HR: 14:55h
AN: SM32C-06    [PDF]
TI: Setting Up a Thin Current Sheet and Its Bifurcation
AU: * Singh, N
EM: singh@ece.uah.edu
AF: Electrical and Computer Engineering, University of Alabama in Huntsville, Huntsville, AL 35899 United States
AB: In most studies on magnetic reconnection, Harris equilibrium or its modified versions are initialized. The current in the sheet is primarily carried by ions with peak current occurring in the neutral sheet. However, recent particle simulations of reconnection with initialized perturbations in the magnetic field show that soon after the start, an electron current dominates the neutral sheet. This current is set up by the induction electric field associated with the initial magnetic perturbations and plays a crucial role in further evolution of the reconnection. In nature the magnetic field perturbations of the Harris type of equilibrium must be a rule and not exception. For strong enough perturbations in the lobe magnetic field, the electron current density may exceed threshold for Buneman and/or acoustic instabilities. The anomalous resistivity created by such instabilities may trigger spontaneous reconnection. We report 3-D PIC simulation of (1) setting up of thin current sheet with strong electron current, (2) generation of instabilities and (3) magnetic reconnection. The onset of reconnection is accompanied by (1) electron and ion acceleration, (2) plasma evacuation in the central current sheet, (3) disruption of current in the neutral sheet, and (4) bifurcation of the original current sheet. In the region of low current between the two large currents, strong plasma turbulence ensues.
DE: 2788 Storms and substorms
DE: 7835 Magnetic reconnection
DE: 7843 Numerical simulation studies
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting