Experiments and simulations have been conducted to investigate the efficacy of Ta₂O₅-lined Hohlraum walls at reducing stimulated Brillouin backscattering (SBS) as well as any subsequent effects on the Hohlraum dynamics and capsule implosions in indirect drive experiments at the National Ignition Facility. Using a 1.1 MJ 400 TW, 351 nm, shaped laser pulse, we measure a 5× reduction in SBS power in the peak of the pulse from the wall on the outer 50° cone beams. The SBS spectrum indicates a reduction in the high-Z spectral signature when using multispecies wall materials. Detailed hydrodynamic simulations were performed using different heat conduction models with flux limiters. Additional simulations were performed on the plasma maps using the 3D parallel paraxial code pF3D to compare backscatter powers between the pure Au and Ta₂O₅-lined Hohlraums. Further analysis, using hydrodynamically equivalent plasmas, shows that the SBS reduction is clearly a result of the added ion Landau damping caused by the oxygen ions and not from differences in plasma conditions. The experimental and simulation results also show an increase in the wall plasma expansion when using the Ta₂O₅ liner leading to a 70% more oblate implosion.

中文翻译：

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多物种Hohlraumwalls对受激布里渊散射、Hohlraum动力学和光束传播的影响

实验和模拟已进行了调查Ta的功效_2周ø _5周-lined黑腔的壁，以减少受激布里渊散射（SBS），以及在任何后续的影响黑腔国家点火设施间接驱动实验中的动力学和胶囊内爆。使用 1.1 MJ 400 TW、351 nm 整形激光脉冲，我们测量了来自外部 50° 锥形光束壁的脉冲峰值中 SBS 功率的 5 倍降低。SBS 光谱表明使用多物种壁材料时高 Z 光谱特征减少。使用具有通量限制器的不同热传导模型进行了详细的流体动力学模拟。附加模拟，等离子体上执行使用地图上的3D平行近轴代码pF3D比较后向散射的纯Au和钽之间的权力₂ ö ₅ -lined Hohlraums. 使用流体动力学等效等离子体的进一步分析表明，SBS 减少显然是由氧离子引起的附加离子朗道阻尼的结果，而不是等离子体条件的差异。实验和模拟结果还显示，当使用 Ta ₂ O ₅衬垫时，壁等离子体膨胀增加，导致扁圆内爆增加 70%。