Spatial distributions of quantities governing acceleration mechanisms at t = 130 s. Panels (a)–(c) show the factors for Fermi reflection: (a) vertical plasma flow (u_ey), (b) magnetic curvature ([(b · ∇)b]_y), and (c) the resulting acceleration rate. Panels (d)–(f) show the factors for betatron acceleration: (d) transverse plasma flow (u_ex), (e) magnetic field gradient (∂B/∂x), and (f) the resulting acceleration rate. Black boxes mark the selected electron trajectory regions from Figure 2.