HR: 11:00h
AN: SM22A-03    [Abstracts]
TI: A Mechanism for Electron Heating at the Magnetopause
AU: * McFadden, J P
EM: mcfadden@ssl.berkeley.edu
AF: Space Science Lab University of California, 7 Gauss Way, Berkeley, CA 94720 United States
AU: Fazakerley, A
AF: Mullard Space Science Laboratory Univ. College London, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, United Kingdom
AB: A simple picture of the reconnection geometry, including the high density magnetosheath ion expansion into the low density magnetosphere, may be adequate to explain the "heated" electron distributions observed streaming away from the dayside high-shear magnetopause. Reconnection flows at the high shear magnetopause provide velocity kicks of twice the deHoffmann-Teller velocity. In addition, electrons will interact with an ambipolar field at the front of the magnetosheath ion expansion into the magnetosphere. The ambipolar field prevents the sheath electrons from running away and violating quasi-neutrality. The magnitude of the ambipolar field should be the order of Te/e and will decrease as the sheath ions fill the magnetospheric portion of the flux tube. This ambipolar field propagates with the ion expansion front, therefore electrons that reflect off the front will lose energy in the Earth frame. Higher energy electrons that penetrate the front, magnetically mirror, and pass back through the front will also lose energy. These two acceleration mechanisms may be adequate to explain electron distributions observed both inside and outside the magnetopause on newly reconnected field lines. Data from the Cluster spacecraft will be compared to the model fits.
DE: 2700 MAGNETOSPHERIC PHYSICS
DE: 2724 Magnetopause, cusp, and boundary layers
DE: 2740 Magnetospheric configuration and dynamics
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: 2005 Joint Assembly