HR: 0800h
AN: SM41C-1198    [Abstracts]
TI: Charge-Driven Plasma Instabilities on Auroral Field Lines
AU: * Lennartsson, O W
EM: lenn@spasci.com
AF: Lockheed Martin ATC, ADCS, B255, 3251 Hanover St, Palo Alto, CA 94304 United States
AB: The Polar satellite in its initial orbit regularly observed time-dispersed earthward bursts of hot protons (tens of keV and less) along high-latitude magnetic field lines, together with hot electrons and outflowing accelerated ions from the ionosphere. Beside their dispersion signatures, these bursts, when observed at several Earth radii altitude, have a filamentary structure with transverse scale sizes comparable to the local hot proton gyroradii, often less than 100 km. This fine a structure implies that the protons and accompanying electrons must undergo differential mirroring and electric charge separation, with the strongest electric fields generated transverse to the magnetic field. It can be reasonably assumed that these fields grow sufficiently strong and non-uniform to locally disrupt the first invariant of ions, especially of any ambient O⁺ ions, and generate strong plasma waves. Indeed, it is easy to find burst events that have very large amplitude electric fields (~ 0.1 Vm^-1) fluctuating at roughly the O⁺ gyration frequency. The observed scale sizes, when projected to Earth, are those of auroral arcs.
DE: 2700 MAGNETOSPHERIC PHYSICS (6939)
DE: 2704 Auroral phenomena (2407)
DE: 2723 Magnetic reconnection (7526, 7835)
DE: 2736 Magnetosphere/ionosphere interactions (2431)
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005