In-situ observations of flux ropes formed in association with a pair of spiral nulls in magnetotail plasmas
In-situ observations of flux ropes formed in association with a pair of spiral nulls in magnetotail plasmas
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DOI：
10.1063/1.4948415
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发表时间：
2016-05
影响因子：
2.2
通讯作者：
R. Guo;Z. Pu;Li‐Jen Chen;S. Fu;L. Xie;Xiaogang Wang;M. Dunlop;Y. Bogdanova;Z. Yao;C. Xiao;Jiansen He;A. Fazakerley
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文献类型：
--
作者：
R. Guo;Z. Pu;Li‐Jen Chen;S. Fu;L. Xie;Xiaogang Wang;M. Dunlop;Y. Bogdanova;Z. Yao;C. Xiao;Jiansen He;A. Fazakerley
在磁尾等离子体的磁重联区经常观察到二次岛的特征。本文采用拟合重建方法，对具有Cluster观测到的次级岛特征的磁性结构进行了重组。结果表明，二次岛事件可以在三维上表现出由a型零和b型零通过它们的脊成对形成的通量绳。我们称这种As-spine-Bs-like构型为螺旋缠绕脊柱模型。重建的磁场线缠绕在脊柱周围形成磁通绳，因此在垂直于脊柱的平面上可以看到o型拓扑结构。磁化的电子在风扇表面上旋转并穿过风扇表面，这表明在这种结构中发生了扭转脊柱和脊柱-风扇的重新连接。此外，详细分析表明，螺旋空洞和通量绳是在航天器附近的重接出口区域局部产生的，这表明二次重接可能发生在远离一次重接地点的排气中。
Signatures of secondary islands are frequently observed in the magnetic reconnection regions of magnetotail plasmas. In this paper, magnetic structures with the secondary-island signatures observed by Cluster are reassembled by a fitting-reconstruction method. The results show three-dimensionally that a secondary island event can manifest the flux rope formed with an As-type null and a Bs-type null paired via their spines. We call this As-spine-Bs-like configuration the helically wrapped spine model. The reconstructed field lines wrap around the spine to form the flux rope, and an O-type topology is therefore seen on the plane perpendicular to the spine. Magnetized electrons are found to rotate on and cross the fan surface, suggesting that both the torsional-spine and the spine-fan reconnection take place in the configuration. Furthermore, detailed analysis implies that the spiral nulls and flux ropes were locally generated nearby the spacecraft in the reconnection outflow region, indicating that secondary reconnection may occur in the exhaust away from the primary reconnection site.