One of the principal aims of magnetospheric research is to understand how solar wind particles and energy are transported throughout the magnetosphere. The magnetotail plays an important role in this transport. The region at about a radial distance of 8-10RE has recently been observed to be in the so- called current disruption region which may be a signature of the onset of a magnetospheric substorm. This grant is to investigate the role the collisionless tearing instability plays in the current disruption process. The research will focus of the verification of the analytical theory of tearing modes by particle simulations and the development of a nonlinear theory of such modes. ***
