HR: 11:05h
AN: SM12B-04    [Abstracts]
TI: Plasma Sheet Structure and Population When the IMF is Northward
AU: * Ashour-Abdalla, M
EM: mabdalla@igpp.ucla.edu
AF: UCLA, IGPP 405 Hilgard Avenue, Los Angeles, CA 90095-1567, United States
AU: Bosqued, J
EM: bosqued@cesr.fr
AF: CESR/CNRS, 9 Ave Colonel-Roche, Toulouse, CDX 31028, France
AU: El-Alaoui, M
EM: mostafa@igpp.ucla.edu
AF: UCLA, IGPP 405 Hilgard Avenue, Los Angeles, CA 90095-1567, United States
AU: Peroomian, V
EM: vahe@igpp.ucla.edu
AF: UCLA, IGPP 405 Hilgard Avenue, Los Angeles, CA 90095-1567, United States
AU: Walker, R
EM: rwalker@igpp.ucla.edu
AF: UCLA, IGPP 405 Hilgard Avenue, Los Angeles, CA 90095-1567, United States
AB: We have used Cluster and Double Star observations along with magnetohydrodynamic (MHD) and large scale kinetic (LSK) simulations to investigate the population and structure of the plasma sheet during an extended interval with northward and dawnward IMF on October 10, 2005. Both Double Star TC 1 and the Cluster spacecraft probed the near-Earth (< 15 R_E) plasma sheet during this interval. First we used Wind observations of the solar wind to drive our MHD simulation. Then using Cluster and TC1 plasma distribution functions as a guide we traced particle trajectories backward in time in the electric and magnetic fields from the MHD calculation to determine possible sources of the plasma sheet particles and found that most of the ions came from the low latitude boundary layer (LLBL). Finally we launched ions forward in time from the LLBL and examined the processes by which these ions populated the plasma sheet. We found that the plasma sheet was divided into two segments by a previously existing neutral line which persisted even though the IMF was northward for several hours. Dawnward of Y_GSM ~ 5 R_E the LLBL particles first formed a plasma sheet boundary layer like (PSBL) region and then populated the central plasma sheet from this PSBL. Duskward of 5 R_E the plasma sheet formed as a series of bands oriented approximately parallel to the equator. This structure closely resembled that inferred from Cluster CIS observations. Both regions were formed independently by non-adiabatic motion of the ions on closed field lines on the dawn and dusk sides of the tail. The source regions are separated by flux rope like structures associated with the tail reconnection. The dusk side plasma sheet formed as a series of independent ion beams each accelerated by non-adiabatic motion at different distances down the tail. The result was that the entire dusk side plasma sheet consisted of a series of plasma sheet boundary layer like regions.
DE: 2744 Magnetotail
DE: 2748 Magnetotail boundary layers
DE: 2753 Numerical modeling
DE: 2764 Plasma sheet
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting