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 Forestthis该项目在等离子体实验中开始了有史以来对磁化不稳定性（MRI）的首次研究。 在血浆天体物理学中，MRI可能非常重要，但仅在理论上，数值和有限的液体金属实验中进行了研究，以替代等离子体。 这里计划的MRI研究将在等离子体COUETTE实验（PCX）中进行，该实验既限制并激发热等离子体，均与观察MRI所需的参数。 积聚是天体物理学的一个基本过程，在该过程中，星际气体和等离子体崩溃成围绕中央，点状积聚物体的旋转磁盘。 必须有一种机制，使磁盘物质失去轨道能量，向外传输角动量并落入中心物体。 基于理论和数值模拟，MRI是该机制的领先候选者。 这项研究基于液态金属实验引起的最近兴奋，以研究MRI的发作条件。 等离子体实验比液态金属实验具有多个优点，包括大多数天然发生的积聚盘是由等离子体组成的，它允许更大，更真实的磁性雷诺数，并且可以独立调整粘度和电导率。 PCX最近证明了高速，MRI稳定的COUETTE流，这项工作将1）搜索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运输； 4）确定物理效应是血浆特异性的，超出了标准的磁水动力学模型。PCX实验将对所有流动驱动的MHD问题产生广泛的影响，并将继续在实验室和天体物理物理学等等离子上促进NSF磁性中心实验室等离子物理学和天文学之间的牢固联系。 该奖项支持一名研究生，可以进行拟议的实验，并为技术人员和学生监督提供部分支持。