Casey D T, MacGowan B J, Sater J D, Zylstra A B, Landen O L, Milovich J, Hurricane O A, Kritcher A L, Hohenberger M, Baker K, Le Pape S, Döppner T, Weber C, Huang H, Kong C, Biener J, Young C V, Haan S, Nora R C, Ross S, Robey H, Stadermann M, Nikroo A, Callahan D A, Bionta R M, Hahn K D, Moore A S, Schlossberg D, Bruhn M, Sequoia K, Rice N, Farrell M, Wild C
Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
General Atomics, San Diego, California 92186, USA.
Phys Rev Lett. 2021 Jan 15;126(2):025002. doi: 10.1103/PhysRevLett.126.025002.
Inertial confinement fusion implosions must achieve high in-flight shell velocity, sufficient energy coupling between the hot spot and imploding shell, and high areal density (ρR=∫ρdr) at stagnation. Asymmetries in ρR degrade the coupling of shell kinetic energy to the hot spot and reduce the confinement of that energy. We present the first evidence that nonuniformity in the ablator shell thickness (∼0.5% of the total thickness) in high-density carbon experiments is a significant cause for observed 3D ρR asymmetries at the National Ignition Facility. These shell-thickness nonuniformities have significantly impacted some recent experiments leading to ρR asymmetries on the order of ∼25% of the average ρR and hot spot velocities of ∼100 km/s. This work reveals the origin of a significant implosion performance degradation in ignition experiments and places stringent new requirements on capsule thickness metrology and symmetry.
惯性约束聚变内爆必须实现高飞行中壳层速度、热点与内爆壳层之间足够的能量耦合以及停滞时的高面密度（ρR = ∫ρdr）。ρR的不对称性会降低壳层动能与热点的耦合，并减少该能量的约束。我们首次证明，在国家点火装置的高密度碳实验中，烧蚀层壳层厚度的不均匀性（约为总厚度的0.5%）是观察到的三维ρR不对称性的一个重要原因。这些壳层厚度的不均匀性对一些近期实验产生了重大影响，导致ρR不对称性达到平均ρR的约25%左右，热点速度约为100 km/s。这项工作揭示了点火实验中内爆性能显著下降的根源，并对胶囊厚度计量和对称性提出了严格的新要求。
