Magnetotail Dynamics: Plasma Wave Turbulence and Particle Chaos

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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. ***