Relaxation of the electron energy in the post-discharge of an He-N-2 mixture

The electron energy distribution function in the post-discharge of a pulsed RF discharge has been measured by means of a time-resolved Langmuir probe technique, in an He-N-2 mixture at 0.2 and 0.5 Torr. Within the limits of the technique, it is shown that the presence of N-2 has the effect of slowing the decay of the electron average energy, this being more evident the higher is the N-2 content of the mixture. This phenomenon can be ascribed to the presence of long-lived vibrational or electronic states in the afterglow which release their energy to the electron gas.