Magnetotail Dynamics: Plasma Wave Turbulence and Particle Chaos

地球磁层的磁尾，包括等离子体层及其边界层，在能量储存和随后的释放中起着重要作用，在磁暴期间为粒子提供能量。电流片通常被认为是尾部通电的主要位置。在磁尾物理方面，我们拟开展四个研究项目：1)电流片尾磁场非零y分量下的粒子运动；2)电流片突变模型的触发机制；3)中性线特征与建模；4)等离子体片边界层动力学。项目1涉及非线性粒子动力学的工具，如轨道分析、庞加莱截面图和潜在的不变量。项目2将使用一维混合模拟代码来研究作为当前薄片突变模型内部触发因素的动力学不稳定性。项目3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种的弗拉索夫模型来研究剪切、非均匀等离子体片边界层的平衡结构和非线性演化。采用2- 1/2D粒子模拟模型研究高离子密度梯度边界的非线性演化。本研究的总体主题是了解微观和中尺度过程在地球磁尾电流片和等离子体片边界层区域的全球动力学中的作用。＊＊＊

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. ***