Equatorial bubbles updrafting at supersonic speeds
Equatorial bubbles updrafting at supersonic speeds
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DOI：
10.1029/92ja00644
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发表时间：
1992-06
影响因子：
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通讯作者：
T. Aggson;W. J. Burke;N. Maynard;W. B. Hanson;P. Anderson;J. Slavin;W. Hoegy;J. Saba
中科院分区：
文献类型：
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作者：
T. Aggson;W. J. Burke;N. Maynard;W. B. Hanson;P. Anderson;J. Slavin;W. Hoegy;J. Saba
我们提供了两次卫星与赤道等离子体气泡以~ 2 km/s的速度上升的观测结果。这些巨大的向上的速度与钱德拉塞卡的等离子体在磁场的支持下抵抗重力的运动模型相一致；即Vz≈−g。在其中一个气泡遭遇期间，矢量磁场测量显示，在最深处等离子体耗尽的西壁附近，从地球径向向外的扰动为~ 150 nT。这种磁场变化太大，不可能由沿气泡边缘的g × B电流的简单分流引起。更确切地说，它本质上是阿尔芬尼克的，从位于磁赤道附近的发生器辐射出来，在气泡前缘外的等离子体中。一个具有恒定圆截面向上移动通过背景等离子体的耗尽通量管的启发式模型预测了大多数测量的定性特征。
We present plasma and electric field observations from two satellite encounters with equatorial plasma bubbles updrafting at velocities of ∼2 km/s. These large, upward velocities are consistent with an adaptation of Chandrasekhar's model for the motion of plasma blobs supported against gravity by a magnetic field; that is, Vz ≈ −g. Vector magnetic field measurements, available during one of the bubble encounters show a perturbation of ∼150 nT, directed radially outward from the Earth, near the western wall of deepest plasma depletion. This magnetic variation is too large to be caused by simple shunting of the g × B current along the bubble's edge. Rather, it is Alfvenic in nature, radiating from a generator located near the magnetic equator, in the plasma outside the bubble's leading edge. A heuristic model of a depleted flux tube with constant circular cross section moving upward through a background plasma predicts most of the measurements' qualitative features.