Simulations of internal target defect clusters in direct-drive targets

Internal defects within inertial confinement fusion (ICF) targets are a significant source of hydrodynamic instability, capable of degrading implosion performance. In targets used on OMEGA, such defects—originating from permeation filling, cooling cycles, or material inhomogeneities—can number in the thousands and span a wide range of sizes and morphologies. These embedded imperfections act as seeds for instability growth during shock transit and shell acceleration, potentially compromising shell integrity and symmetry. Simulating the collective impact of internal defects presents a major challenge due to the need for high spatial resolution and accurate physics models to capture their hydrodynamic evolution. To address this, we employ the multi-physics code Cygnus to conduct 3D simulations of targets containing distributions of internal defects. We analyze the resulting wave dynamics and the role of defects in seeding Rayleigh-Taylor instabilities. This material is based upon work supported by the Department of Energy [National Nuclear Security Administration] University of Rochester "National Inertial Confinement Fusion Program" under Award Number(s) DE-NA0004144.