This work is focused on the analysis of the oscillation character of electron temperature, electron density and concentration of excited atoms under plasma relaxation conditions. A theoretical model of this phenomenon is presented, which is based on self-consistent balance
equations as a dynamic system.
It is shown that in case of a low ionisation degree the oscillations may arise when the relaxation frequencies of free electron energy losses, which are determined elastic electron-atom collisions, the radiative population of resonant levels and their quenching due to inelastic collisions are almost equal to each other. In case of rather high ionisation degree the self-oscillations can arise when the energy losses of free electrons are determined by electron-ion collisions.