Nonlocal Magneto-Curvature Instabilities and their Associated Nonlinear Transport in Astrophysical Disks

天体物理盘中的非局域磁曲率不稳定性及其相关的非线性输运

• 批准号: 2308839
• 负责人: Fatima Ebrahimi
• 金额: $ 45.8万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-15 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2308839&HistoricalAwards=false
• 关键词: Nonlocal; Magneto; Curvature; Instabilities; their

This award supports a study of the physics of rotating magnetized plasmas observed in many astrophysical systems and laboratory experiments. New observational discoveries about black holes and accretion disks increasingly uncover that our universe is immersed in magnetized plasma, an ionized and electrically conducting gas. One of the mysteries in the astrophysical rotating systems has been the rate at which matter accretes from astrophysical disks onto a central body, such as a black hole. The angular momentum redistribution in these systems is observed to be far too rapid to be explained by known physical mechanisms. The resolution may be in the interaction between the rotating plasma and the magnetic field via the so-called Magneto-Rotational Instability (MRI). This instability leads to stretching and folding of magnetic field lines that connect the rotating plasma elements and contribute to the enhancement of turbulent angular momentum transport. This project will explore the MRI mechanism and associated magnetized plasma instabilities via three-dimensional computer simulations, with potential implications for improved understanding of both astrophysical and laboratory plasmas, including novel plasma confinement concepts for fusion energy development.This project will investigate key physical effects of global space and magnetic curvature in a rotating magnetized plasma which have not previously been taken into account. In particular, the subject of this study will be the onset and sustainment of three-dimensional non-axisymmetric perturbations in differentially rotating systems where exponentially growing axisymmetric MRI modes could be a partial driver. The question to be addressed is whether in a domain with spatial curvature global non-axisymmetric modes with real frequencies can persist. Distinct global modes, which are Alfven-continuum-driven modes due to global differential rotation and magnetic curvature, have recently been discovered. These are so-called magneto-curvature instability modes. Using both global simulations in a flow-driven media and analytical calculations, this project will investigate (1) the onset of the magneto-curvature global modes in magnetohydrodynamic (MHD) and Hall MHD regimes; and (2) the effect of these global modes on momentum transport, reconnection, and dynamo.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.

该奖项支持在许多天体物理系统和实验室实验中观察到的旋转磁化等离子体物理学研究。 关于黑洞和吸积盘的新观测发现越来越多地揭示，我们的宇宙沉浸在磁化等离子体中，这是一种电离的导电气体。天体物理旋转系统中的一个谜团是物质从天体物理盘吸积到中心体（如黑洞）的速率。在这些系统中的角动量重新分布被观察到是太快，无法用已知的物理机制来解释。分辨率可能是旋转等离子体和磁场之间的相互作用，通过所谓的磁旋转不稳定性（MRI）。这种不稳定性导致连接旋转等离子体元素的磁场线的拉伸和折叠，并有助于增强湍流角动量输运。 该项目将通过三维计算机模拟探索磁共振成像机制和相关的磁化等离子体不稳定性，对提高对天体物理和实验室等离子体的理解具有潜在意义，包括用于聚变能源开发的新等离子体约束概念，该项目将研究全球空间和旋转磁化等离子体中磁曲率的关键物理效应，这些效应以前没有考虑在内。 特别是，本研究的主题将是发病和维持的三维非轴对称扰动差分旋转系统中，指数增长的轴对称MRI模式可能是一个部分的驱动程序。要解决的问题是是否在一个域的空间曲率全球非轴对称模式与真实的频率可以持续。 最近，人们发现了由整体微分转动和磁曲率引起的阿尔芬连续模。 这就是所谓的磁曲率不稳定模式。本计画将利用流体驱动介质中的整体模拟与解析计算，研究（1）磁流体力学（MHD）与霍尔磁流体力学（Hall MHD）领域中磁曲率整体模的起始;以及（2）这些全球模态对动量输送，重联，该奖项反映了NSF的法定使命，并通过使用基金会的智力价值进行评估，被认为值得支持和更广泛的影响审查标准。