Combined Phase Contrast Imaging and Small-Angle X-Ray Scattering Diagnostic of Relativistic Plasmas at the High Energy Density Instrument at European XFEL

The High Energy Density (HED) instrument at the European XFEL provides a platform to study hot and warm dense matter. The Helmholtz International Beamline for Extreme Fields (HiBEF) is a User Consortium supplying HED with two laser systems (the high-intensity ReLaX laser, by Amplitude Technologies, and the high-energy Dipole-100X laser, by STFC), Diamond Anvil Cells setup and high-pulsed magnetic fields. These tools in combination with the XFEL beam enable the investigation of relativistic laser plasmas, strong-field QED phenomena, high-pressure astro- and planetary physics as well as magnetic phenomena in condensed matter. The successful commissioning of the ultra-short pulse high-intensity ReLaX laser, provides new unique opportunities in the plasma and high-field physics fields [1].
ReLaX is a double CPA Ti:Sa laser capable of delivering up to 300 TW pulses on target. In the first commissioning phase, 100 TW pulses were used, reaching
intensities up to 1020 W/cm2. Small-Angle X-Ray Scattering (SAXS) without the need of a beamstop was first commissioned at HED in September 2019. Two highly annealed pyrolytic graphite (HAPG) crystals were used to reflect the SAXS photons onto a detector while allowing the main XFEL beam to go through [2]. In April and May 2021, Small Angle X-Ray Scattering and Phase Contrast Imaging (PCI) were simultaneously demonstrated in pump-probe experiments at HED in a community experiment involving 15 institutions from all over the world. In this talk we will present the preliminary results of this community experiment probing ultrafast phenomena in a wide array of target configurations: hole boring in wires, shockwave generation in CH blocks, buried heating of a wire inside a CH medium, foam ionization and collective effects in heated foils.

[1] A. Laso Garcia, H. Hoeppner, A. Pelka et al., “ReLaX: the HiBEF high-intensity short-pulse laser driver for relativistic laser-matter interaction and strong-field science at the HED instrument at EuXFEL”. High Power Laser Science and Engineering, 1-15. doi:10.1017/hpl.2021.47
[2] M. Šmíd, et al., "Mirror to measure small angle x-ray scattering signal in high energy density experiments", Review of Scientific Instruments 91, 123501 (2020). doi:10.1063/5.0021691