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Cassini observations of low energy electrons in and around Saturn's magnetosphere

McAndrews, HJ; (2007) Cassini observations of low energy electrons in and around Saturn's magnetosphere. Doctoral thesis , UCL (University College London). Green open access

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The work in this thesis utilises data from the Cassini spacecraft in the analysis of the Saturnian system. Data from the electron spectrometer (ELS), the ion spectrometer (IMS) and the magnetometer (MAG) gathered during the first two years of the mission have been used in two main areas of research. The first is the investigation of the magnetopause, which forms the boundary between the region of space dominated by the planetary magnetic field and currents, and the interplanetary magnetic field. The second concerns the high energy electrons fluxes in the inner magneto sphere, and the effects caused when the icy moons carve out cavities in these populations. We find evidence strongly suggestive of reconnection events as observed at Earth at two separate encounters with the magnetopause. The energisation of the plasma, together with the open field configuration provides us with an estimate for the reconnection voltage at Saturn. It is found to, at times, be comparable to the corotation electric field, which is assumed to dominate the dynamics of the system. The large database of 200 crossings of the magnetopause is also used to derive general characteristics of the electron behaviour at this boundary. We find that boundary layer plasma is often present inside the magnetopause of Saturn, although the evidence suggests that internal plasma may play a role in formation of this layer. The ELS is able to utilise the penetration of high energy electrons directly into the detector to study the 'microsignatures' of the icy moons in the inner magnetosphere. The absorption of the high energy electrons leaves a cavity in the plasma. The subsequent re-filling over time by the surrounding plasma has allowed us to derive diffusion rates at Tethys, Enceladus and Mimas. In general, outward diffusion is faster than inward diffusion, although this varies at Enceladus.

Type: Thesis (Doctoral)
Title: Cassini observations of low energy electrons in and around Saturn's magnetosphere
Identifier: PQ ETD:593667
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest. Third party copyright material has been removed from the ethesis. Images identifying individuals have been redacted or partially redacted to protect their identity.
UCL classification: UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/1446320
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