Experimental protocol and critical assessment of the Pockels method for the measurement of surface charging in a dielectric barrier discharge

摘要

The behaviour of dielectric barrier discharges (DBDs) is controlled by the successive charging and discharging of the dielectric surface. Measuring the space and time evolution of the charges on the dielectric layers is of great interest to optimize these discharges and better understand the transition from homogeneous to filamentary regimes and the formation of patterns. Such measurements can be performed using a diagnostic technique based on the Pockels effect, where an electro-optic crystal is used as the dielectric layer of a DBD and as a probe of the electric field across the layer. The surface charge density is related to this field and can, in some limited conditions, be simply deduced from it. The principle of this technique is relatively simple but the necessary care that must be taken in its application to DBDs has not been described in detail in the literature. The aim of this paper is to provide a critical assessment of the method and to illustrate its application in the case of a low pressure dielectric barrier glow discharge.