Detailed high-resolution three-dimensional simulations of OMEGA separated reactants inertial confinement fusion experiments
Detailed high-resolution three-dimensional simulations of OMEGA separated reactants inertial confinement fusion experiments
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DOI：
10.1063/1.4959117
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发表时间：
2016-07-01
影响因子：
2.2
通讯作者：
Wilhelmy, Jerry B.
中科院分区：
文献类型：
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作者：
Haines, Brian M.;Grim, Gary P.;Wilhelmy, Jerry B.
我们展示了高分辨率三维 (3D) 模拟与 OMEGA 激光设施上分离反应物惯性约束聚变胶囊内爆数据的比较结果。每个胶囊被称为“CD Mixcap”，充满氚并具有聚苯乙烯（CH）壳和氘化聚苯乙烯（CD）层，其埋藏深度各不相同。在这些内爆中，氘和氚离子之间的聚变反应只有在气体填充和壳材料之间存在原子混合物的情况下才会发生。该模拟为所有已知的实验不对称性提供了准确的模型，并且不采用任何可调整的参数来提高与实验数据的一致性。使用 RAGE 辐射流体动力学代码使用隐式大涡模拟 (ILES) 流体动力学策略进行模拟。对于氘化壳层的所有埋藏深度，我们获得了与实验数据良好的一致性，包括用于诊断混合的 DT/TT 中子产率比。此外，模拟表明与采用等离子体扩散和粘度显式模型的收敛模拟具有良好的一致性，这表明 ILES 中使用的隐式子网格模型足以对这些实验中的这些过程进行建模。在我们的模拟中，混合是由短波长不对称性驱动的，而长波长特征则负责形成将混合材料输送到热点中心的流动。即使对于具有与氚燃料相邻的 CD 层的胶囊来说，通过该过程运输的混合材料也是大部分混合 (DT) 产量的原因。与我们之前的结果一致，混合在 TT 中子产额下降中没有发挥显着作用；相反，这主要是由于长波长不对称性引发的湍流不稳定性的发展，导致燃料从内爆中心发生位移。通过这些过程，长波长不对称性对 TT 产额的降低程度大于 DT 产额，从而使 DT/TT 中子产额比与实验相符。最后，我们对 2D 和 3D 模拟中的流动进行了详细比较。由 AIP 出版社出版。
We present results from the comparison of high-resolution three-dimensional (3D) simulations with data from the implosions of inertial confinement fusion capsules with separated reactants performed on the OMEGA laser facility. Each capsule, referred to as a "CD Mixcap," is filled with tritium and has a polystyrene (CH) shell with a deuterated polystyrene (CD) layer whose burial depth is varied. In these implosions, fusion reactions between deuterium and tritium ions can occur only in the presence of atomic mix between the gas fill and shell material. The simulations feature accurate models for all known experimental asymmetries and do not employ any adjustable parameters to improve agreement with experimental data. Simulations are performed with the RAGE radiation-hydrodynamics code using an Implicit Large Eddy Simulation (ILES) strategy for the hydrodynamics. We obtain good agreement with the experimental data, including the DT/TT neutron yield ratios used to diagnose mix, for all burial depths of the deuterated shell layer. Additionally, simulations demonstrate good agreement with converged simulations employing explicit models for plasma diffusion and viscosity, suggesting that the implicit sub-grid model used in ILES is sufficient to model these processes in these experiments. In our simulations, mixing is driven by short-wavelength asymmetries and longer-wavelength features are responsible for developing flows that transport mixed material towards the center of the hot spot. Mix material transported by this process is responsible for most of the mix (DT) yield even for the capsule with a CD layer adjacent to the tritium fuel. Consistent with our previous results, mix does not play a significant role in TT neutron yield degradation; instead, this is dominated by the displacement of fuel from the center of the implosion due to the development of turbulent instabilities seeded by long-wavelength asymmetries. Through these processes, the long-wavelength asymmetries degrade TT yield more than the DT yield and thus bring DT/TT neutron yield ratios into agreement with experiment. Finally, we present a detailed comparison of the flows in 2D and 3D simulations. Published by AIP Publishing.