Energetic ion composition and acceleration mechanisms in the magnetosphere of Jupiter
Univ. Zugl.: Braunschweig
Link zum Zitieren/Bookmarken: http://hdl.handle.net/11858/00-1735-0000-0001-3101-B
Based on the first 15 orbits of the Galileo spacecraft the composition of the energetic ion population of the Jovian magnetosphere has been studied for the first time on a global scale. More specific, three different types of ions are investigated: helium as the tracer of the solar wind, sulfur and oxygen to a large extent as tracers of the internal source Io and protons with a mixed origin from the solar wind, Jovian atmosphere/ionosphere and the Europa gas torus. The ion energy spectrum fundamental for the study of the ion composition is investigated and a characteristic shape is established as a distinct feature of the Jovian magnetosphere. Based on the observed ion energy spectra the relative ion abundance ratios of S/O, S/He, O/He and p/He at a specific energy/nucleon are derived and global maps are constructed. The global coverage of the Galileo trajectories enables a quantitative comparison with results of previous flyby missions for the same radial distance and local time. The large discrepancies derived from the comparison with the Voyager 2 results are attributed to temporal variations and to a strong energy dependence of the ion abundance ratios associated with the energy spectral shapes ...