Investigation of plasma flow and interface dynaics in Ta₂O₅- and SiO₂-lined hohlraums at OMEGA

In indirect drive inertial confinement fusion (ICF) experiments, laser interactions with the hohlraum wall generate dense, high-Z blowoff, which can contribute to an asymmetric capsule drive by shifting laser absorption areas and preventing beams from reaching the inner hohlraum wall. Effective means of mitigating this high-Z blowoff have included the use of a gas fill and/or non-cylindrical hohlraum geometries, but even these configurations have drawbacks. Within the last few years, another promising alternative for tamping wall blowoff has been demonstrated through simulations and experiments: using inner-wall, high-Z foam linings. Presented here are studies of Ta₂O₅- and SiO₂-lined hohlraums through experiments at OMEGA. Proton radiographs, self-emission x-ray images, and Thomson scattering spectra are used to reconstruct the self-generated electric and magnetic fields in hohlraums lined with ~200 um thick, ~30 mg/cc and ~5 mg/cc Ta₂O₅ and SiO₂ aerogel foams, respectively. In parallel, 2D and 3D HYDRA simulations were performed. These measurements and simulations help shed light on the associated plasma flow and interface dynamics during the hohlraum drive and contribute to the physics understanding and optimization of high-Z foam linings in hohlraums.