Energy time-history and position of one of the most accelerated particles in the simulations. (a): total (black), perpendicular (red), and parallel (blue) energy for one of the most accelerated particles in the simulations. (b)–(d): particle position during the shaded times in (a) colored by particle energy. In the background, the magnetic field magnitude is shown in gray scale for the z = L_box/2 plane.