Electron VDFs measured in BM averaged over the time periods corresponding to those shown in Figs. 5 and 7, in two representations highlighting departures from an isotropic distribution function. The first row displays the ‘scaled’ VDFs, where the values in each energy belt are scaled between 0 and 1. The second row displays the ‘normalised’ VDFs, where all values are normalised to the cut along the perpendicular direction. The magnetic-field direction is indicated with an arrow on the right-hand side and is aligned with the Y-axis. Black dashed semi-circles denote 1, 2, and 3 w_c.