HR: 1340h
AN: SM23A-0401    [Abstracts]
TI: 3-Dimensional Alfvenic Reconnection: Theory
AU: * Song, Y
EM: yan@fields.space.umn.edu
AF: University of Minnesota, 116 Church Street, S. E., Minneapolis, MN 55455 United States
AU: Lysak, R L
EM: bob@aurora.space.umn.edu
AF: University of Minnesota, 116 Church Street, S. E., Minneapolis, MN 55455 United States
AB: Observations show that the breakdown of the frozen-in condition commonly and universally occurs in cosmic plasmas. Reconnection is often a 3D dynamical process occurring in a patchy and sporadic manner, involving the energization of plasmas, the generation of Alfven waves and reconfiguration of magnetofluids. Magnetic reconnection often occurs when a pre-existing current sheet is compressed locally by external plasma forces. For example, when fast mode wave packets and wave (or shock) fronts impinge on a current sheet at the magnetopause or in the magnetotail, the fast mode wave packets can be nonlinearly converted into shear Alfven wave packets. Thus, reconnection is 3D and Alfvenic. We derive a dynamical relationship between the generation of parallel electric fields, temporal and spatial changes of magnetic and velocity shears, and show that the generation parallel electric fields favors low plasma density. We point out that parallel electric fields can be supported by releasing localized magnetic or velocity stresses caused by nonlinear MHD wave packet interaction. We demonstrate how the frozen-in condition is broken down at the current sheet by using approximate conservation of magnetic and cross helicity during the wave mode conversion. These processes are mostly inductive and capacitive in nature and so the mass, momentum and energy transport related to reconnection is reactive. The characteristics and theoretical predictions of 3D Alfvenic reconnection including the signatures of reconnection, the density and plasma beta dependence of reconnection onset, will be given.
DE: 2723 Magnetic reconnection (7526, 7835)
DE: 2752 MHD waves and instabilities (2149, 6050, 7836)
DE: 7835 Magnetic reconnection (2723, 7526)
DE: 7836 MHD waves and instabilities (2149, 2752, 6050)
DE: 7839 Nonlinear phenomena (4400, 6944)
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005