Stability of Thin Current Sheet in the Magnetotail: Theory, Simulations, and Observations

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The principal goal of this research program is to investigate the role of ballooning instabilities, collisionless reconnection and other current-driven instabilities in the triggering and temporal evolution of magnetospheric substorms. The project will use a combination of Hall MHD (Magnetohydrodynamic), fully kinetic particle-in-cell (PIC) simulations, and analytical theory. The project will carry out a comparative study of the linear stability of ballooning modes in realistic magnetotail equilibria to determine the role of plasma compressibility and trapped particle effects in the fluid and kinetic regimes. It will also investigate the nonlinear evolution of ballooning instabilities in realistic magnetotail equilibria using similar initial conditions to determine if and how kinetic effects modify the rapid exponential nonlinear growth. The project will investigate current-driven kinetic instabilities within extended thin current sheets in the magnetotail, and the interactive coupling between reconnection, ballooning and other current-driven instabilities for magnetotail configurations with embedded thin current sheets. The results of theory and simulations will be compared with observations from the European CLUSTER satellites and NASA's THEMIS mission. Although the focus of this project is on applications to magnetospheric physics, the stability of thin current sheets is a subject of broad and interdisciplinary interest. In particular, the role of collisionless reconnection and ballooning instability in the dynamics of thin current sheets has important applications to coronal physics as well as to sawtooth oscillations and current disruption phenomena in fusion and other laboratory plasmas. The project also includes a significant education and public outreach component, which includes lectures at a summer institute at the University of New Hampshire called Project SMART (Science and Mathematics Achievement through Research Training). The SMART program provides research experiences for high school students. In addition to the PI and the Department of Energy funded collaborator at the Los Alamos National Laboratory, the project involves one Research Scientist and two junior faculty members, one of whom is a woman.