[P-EM09] Dynamics of Magnetosphere and Ionosphere

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

*国吉 秀鷹¹、Hesse Michael²、Nogren Cecilia³、Tenfjord Paul³、Kwagala Norah³ (1.東京大学地球惑星科学専攻、2.アメリカ航空宇宙局エイムズ研究センター、3.ベルゲン大学宇宙プラズマ物理学グループ)

キーワード：磁気リコネクション、オーロラ加速、電磁流体力学

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.