Top panel: time evolution of the different magnetic energies relative to their respective initial values: total (, black dashed line), of the potential magnetic fields (, purple line), of the non-solenoidal component (, orange line), and free magnetic energy (, red line). Bottom panel: relative magnetic helicity (, black dashed line) and its decompositions, Eqs. (11), (15), computed with the practical DeVore method: proper helicity (H_m, blue line), potential field helicity (H_p, purple line), and the mixed helicity (H_mix, green line); current-carrying helicity (H_j, red line), mutual helicity between potential and current-carrying fields (H_pj, orange line). In both panels, as in all figures hereafter, the dot-dashed vertical line at t = 920 indicates the transition between the quasi-ideal-MHD/energy accumulation and the non-ideal/jet-generation phases.