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 backgr ound current increased with decreasing bead size and decreased as the separ ation between the disc and the electrode increased. The current had an extr emely slow and nonlinear transient behaviour when the de high-voltage sourc e was switched on. The frequency of the current pulses decreased with incre asing bead size and disc-electrode separation. The average amplitude of the pulses, in contrast, increased with increasing bead size and disc-electrod e separation. A significant dependence of the properties of the current pul ses on the polarity of the applied voltage was observed, although the de cu rrent was almost independent of the polarity. It was found that the enhance ment of the electric field near the contact points between the electrode an d the beads, where the current concentrates, initiates the discharge. The d ensity of ozone produced by the discharge was also measured. Damage to the discs by the discharge was also observed, thereby altering the properties o f the discharge.