This project is dealing with the theory of current disruption and diversion during that is presented during substorms. Collisionless tearing modes, which have been recently shown to be linearly unstable with wavelengths of the order of a By-field, are proposed as a possible candidate for current disruption and diversion. It is shown that nonlinear mode- coupling effects enhance the growth rate of the mode by two orders of magnitude compared with the linear growth rate. For parameters typical of the magnetotail, the current disruption is predicted to occur on a timescale of 1-10 seconds. Estimates are given for the electric fields excited by the microturbulence, and the resultant acceleration of electrons and protons. Estimates indicates ion energies up to 0.7 MeV and electron energies up to 8.1 MeV which are not inconsistent with observations.
