On 12 November 2015 the Magnetospheric Multiscale (MMS) spacecraft traversed the magnetopause from the magnetosphere to the magnetosheath encountering evidence of magnetic reconnection and a tiny flux transfer event (FTE) on the magnetosheath side of the magnetopause boundary layer. The FTE exhibited a large negative‐positive bipolar variation in the normal magnetic field component (B_N), an enhanced (negative) north‐south component direction (B_L), and a variation in the third component B_M resembling a “W” shape with negative values close to the edges and positive values near the center. Using the tetrahedron formation, we estimate that the FTE moved southward and duskward with a speed of V_FTE = 324 km/s. The FTE size in the transverse direction is 518 km, which corresponds to 4.42 ion gyroradii. We identify an internal layer where the electron bulk flow velocity exhibits different behaviors at each of the four spacecraft and the current density was more intense at two spacecraft. Within the FTE's core region, the ion bulk flow behavior was similar for all four spacecraft. Using the velocity obtained from timing analysis, we estimate a dimension of this core region to be 181.4 km, which corresponds to 1.5 ion gyroradii. It is evident that the internal region is not large enough to affect the ion behavior but can do so for electrons. We conclude that the FTE's core is an electron‐scale substructure.

中文翻译：

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磁层多尺度任务观测到的具有电子尺度子结构的通量传递事件

2015年11月12日，磁层多尺度（MMS）航天器从磁层穿入了磁层顶，到达了磁层，在磁层顶边界层的磁层侧遇到了磁重新连接和微小磁通转移事件（FTE）的迹象。FTE在正常磁场分量（B _N），北-南分量方向（B _L）增强（负）和第三分量B _M的变化类似“ W”时表现出很大的负-正双极性变化。形状，其负值靠近边缘，正值靠近中心。利用四面体形成，我们估计FTE以V _F的速度向南和向黄昏移动_{T E}  = 324 km / s。横向上的FTE大小为518 km，对应于4.42离子陀螺半径。我们确定了一个内层，在该内层中，电子体积流速在四个航天器中的每个航天器上表现出不同的行为，并且电流密度在两个航天器中更为强烈。在FTE的核心区域内，所有四个航天器的离子体积流动行为均相似。使用从时序分析获得的速度，我们估计此核心区域的尺寸为181.4 km，对应于1.5离子陀螺半径。显然，内部区域的大小不足以影响离子行为，但对于电子而言却可以。我们得出结论，FTE的核心是电子尺度的子结构。