Emission measure as a function of temperature at different instants, computed with temperature bins of width δT = 2.5 × 10⁵ K. The instant represented in the first three panels are, from top to bottom, t = 12 s (linear phase), t = 63 s (beginning of the saturation phase) and t = 125 s (early stage of the relaxation phase). The initially narrow (centred at T₀ = 1.2 × 10⁶ K) quickly extends into the higher temperature range as the plasma is strongly heated up during the initial phases. The EM profile then slowly converges to a power-law distribution EM ∝ T^-4.2 for T ≳ 2 × 10⁶ K. The last panel represents the relaxation phase at t ≈ 25τ_A for different cases: the standard case, a case with lower twist, a flux-rope twice as thin, a flux-rope twice as long, a weak-B, and a denser flux-rope. The dotted line indicates the slope of a curve EM ∝ T^-4 for visual reference.