HR: 0800h
AN: SM51A-0354    [Abstracts]
TI: The Dynamics of a Double-Layer Along an Auroral Field Line: An Improved Model
AU: * Barakat, A R
EM: arb@cc.usu.edu
AF: Center for Atmospheric and Space Sciences, Utah State University 4405 Old Main Hill, Logan, UT 84322-4405 United States
AB: The auroral field lines represent an important channel through which the ionosphere and the magnetosphere exchange mass, momentum, and energy. When the cold, dense ionospheric plasma interacts with sufficiently warm magnetospheric plasma along the field lines (with upward currents), double layers form with large parallel potential drops. The potential drops accelerate ionospheric ions, which in turn cause ion-beam-driven instabilities. The resulting wave-particle interactions (WPI) further heat the plasma, and hence, influence the behavior of the double layer. Understanding the coupling between these microscale and macroscale processes is crucial in quantifying the ionosphere-magnetosphere (I-M) coupling. Previous theoretical studies addressed the different facets of the problem separately. We developed a particle-in-cell (PIC) model that simulate the behavior of the double layer along auroral field lines, with special emphasis on the effect of the current along filed lines. Moreover, our model includes the effects of ionospheric collision processes, gravity, magnetic mirror force, electrostatic fields, as well as wave instabilities, propagation, and wave-particle interactions. The resulting self-consistent electrodynamics of the plasma in an auroral flux tube with an upward current is presented with emphasis on the formation and evolution of the double layer. In particular, we address questions such as: (1) what is the I-V relationship along the auroral field line, and (2) how the potential drop is distributed along the filed lines. These, and other results, are presented.
DE: 2704 Auroral phenomena (2407)
DE: 2708 Current systems (2409)
DE: 2716 Energetic particles, precipitating
DE: 2736 Magnetosphere/ionosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting