介质阻挡放电中同心圆环斑图的产生机理

在氩气空气混合气体介质阻挡放电中, 得到了同心圆环斑图. 采用高速照相机拍摄了同心圆环斑图在外加电压半周期时间尺度内的放电照片, 发现放电丝是构成同心圆环斑图的基本单元. 通过对比高速照相机拍摄的连续三个正半周期和负半周期的六张放电图像, 证实肉眼看到的同心圆环斑图是由不同半周期放电位置和不同的大量放电丝长时间积累叠加产生的. 随着外加电压升高, 同心圆环斑图会演化成螺旋波, 然后重新转变成同心圆环斑图. 通过对两种斑图的形成和转化特点进行分析, 推断该螺旋波应具有和同心圆环斑图相似的动力学机理. 计算了两种斑图的放电功率, 发现功率随外加电压增加近似满足线性增长的关系. 利用相关计算的方法计算并对比了不同延迟时间下两种斑图的互相关系数, 结果表明, 同心圆环斑图的互相关系数相对较低且无明显规律, 螺旋波的互相关系数稍高且具有随延迟时间增大呈现振荡的特点.

Formation mechanism of concentric-ring pattern in dielectric barrier discharge

Concentric-ring pattern is observed in an Ar/air mixture dielectric barrier discharge. The discharge images within one half voltage circle are taken by an intensified-charge coupled device camera, indicating that the discharge filaments are the basic units of the concentric-ring pattern. By comparing the six instantaneous images corresponding to three successive positive and negative half voltages, it is proved that the concentric-ring pattern seen with naked eyes is formed by the numerous discharge filaments located at different positions during successive acquisition intervals. With applied voltage increasing, concentric-ring pattern can transform into spiral, and then into concentric-ring pattern again. By analyzing the features of formation and transformation of these two patterns, it is inferred that the two patterns have similar dynamic mechanisms. Discharge powers of concentric-ring pattern and spiral are calculated respectively, and the results show that the power increases linearly approximately with applied voltage increasing. The correlation coefficients of concentric-ring pattern are compared with those of spiral, and the results show that the correlation coefficient of concentric-ring pattern is relatively low and irregular, while the correlation coefficient of spiral is relatively high and has an oscillatory characteristic.