Logarithm of the horizontal kinetic energy spectrum normalized by 2e₁₁ (top panel) and the total normalized turbulent kinetic energy spectrum normalized by e_t, 0 (bottom panel) vs. the logarithm of the horizontal wave-number in the HI zone (blue) and the HeII zone (orange) for different models: v036_6_150x20 (solid line); v036_6_150x40 (dotted line); v036_12_150x60 (dashed line); v036_45_150x20 (dash-dotted line). We show the Kolmogorov −5/3 slope as a dashed black line for comparison. The low-resolution model does not show the granulation energy cascade as it is damped already at the energy maximum. Simultaneously, the amount of total kinetic energy is lower in the HeII region, and L₁₁ and L₂₂ are larger. Thus, the spectrum has κ_max at a lower wavenumber.