Sequentially released tilted flux ropes in the Earth's magnetotail
Sequentially released tilted flux ropes in the Earth's magnetotail
复制标题
地球磁尾中顺序释放的倾斜磁力绳
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
A. Isavnin
中科院分区：
文献类型：
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作者：
H. Hietala;J. Eastwood;A. Isavnin
2011年7月14日，两艘Artemis航天器观测到地球磁尾重新连接时产生的一系列磁通绳。研究发现，磁通绳可以将90多个离子惯性长度延伸到重联面之外。我们通过采用两个航天器定时的全局定向和Grad-Shafrov重建(GSR)局部定向的新组合来分析其中的六条通量绳。我们发现它们的直径为∼10离子惯性长度，时间间隔为∼10 0离子回转周期，它们的速度从∼速度的30%增加到∼速度的70%。考虑到它们在时间和空间上的分离，我们可以推断它们是通过二次不稳定而顺序产生的。所有的磁通绳在电流片平面上都是倾斜的，这表明二次不稳定沿电子电流方向(−)沿X线发展。前5例在−14°和−26°之间倾斜。根据GSR轴，它们的形状在∼300回转周期内变得越来越复杂，这表明它们是扭结的。第六个事件也是相当线性的，具有更大的倾角(−38°)、截面和核心磁场；这些变化很可能与边界条件的变化有关。
On 14 July 2011, the two ARTEMIS spacecraft observed a chain of flux ropes generated by reconnection in the Earth's magnetotail. The flux ropes are found to extend more than 90 ion inertial lengths out of the reconnection plane. We analyze six of these flux ropes by employing a novel combination of two-spacecraft-timing for their global orientation and Grad–Shafranov reconstruction (GSR) for their local orientation. We find that their diameter was ∼10 ion inertial lengths, temporal separations ∼100 ion gyroperiods, and that their speed increased from ∼30% to ∼70% of the Alfvén velocity. Given their temporal and spatial separations, we can infer that they were produced sequentially via a secondary instability. All of the flux ropes were tilted in the current sheet plane, suggesting that the secondary instability grew along the X-line in the direction of the electron current (−YGSM). The first five had a tilt between −14° and −26°. Based on the GSR axes their shape became increasingly complex over a period of ∼300 gyroperiods indicating kinking. The sixth event was again rather linear, and had a larger tilt (−38°), cross-section and core magnetic field; these changes are most likely related to a change in the boundary conditions.