HR: 14:00h
AN: SM53D-02 INVITED    [Abstracts]
TI: Excitation of Alfven vortices in the ionosphere by the magnetospheric convection
AU: * Trakhtengerts, V Y
EM: vyt@appl.sci-nnov.ru
AF: Institute of Applied Physics, Russian Academy of Sciences, 46, Ulyanov st., Nizhny Novgorod, 603950, Russian Federation
AB: Excitation of ULF waves due to the positive feedback instability is considered in Ionospheric Alfvén Resonator (IAR) taking into account an inhomogeneous profile of velocity of the magnetospheric convection. This profile is formed by interaction of the convective flow with the neutral atmosphere at heights 90--150~km. ULF waves include oblique Alfvén waves, trapped in IAR, and drift ionospheric waves, which are in a resonance with each other. These waves together form strongly anisotropic closed current loops with the scale along the magnetic field l_\| ~ 1000~km and with the scale l_\perp ~ 1~km across the magnetic field and can be considered as Alfvén vortices. The instability threshold and the growth rate are investigated as functions of different parameters (wave vector k_\perp, angle between the wave vector and convection velocity, ratio of Alfvén wave and Pedersen conductivities) in a model of ionosphere close to the real one. Possible acceleration mechanisms of electrons by oblique Alfvén waves and the role of energetic electron precipitation in the feedback instability development are discussed. Some estimations are given in application to observed short-scale field- aligned currents and auroral arcs in the auroral ionosphere.
DE: 2435 Ionospheric disturbances
DE: 2451 Particle acceleration
DE: 2704 Auroral phenomena (2407)
DE: 2721 Field-aligned currents and current systems (2409)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting