  Energetic ion composition during reconfiguration events in the Jovian magnetotailRadioti, Aikaterini  ; ; et alin Journal of Geophysical Research. Space Physics (2007), 112(A6), [1] On the basis of the first 15 orbits of the Galileo spacecraft the composition of the energetic ion population of the Jovian magnetosphere is studied on a global scale. Analyzing data from the ... [more ▼] [1] On the basis of the first 15 orbits of the Galileo spacecraft the composition of the energetic ion population of the Jovian magnetosphere is studied on a global scale. Analyzing data from the energetic particles detector onboard Galileo, we study the relative ion abundance ratios of S/O, S/He, O/He and p/He at various energy/ nucleon values. Prominent enhancements of S/O, S/He, and O/He abundance ratios are observed in the predawn sector and are associated with substorm-like events in the Jovian magnetotail. During these reconfiguration events, frequent small-scale variations of the south-north component of the magnetic field are present. Acceleration by such magnetic field variations is examined as a possible mechanism for particle energization in that region. When the timescale of the magnetic field variation is comparable to the particle gyro period, the particle is accelerated by the induced electric field. It is shown that, during the Jovian substorm-like events, the heavier ions are more efficiently energized than the lighter leading to the observed ion abundances. Ion composition measurements in other parts of the magnetosphere have shown quasiperiodic 3-day modulations suggesting that the internally driven processes affect the ion composition in the whole magnetosphere. [less ▲] Detailed reference viewed: 10 (3 ULg)Internal control of the magnetospheric processes at Jupiter and SaturnRadioti, Aikaterini ; ; et alConference (2006) Detailed reference viewed: 2 (0 ULg)Temporal variability of the ion abundance ratios in the Jovian magnetosphereRadioti, Aikaterini ; ; et alConference (2006) Ion abundance ratios in the Jovian magnetosphereRadioti, Aikaterini ; ; et alin Journal of Geophysical Research - Space Physics (2005), 110 Galileo, as the first orbiting spacecraft around Jupiter, provides the opportunity to study globally the composition of the energetic ion population in the equatorial plane of the Jovian magnetosphere ... [more ▼] Galileo, as the first orbiting spacecraft around Jupiter, provides the opportunity to study globally the composition of the energetic ion population in the equatorial plane of the Jovian magnetosphere. This enables us to derive the relative importance of the various sources and sinks of plasma and energetic particles in the largest magnetosphere of our solar system. In this paper we use data from the Energetic Particles Detector (EPD) on board Galileo and derive relative ion abundance ratio maps of S/O, S/He, O/He, and p/He. We extend the previous work in terms of global coverage, species, and energy range. In addition we compare them with previous results and especially with those derived on board Voyager 2. We found that the S/O abundance ratio is relatively constant throughout the magnetosphere decreasing slightly with radial distance. Within the error bars the S/O ratios could be reproduced. Only a minor energy dependence is observed for this ratio pointing to a common source for both ions. The S/He-, O/He-, and p/He-ratios decrease with increasing radial distance, furthering the notion that sulfur, oxygen, and protons originate mainly from a source within the Jovian system, in contrast with helium, which originates from the solar wind. A spectral kink observed at energies of several 100 keV/ nuc for all species and most pronounced for helium explains the observed energy dependence of the ratios relative to helium. Differences in the abundance ratios up to more than one order of magnitude between sequential orbits are evidence of large temporal variations taking place in the Jovian magnetosphere. These variations and the strong energy dependence can explain the differences between the results derived from Galileo EPD measurements and those from Voyager data. [less ▲] Detailed reference viewed: 8 (0 ULg)Ion stochastic acceleration by Alfven waves; Implications for energetic ion composition in the Jovian magnetosphereRadioti, Aikaterini ; ; et alPoster (2005) Detailed reference viewed: 3 (0 ULg)Jovian ion energy spectra - Ion stochastic acceleration by Alfven wavesRadioti, Aikaterini ; ; et alConference (2005) Detailed reference viewed: 2 (0 ULg)Energy dependence of the Jovian ion abundance ratios - Ion accelerarion by Alfven wavesRadioti, Aikaterini ; ; et alConference (2005) Ion abundance rations of the Jovian magnetosphereRadioti, Aikaterini ; ; et alConference (2004) Detailed reference viewed: 2 (0 ULg) |
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