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Jupiter's ion radiation belts inward of Europa's orbit
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  • Peter Kollmann,
  • George Clark,
  • Christopher P. Paranicas,
  • Barry H. Mauk,
  • Elias Roussos,
  • Quentin Nénon,
  • Henry Berry Garrett,
  • Angélica Sicard,
  • Dennis K Haggerty,
  • Abigail Mary Rymer
Peter Kollmann
The Johns Hopkins University Applied Physics Laboratory

Corresponding Author:[email protected]

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George Clark
Johns Hopkins University Applied Physics Laboratory
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Christopher P. Paranicas
Johns Hopkins University
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Barry H. Mauk
Johns Hopkins University
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Elias Roussos
Max Planck Institute for Solar System Research
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Quentin Nénon
University of California, Berkeley
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Henry Berry Garrett
California Institute of Technology
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Angélica Sicard
ONERA, the French Aerospace Lab
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Dennis K Haggerty
Johns Hopkins University Applied Physics Laboratory
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Abigail Mary Rymer
Johns Hopkins Applied Physics Laboratory
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Jupiter is surrounded by intense and energetic radiation belts, yet most of the available in-situ data, in volume and quality, were taken outside of Europa’s orbit, where radiation conditions are not that extreme. Here we study measurements of ions of tens of keV to tens of MeV at <10 Jupiter radii (RJ) distance to Jupiter, therefore inward of the orbit of Europa. Ion intensities drop around 6RJ, near Io’s orbit. Previous missions reported on radiation belts of tens and hundreds of MeV ions located between 2 and 4 RJ. Measurements of lower energies were not conclusive because high energy particles typically contaminate the measurement of lower energy particles. Here we show for the first time that ions in the hundreds of keV range are present and suggest that ions may extend even into the GeV range. The observation of charged particles yields information on the entire field line, not just the local field. We find that there is a region close to Jupiter where no magnetic trapping is possible. Jupiter’s innermost radiation belt is located at <2RJ, inward of the main ring. Previous work suggested that this belt is sourced by reionized energetic neutral atoms coming steadily inward from distant regions. Here we perform a phase space density analysis that shows consistency with such a local source. However, an alternative explanation is that the radiation belt is populated by occasional strong radial transport and then decays on the timescale of years.
Apr 2021Published in Journal of Geophysical Research: Space Physics volume 126 issue 4. 10.1029/2020JA028925