Shock-driven hydrodynamic instabilities in a plasma usually lead to interfacial mixing and the generation of electromagnetic fields, which are nonequilibrium processes coupling kinetics with meso- and macroscopic dynamics. The understanding and modeling of these physical processes are very challenging tasks for single-fluid hydrodynamic codes. This work presents a new framework that incorporates both kinetics and hydrodynamics to simulate shock waves and hydrodynamic instabilities in high-density plasmas. In this hybrid code, ions are modeled using the standard particle-in-cell method together with a Monte Carlo description of collisions while electrons are modeled as a massless fluid, with the electron heat flux and fluid–particle energy exchange being considered in the electron pressure equation. In high-density plasmas, Maxwell’s equations are solved using Ohm’s law instead of Ampère’s law. This hybrid algorithm retains ion kinetic effects and their consequences for plasma interpenetration, shock wave propagation, and hydrodynamic instability. Furthermore, we investigate the shock-induced (or gravity-induced) turbulent mixing between a light and a heavy plasma, where hydrodynamic instabilities are initiated by a shock wave (or gravity). This study reveals that self-generated electromagnetic fields play a role in the formation of baroclinic vorticity along the interface and in late-time mixing of the plasmas. Our results confirm the ability of the proposed method to describe shock-driven hydrodynamic instabilities in a plasma, in particular, nonequilibrium processes that involve mixing and electromagnetic fields at the interface.

中文翻译：

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等离子体中冲击驱动的水动力不稳定性的混合流体-颗粒建模

等离子体中由冲击驱动的流体动力学不稳定性通常会导致界面混合和电磁场的产生，这是将动力学与中观和宏观动力学耦合的非平衡过程。对于单流体流体力学代码，对这些物理过程的理解和建模是非常具有挑战性的任务。这项工作提出了一个新的框架，其中结合了动力学和流体动力学，以模拟高密度等离子体中的冲击波和流体动力学的不稳定性。在此混合代码中，使用标准的“单元内粒子”方法对离子进行建模，并对碰撞进行蒙特卡洛描述，而将电子建模为无质量流体，并在电子中考虑了电子的热通量和流体-粒子的能量交换压力方程。在高密度等离子体中 麦克斯韦方程组是使用欧姆定律而不是安培定律求解的。这种混合算法保留了离子动力学效应及其对等离子体互穿，冲击波传播和流体动力学不稳定性的影响。此外，我们研究了轻等离子体和重等离子体之间的激振（或引力）湍流混合，其中流体动力的不稳定性是由激波（或引力）引发的。这项研究表明，自生电磁场在沿界面的斜压涡旋形成和等离子体的后期混合中起着作用。我们的结果证实了所提出的方法能够描述等离子体中冲击驱动的流体动力不稳定性的能力，尤其是涉及界面处混合和电磁场的非平衡过程。