[P-EM09] Dynamics of Magnetosphere and Ionosphere

[PEM09-02] Magnetic Reconnection in a Sheared Magnetic Flux Tube: Slippage versus Tearing

*Hidetaka Kuniyoshi¹, Michael Hesse², Cecilia Nogren³, Paul Tenfjord³, Norah Kaggwa Kwagala³ (1.The University of Tokyo, Department of Earth and Planetary Science, 2.NASA Ames Research Center, 3.University of Bergen, Space Plasma Physics Group)

Keywords:Magnetic Reconnection, Auroral acceleration, Magnetohydrodynamics

Although it still remains controversial whether auroral acceleration is, in fact, a manifestation of a reconnection process, discussions of a different type of reconnection in this context began with 'reconnection type II' by Haerendel (Haerendel, 2007, 2011), which recognized early on that auroral acceleration may be a form of magnetic reconnection. According to the author, the reconnection process enhances the auroral acceleration by reducing the flux tubes’ shear magnetic stress of field aligned current sheets. The process of magnetic reconnection in a flux tube can occur in a time-stationary fashion as slippage reconnection or in a time-dependent manner, for example, tearing instability. However, it is not well known how a system can be set up to sustain slippage reconnection, whether there is a combination of slippage reconnection and time-dependent reconnection. To investigate this question, using a 3D MHD simulation, we model a twisted flux tube, adding a spatially localized resistive region in the center of the simulation box. As a result, firstly, the Poynting flux injected at the boundary propagates to the resistive region and dissipates there. Secondly, tearing instability occurs with slippage reconnection in the resistive region when the resistivity is strong enough and the cross section of the flux tube is elliptical enough, otherwise only slippage reconnection occurs. Finally, magnetic field generated by tearing instability propagates to both ends of the flux tube.