Influence of dielectric and electrode on DBD at atmospheric pressure

Summary form only given. Experiments of DBD in a 2-mm air gap were performed. When fine wire mesh electrodes covered with 0.1 mm PET film and 50 Hz AC power source were used, the breakdown voltage of the gap is 6.4 kV, about 1.3 W lower than that using plate electrodes covered with 1 mm quartz plate. The discharge using the mesh electrodes covered by PET film looks more uniform than that using plate electrodes covered by quartz plate. Even when a uniform discharge was observed, multipulses of discharge current in the half cycle of the applied voltage were recorded, which indicates the discharge is filament discharge rather than glow discharge. When 50 Hz source is replaced by a high frequency source, the uniform discharge turns to strong filaments. It may be explained by the thermal instability. The reason for the mesh electrodes covered by PET film making discharge more uniform is still not fully understood. The calculations of the electric field in the gap show that the wire mesh electrodes couldn´t enhance much the gap field close to the PET film when the film is thicker than 0.05 mm. In helium APGD experiments with one electrode uncovered by dielectric it was found that discharge current peak is higher and breakdown voltage of the gap is lower in the half voltage cycle when the uncovered electrode was operated as cathode. It seems not to be closely related to the second electron emission from the uncovered cathode since no much differences were found when the uncovered electrode of stainless steel was replaced by an aluminium one