Utilizing Magnetospheric Multiscale (MMS) observation in the tail plasma sheet, we study the vorticity field (ω = ∇ × V) of the plasma bulk (convective) velocity within the bursty bulk flow (BBF) in detailed. Two typical events are presented. In the event on 25 June 2017, E_y is the main component. In the other event on 6 July 2017, E_z is the main component. For both cases, the BBF electric field is dominated by the convective electric field (Ec = − V × B). Our case studies show clearly the existence of the convective vorticity field within the BBF. The vorticity field has prominent anisotropy (quantified by the anisotropic angle (θaa = arctan(ω_⊥/ω_∥)). More often, the BBF ω field has stronger perpendicular vorticity (ω_⊥) than the parallel vorticity (ω_∥). The dominance of vorticity by ω_⊥‐dominating BBF is confirmed in the statistical sense. In particular, event on 25 June shows the significant evolution of the ion flux energy with the strength of the ω field. The strong ω field corresponds to the ion flux enhancement at high energy (above 10 keV), while the weak ω field corresponds to the ion flux enhancement at medium energy (2–5 keV). Investigation of the subset of channel from fast plasma investigation partial moment measurement reveals that the ion behaviors in the strong and decayed BBFs are distinctly different. The channeled ions form the narrow band distribution in the strong BBF but the multiple‐layer distribution in the weak BBF. Finally, spectrum analysis indicates that the BBF ω_⊥ and ω_∥ have a similar scaling about −2.0 (below 0.2 Hz).

中文翻译：

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爆发性湍流内的各向异性涡度

利用尾部等离子体片中的磁层多尺度（MMS）观测，我们详细研究了突发性整体流（BBF）内的等离子体整体（对流）速度的旋涡场（ω  =∇×  V）。介绍了两个典型事件。在2017年6月25日的事件中，E _y是主要成分。在2017年7月6日的另一事件中，E _z是主要成分。对于这两种情况，BBF电场都由对流电场控制（Ec  =  -V  ×  B）。我们的案例研究清楚地表明了BBF内部存在对流涡度场。涡度场具有显着的各向异性（通过各向异性角（θ AA =反正切（ω _⊥ / ω _∥））。更多的时候，BBF ω场具有较强的垂直涡度（ω _⊥）比平行涡（ω _∥）。涡由优势ω _⊥ -dominating BBF在统计意义上得到了证实。特别是，6月25日的事件显示出离子通量能量随ω场强度的显着变化。强大的ω场对应于高能量（10 keV以上）的离子通量增强，而弱的ω电场对应于中等能量（2–5 keV）时的离子通量增强。从快速等离子体研究部分矩测量中对通道子集的研究表明，强和衰变BBF中的离子行为明显不同。通道离子在强BBF中形成窄带分布，而在弱BBF中形成多层分布。最后，频谱分析表明BBF ω _⊥和ω _∥具有大约-2.0（低于0.2赫兹）类似的缩放。