-lined hohlraums at OMEGA

In indirect-drive inertial confinement fusion experiments, laser interactions with the inner hohlraum wall generate a high-Z blowoff plasma, which impedes the outer-beams propagation and leads to an asymmetric capsule implosion. Effective blowoff mitigation has included the use of non-cylindrical hohlraum geometries or a tamping gas-fill, but the drawbacks of these configurations motivate an alternative approach using inner-wall, high-Z foam linings. Experiments at Lawrence Livermore National Laboratory have shown that simulations overpredict the symmetry control improvements from foam-liners. This could be in part due to the omission of self-generated electric and magnetic fields in both simulations and experimental diagnosing. Through experiments at OMEGA and complementary simulations using the radiation hydrodynamics code HYDRA, the impact of self-generated fields on Ta₂O₅- and SiO₂- lined hohlraum plasma dynamics are being studied. Here, we present updates on the analysis and interpretation of proton radiographs, x-ray self-emission images, and Thomson scattering data of these under-dense foam-lined targets and compare with synthetic diagnostic data from 2D and 3D HYDRA simulations.

The work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, and is additionally supported in part by the U.S. DOE, NLUF, LLNL, and LRGF.