Externally Driven Onset of Localized Magnetic Reconnection and Disruption in a Magnetotail Configuration

The response of a magnetotail equilibrium containing dipole magnetic field and plasma sheet regions to the imposition of a longitudinally limited, high-latitude driving electric field is investigated using 3-D particle-in-cell simulations. The initial response involves a reduction in the equatorial B-z field that is then followed by the development of a dawn-dusk asymmetric thin current sheet relative to the meridian plane of the driving field. Continued driving leads to the onset of localized reconnection and the emergence of magnetic flux ropes. The cross-tail extent of the reconnection expands but remains limited to similar to 30d(i), where d(i) is the ion inertia length. A later stage involves disruption of the plasma sheet earthward of the initial X-line with the formation of multiple field-aligned currents connecting to the earthward boundary and strong local energization of the ions (4 times thermal) and electrons (10 times thermal). These results demonstrate the ability of a high-latitude disturbance that may be connected to dayside flow channels to initiate localized magnetic reconnection and disruption in the magnetotail.