Laboratory Studies of the Magneto-Rotational Instability in a Plasma

等离子体磁旋转不稳定性的实验室研究

• 批准号: 1211937
• 负责人: Cary Forest
• 金额: $ 25.5万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-15 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1211937&HistoricalAwards=false
• 关键词: Laboratory; Studies; Magneto; Rotational; Instability

AST-1211937ForestThis project begins the first ever study of the magnetorotational instability (MRI) in a plasma experiment. The MRI is potentially very important in plasma astrophysics, but it has only been studied theoretically, numerically, and in a limited fashion in liquid metal experiments as a substitute for plasma. The MRI studies planned here will be carried out in the Plasma Couette Experiment (PCX), a novel experiment that both confines and stirs a hot plasma, with the parameters necessary for observing the MRI. Accretion is a fundamental process in astrophysics whereby interstellar gas and plasma collapse into rotating disks around a central, point-like accreting object. There must be a mechanism that causes disk matter to lose orbital energy, transport angular momentum outward, and fall into the central object. The MRI is a leading candidate for this mechanism, based on theory and numerical simulations. This study builds on the recent excitement caused by liquid metal experiments to investigate the onset conditions for the MRI. A plasma experiment has several advantages over a liquid metal experiment, including that most naturally occurring accretion disks are made up of plasmas, that it allows larger and more realistic magnetic Reynolds numbers, and that it permits independent adjustment of the viscosity and the conductivity. The PCX has recently demonstrated high speed, MRI-stable Couette flows, and this work will 1) search for signs of the MHD instability, 2) compare results with numerical simulations; 3) measure the effective momentum transport of the saturated instability; and 4) identify physical effects which are plasma specific and beyond the standard magnetohydrodynamics model.The PCX experiments will have broad impact on all flow-driven MHD problems and will continue a strong connection between laboratory plasma physicists and astrophysics facilitated by the NSF Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas. This award supports a single graduate student to carry out the proposed experiments, with partial support for technical staff and student supervision.

AST-1211937森林这个项目开始了有史以来第一次在等离子体实验中研究磁旋转不稳定性（MRI）。 磁共振成像在等离子体天体物理学中具有潜在的重要性，但它仅在理论上，数值上进行了研究，并且在液态金属实验中以有限的方式作为等离子体的替代品。 这里计划的MRI研究将在等离子体库埃特实验（PCX）中进行，这是一种新颖的实验，既限制又搅拌热等离子体，具有观察MRI所需的参数。 吸积是天体物理学中的一个基本过程，星际气体和等离子体坍缩成围绕中心点状吸积物体旋转的圆盘。 必须有一种机制，使盘物质失去轨道能量，向外输送角动量，并落入中心物体。 基于理论和数值模拟，MRI是这种机制的主要候选者。 这项研究建立在最近的兴奋引起的液态金属实验，以调查的MRI的发病条件。 等离子体实验比液态金属实验有几个优点，包括大多数自然发生的吸积盘是由等离子体组成的，它允许更大和更现实的磁雷诺数，并且它允许独立调整粘度和电导率。 PCX最近演示了高速、MRI稳定的Couette流，本工作将1）寻找MHD不稳定性的迹象，2）将结果与数值模拟进行比较，3）测量饱和不稳定性的有效动量输运，4）测量饱和不稳定性的有效动量输运。4）识别等离子体特有的、超出标准磁流体力学模型的物理效应。PCX实验将对所有流动产生广泛的影响，驱动的MHD问题，并将继续实验室等离子体物理学家和天体物理学之间的强有力的联系，促进了NSF中心的磁自组织在实验室和天体物理等离子体。 该奖项支持一名研究生进行拟议的实验，部分支持技术人员和学生监督。