Plasma injection near Io
Plasma injection near Io
复制标题
木卫一附近的等离子体注入
DOI：
10.1029/98je00945
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发表时间：
1998
影响因子：
--
通讯作者：
D. Pontius
中科院分区：
文献类型：
--
作者：
T. Hill;D. Pontius
伽利略号飞船第一次与木卫一近距离接触时获得的等离子体和磁场观测表明，木卫一的电动力相互作用比预期的要强得多。如果假设木卫一环面等离子体的很大一部分在卫星附近被电离，这种相互作用的强度就可以解释。我们采用一个简单的模型来计算由局域赤道电离源引起的流动扰动的强度和模式，其尺寸远小于环面本身的径向厚度。与伽利略观测结果的比较表明，当适当考虑模型中的过度简化时，观测结果与环面质量加载率高度定位于木卫一附近的假设相一致，伽利略在其最接近高度约0.5木卫一半径处遇到了这个集中的质量加载区域。这一假设也有助于解释在伽利略号相遇之前已知的环面的两个其他令人困惑的特性，低离子温度（相对于自转能量）和明亮的、径向受限的“带状”特征的存在。
Plasma and field observations obtained by the Galileo spacecraft during its first close encounter with Io indicate a much stronger electrodynamic interaction than anticipated. The strength of this interaction can be explained if one assumes that a significant fraction of the Io torus plasma is ionized in the immediate vicinity of the satellite. We adopt a simple model to calculate the strength and pattern of the flow perturbation resulting from a localized equatorial ionization source with dimensions much less than the radial thickness of the torus itself. Comparison with Galileo observations suggests that, when due allowance is made for the oversimplifications in the model, the observations are consistent with the hypothesis that the torus mass loading rate is highly localized near Io, and that Galileo encountered this region of concentrated mass loading at its closest approach altitude of about 0.5 Io radius. This hypothesis may also help explain two otherwise puzzling properties of the torus that were known before the Galileo encounter, the low ion temperature (relative to corotation energy) and the existence of a bright, radially confined “ribbon” feature.