Current Measurements and Diagnosis on Dielectric Barrier Discharge in a Coaxial Geometry at Atmospheric Pressure

Discharge current has been measured to diagnose the discharge modes of dielectric barrier discharge in a coaxial geometry through a mixture flows of argon and trace of air at one atmospheric pressure. Experimental results show that there are two discharge modes in the dielectric barrier discharge, corona discharge mode and glow discharge mode. The corona discharge only occurs in the tip of needle when the applied voltage not reaches the critical value for breakdown of the whole gas gap, and the current intensity is very low. The glow discharge is generated from the vicinity of needle tip to the entire tube gradually and turns uniform at last when the applied voltage exceeds the breakdown voltage for the whole gap, and the current intensity becomes higher. Under the same experimental parameters, the current intensity decreases with increasing the content of air. Experimental results also show that the critical value for breakdown of the whole gas gap becomes higher with increasing the content of air. However, it will decreases with increasing the gas velocity and the frequency of the applied voltage.