HR: 1340h
AN: SM13B-1213    [Abstracts]
TI: Magnetic reconnection within MHD-scale Kelvin-Helmholtz vortices triggered by electron inertial effects
AU: * Nakamura, T
EM: takuma@geo.titech.ac.jp
AF: Department of Earth and Planetary Sciences Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551 Japan
AU: Fujimoto, M
EM: fujimoto@geo.titech.ac.jp
AF: Department of Earth and Planetary Sciences Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551 Japan
AB: In understanding the structure of an MHD-scale Kelvin-Helmholtz (KH) vortex, magnetic reconnection within the vortex must not be neglected. Indeed reconnection seems almost unavoidable. Here we have performed two-dimensional two-fluid simulations including finite electron inertial effects to investigate this issue. In the two-fluid system, magnetic reconnection occurs spontaneously because the _efrozen-in_f condition can be broken by the electron inertial effects. An MHD-scale velocity shear is set up and evolution of MHD-scale KH mode is followed with in-plane magnetic component taken into account. In this study, we focus on two cases with different initial magnetic configuration: (1) Initial in-the-plane magnetic field is parallel across the shear layer. (2) The magnetic field is anti-parallel. In both cases, when the Alfven Mach number of the shear is strong enough for the vortex to highly roll-up, magnetic reconnection occurs spontaneously within the vortex by the electron inertial effects. On the other hand, when the Alfven Mach number is not strong, magnetic reconnection occurs only in the anti-parallel case. Furthermore, in this case, magnetic reconnection act to promote the vortex activity to produce substantial effects which are not available when the coupling between the weak instability and reconnection is not possible, that is, substantial effects that are not observed in the parallel case are seen to emerge. These results presented here imply that magnetic reconnection within a MHD-scale vortex plays an important role in determining the MHD-scale structure of the vortex itself.
DE: 7800 SPACE PLASMA PHYSICS
DE: 7835 Magnetic reconnection
DE: 7843 Numerical simulation studies
DE: 7859 Transport processes
DE: 7871 Waves and instabilities
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting