大气压针–板介质阻挡放电丝的时空演化

Spatial-temporal Evolution of Dielectric Barrier Discharge Filament in Pin-to-plate Geometry at Atmospheric Pressure

为了分析在小间隙下介质阻挡放电丝的生成机理,以体放电和沿面放电为研究对象,探讨了其在流光放电机制下的形成过程。采用针–板介质阻挡放电装置,在大气压氩气中形成了稳定的放电。利用电学和光学方法,研究发现,随外加电压的增加放电由单丝发展为多丝,在此过程中,发光脉冲的强度增加,且半周期的发光脉冲个数也增加。对于正半周期放电的起始电压,发现其随氩气体积流量的增加而增加,随外加电压峰值的增加而减小。在纳秒曝光时间尺度下,利用高速相机对单丝放电在一个外加电压周期的时间演化过程进行了研究。发现该介质阻挡放电由气隙中的体放电和电介质板上的沿面放电两部分组成。不论电压正半周期还是电压负半周期,体放电均源于正流光机制,而沿面放电的机制与电极的极性有关。瞬时阴极上的沿面放电对应正流光传播过程,而瞬时阳极对应负流光机制。

In order to analyze the formation mechanism of the dielectric barrier discharge filament in the small gap, the discharge forming process of streamer discharge mechanism was studied by taking volume discharge and surface discharge as the research object. After using a dielectric barrier discharge device in a pin-to-plate geometry, stable discharge was generated in atmospheric pressure argon. It is found that the discharge transits from a mono-filament into a multi-filament with increasing the peak value of the applied voltage. With increasing the peak voltage, the intensity of the total light emission signal from the discharge increases as well as the light pulse number per half voltage cycle. Moreover, the inception voltage in the positive half cycle increases with increasing the argon flow rate, and decreases with increasing the peak value of applied voltage. Temporal evolution of the mono-filament discharge is investigated during one voltage cycle by an high-speed camera with an exposure time of several nanoseconds. It is found that the discharge consists of volume discharge in the air gap between the two electrodes and surface discharges on the dielectric plates. The volume discharge corresponds to a positive streamer mechanism for both the positive and the negative half voltage-cycles, however, the discharge mechanism of the surface discharge is related with the polarity of the electrode. The surface discharge on the instantaneous cathode corresponds to a positive streamer, and a negative streamer mechanism is involved for the surface discharge on the instantaneous anode.