Acceleration of ions in the Jupiter magnetotail: Particle resonant interaction with dipolarization fronts

In this paper we describe ion acceleration in the Jupiter magnetotail due to resonant interaction with dipolarization fronts. We present Galileo observations of dipolarization fronts accompanied by observations of increased fluxes of high-energy protons and heavy ions. We develop the analytical model of ion interaction with dipolarization fronts embedded into the magnetotail horizontal current sheet. This model predicts that the maximum energy gained by ions is W max ∼ H 0 3 / 4 L Ω x where H0 is an initial ion energy, L is a spatial scale of dipolarization fronts across the neutral plane of the horizontal current sheet, and Ω x is a Larmor frequency of ions in the boundary of the horizontal current sheet. Presented model can describe acceleration of 10–100 keV ions up to 50–300 keV for typical conditions of the Jupiter magnetotail. Analytical estimates are supported by numerical calculations of test-particle trajectories. We reproduce observed increases of proton fluxes up to one order of magnitude in the vicinity of dipolarization fronts.