Magnetospheric Hydromagnetic Waves: Internal and External Coupling

该项目的目标是对磁层强磁模式及其与环流等外部和内部自由能来源的耦合有一个定量的了解。接下来将研究三个相互关联的领域：(1)磁层内空腔模式，(2)场线共振模式的一般性质，以及(3)高能环电流粒子激发内部驱动的场线共振模式。要研究的关键问题是：(1)内磁层的腔模结构是什么，人们应该在地面和卫星磁数据中看到的频率，以及从外磁层传输的效率是什么，(2)是什么控制着场线共振模径向结构，(3)是什么导致了漂移-反弹共振模的非线性饱和，以及这种模对离子运动的自洽效应是什么。将采用的方法是：(1)用于腔模研究、偶极子和一般几何的本征模分析和MHD模拟；(2)用于场线共振模式的研究、包括有限Larmor半径效应和电离层阻尼的盒形和偶极几何的MHD模拟；以及(3)用于内驱动场线共振模式的研究、盒形和偶极几何的混合MHD/陀螺动力学模拟。目标是将尚未包括在这些模式研究中的关键物理学纳入其中。将与航天器数据进行比较，以检验理论预测，并对观测到的波特性和相关粒子测量产生新的见解。

The objective of this project is to obtain a quantitative understanding of magnetospheric hudromagnetic modes and their coupling to external and internal sources of free energy, such as the ring current. Three interrelated areas of study will be followed: (1) inner magnetospheric cavity modes, (2) general properties of field line resonance modes, and (3) excitation of internally-driven field line resonance modes by energetic ring current particles. Key questions to be examined are: (1) what is the cavity mode structure in the inner magnetosphere and the frequencies one should expect to see in ground and satellite magnetic data and what is the efficiency of transport from the outer magnetosphere, (2) what controls the field line resonant mode radial structure, and (3) what causes the nonlinear saturation of the drift-bounce resonant mode, and what is the self-consistent effect of the mode on ion motion. The methods to be employed are: (1) for the cavity mode study, eigenmode analysis in dipole and general geometry and MHD simulations, (2) for the field line resonance mode study, MHD simulations in box and dipole geometry including finite Larmor radius effects as well as ionospheric damping, and (3) for the study of internally-driven field line resonance modes, hybrid MHD/gyrokinetic simulations in box and dipole geometry. The goal is to incorporate the key physics which has not yet been included in studies of these modes. Comparisons with spacecraft data will be made to test the theoretical predictions and yield new insights into observed wave properties and associated particle measurements.