Chaos and Structures in the Magnetosphere

The nonlinear plasma transport mechanisms that control the collisionless heating in the Earth’s magnetosphere and the onset of geomagnetic substorms are reviewed. In the high pressure plasma trapped in the reversed magnetic field loops on the nightside of the magnetosphere, the key issue of the role of the ion orbital chaos as the mechanism for the plasma sheet energization is examined. The energization rate is governed by a collisionless conductance and the solar wind driven dawn-to-dusk electric field. The low-frequency response function is derived and the fluctuation dissipation theorem is given for the system. Returning to the global picture the collisionless energization rate from the transport physics is the basis for a low-dimensional energy-momentum conserving dynamical model of magnetospheric substorms. To appear in the Physics Reports Proceedings of the Plasma Physics Program at the Institute for Theoretical Physics, Santa Barbara, 1995