Modeling Unsteady Reconnection in the Magnetotail

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The onset of reconnection in tail-like plasma configurations is one of the most fundamental energy transformation processes in space plasmas. It results in acceleration and heating of plasma particles, new plasma structures and turbulence. It gives rise to substorms in Earth's magnetosphere. Similar processes occur in the magnetospheres of Jupiter, Saturn, Mercury, other planets and their moons, in the solar corona and in the laboratory plasmas, including the laboratory experiments on magnetic reconnection. This project will examine kinetic models of magnetic reconnection in Earth's magnetotail. In the magnetotail the onset of reconnection is determined not only by different motions of ions and electrons but also by different motions of the electrons trapped inside the current sheet and those passing through the tearing instability region. It also depends on the structure of the current sheet, whether the reconnecting current layer is embedded into a thicker plasma sheet or not. Significant progress in understanding of the magnetotail reconnection becomes possible because of the availability of( a) nonlocal kinetic stability analysis codes, (b) new models of thin current sheets embedded into thicker plasma sheets or split into two current layers, and (c) kinetic particle simulation codes with open boundaries (as opposed to periodic boundary conditions) for both fields and particles. The goal of this project is to use and develop the above tools and models to investigate: 1) the kinetic mechanisms of the reconnection onset in the magnetotail, 2) different types of thin current sheets that precede the onset and arise in process of reconnection, and 3) the regimes of reconnection characteristic of the tail-like, collisionless plasmas. New regimes of reconnection available in collisionless tail-like systems, are very different from the standard picture of magnetic reconnection, with the electron dissipation region at the magnetic X-point and with the fast reconnection mediated by whistler or kinetic Alfven waves and dominated by the Hall fields. The project will develop new tools (thin current sheet models and full-particle simulations with open boundaries) that will be useful in other areas of plasma physics and astrophysics, magnetic-confinement fusion, solar physics, and plasma propulsion. The work will also provide hands-on research training for student summer interns via The Johns Hopkins University Applied Physics Laboratory summer intern program.