An investigation of a dc dielectric barrier discharge using a disc of glass beads

We discuss the properties of a de discharge which occurs at the interfaces between a disc of fused glass beads and parallel electrodes. The discharge consisted of a large number of microdischarges. The discharge current had a large number of pulses superimposed on a de background current. The background current increased with decreasing bead size and decreased as the separation between the disc and the electrode increased. The current had an extremely slow and nonlinear transient behaviour when the de high-voltage source was switched on. The frequency of the current pulses decreased with increasing bead size and disc-electrode separation. The average amplitude of the pulses, in contrast, increased with increasing bead size and disc-electrode separation. A significant dependence of the properties of the current pulses on the polarity of the applied voltage was observed, although the de current was almost independent of the polarity. It was found that the enhancement of the electric field near the contact points between the electrode and the beads, where the current concentrates, initiates the discharge. The density of ozone produced by the discharge was also measured. Damage to the discs by the discharge was also observed, thereby altering the properties of the discharge.