Space Plasma Transport by Kinetic Alfven Waves

该项目将评估动力阿尔芬波将受冲击的太阳风(磁鞘)等离子体穿越地球磁场(磁层)外边界(称为磁层顶)的能力。经典地说，这一边界应该是不可穿透的，因为磁鞘等离子体穿透地球磁层的幅度不超过陀螺半径。然而，现场观测显示穿透宽度超过10s的回转半径，事实上，地球磁层的大部分等离子体是由磁鞘等离子体组成的。值得注意的是，磁鞘和磁层等离子体混合的磁层顶边界层总是充满了低频电磁波动。有人认为这些波是动能阿尔芬波。理论研究表明，动力学Alfven波在传输等离子体穿过磁场时可能是有效的。该项目将使用磁层顶集群航天器的多点场和等离子体观测，以确定存在的波，并评估它们解释在那里看到的等离子体传输的能力。尽管该项目专门针对地球磁层顶的等离子体传输，但这个问题是许多物理情况下等离子体传输的核心问题，包括太阳上的磁环和托克马克和其他实验室等离子体设备中的等离子体传输。研究结果将被纳入一系列研讨会，旨在向K-12教师介绍地球空间环境的物理知识。

This project will asses the ability of the kinetic Alfven waves to transport shocked solar wind (magnetosheath) plasmas across the outer boundary of the Earth's magnetic field (magnetosphere) known as the magnetopause. Classically this boundary should be impenetrable with magnetosheath plasma penetrating not more than a gyro-radius into the Earth's magnetosphere. However in-situ observations show penetration over widths of 10s of gyro-radii and indeed much of the plasma of the Earth's magnetosphere is populated by magnetosheath plasmas. Significantly, the boundary layer at the magnetopause where magnetosheath and magnetospheric plasma mix is invariably filled with low frequency electromagnetic fluctuations. It has been suggested that these waves are kinetic Alfven waves. Theoretical studies have suggested that kinetic Alfven waves may be effective in transporting plasmas across magnetic fields. This project will use multi-point fields and plasma observations from the Cluster spacecraft at the magnetopause to identify the waves that are present and evaluate their ability to account for plasma transport seen there. Although the project is specifically directed at plasma transport at Earth's magnetopause, the problem is central to plasma transport in many physical situations, including in magnetic loops on the sun and plasma transport in tokomaks and other laboratory plasma devices. The results from the research will be incorporated into a series of workshops designed to introduce K-12 teachers to the physics of Earth's space environment.