Self‐consistent seeding of the interchange instability in dipolarization fronts
Self‐consistent seeding of the interchange instability in dipolarization fronts
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DOI：
10.1029/2011gl047742
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发表时间：
2011-05
影响因子：
5.2
通讯作者：
G. Lapenta;L. Bettarini
中科院分区：
文献类型：
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作者：
G. Lapenta;L. Bettarini
我们报道了一个三维磁流体力学模拟，它研究了磁尾重联过程中偶极阵面的形成。在目前的3D模拟中发现的关键的新特征是，重新连接的过程产生了在重新连接区域内发展的通量绳。这些磁绳对扭结模是不稳定的，并在黎明-黄昏方向引入自发结构。在重联下游形成的偶极阵面受扭绳的影响很大。在前缘，密度梯度与加速度场方向相反，并导致交换不稳定。我们提出了一种因果联系的证据，在这种联系中，扭结通量绳的扰动及其自然和明确的标度驱动并选择了偶极锋面中的交换模式的标度。模拟结果与THEMIS任务观测到的测量结构进行了验证。
We report a 3D magnetohydrodynamics simulation that studies the formation of dipolarization fronts during magnetotail reconnection. The crucial new feature uncovered in the present 3D simulation is that the process of reconnection produces flux ropes developing within the reconnection region. These flux ropes are unstable to the kink mode and introduce a spontaneous structure in the dawn‐dusk direction. The dipolarization fronts forming downstream of reconnection are strongly affected by the kinking ropes. At the fronts, a density gradient is present with opposite direction to that of the acceleration field and leads to an interchange instability. We present evidence for a causal link where the perturbations of the kinking flux ropes with their natural and well defined scales drive and select the scales for the interchange mode in the dipolarization fronts. The results of the simulation are validated against measured structures observed by the THEMIS mission.