介质阻挡放电中亮暗点超六边形斑图的光谱研究

摘要

采用双水电极介质阻挡放电装置 ,在空气和氩气的混合气体中 ,首次研究了由中心亮点和暗点组成的亮暗点超六边形斑图.通过观察斑图照片 ,可以发现暗点位于周围其他三个亮点的质心处 ,并且亮点和暗点的亮度有所不同 ,这说明亮点和暗点的等离子体状态可能不同.利用发射光谱法 ,研究了亮暗点超六边形斑图中亮点和暗点的等离子体参量随氩气含量的变化趋势.首先通过采集氮分子(N2 )第二正带系( C 3Πu→ B 3Πg )发射谱线 ,计算出了亮点和暗点的分子振动温度 ;之后利用氮分子离子391. 4 nm和氮分子394. 1 nm两条发射谱线的相对强度之比 ,得到了此斑图中亮点和暗点的电子平均能量 ;最后通过氩原子696. 57 nm(2P2 →1S5 )谱线的展宽 ,研究了此斑图中亮点和暗点的电子密度.实验结果发现 :在同一氩气含量下 ,亮暗点超六边形斑图中暗点的分子振动温度、电子平均能量和电子密度均高于亮点的相应等离子体参量 ;保持其他实验参数不变 ,随着氩气含量从70% 变化到95% ,亮点和暗点的分子振动温度和电子密度均是逐渐增大的 ,而电子平均能量则是逐渐减小的.亮点和暗点的等离子状态的不同 ,说明二者的放电机制可能不同.进一步采用高速录像机对斑图进行短曝光拍摄 ,发现亮点存在沿面放电 ,这些沿面放电交汇形成暗点.%The hexagonal super-lattice pattern composed of the light spot and the dim spot is firstly observed and investigated in the discharge of gas mixture of air and argon by using the dielectric barrier discharge device with double water electrodes .It is found that the dim spot is located at the center of its surrounding three light spots by observing the discharge image .Obviously , the brightness of the light spot and the dim spot are different ,which indicates that the plasma states of the light spot and the dim spot may be different .The optical emission spectrum method is used to further study the several plasma parameters of the light spot and the dim spot in different argon content .The emission spectra of the N2 second positive band( C3Πu → B3Πg )are meas-ured ,from which the molecule vibration temperatures of the light spot and the dim spot are calculated .Based on the relative in-tensity ratio of the line at 391.4 nm and the N2 line at 394.1 nm ,the average electron energies of the light spot and the dim spot areinvestigated.Thebroadeningofspectralline696.57nm(2P2 →1S5)isusedtostudytheelectrondensitiesofthelightspot and the dim spot .The experiment shows that the molecule vibration temperature ,average electron energy and the electron densi-ty of the dim spot are higher than those of the light spot in the same argon content .The molecule vibration temperature and elec-tron density of the light spot and dim spot increase with the argon content increasing from 70% to 95% ,while average electron energies of the light spot and dim spot decrease gradually .The short-exposure image recorded by a high speed video camera shows that the dim spot results from the surface discharges (SDs) .The surface discharge induced by the volume discharge (VD) has the decisive effect on the formation of the dim spot .The experiment above plays an important role in studying the formation mechanism of the hexagonal super-lattice pattern with light spot and dim spot .In addition ,the studies exert influences on the application of surface discharge and volume discharge in different fields .