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.

该奖项支持对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的物理学研究。 关于黑洞和吸积盘的新观测发现越来越多地表明，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。天体物理旋转系统的谜团之一是物质从天体物理圆盘吸积到中心天体（例如黑洞）的速度。据观察，这些系统中的角动量重新分布速度太快，无法用已知的物理机制来解释。解决办法可能在于旋转等离子体和磁场之间通过所谓的磁旋转不稳定性（MRI）相互作用。这种不稳定性导致连接旋转等离子体元件的磁场线的拉伸和折叠，并有助于增强湍流角动量传输。 该项目将通过三维计算机模拟探索 MRI 机制和相关的磁化等离子体不稳定性，这对于增进对天体物理和实验室等离子体的理解具有潜在意义，包括用于聚变能开发的新颖等离子体约束概念。该项目将研究磁化等离子体的关键物理效应旋转磁化等离子体中的全局空间和磁曲率以前没有被考虑到。 特别是，本研究的主题将是差分旋转系统中三维非轴对称扰动的发生和维持，其中指数增长的轴对称 MRI 模式可能是部分驱动因素。要解决的问题是在具有空间曲率的域中具有真实频率的全局非轴对称模式是否能够持续存在。 最近发现了不同的全局模式，即由于全局差分旋转和磁曲率而引起的阿尔文连续介质驱动模式。 这些是所谓的磁曲率不稳定模式。该项目将利用流动驱动介质中的全局模拟和分析计算来研究（1）磁流体动力学（MHD）和霍尔 MHD 体系中磁曲率全局模式的开始； (2) 这些全球模式对动量传输、重新连接和发电机的影响。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。