A comparative study on the frequency effects of the electrical characteristics of the pulsed dielectric barrier discharge in He/O2 and in Ar/O2 at atmospheric pressure

Abstract

In this work, a comparative study on the frequency effects of the electrical characteristics of the pulsed dielectric barrier discharges in He/O2 and in Ar/O2 at atmospheric pressure has been performed by means of the numerical simulation based on a 1-D fluid model at frequencies below 100 kHz. The frequency dependences of the characteristic quantities of the discharges in the two gases have been systematically calculated and analyzed under the oxygen concentrations below 2%. The characteristic quantities include the discharge current density, the averaged electron density, the electric field, and the averaged electron temperature. Especially, the frequency effects on the averaged particle densities of the reactive species have also been calculated. This work gives the following significant results. For the two gases, there are two bipolar discharges in one period of applied voltage pulse under the considered frequency range and oxygen concentrations, as occurred in the pure noble gases. The frequency affects the two discharges in He/O2, but in Ar/O2, it induces a strong effect only on the first discharge. For the first discharge in each gas, there is a characteristic frequency at which the characteristic quantities reach their respective minimum, and this frequency appears earlier for Ar/O2. For the second discharge in Ar/O2, the averaged electron density presents a slight variation with the frequency. In addition, the discharge in Ar/O2 is strong and the averaged electron temperature is low, compared to those in He/O2. The total averaged particle density of the reactive species in Ar/O2 is larger than those in He/O2 by about one order of magnitude.