Magnetotail Dynamics: Plasma Wave Turbulence and Particle Chaos

9301801杜森伯里地球磁层的磁尾，包括等离子体片及其边界层，在能量储存及其随后的释放中发挥重要作用，在磁亚风暴期间为粒子提供能量。电流片通常被认为是尾部能量的主要轨迹。我们建议在磁尾物理方面开展四个研究项目：1)电流片尾磁场中非零y分量的粒子运动，2)电流片突变模型的触发机制，3)中性线特征和模拟，4)等离子体片边界层动力学。项目1涉及来自非线性粒子动力学的工具，如轨道分析、庞加莱截面曲线图和基本不变量。一维混合模拟代码将用于项目2，以调查动力学不稳定性，作为当前薄层灾变模型的内部触发因素。在项目3中，将使用单粒子模拟模型来模拟中性线附近的离子分布。最后一个项目使用扩展到包括多离子物种的Vlasov模型来研究剪切的、非均匀的等离子体片边界层的平衡结构和非线性演化。还将使用2-1/2D粒子模拟模型来研究高离子密度梯度边界的非线性演化。拟议研究的总主题是了解微观和中尺度过程对地球磁尾电流片和等离子体片边界层区域的全球动力学的作用。***

9301801 Dusenbery The magnetotail of the Earth's magnetosphere, including the plasma sheet and its boundary layers, plays a major role in energy storage and its subsequent release, energizing particles during magnetic substorms. The current sheet is generally regarded as the primary locus of tail energization. We propose to carry out four research projects in magnetotail physics: 1) particle motion in a nonzero y- component of the tail magnetic field at the current sheet, 2) trigger mechanisms of the current sheet catastroophe model, 3) neutral line signatures and modeling, and 4) dynamics of the plasma sheet boundary layer. Project 1 involves tools from nonlinear particle dynamics such as orbit analysis, Poincare surface-of- section plots, and the underlying invariants. A 1D hybrid simulation code will be used for Project 2 to investigate kinetic instabilities as an internal trigger for the current sheet catastrophe model. A single-particle simulation model will be used to model ion distributions near a neutral line for Project 3. The last project examines the equilibrium structure and nonlinear evolution of a sheared, inhomogeneous plasma sheet boundary layer using a Vlasov model exended to include multi-ion species. A 2- 1/2D particle simulation model will also be used to study nonlinear evolution of the boundary with high ion density gradients. The overall theme of the proposed research is to understand the role of microscopic and mesoscale processes on the global dynamics of the current sheet and the plasma sheet boundary layer regions of the Earth's magnetotail. ***