介质阻挡放电中过零放电特性研究

Role of Streamers Before Voltage Reversal in Dielectric Barrier Discharges

大气压下空气介质阻挡放电通常表现为丝状放电模式,但在放电间隙较短(约1 mm)的条件下增大放电电压的幅值,丝状模式就能转化为均匀放电模式。实验研究发现,该放电机制仍然是流注放电,而放电模式的转化与过零放电即外加电压反向之前的流注放电有关。随着外加电压幅值的不断增大,前半周期放电后的残余电场随之增强,导致在外加电压反向之前本身的残余电场可引起气隙击穿。在放电间隙较小时,放电细丝密集,细丝之间的区域也存在相当数量的沉积电荷,过零流注放电将导致后续流注放电位置发生改变,从而妨碍放电细丝的形成。

The dielectric barrier discharge at atmospheric pressure is widely used in multiple technological applications, such as ozone production, gas cleaning, surface treatment, production of plasma display panel cells, etc. The dielectric barrier discharge of atmospheric gas is usually filamentary, but homogeneous dielectric harrier discharge allows one to treat surfaces more uniformly. Moreover, the homogeneous discharge parameters can be controlled in space and time, whereas the parameters of a filamentary discharge are stochastic. In atmospheric air, the transition from filamentary mode to uniform mode can be observed provided that the discharge gap is very short（-1 mm） and the magnitude of the applied voltage is relatively large This paper presents some experimental results of the characteristics of this uniform discharge and proposes a new explanation for the mechanism of its formation. It is found that this kind of uniform discharge is still the streamers, and the streamers before the voltage reversal play an important role in the formation of this kind of uniform discharge. The increase of the voltage magnitude will lead to a stronger remnant electric field of the discharge, thus the moment of discharge breakdown is shifting towards the time before the applied voltage polarity reverses. If the number density of the filaments is large enough and the distribution of the deposited charges on the dielectric surfaces is relatively even, the effects of those streamers on the remnant electric field will cause their subsequent steamers to develop in new spots each time the voltage polarity changed, therefore, the uniform discharge can be obtained.