研究期間：10108~10207;From the Galileo mission to Jupiter and the Cassini mission to Saturn, we have learnt that the plasma dynamics and ion composition of the magnetospheric systems of these outer planets are strongly influenced by neutral gas clouds emitted from their moons. For Jupiter, it is Io with extremely high level of volcanic activity injecting sulfur and oxygen atoms and ions into the Jovian magnetosphere. For Saturn, it is Enceladus with active injection of water gas and icy grains from its south pole into an extended region surrounding the central planet. The energetic neutral atoms created in charge exchange process between the neutral gas cloud and the energetic protons and other heavy ions have been used to remote-sense the global distribution and quasi-periodic time-variability of magnetospheric charged particles in the Saturnian system. In this proposed work, we will make use of the Cassini measurements obtained by the energetic particle detectors to investigate the cause and effect of the interaction of the substorm-like injection events and the neutral gas cloud on the quasi-periodic behavior of the corresponding plasma dynamics. With emphasis on the Saturnian system, we will also study the origin and structures of the exospheres of the Saturnian icy moons: Rhea, Dione and Tethys by a Monte Carlo model which has been developed before for Mercury’s exosphere. Another aspect of plasma-netural interaction in planetary magnetospheres has to do with the direct contact of the solar wind plasma with the extended exospheres of Mars and Venus. This type of process is very much akin to the magnetospheric interaction of Titan and the cometary interaction with solar wind. The study of the comet-like solar wind interaction and the potential impact on the long-term evolution of the planetary atmospheres of these terrestrial planets will be our another scientific goal.
