Charged particle acceleration by induction electric field in Neptune magnetotail

The precession of the Neptune magnetic dipole leads to strong dynamics of the magnetosphere and results in continuous transformation from the “Earth-like” configuration to the “pole-on” one and vice versa. In the present work we use simple model of the Neptune magnetotail to investigate the influence of magnetotail topology transformation on particle acceleration and transport through the tail. Energy spectra are obtained for protons penetrating from the solar wind and heavier ions N + from the Neptune ionosphere. We have found that protons and heavier ions are accelerated up to ∼ 330 keV and ∼ 150 keV , respectively. More particles are accelerated and leave the tail during transformations from the “pole-on” configuration to the “Earth-like” one than during inverse transformations. We have shown that the dusk–dawn convection field is responsible for particle leaving through the dawn flank. We briefly compare our results with Voyager-2 observations.