标题： 间接驱动惯性约束聚变中等离子体混合过程的研究 显示英文标题

标题： Investigation of Plasma Mixing Processes in the Context of Indirect Drive Inertial Confinement Fusion

摘要： 在惯性约束聚变（ICF）中，腔体中等离子体混合的动力学对激光-等离子体不稳定性（LPI）和压缩性能有关键影响。 本研究利用一维粒子-网格（PIC）模拟，研究了腔体烧蚀金等离子体与填充的C$_5$H$_{12}$等离子体的混合。 我们发现，离子-离子碰撞减缓了离子的扩散，使得金离子呈现亚扩散特性，而碳和氢离子则保持超扩散特性。 由于氢离子的碰撞率较低，它们比碳离子更快地扩散到金区域，导致界面处碳和氢离子出现明显的分离。 尽管在存在碰撞的情况下，等离子体界面仍会产生静电激波，但其电场强度和传播速度显著降低。 为了系统地探索腔体环境中的等离子体混合，我们评估了入射激光辐照、等离子体流动和非均匀密度分布对离子混合的单独影响。 我们发现，与扩散驱动过程相比，激光辐照和等离子体流动对离子混合的影响较小，而非均匀密度分布限制了从低密度区域到高密度区域的扩散。 通过将来自辐射流体动力学模型的现实腔体等离子体条件引入PIC模拟，我们证明碳和氢离子的扩散继续主导离子混合。 我们推导出简单的现象学拟合公式，以描述腔体条件下混合宽度的演变。 进一步的理论计算表明，氢和碳渗透到金等离子体中会抑制混合层内的受激布里渊散射（SBS）。 这一发现强调了将离子混合效应整合到LPI代码中的重要性，以更准确地模拟ICF腔体动力学。 显示英文摘要

摘要： In inertial confinement fusion (ICF), the dynamics of plasma mixing in hohlraums critically influence laser-plasma instabilities (LPI) and implosion performance. This study investigates the mixing of hohlraum ablated Au plasmas and filling C$_5$H$_{12}$ plasmas using one-dimensional particle-in-cell (PIC) simulations. We find that ion-ion collisions slow the diffusion of ions, rendering Au ions sub-diffusive, while C and H ions remain super-diffusive. Due to their lower collisionality, H ions diffuse faster into Au regions than C ions, leading to a distinct separation between C and H ions at the interface. Although an electrostatic shock is still generated at the plasma interface in the presence of collisions, its electric field strength and propagation speed are notably reduced. To systematically explore plasma mixing in hohlraum environments, we evaluate the individual effects of incident laser irradiation, plasma flow, and inhomogeneous density profiles on ion mixing. We find that laser irradiation and plasma flow have a minor impact on ion mixing compared to diffusion-driven processes, while the inhomogeneous density profile restricts diffusion from low-density to high-density regions. By incorporating realistic hohlraum plasma conditions derived from radiation hydrodynamic models into the PIC simulations, we demonstrate that the diffusion of C and H ions continues to dominate ion mixing. Simple phenomenological fits are derived to describe the evolution of the mixing width in a hohlraum condition. Further theoretical calculations indicate that the penetration of H and C into Au plasmas suppresses stimulated Brillouin scattering (SBS) within the mixing layer. This finding underscores the importance of integrating ion mixing effects into LPI codes for more accurate modeling of ICF hohlraum dynamics.