介质阻挡放电中超四边斑图沿面放电的光谱研究

Study on Square Super-Lattice Pattern with Surface Discharge in Dielectric Barrier Discharge by Optical Emission Spectra

利用水电极介质阻挡放电装置,在氩气和空气的混合气体中,首次观察到了超四边斑图沿面放电,它是由中心点和暗点组成的。通过观察普通相机的斑图照片,可以发现中心点位于周围四个暗点的中心处。利用高速录像机对斑图进行短曝光拍摄,观察发现中心点对应体放电,暗点对应沿面放电,暗点由这些沿面放电形成。中心点和暗点的亮度有所不同,这说明中心点和暗点的等离子体状态可能不同。采用发射光谱法,研究了超四边斑图沿面放电的的中心点和暗点的等离子体参量随氩气含量的变化趋势。利用氮分子第二正带系(C^3Π_u→B^3Π_g)发射谱线,计算得出了中心点和暗点的分子振动温度;然后通过氩原子696.57nm(2P_2→1S_5)谱线的展宽,研究了中心点和暗点的电子密度。实验结果表明:在相同氩气含量下,暗点的分子振动温度和电子密度均高于中心点的相应等离子体参量;在其他实验条件不变的情况下,随着氩气含量从90%增大到99.9%,中心点和暗点的分子振动温度和电子密度均逐渐增大。结果表明中心点和暗点的等离子状态不同,说明二者的放电机制可能不同。

Square super-lattice pattern with surface discharge consisting of central spots and dim spots is firstly observed in the mixture of argon and air by using a dielectric barrier discharge device with water electrodes.By observing the image,it is found that the central spot is located at the centriod of its surrounding four dim spots.The short-exposure image recorded by a high speed video camera shows that the dim spot results from the surface discharges（SDs）.The brightness of the central spot and is quite different from that of the dim spot,which indicates that the plasma states of the central spot and the dim spot may be differentiated.The optical emission spectrum method is used to further study the several plasma parameters of the central spot and the dim spot in different argon content.The emission spectra of the N_2 second positive band（C^3Π_u → B^3Π_g）are measured,from which the molecule vibration temperatures of the central spot and the dim spot are calculated respectively.The broadening of spectral line 696.57nm（2P_2→1S_5）is used to study the electron densities of the central spot and the dim spot.It is found that the molecule vibration temperature and electron density of the dim spot are higher than those of the central spot in the same argon content.The molecule vibration temperature and electron density of the central spot and the dim spot increase with the argon content increasing from 90%to 99.9%.The surface discharge induced by the volume discharge（VD）has the determinative effect on the formation of the dim spot.The experimental results above play an important role in studying the formation mechanism of surface discharge of square super-lattice pattern with surface discharge.In addition,the studies exert an influence on the application of surface discharge and volume discharge in different fields.