Effective atomic number diagnostics for plasma instabilities using Talbot-Lau X-ray Moire Deflectometry*

The Talbot-Lau X-ray Moire Deflectometer (TXD) is a single image phase-retrieval plasma diagnostic. TXD can simultaneously provide x-ray attenuation, refraction, elemental

composition, and scatter images with angular sensitivity and spatial resolution that are suitable for characterizing High Energy Density (HED) plasma. In HED systems such as in Inertial Confinement Fusion, a diagnostic for material composition is of high interest because material mixing in the capsule results in hydrodynamic instabilities which are detrimental to ignition. An experimental investigation focused on developing a retrieval method for effective atomic number (Z_eff) was carried out. Static complex objects composed of different materials were probed through TXD. The Moire deflectometry images obtained were analyzed and electron density maps were extracted from refraction measurements. Effective atomic numbers were then calculated from refraction and absorption data retrieved through TXD methods, closely matching the expected values. Furthermore, FLASH simulations will be performed to aid in the design of a future experiment where foils with seeded instabilities will be driven by a high-intensity laser and characterized experimentally using the newly benchmarked Z_eff retrieval TXD technique. To validate the TXD Z_eff retrieval method, the experimental and FLASH simulation Z_eff data will be compared. Additionally, the FLASH simulation data will be post-processed with the Talbot-Interferometry Analyzer (TIA), a forward-modeling software, to obtain synthetic TXD Moire data that can be compared to experimental images from these future hydrodynamic studies, thus helping with code benchmarking.