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

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揭示了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盘吸积到中心物体（如黑洞）的速度。在这些系统中，角动量的重分布速度非常快，无法用已知的物理机制来解释。通过所谓的磁旋转不稳定性（MRI），可能在旋转等离子体和磁场之间的相互作用中得到解决。这种不稳定性导致连接旋转等离子体元素的磁力线的拉伸和折叠，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MRI机制和相关磁化等离子体的不稳定性，这对提高对天体物理和实验室等离子体的理解有潜在的影响，包括用于聚变能发展的新型等离子体约束概念。该项目将研究旋转磁化等离子体中全球空间和磁曲率的关键物理效应，这是以前没有考虑到的。特别是，本研究的主题将是微分旋转系统中三维非轴对称扰动的开始和维持，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内，具有实频率的全局非轴对称模态能否持续存在。最近发现了不同的全球模态，即由于全球微分旋转和磁曲率导致的阿尔文连续驱动模态。这些就是所谓的磁曲率不稳定模式。利用流动驱动介质的全局模拟和分析计算，该项目将研究(1)磁流体动力学（MHD）和霍尔MHD体系中磁曲率全局模态的开始；(2)这些全局模态对动量输运、重连和动力的影响。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。

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.