Vertical structure and plasma characteristics of the Encelauds plume

Saturn's icy moon Enceladus expels the water grains and neutral gases, which become a source of the plasma in the magnetosphere. Recent Cassini observations revealed that the plume dust consists of nano- to micro-meter sized dust that are negatively charged and electrically coupled to the background plasma. The results from the Radio Plasma Wave Science (RPWS) showed that the electron densities were less than 1% of the ion densities up to the altitudes of 7 Enceladus radius above the south pole. We will present the Cassini RPWS/Langmuir probe (LP) observations from the Enceladus flybys (E07, 08, 09, and 14), where Cassini was across the plume in various altitudes, to determine the vertical and altitudinal structure of the Enceladus plume and its the dust and plasma characteristics. The ion/electron densities were about 104 cm-3 and 102 cm-3 for E07 where the Cassini was at the altitudes of 100 km, while they decrease to 102 cm-3 and 10 cm-3 as the altitudes increase to 1500 km. We will discuss the dust charge state and the plasma characteristics in the plume. The electrical potential of the dust was mostly negative in the plume from the early observations. On the other hand, the positive dust potentials have been found near the Enceladus plume.