Resolution requirements for late-stage FMS wave generation. The bottom panel is as in Figure 3 but for a fixed injection amplitude (b _eq ≈ 0.2) and varying numerical resolution. The top panel shows the excess magnetospheric energy ΔE _tot = E _tot − E _dip, normalized to the injected Alfvén wave energy E _inj. For an injection colatitude of θ _s = 45°, field lines have a length of L ≈ 3.5R _*; we denote the light-crossing time of this length as T _bounce.