (153 ± 4) μm. The feasibility of this technique was demonstrated in #6659, with XRD showing the silicon and copper slurry targets possessed near-random crystallite distributions, and were successfully compressed. The silicon underwent multiple phase transformations, whilst copper reached melting.