CAREER: Continuum Kinetic Studies of Hydrodynamic and Magneto Hydrodynamic Instabilities

对恒星死亡时发生的超新星爆炸的观测已经记录了数千年。这样的观察激发了实验室实验来复制天体物理现象。同时，计算建模能力也得到了发展，目的是再现观测和实验的结果。该项目的目标是最终解决与天体物理学相关的数值模拟和现实世界测量之间存在的差异。作为本研究的一部分，将开发的新型数值工具将广泛适用于基础科学问题、国家安全、能源和航天器工程。这一高度整合的教育计划将通过在线用户体验，吸引从K-12到研究生院的学生参与科学、技术、工程和数学（STEM）领域的研究和就业机会。教育和推广活动还将通过与弗吉尼亚理工大学工程多样性增强中心和弗吉尼亚州少数族裔社区学院的合作，努力鼓励女性和代表性不足的群体追求STEM职业。在高能量密度区域，几十年来，数值模拟一直无法再现实验和观测的结果。高能量密度天体物理和实验室等离子体的最先进的数值模拟使用流体模型，特别是辐射流体动力学和辐射磁流体动力学模型。这些单流体模型的重大缺陷包括无法捕捉更先进的高保真多流体模型中包含的物理效应。缺失的物理会显著影响等离子体输运，等离子体输运可能具有显著的各向异性。此外，即使是最先进的流体模型也可能忽略非热粒子群对等离子体输运的影响。匹配实验数据的关键是在流体模拟中加入特别的可调参数。必要的，但直到最近由于计算限制而不切实际的是第一性原理高维动力学计算，它可以最终解决实验和流体力学代码之间的差异是否可以用动力学物理来解释。目前的研究将包括第一性原理动力学计算，使用一种新颖的、连续动力学的、高阶精度的、计算效率高的算法来研究高能量密度等离子体中存在流体动力学和磁流体动力学不稳定性的等离子体动力学和输运。该项目将解决高能量密度实验和模拟之间长期存在的差异，因此，可以显著推进我们对等离子体输运的理解，并在许多研究领域产生影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Observations of supernovae explosions that occur upon the death of a star have been made and documented for thousands of years. Such observations have motivated laboratory experiments to replicate astrophysical phenomena. Concurrently, there has been development of computational modeling capabilities aimed at reproducing results from both observations and experiments. The goal of this project is to conclusively address the existing discrepancies between numerical simulations and real world measurements in regimes of relevance to astrophysics. Novel numerical tools to be developed as part of this study will have broad applicability to fundamental science questions, national security, energy, and spacecraft engineering. The strongly integrated education plan will engage students from K-12 through graduate school in research and career opportunities in science, technology, engineering, and mathematics (STEM) through an online user experience. The education and outreach activities will also strive to encourage women and under-represented groups to pursue STEM careers through collaborations with the Center for the Enhancement of Engineering Diversity at Virginia Tech and minority-serving community colleges in Virginia.In high-energy-density regimes, numerical simulations have been unable to reproduce the results from experiments and observations for decades. The state-of-the-art in numerical simulations of high-energy-density astrophysical and laboratory plasmas uses fluid models, specifically radiation-hydrodynamic and radiation-magnetohydrodynamic models. Significant deficiencies in these single-fluid models include the inability to capture physics effects included in more advanced high-fidelity multi-fluid models. The missing physics can notably impact plasma transport, which may have significant anisotropies. Furthermore, the effect of non-thermal particle population on plasma transport may be missed even by most advanced fluid models. The key to matching experimental data has been to include ad hoc tunable parameters in fluid simulations. What is necessary, but has been impractical until recently due to computational limitations, are first-principles high-dimensional kinetic calculations that can address conclusively whether the discrepancies between experiments and hydrodynamic codes could be explained using kinetic physics. The present study will include first-principles kinetic calculations using a novel, continuum-kinetic, high-order accurate, and computationally efficient algorithm to study plasma dynamics and transport in the presence of hydrodynamic and magnetohydrodynamic instabilities in high-energy-density plasmas. This project will address long-standing discrepancies between high-energy-density experiments and simulations and, as a result, could significantly advance our understanding of plasma transport with implications in a number of research areas.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.