Corotation-bounce resonance of ions in Jupiter's magnetosphere

TL;DR

This paper presents evidence of simultaneous bounce-resonant acceleration of multiple ion species in Jupiter's magnetosphere, revealing a fundamental interaction between corotation and bounce motions of ions below 10 keV.

Contribution

It uncovers a previously unknown resonance process involving corotation and bounce motions of ions in Jupiter's magnetosphere.

Findings

Detection of banded energy distributions for multiple ion species.

Identification of bounce frequencies matching harmonic of corotation frequency.

Evidence of a fundamental, persistent ion acceleration process in Jupiter's magnetosphere.

Abstract

Banded energy distributions of H$^{+}$, O$^{++}$, S$^{+++}$, and O$^+$ or S$^{++}$ ions between 100 eV to ~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.