HR: 0830h
AN: SH31A-1086    [PDF]
TI: Three-Dimensional Alfvenic Reconnection
AU: * Song, Y
EM: yan@fields.space.umn.edu
AF: University of Minnesota, School of Physics and Astronomy, 116 Church Street, S.E., Minneapolis, MN 55455 United States
AU: Lysak, R L
EM: bob@belka.space.umn.edu
AF: University of Minnesota, School of Physics and Astronomy, 116 Church Street, S.E., Minneapolis, MN 55455 United States
AB: Observations in space plasmas and laboratory plasmas show reconnection is a three-dimensional dynamical process occurring often in a patchy and sporadic manner involving the energization of charged particles and fluctuations of magnetic and velocity fields. However most traditional reconnection models describe large scale, quasi-steady processes occurring in a specific, two-dimensional configuration. In active cosmic plasma regions, the nonlinear conversion of fast mode waves to shear Alfven waves is an important physical process. For example, during the impinging of fast mode wave packets on a current sheet at the magnetopause or in the magnetotail, the fast mode wave packets can be nonlinearly converted into shear Alfv‚n wave packets. In this process, the localized breakdown of the frozen-in condition is a consequence of the interaction between the fast mode wave packets and the current sheet. It is also a necessary condition for further irreversible nonlinear evolution of the MHD wave packets. Nonlinear MHD wave mode conversion can be considered to be a three-dimensional Alfvenic reconnection process, where the generated shear Alfven wave packets carry energy, momentum, magnetic twist and angular momentum away from the reconnection site. This process corresponds to a reactive, rather than a resistive, transport process, where the parallel electric field has an inductive nature. The radiation of shear Alfven waves, accompanied by fluctuations of magnetic and velocity fields, provides the impedance causing fast reconnection. The Poynting flux of electromagnetic energy flowing into the reconnection region is converted not only into Joule heating, the kinetic energy of plasma flows and accelerated particles, but also into electromagnetic energy associated with the Alfv‚n wave packet. Approximate conservation of magnetic helicity and cross helicity leads to the energization of charged particles on current sheets. In space plasmas and laboratory plasmas, the three-dimensional fast reconnection process has a reactive nature. However, due to the limitations of laboratory experiments, some physical processes occurring in space plasmas may not occur in laboratory plasmas.
DE: 2752 MHD waves and instabilities
DE: 7827 Kinetic and MHD theory
DE: 7835 Magnetic reconnection
DE: 7839 Nonlinear phenomena
DE: 7868 Wave/wave interactions
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting