标题： 磁偶极磁场配置中磁通量绳形成的磁流体动力学模拟 显示英文标题

标题： Magnetohydrodynamics simulation of magnetic flux rope formation in a quadrupolar magnetic field configuration

摘要： 磁通绳（MFRs）在太阳大气中的高能事件如太阳耀斑和日冕物质抛射中起着重要作用。 重要的是，太阳观测表明某些耀斑事件与四极磁构型有关。 然而，这种磁构型中MFR的形成及其后续演化仍需完全理解。 在本文中，我们展示了在四极磁构型中MFR形成的理想化磁流体动力学（MHD）模拟。 通过修改三维（3D）线性力自由磁场，构建了一个具有四极构型的合适初始磁场。 初始磁场包含中性线，这些中性线由X型零点组成。 模拟的动力学最初显示，位于极性反转线（PILs）两侧的相反方向磁力线相互靠近，导致磁重联。 由于这些重联，在PILs上形成了四个高度扭曲的MFR。 随着时间的推移，MFR的足点向X型中性线移动并重新连接，在中性线周围生成复杂的磁结构，从而使四极构型中的MFR拓扑结构比双极环系统中形成的更复杂。 进一步的演化揭示了MFR的非均匀上升。 重要的是，模拟表明磁构型中预先存在的X型零点可能对MFR的演化至关重要，并可能导致四极构型中某些耀斑事件开始时观察到的明亮现象。 显示英文摘要

摘要： Magnetic flux ropes (MFRs) play an important role in high-energetic events like solar flares and coronal mass ejections in the solar atmosphere. Importantly, solar observations suggest an association of some flaring events with quadrupolar magnetic configurations. However, the formation and subsequent evolution of MFRs in such magnetic configurations still need to be fully understood. In this paper, we present idealized magnetohydrodynamics (MHD) simulations of MFR formation in a quadrupolar magnetic configuration. A suitable initial magnetic field having a quadrupolar configuration is constructed by modifying a three-dimensional (3D) linear force-free magnetic field. The initial magnetic field contains neutral lines, which consist of X-type null points. The simulated dynamics initially demonstrate the oppositely directed magnetic field lines located across the polarity inversion lines (PILs) moving towards each other, resulting in magnetic reconnections. Due to these reconnections, four highly twisted MFRs form over the PILs. With time, the foot points of the MFRs move towards the X-type neutral lines and reconnect, generating complex magnetic structures around the neutral lines, thus making the MFR topology more complex in the quadrupolar configuration than those formed in bipolar loop systems. Further evolution reveals the non-uniform rise of the MFRs. Importantly, the simulations indicate that the pre-existing X-type null points in magnetic configurations can be crucial to the evolution of the MFRs and may lead to the observed brightenings during the onset of some flaring events in the quadrupolar configurations.