HYBRID-E is an inertial confinement fusion implosion design that increases energy coupled to the hot spot by increasing the capsule scale in cylindrical hohlraums while operating within the current experimental limits of the National Ignition Facility. HYBRID-E reduces the hohlraum scale at a fixed capsule size compared to previous HYBRID designs, thereby increasing the hohlraum efficiency and energy coupled to the capsule, and uses the cross-beam energy transfer (CBET) to control the implosion symmetry by operating the inner (23° and 30°) and outer (44° and 50°) laser beams at different wavelengths ($\Delta \lambda >$ 0). Small case to capsule ratio designs can suffer from insufficient drive at the waist of the hohlraum. We show that only a small amount of wavelength separation between the inner and outer beams ($\Delta \lambda$ 1–2 Å) is required to control the symmetry in low-gas-filled hohlraums (0.3 mg/cm³ He) with enough drive at the waist of the hohlraum to symmetrically drive capsules 1180 μm in outer radius. This campaign is the first to use the CBET to control the symmetry in 0.3 mg/cm³ He-filled hohlraums, the lowest gas fill density yet fielded with $\Delta \lambda >$ 0. We find a stronger sensitivity of hot spot P2 in μm per Angstrom (40–50 μm/Å wavelength separation) than observed in high-gas-filled hohlraums and previous longer pulse designs that used a hohlraum gas fill density of 0.6 mg/cm³. There is currently no indication of transfer roll-off with increasing $\Delta \lambda$, indicating that even longer pulses or larger capsules could be driven using the CBET in cylindrical hohlraums. We show that the radiation flux symmetry is well controlled during the foot of the pulse, and that the entire implosion can be tuned symmetrically in the presence of the CBET in this system, with low levels of laser backscatter out of the hohlraum and low levels of hot electron production from intense laser–plasma interactions. Radiation hydrodynamic simulations can accurately represent the early shock symmetry and be used as a design tool, but cannot predict the late-time radiation flux symmetry during the peak of the pulse, and semi-empirical models are used to design the experiments. Deuterium–tritium (DT)-layered tests of 1100 μm inner radius implosions showed performance close to expectations from simulations at velocities up to ∼360 km/s, and record yields at this velocity, when increasing the DT fuel layer thickness to mitigate hydrodynamic mixing of the ablator into the hot spot as a result of defects in the ablator. However, when the implosion velocity was increased, mixing due to these defects impacted performance. The ratio of measured to simulated yield for these experiments was directly correlated with the level of observed mixing. These simulations suggest that reducing the mixing, e.g., by improving the capsule defects, could result in higher performance. In addition, future experiments are planned to reduce the coast time at this scale, delay between the peak compression and the end of the laser, to increase the hot spot convergence and pressure. To reduce the coast time by several hundred ps compared to the 1100 μm inner radius implosions, HYBRID-E has also fielded 1050 μm inner radius capsules, which resulted in higher hot spot pressure and a fusion energy yield of ∼170 kJ.

中文翻译：

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在 HYBRID-E 中通过 NIF 上的大 HDC 内爆实现创纪录的热点能量

HYBRID-E 是一种惯性约束聚变内爆设计，它通过增加圆柱形空腔中的胶囊规模来增加耦合到热点的能量，同时在国家点火设施的当前实验限制内运行。与之前的 HYBRID 设计相比，HYBRID-E 在固定胶囊尺寸下减小了空腔规模，从而提高了空腔效率和耦合到胶囊的能量，并使用横梁能量转移 (CBET) 来控制内爆对称性，通过操作内部（23° 和 30°）和外部（44° 和 50°）不同波长的激光束（$\Delta \lambda >$ 0）。小外壳与胶囊比的设计可能会导致黑腔腰部驱动不足。我们表明，内光束和外光束之间只有少量的波长分离（$\Delta \lambda$ 需要 1–2 Å) 来控制低充气空腔 (0.3 mg/cm ³ He) 的对称性，在空腔腰部有足够的驱动力以对称驱动外半径1180 μm 的胶囊 。该活动是第一个使用 CBET 控制 0.3 mg/cm ³ He 填充空腔的对称性，这是迄今为止最低的气体填充密度$\Delta \lambda >$ 0. 我们发现热点 P2 的灵敏度更高，单位为μ m/埃（40-50 μ m/Å 波长间隔）比在高填充气体的空腔和以前使用 0.6 的空腔气体填充密度的更长脉冲设计中观察到的更高毫克/厘米³。目前没有迹象表明转移滚降随着增加$\Delta \lambda$，表明在圆柱形空腔中使用 CBET 可以驱动更长的脉冲或更大的胶囊。我们表明，在脉冲底部期间，辐射通量对称性得到了很好的控制，并且在该系统中存在 CBET 的情况下，整个内爆可以对称地调谐，从空腔向外散射的激光水平较低，而从强烈的激光-等离子体相互作用中产生热电子。辐射流体动力学模拟可以准确地表示早期激波的对称性，可作为设计工具，但不能预测脉冲峰值期间的后期辐射通量对称性，需要使用半经验模型来设计实验。1100 μ 的氘-氚 (DT) 分层测试 m 内半径内爆的性能接近于模拟的预期，速度高达 ~360 公里/秒，并在该速度下记录产量，当增加 DT 燃料层厚度以减轻消融器进入热点的流体动力混合时消融器的缺陷。然而，当内爆速度增加时，由于这些缺陷导致的混合会影响性能。这些实验的测量产量与模拟产量之比与观察到的混合水平直接相关。这些模拟表明，减少混合，例如通过改善胶囊缺陷，可能会导致更高的性能。此外，未来的实验计划在这个尺度上减少滑行时间、峰值压缩和激光结束之间的延迟，以增加热点收敛和压力。 μ m 内半径内爆，HYBRID-E 还部署了 1050  μ m 内半径胶囊，这导致更高的热点压力和约 170 kJ 的聚变能量产额。