HR: 10:20h
AN: SM12B-01 [Abstracts]
TI: Plasma Sheet Response to the Ionosphere's Demand for Field-Aligned Current
AU: Coroniti, F V
EM: coroniti@astro.ucla.edu
AF: Department of Physics and Astronomy, University of California, Los Angeles, 405 Hilgard
Avenue, Los Angeles, CA 90095-1547, United States
AU: * Pritchett, P L
EM: pritchet@physics.ucla.edu
AF: Department of Physics and Astronomy, University of California, Los Angeles, 405 Hilgard
Avenue, Los Angeles, CA 90095-1547, United States
AB:
Magnetospheric convection electric fields and plasma
stresses are transmitted to the ionosphere by Alfvén
wave electric fields and field-aligned currents (FACs).
The closure of the FACs by ionospheric Hall and Pedersen
currents drives the ionospheric convection system.
However, the ionospheric system does not necessarily
mesh smoothly with the magnetospheric drivers, and the
magnetosphere must respond by altering its convection
and plasma stress configuration, thereby creating
self-consistent closure paths for the complete coupled
system of currents and electric potentials.
Three-dimensional particle-in-cell plasma kinetic
simulations are used to determine the plasma sheet
response to various current systems imposed as boundary
conditions at the near-Earth boundary. These systems
consist of separate downward and upward tubes of FAC
and a substorm current wedge configuration. The results
demonstrate that the creation of closure paths for
ionospheric FACs can result in large configuration
changes within the near-Earth plasma sheet. The plasma
sheet is forced to establish polarization electric
fields that locally increase the cross-tail current by
producing a duskward Hall electron current; this results
in the formation of thin (in z), spatially localized
(in y) electron-dominated Hall current sheets. The
observed complex magnetic field configuration with
opposite polarity Bz fields in close proximity
separated by electron scale thin current sheets is
reminiscent of the turbulent magnetic fields that are
observed within the near-Earth current disruption region
at substorm breakup [ Lui et al., 1988, 1992].
DE: 2721 Field-aligned currents and current systems (2409)
DE: 2723 Magnetic reconnection (7526, 7835)
DE: 2744 Magnetotail
DE: 2764 Plasma sheet
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting