Stability of Thin Current Sheets in the Earth's Magnetotail: Theory, Simulations, and Observations

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Thin sheets of electric current form in the Earth's magnetotail during the growth phase of a magnetospheric substorm. It is likely that the stability or lack thereof of the current sheets plays an important role in the triggering of the substorm expansion phase. This project will utilize analytical theory, Hall Magnetohydrodynamic (Hall-MHD) simulations and Particle-In-Cell (PIC) simulations to study the stability of thin current sheets. The theoretical and simulation results will be compared with observations from the Cluster and Polar satellites. The high-performance computing tools to be used include a 3D Hall MHD code which incorporates Adaptive Mesh Refinement, and a fully electromagnetic PIC code. The tasks proposed are: (i) a comparative study of the linear stability of the kinetic drift-ballooning instability in Hall MHD and PIC models, including the effect of sheared flows and the effects of line-tying at the ionosphere, (ii) investigation of the nonlinear stability and possible near-explosive growth of drift-ballooning instabilities and possible coupling to reconnection dynamics at substorm onset, and (iii) the comparison of the predictions of theory and simulations with CLUSTER and POLAR observations at mid-tail and near-Earth distances. The proposed work integrates teaching and research at all levels, from high-school to postdoctoral studies. It includes: (i) participation in a summer institute at the University of New Hampshire called Project SMART (Science and Mathematics Achievement through Research Training) which provides exciting research experiences for local high school students, (ii) co-sponsorship of a pilot Summer Internship in the Research And Discover (RAD) program for undergraduates in their junior and senior years, and (iii) mentorship of postdoctoral and junior research scientists.