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研究。关于黑洞和吸积盘的新的观测发现越来越多地揭示出，我们的宇宙沉浸在磁化的等离子体中，这是一种电离和导电的气体。天体物理旋转系统中的谜团之一是物质从天体物理圆盘吸积到中心天体(如黑洞)的速度。观察到这些系统中的角动量重新分布太快，无法用已知的物理机制来解释。分辨率可能来自旋转等离子体与磁场之间的相互作用，即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力线的伸展和折叠，并有助于增强湍流角动量输运。这个项目将通过三维计算机模拟来探索核磁共振机制和相关的磁化等离子体不稳定性，这可能有助于更好地理解天体物理和实验室等离子体，包括用于聚变能量开发的新的等离子体约束概念。这个项目将研究旋转磁化等离子体中以前没有考虑到的全球空间和磁曲率的关键物理效应。具体地说，这项研究的主题将是差动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。需要解决的问题是，在具有空间曲率的区域中，具有实频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，它们是由于全局微分旋转和磁曲率而由Alfven连续谱驱动的模。这就是所谓的磁曲率不稳定模。使用流动驱动介质中的全球模拟和分析计算，该项目将调查(1)磁流体动力学(MHD)和霍尔MHD体系中磁曲率全球模式的开始；以及(2)这些全球模式对动量传输、重联和发电机的影响。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.