Dynamic behaviour of an oxygen dc discharge

The dynamic behaviour of a positive column oxygen plasma is investigated both experimentally and theoretically. In the experiment the response of the discharge current to small external perturbations of the electrical field is measured. Using these data the electrical impedance of the plasma is obtained dependent on the frequency of the external perturbation. A drift approximation model is presented, which covers the experimental findings over a wide range of the perturbation frequency. It appears that the influence of the fluctuations of the neutral species is negligible and the dynamic behaviour of the plasma is mostly governed by the charged particles. This provides a simple expression for the plasma impedance which allows the reaction rate and transport coefficients, as well as discharge parameters, to be validated.