Coates Andrew J, Wellbrock Anne, Waite J Hunter, Jones Geraint H
Mullard Space Science Laboratory University College London London UK; Centre for Planetary Sciences at UCL/Birkbeck London UK.
Southwest Research Institute San Antonio Texas USA.
Geophys Res Lett. 2015 Jun 28;42(12):4676-4684. doi: 10.1002/2015GL064474. Epub 2015 Jun 18.
Neutral particles dominate regions of the Saturn magnetosphere and locations near several of Saturn's moons. Sunlight ionizes neutrals, producing photoelectrons with characteristic energy spectra. The Cassini plasma spectrometer electron spectrometer has detected photoelectrons throughout these regions, where photoelectrons may be used as tracers of magnetic field morphology. They also enhance plasma escape by setting up an ambipolar electric field, since the relatively energetic electrons move easily along the magnetic field. A similar mechanism is seen in the Earth's polar wind and at Mars and Venus. Here we present a new analysis of Titan photoelectron data, comparing spectra measured in the sunlit ionosphere at ~1.4 Titan radii () and at up to 6.8 away. This results in an upper limit on the potential of 2.95 V along magnetic field lines associated with Titan at up to 6.8 , which is comparable to some similar estimates for photoelectrons seen in Earth's magnetosphere.
中性粒子在土星磁层区域以及土星几颗卫星附近占据主导地位。阳光使中性粒子电离，产生具有特征能谱的光电子。卡西尼等离子体光谱仪电子光谱仪在这些区域都检测到了光电子，在这些区域光电子可用作磁场形态的示踪剂。由于能量相对较高的电子容易沿着磁场移动，它们还通过建立双极电场增强了等离子体逃逸。在地球的极风以及火星和金星上也观察到了类似的机制。在此，我们对土卫六光电子数据进行了新的分析，比较了在约1.4个土卫六半径（）以及高达6.8 处的阳光电离层中测量的光谱。这导致在高达6.8 处与土卫六相关的磁力线上电势上限为2.95 V，这与在地球磁层中观察到的一些类似的光电子估计值相当。
