Left panels: simulated particle trajectories on the x−z plane. Right panels: corresponding energy gains vs. the x-coordinate of the particles. Panels a and b: sampled electrons in a simulation with d = 1 m, ξ_y = 0.1, B₀ = 100 G, E_y = 100 V m⁻¹. Light and dark blue lines represent the transit and bounced electrons, respectively. Panels c and d: sampled protons from the same parameters as in panels a and b, respectively. Panels d and f: trajectories of protons from a different simulation with a different d = 5 m. Panels g and h: trajectories of protons in a stronger guiding field, ξ_y = 1.0 and d = 1 m.