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进行了数千年，并被记录在案。这些观测激发了实验室实验复制天体物理现象的动机。同时，已经发展了旨在再现观测和实验结果的计算建模能力。该项目的目标是最终解决在与天体物理相关的区域中数值模拟和真实世界测量之间存在的差异。作为这项研究的一部分，将开发的新型数值工具将在基础科学问题、国家安全、能源和航天器工程中具有广泛的适用性。高度整合的教育计划将通过在线用户体验，让从K-12到研究生院的学生参与科学、技术、工程和数学(STEM)的研究和职业机会。教育和外展活动还将努力通过与弗吉尼亚理工大学加强工程多样性中心和弗吉尼亚州为少数族裔服务的社区大学的合作，鼓励妇女和代表性不足的群体从事STEM职业。在高能量密度制度下，数值模拟几十年来一直无法再现实验和观察的结果。在高能量密度天体物理和实验室等离子体的数值模拟中，最先进的是使用流体模型，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。缺失的物理可能会显著影响等离子体传输，而等离子体传输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布居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包括特殊的可调参数。第一原理高维动力学计算是必要的，但直到最近由于计算限制一直是不切实际的，它可以最终解决实验和流体动力学代码之间的差异是否可以用动力学物理解释的问题。本研究将包括第一原理动力学计算，使用一种新的、连续介质动力学、高精度和计算效率高的算法来研究高能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时的等离子体动力学和输运。这个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，可以显著提高我们对等离子体传输的理解，这将在许多研究领域产生影响。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.