ion resonance acceleration by dipolarization fronts: analytic theory and spacecraft observation

In this paper, we consider the mechanism of ion acceleration by dipolarization fronts in the Earth's magnetotail. The statistics of dipolarization front observations by Interball-tail have been collected from 1995 to 1998 (51 events). We demonstrate that near dipolarization fronts bursts of energetic ions are often observed with an average energy of about 100–200 keV. We develop the analytical model of the ion resonance interaction with dipolarization fronts to describe the observed acceleration. We compare the model and the observations to estimate the width of fronts along the dawn-dusk direction, R_y. The mean value is ⟨ R_y ⟩ ~6 R_E.