Experiments in Magnetohydrodynamic and Hydrodynamic Instabilities of Astrophysical Interest

天体物理学感兴趣的磁流体动力学和流体动力学不稳定性实验

• 批准号: 1312463
• 负责人: Jeremy Goodman
• 金额: $ 48.76万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-15 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1312463&HistoricalAwards=false
• 关键词: Experiments; Magnetohydrodynamic; Hydrodynamic; Instabilities; Astrophysical

Efficient dissipation of the orbital energy of plasma occurs in accretion disks ranging from those in which planets form around protostars, to those around supermassive black holes in active galactic nuclei. Two mechanisms have been proposed for the turbulence that drives dissipation and angular-momentum transport in such disks: (1) a linear instability of magnetized and electrically conducting flow known as magnetorotational instability (MRI); and (2) nonlinear hydrodynamic shear-flow instability. Two experiments are running at Princeton: the Liquid-Metal experiment studies MRI and related magnetohydrodynamic (MHD) instabilities, while the Hydrodynamic Turbulence Experiment studies nonlinear hydrodynamic transitions. Recently, the MHD experiment has demonstrated robust nonaxisymmetric Shercliff-layer instabilities in strong axial magnetic fields, paving a clear path towards a first conclusive demonstration of MRI in the laboratory. The present contribution to this research will focus on experimental studies of the following questions: (1) Why are quasi-keplerian flows resistant to turbulence? and (2) How do MRI, Shercliff-layer instabilities, and other MHD activity, drive angular momentum transport? This requires adding crucial diagnostics for direct global torque measurements, measuring local Reynolds and Maxwell stresses in the liquid-metal flow; and making critical hardware improvements to increase and control rotation speeds. This research will educate the next generation of scientists and forge links with neighboring disciplines such as geophysics, fluid dynamics, and plasma physics, while advancing laboratory astrophysics generally.

等离子体轨道能量的有效耗散发生在吸积盘中，从行星在原恒星周围形成的吸积盘到活动星系核中超大质量黑洞周围的吸积盘。 对于驱动这种圆盘中耗散和角动量输运的湍流，已经提出了两种机制：（1）被称为磁旋转不稳定性（MRI）的磁化和导电流的线性不稳定性;（2）非线性流体动力学剪切流不稳定性。 普林斯顿大学正在进行两个实验：液态金属实验研究MRI和相关的磁流体动力学（MHD）不稳定性，而流体动力学湍流实验研究非线性流体动力学转变。 最近，MHD实验已经证明了强大的非轴对称Shercliff层不稳定性在强轴向磁场，铺平了道路，在实验室中的MRI的第一个结论性的演示。 本文的工作主要集中在以下几个问题的实验研究上：（1）为什么准开普勒流是抗湍流的？MRI、Shercliff层不稳定性和其他MHD活动如何驱动角动量输运？ 这需要增加直接全局扭矩测量的关键诊断，测量液态金属流中的局部雷诺和麦克斯韦应力;并进行关键硬件改进以增加和控制转速。 这项研究将教育下一代科学家，并与邻近学科建立联系，如天体物理学，流体动力学和等离子体物理学，同时推进实验室天体物理学。