Fig. 16.

Proton trapping and acceleration at an isolated dipolarization front. Panels (a)–(d) show snapshots of the proton trajectory at different times of the simulation projected onto the equatorial plane; each snapshot shows the trajectory from T = 0 to the instance indicated by the magenta circle. Evolution of particle energy along the trajectory is indicated with color. The external magnetic field, $\mathrm{\Delta }$B$z$, is shown with color. Contours of constant total magnetic field for each snapshots are shown with black lines (from Ukhorskiy et al. 2018)