Paper#: 157
Poster #:
Session Name: Workshop 5C: Tail Processes
Room: West Ballroom
Day: Thursday
Time: 4:30-4:55 p.m.
Abstract Title: Evolution of a Thin Current Sheet during Substorms: GEOTAIL Observations
PresentSurname: Mukai, T.
All Authors: T. Mukai, Y. Asano, M. Hoshino
Abstract : The formation of a thin current sheet, in which particle inertial effects are significant, is believed to be essential for initiation of magnetic reconnetion in collisionless plasmas. GEOTAIL observations have revealed that an extremely thin current sheet is really formed in the Earth's midtail plasma sheet in the late growth phase to the expansion onset of a substorm. The cross-tail current density is significantly intensified, and the estimated thickness becomes several hundreds km, which is comparable to the ion inertial length. It is worth stressing that the current is carried mainly by electrons drifting dawnward, which indicates that the electric field is directed toward the neutral sheet. We discuss electron and ion dynamics in terms of the evolution of the thin current sheet and the associated occurrence of magnetic reconnection.