Corotation-Bounce Resonance of Ions in Jupiter's Magnetosphere

Banded energy distributions of H⁺, O⁺⁺, S⁺⁺⁺, and O⁺ or S⁺⁺ ions between 100 eV and ∼20 keV are consistently observed in Jupiter's magnetosphere mapping to M-shells between M = 10–20. The bands correspond to flux enhancements at similar speeds for different ion species, providing the first evidence of simultaneous bounce-resonant acceleration of multiple ion species in Jupiter's magnetosphere. Ion enhancements occur for energies at which the bounce frequencies of the trapped ions matched integer harmonics of the System-III corotation frequency. The observations highlight a previously unknown interaction between corotation and bounce motion of <10 keV energy ions that is a fundamental and persistent process occurring in Jupiter's magnetosphere.