Plasma mass loading from the extended neutral gas torus of Enceladus as inferred from the observed plasma corotation lag
Plasma mass loading from the extended neutral gas torus of Enceladus as inferred from the observed plasma corotation lag
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根据观测到的等离子体共转滞后推断出土卫二扩展中性气体环面的等离子体质量负载
DOI：
10.1029/2009gl041030
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发表时间：
2009
影响因子：
5.2
通讯作者：
T. Hill
中科院分区：
文献类型：
--
作者：
D. Pontius;T. Hill
在土星，显著的等离子体质量加载和径向输运一起发生在扩展的中性环面，两者都产生自转滞后。我们提出了一种理论，它依赖于两类过程的比率：那些注入新质量的过程（简单电离）和那些在不改变等离子体质量密度的情况下有效去除动量的过程（弹性离子中性碰撞，如种电荷交换）。两者都引起电离层扭矩，但只有前者增加了向外的总质量通量。根据观察到的角速度，我们的模型计算了质量载荷随径向距离的分布。我们提出了基于卡西尼等离子体光谱仪测量和土星磁层理论化学模型的解决方案。我们发现在土卫二轨道附近有一个明显的相互作用峰，在5到8个土星半径（Rs）之间有一个宽的电离区。8Rs时的总质量输出是100 kg/s × （Σ/0.1 s），其中Σ是土星电离层的彼得森电导。报告的滞后降低超过8Rs要求Σ≠恒定或减少总质量流出。
At Saturn, significant plasma mass loading and radial transport occur together throughout the extended neutral torus, both producing corotation lags. We present a theory that depends upon the ratio of two classes of process: those injecting new mass (simple ionization) and those effectively removing momentum without changing plasma mass density (elastic ion‐neutral collisions, like‐species charge exchange). Both induce ionospheric torques, but only the former increases total outward mass flux. From an observed angular velocity, our model calculates the distribution of mass loading with radial distance. We present solutions based on Cassini Plasma Spectrometer measurements and theoretical chemistry models for Saturn's magnetosphere. We find a pronounced interaction peak near Enceladus' orbit and a broad ionization region between 5 and 8 Saturn radii (Rs). The total mass outflux at 8Rs is 100 kg/s × (Σ/0.1 S), where Σ is Saturn's ionospheric Pedersen conductance. The reported decrease in lag beyond 8Rs requires that Σ ≠ const or reducing the total mass outflux.