Two-dimensional magnetic energy spectra of a peak at normalised wavenumber 8. Red regions are at higher energies compared to the blue ones. The parallel and perpendicular wavenumbers are given as absolute values. The time development is shown for mid-drive (Δt ≈ 0.85s), max-peak (Δt ≈ 1.7s) and the decay 17 s after the driving. The colours of the contours were normalised for comparison between the three plots. The colours indicate the logarithm of the total spectral energy. The simulation setup SI was used.