Talbot-Lau X-ray Deflectometry of laser-irradiated foils: comparison of experimental results and simulations

For the first time, the ablation front of an irradiated CH foil (150 J, 2 ns) was imaged on Omega EP with the newly established TIM-based Talbot-Lau X-ray Deflectometer (TXD). TXD diagnostics can measure electron density gradients to characterize HED plasmas through phase-contrast methods. A Moiré fringe pattern was recorded using 8 keV x-ray backlighting generated by irradiating a thin copper foil with a short pulse laser (150 J, 10 ps, 70 µm) 5 ns after main driving beam. A 2D refraction angle map (<150 µradians) was obtained through phase-retrieval methods even though the fringe contrast measured was less than the theoretical maximum. The experimentally retrieved map matches post-processed 8 keV refraction angle maps obtained using 2D FLASH electron density simulations. Additionally, the experimental Moire image was analyzed using the newly developed Talbot Interferometry Analysis (TIA) tool which can produce synthetic Moire images using electron density and temperature information from FLASH simulations. The comparison between experimental and simulated results, including advanced analysis tools and techniques, demonstrates the potential of Talbot-Lau x-ray interferometry as a reliable HEDP diagnostic. Further developments to the TXD diagnostic, including monochromatic backlighting to improve fringe contrast and x-ray backlighter optimization to improve spatial resolution, are discussed.