Two distinct proton populations are observed over Jupiter's southern polar cap: a ~1 keV core population and ~1-300 keV dispersive conic population at 6–7 R_J planetocentric distance. We find the 1 keV core protons are likely the seed population for the higher-energy dispersive conics, which are accelerated from
a distance of ∼3-5 R_J. Transient wave-particle heating in a “pressure-cooker” process is likely responsible for this proton acceleration. The plasma characteristics and composition during this period show Jupiter's polar- most field lines can be topologically closed, with conjugate magnetic footpoints connected to both hemispheres. Finally, these observations demonstrate energetic protons can be accelerated into Jupiter's magnetotail via wave- particle coupling.

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