Experimental study on the transition of the discharge modes in air dielectric barrier discharge

Dielectric barrier discharge (DBD) usually manifests as a filamentary streamer discharge in atmospheric air, which limits its industrial application prospect, and the homogeneous DBD with homogeneity and stability has a wider application prospect in the field of material surface treatment, thin film deposition and plasma sterilization than the filamentary one. In order to study the generation condition for the homogeneous DBD in atmospheric air, the characteristics of DBD in the pressure range from 10 Pa to atmospheric pressure are experimentally studied by measuring their electrical discharge parameters and observing their light emission phenomena. The transition of the discharge mode with a change in pressure is observed, and a critical pressure value for generating the homogeneous DBD is obtained, with the influence of barrier materials, their thickness and surface roughness and the air gap distance on the critical pressure values being investigated experimentally. The experimental results show that three characteristic types of discharge modes, including the homogeneous mode, the mixed mode and the filamentary mode, are observed with an increase in pressure. The dielectric barrier plays an important role in the generation of the homogeneous DBD, and the critical pressure values will be larger if the barrier thickness is smaller and the air gap distance is smaller. The critical pd values (the product of gas pressure p and gas gap width d) are almost constant with the change in the air gap distance, which can be improved by reducing the thickness of the dielectric barrier and by selecting appropriate barrier materials, as is validated by the experimental results.