During the growth phase of a substorm the magnetic field in the Earth's magnetotail stretches out in the anti-sunward direction and becomes compressed in the N-S direction. This produces a thin sheet of electric current near the center. The proposed research will examine the physics of these thin current sheets and investigate the conditions under which the sheet may become unstable. Instabilities in the current sheet are a likely cause of the explosive release of energy known as a magnetic sub-storm. The proposed research will use a nonlocal linear stability analysis for a two-fluid plasma. Several potential instabilities will be examined, including the Cross-field current Instability, the ballooning mode instability and various interchange instabilities. After the nonlocal stability analysis has been completed the results will be generalized to a kinetic formalism that can be used to examine the collisionless tearing instability.
