介质阻挡放电系统复合气隙中三种放电丝的光谱研究

介质阻挡放电系统（DBD）作为一个典型的非平衡气体放电系统，不仅在工业生产如低温等离子体生产和发光等方面被广泛应用，而且该系统表现出的非线性现象、自组织现象也吸引人们的关注。DBD系统中放电丝的等离子体参量受诸多因素影响，为了探究DBD系统的放电条件对等离子体参量的影响，该实验重新设计放电单元以保证在其他实验条件相同的情况下，对放电气隙间距和气体组分与等离子体参数之间的关系展开研究。本实验的放电单元为一个平板型玻璃框架气隙，该气隙由三个厚度均为1.2 mm，放电区域边长分别为40，30和20 mm的正方形玻璃框架复合而成，因此该放电气隙有三个放电区域，将此复合气隙放置于可调节气体成分和压强的真空室内，可以同时产生三种放电气隙间距分别为1.2，2.4和3.6 mm的等离子体放电丝。高速录像机拍摄的瞬时照片表明三种放电丝均为随机放电丝，即其放电类型均为流光放电。在垂直于放电气隙平面的方向设置光路，使用聚焦透镜获得清晰的成像，移动光纤探头实现空间分辨并采集数据。实验用光谱仪采集三种等离子体的氮分子第二正带系(C3Π_u→B3Π_u) 谱线，根据谱线强度计算得到各类放电丝的分子振动温度；利用谱线中包含的氮分子离子N+₂第一负带系谱线(391.4 nm)和氮分子第二正带系394.1 nm谱线强度的比值反应放电丝中电子平均能量；改变气室内氩气的含量，得到了三种等离子体的分子振动温度和电子平均能量的变化趋势。实验结果表明：在氩气含量0%~60%区间内，随着氩气含量的增加，三种等离子体的分子振动温度均先升高后降低，整体趋势表现为相同氩气含量下放电气隙间距越小分子振动温度越高，即1.2 mm气隙厚度中的放电丝的分子振动温度最高，2.4 mm气隙厚度次之，3.6 mm气隙厚度的最低；随氩气含量的增加放电丝的平均电子能量先升高后降低，氩气含量相同时气隙厚度越小的放电丝的电子平均能量越高，即1.2 mm气隙厚度中放电丝的电子平均能量最高，2.4 mm气隙厚度的次之，3.6 mm气隙厚度中的最低。实验结果对于研究DBD系统中等离子体参量、工业生产等方面具有重要的参考意义。

A Spectral Study of Three Kinds Discharge Filaments in a Multiplicate Gas Gap in Dielectric Barrier Discharge

Dielectric barrier discharge system (DBD) is a typical nonlinear gas discharge system, which not only has many applications in the industrial production such as low temperature plasma production and luminescence, but also has attracted widespread attention for its physical phenomenon such as non-linear phenomenon and self-organization phenomenon. In order to study the influence of gap distance and gas components on plasma parameters of discharge filaments in DBD system, a discharge cell is redesigned to ensure the other experiment conditions are the same. The discharge cell of this experiment is a flat multiplicate gas gap, which is composed of three thickness of 1.2 mm square glass frames with the discharge area side length as 40, 30 and 20 mm respectively. The multiplicate gas gap is placed in a vacuum chamber with adjustable gas composition and pressure, and three discharge filaments can be generated whose discharge gap distance is 1.2, 2.4 and 3.6 mm respectively. The instantaneous photos taken by high speed video camera indicate that the discharge types of three filaments are all streamer discharge. Arranging the optical path on the line perpendicular to the plane of gap, the focus lens is used to obtain a clear image, and optical fiber probe is moved to achieve spatial resolution acquisition data. The emission spectra of the N₂ second positive band (C₃Π_u→B₃Π_u) of the three filaments are collected in the experiment by spectrograph. The molecule vibration temperatures are calculated based on emission intensity; based on the relative intensity of the N+₂ line at 391.4 nm and the N₂ line at 394.1 nm, the electron average energy of the three kinds filaments are investigated. The changing trends of molecular vibration temperature and electron average energy are obtained by changing the Ar content. The results show that, with the increase of Ar content in the 0%~60% range, the molecule vibration temperatures show a trend from rise to drop; The overall trend is that the thinner the thickness of the discharge area, the higher the molecule vibration temperature of the filament in same Ar content. The molecule vibration temperature of the filament in 1.2 mm thick gap is the highest, the second in 2.4 mm thick gap, that in 3.6 mm thick gap is the lowest; As Ar content increases, the electron average energy increases and then decreases; the thinner the thickness of the discharge area, the higher the electron average energy of the filament in same Ar content. The electron average energy of the filament in 1.2 mm air gap thickness is highest, the second in the 2.4 mm gap thickness and the electron average energy of in the 3.6 mm gap thickness is lowest. This paper has an important reference significance for studying plasma parameters and industrial production in DBD system.