Characterization of laser-irradiated foils through advanced phase-contrast imaging techniques: Talbot-Lau X-ray Deflectometry at the Omega EP laser*

High energy density (HED) diagnostics are instrumental to understanding the behavior of matter under extreme conditions. Talbot-Lau x-ray deflectometry is a high-resolution diagnostic technique that allows for simultaneous single-shot radiography and phase-contrast imaging of dense plasmas. A dedicated Omega EP Talbot-Lau X-ray Deflectometry diagnostic platform was backlit with laser-produced Cu K-shell emission (~150 J, 12 ps, 7.7 x10¹⁶ – 1.1 x10¹⁷ W/cm²) to probe plasma ablation fronts. CH foils were irradiated at 2-4 10¹³ W/cm² and probed early in time (∆t = 0.5 ns) for a 1 ns laser pulse and late in time (∆t = 5.0 ns) for a longer pulse length of 2 ns. X-ray refraction 2D maps were retrieved with the Talbot Numerical Tool (TNT) to obtain electron density information. The TNT code demonstrated versatility and robustness at different levels of noise. TXD diagnostic methods validation was performed by comparing experimental results with FLASH simulations, which also provided synthetic TXD Moire interferograms. The results obtained indicate that TXD can be a powerful tool to characterize HED systems with high accuracy and sensitivity.