HR: 0830h
AN: SM21B-0194    [PDF]
TI: Instability At The Leading Edge Of A Reconnection Jet
AU: * Tandokoro, R
EM: rtdokoro@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: Magnetic reconnection is one of the most important phenomena in space plasma physics, which is considered to be concerned with large scale energy releasing processes. Especially, a high-speed plasma jet which emerges with magnetic reconnection, so called reconnection jet, is considered to play an important role in energetic processes such as plasma particle acceleration in solar flares. Despite its importance, less attention than it deserves has been paid to understanding its dynamics. In this study, we focus on behavior of reconnection jets by conducting three-dimensional MHD simulations. In our simulations, initial condition of the magnetic field is the one-dimensional Harris current sheet model. Magnetic reconnection is initiated by time-independent spatially fixed anomalous resistivity. We add small perturbations, with their wave number vectors aligned in the initial current direction, to plasma pressure and density, and study how the seeds grow as the reconnection jet develops. Under this condition, numerical results show that the leading portion of the reconnection jet is deformed into wavy configuration and grows into a mushroom-like shape on the central current sheet plane, that is, the perturbations are brought up to an unstable state and start to grow with development of the reconnection jet. In the reconnection process, the leading part of a reconnection jet pushes and compresses the standing plasma ahead of it, and a strong pressure and density gradient develops between the reconnection jet and the plasma in front of the jet. Consequently, in this circumstance, what is developing at the leading edge of the jet is quite likely an interchange unstable configuration. A reconnection jet has more dynamic structure than we have thought. Indeed an extremely complicated flow pattern emerges in the later stage of the instability. The unstable leading part of the reconnection jet may have effects that have not been considered before. We will also discuss how the instability behaves in a more realistic situation, such as in the presence of a non-zero guide field.
DE: 2740 Magnetospheric configuration and dynamics
DE: 2744 Magnetotail
DE: 2752 MHD waves and instabilities
DE: 2753 Numerical modeling
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting