Magnetic field and plasma wave observations in a plasma cloud at Venus
Magnetic field and plasma wave observations in a plasma cloud at Venus
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金星等离子体云中的磁场和等离子体波观测
DOI：
10.1029/gl009i001p00045
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发表时间：
1982
影响因子：
5.2
通讯作者：
L. H. Brace
中科院分区：
文献类型：
--
作者：
C. Russell;J. Luhmann;R. Elphic;F. Scarf;L. H. Brace
在金星电离层上方等离子体云的一个特别清晰的例子中检查了先锋金星磁场和等离子体波数据。磁性结构表明等离子体云通过磁张力加速。如果等离子体在太阳下点处于静止状态，则可以通过在测量位置观察到的应力将其加速到约 90 公里/秒。这远远超过了逃逸速度，表明等离子体云确实形成了金星电离层的显着损失机制，但不一定表明等离子体云与电离层本身分离。等离子体云伴随着强烈的等离子体波活动，并且比随后在同一路径中遇到的电离层等离子体要热得多。我们估计在此事件期间每秒损失率约为 2 x 10/sup 25/ 离子。这些观测结果表明，其几何形状是一条致密冷等离子体的脊线之一，该脊线始于次太阳区域并流过地球的两极。因此，这些等离子云可能是彗星尾射线的行星类似物。
Pioneer Venus magnetic field and plasma wave data are examined in a particularly clear example of a plasma cloud above the Venus ionosphere. The magnetic configuration is suggestive of acceleration of the plasma cloud by magnetic tension. If the plasma is at rest at the subsolar point, it could be accelerated to approx.90 km/sec by the observed stress at the location of the measurement. This far exceeds the escape velocity and suggests that plasma clouds do form a significant loss mechanism for the Venus ionosphere but do not necessarily indicate that the plasma cloud is detached from the ionosphere proper. The plasma cloud is accompanied by strong plasma wave activity and is significantly hotter than the ionospheric plasma encountered later on the same pass. We estimate a loss rate of the order of 2 x 10/sup 25/ ions per second during this event. The geometry suggested by these observations is one of a ridge of dense cold plasma starting in the sub solar regions and flowing over the poles of the planet. Thus, these plasma clouds may be the planetary analogue of cometary tail rays.