Polar-direct-drive experiments on the National Ignition Facility
Polar-direct-drive experiments on the National Ignition Facility
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DOI：
10.1063/1.4920958
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发表时间：
2015-05-01
影响因子：
2.2
通讯作者：
Zuegel, J. D.
中科院分区：
文献类型：
--
作者：
Hohenberger, M.;Radha, P. B.;Zuegel, J. D.
为了支持国家点火装置（NIF）的直接驱动惯性约束聚变实验[G. H.米勒，E. I. Moses和C. R. Wuest，Opt.Eng.43，2841（2004）]在其间接驱动光束配置中，极性直接驱动（PDD）概念[S. Skupsky等人，Phys. Plasmas 11，2763（2004）]。PDD几何结构中的点火需要直接驱动特定的光束平滑、相位板以及将NIF光束重新指向赤道以确保对称的目标照射。首次在NIF上进行了研究PDD内爆能量学和预热的实验。这些实验利用NIF在其当前的配置，包括光束的几何形状，相位板，和光束平滑。在室温下，2.2 mm直径的填充有D-2气体的塑料壳体内爆，总驱动能量范围为500至750 kJ，峰值功率为120至180 TW，初始靶半径处的峰值靶上辐照度为8 x 10（14）至1.2 x 10（15）W/cm（2）。从这些初步的实验结果，包括测量壳轨迹，内爆对称性，和水平的热电子预热塑料和硅烧蚀。实验模拟与2-D流体动力学代码DRACO，包括一个完整的3-D射线跟踪模型斜束，和模型的非局域电子输运和交叉束能量输运（CBET）。这些模拟表明，CBET影响壳的对称性并导致传递到壳上的能量损失，与实验数据一致。(c)2015 AIP Publishing LLC.
To support direct-drive inertial confinement fusion experiments at the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)] in its indirect-drive beam configuration, the polar-direct-drive (PDD) concept [S. Skupsky et al., Phys. Plasmas 11, 2763 (2004)] has been proposed. Ignition in PDD geometry requires direct-drive-specific beam smoothing, phase plates, and repointing the NIF beams toward the equator to ensure symmetric target irradiation. First experiments to study the energetics and preheat in PDD implosions at the NIF have been performed. These experiments utilize the NIF in its current configuration, including beam geometry, phase plates, and beam smoothing. Room-temperature, 2.2-mm-diam plastic shells filled with D-2 gas were imploded with total drive energies ranging from similar to 500 to 750 kJ with peak powers of 120 to 180 TW and peak on-target irradiances at the initial target radius from 8 x 10(14) to 1.2 x 10(15) W/cm(2). Results from these initial experiments are presented, including measurements of shell trajectory, implosion symmetry, and the level of hot-electron preheat in plastic and Si ablators. Experiments are simulated with the 2-D hydrodynamics code DRACO including a full 3-D ray-trace to model oblique beams, and models for nonlocal electron transport and cross-beam energy transport (CBET). These simulations indicate that CBET affects the shell symmetry and leads to a loss of energy imparted onto the shell, consistent with the experimental data. (c) 2015 AIP Publishing LLC.