HR: 1340h
AN: SM23A-0404    [Abstracts]
TI: Sufficient Conditions for Local Detection of Magnetic Flux Erosion
AU: * Scudder, J D
EM: jack-scudder@uiowa.edu
AF: Dept of Physics and Astronomy, Dubuque at Jefferson Streets, Iowa City, IA 52242 United States
AU: Daughton, W
EM: william-daughton@uiowa.edu
AF: Dept of Physics and Astronomy, Dubuque at Jefferson Streets, Iowa City, IA 52242 United States
AB: The local detection of magneic flux erosion requires the simultaneous measurements of three observables that are not currently available. Claims of penetration of "the" electron diffusion - flux erosion - region have been made in the literature based essentially on the detection of a parallel electric field. Such identifications can be highly misleading, especially at guide field separators that do not possess a magnetic null line and the observable of zero field strength. The sufficient conditions actually involve the product of (i) a non-vanishing parallel electric field and (ii) a non-vanishing component of the curl of B along B. No flux erosion occurs if either condition is violated, demonstrating that non-zero parallel E is necessary, but not sufficient for the detection of erosion. The second condition is actually more complicated than the local detection with particles of a parallel current, being determined by the sum of the parallel and displacement currents. Multi-spacecraft determinations of the curl of B, determine this quantity averaged over the area inscribed by the spacecraft, which may not be the desired local quantity. A full PIC code in a reconnecting geometry will be used to illustrate the locales of magnetic flux erosion and the pitfalls of an experimental approach that determines the passage through the flux erosion region based on one, but not both of these conditions. In particular, regions exist in the PIC simulation that violate (ii) in the presence of non-zero parallel E, while in other regions both terms are simultaneously non-zero. Of interest is the finding that the actual flux erosion sites are not just localized at the separator, but can be found stretching out 1.5 ion skin depths or more out along the intense perpendicular E layers recently reported at the separatrices.
DE: 2723 Magnetic reconnection (7526, 7835)
DE: 7526 Magnetic reconnection (2723, 7835)
DE: 7835 Magnetic reconnection (2723, 7526)
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005