Top panels: ionisation fraction of He III from 48.07 to 48.14 s. Time is increasing from the left to right side of the plots. Middle panels: temperature of the atmosphere. Bottom panels: energy balance of the atmosphere. The quantities displayed are the net energy gain (black), viscous heating (red), work done by pressure (green), radiative losses from transitions solved in radiative transfer (blue), optically thin losses (cyan), conduction (orange), the background-heating function (brown), and the energy input from beam electrons (grey).