Kinematics and dynamic of a randomly chosen sample of accelerated electrons. Panel a: Projection of electron trajectories onto the xz-plane, b) projection of the trajectories onto the xy-plane, and c) variations of the electron energies versus time for ξ = 1. Particles that start to be accelerated from different locations are displayed, and the initial location of each particle is denoted by the solid dot in plane a) and b).