Top panel: trajectory in x-y plane of a particle with identical starting conditions in the presence and absence of a guide field, and with and without collisions. In each case, the particle started the simulation at x = −0.079, y = 0.046, z = 0. and with an initial energy of 1.26 keV. These are the same initial conditions as for the particle whose trajectory is plotted in Fig. 1. Second panel: energy gain vs time for a particle with identical starting conditions in the presence and absence of a guide field, and with and without collisions. Third panel: cosine of particle pitch angle vs. time for a particle with identical starting conditions in the presence and absence of a guide field, and with and without collisions. Bottom panel: x position at every 100th timestep for 100 particles with an identical set of starting conditions in the presence and absence of a guide field, and with and without collisions. For each panel, E = 0.001 and n_e = 10¹⁰ cm^-3, i.e. . The legend shown in the bottom panel applies to all panels.