Statistical analysis of injection/dispersion events in Saturn's inner magnetosphere
Statistical analysis of injection/dispersion events in Saturn's inner magnetosphere
复制标题
土星内磁层注入/扩散事件的统计分析
DOI：
10.1029/2008ja013166
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发表时间：
2008
影响因子：
--
通讯作者：
T. Hill
中科院分区：
文献类型：
--
作者：
Y. Chen;T. Hill
[1]在木星和土星等快速旋转的行星的磁层内，等离子体的径向传输主要包括向内移动的热的、稀薄的等离子体和向外移动的冷的、密集的等离子体。由注入热等离子体的漂移弥散引起的一种独特的现象为这种对流运动提供了直接证据。卡西尼号航天器上的粒子仪器，包括磁层成像仪和卡西尼号等离子体光谱仪，已经对这种特征进行了多次观测。本文通过对26个Cassini轨道的CAPS数据的分析，研究了这类事件的统计性质。统计图片的主要特征，包括年龄的分布，纵向宽度，径向距离，和注入的时间和当地的时间。这些事件的一个意想不到的经度调制出现在旧的SLS经度系统中，该系统是基于旅行者号在1980年左右对土星千米辐射（SKR）的观测，而卡西尼时代的新SKR经度系统似乎不存在这样的调制。然而，Lomb周期图分析显示这些事件没有显著的周期性调制。注入结构被发现占据了一小部分（105 -10）的可用经度空间。
[1] In the inner magnetosphere of a rapidly rotating planet such as Jupiter and Saturn, radial transport of plasma mainly comprises hot, tenuous plasma moving inward and cold, denser plasma moving outward. A distinctive phenomenon resulting from the drift dispersion of injecting hot plasma provides direct evidence for this convective motion. Particle instruments aboard the Cassini spacecraft, including the Magnetospheric Imaging Instrument (MIMI) and the Cassini Plasma Spectrometer (CAPS), have made numerous observations of such signatures. The statistics of the properties of such events are studied in this paper by analyzing CAPS data from 26 Cassini orbits. A statistical picture of their major characteristics is developed, including the distributions of ages, longitudinal widths, radial distances, and longitudes and local times of injection. An unexpected longitude modulation of these events appears in the old SLS longitude system, which is based on the Saturn kilometric radiation (SKR) observations by Voyager around 1980, while no such modulation seems to exist in the new SKR longitude system of the Cassini era. A Lomb periodogram analysis, however, reveals no significant periodic modulation of these events. The injection structures are found to occupy a small fraction (∼5–10) of the available longitude space.