针-板和针-水电极大气压直流辉光放电的光谱特性

利用光谱学方法，对针-水电极和针-板电极直流辉光放电特性进行了比较研究。结果发现两种装置产生的放电都有明显的分区现象, 从阴极到阳极分别为负辉区、阴极暗区、正柱区和阳极辉区。针-板电极放电中可以清晰地观测到阳极暗区, 而针-水电极放电阳极暗区不明显。对比两种放电的伏安特性曲线，发现放电电压均随电流增大而减小，但相同电流下针-水电极间的电压大于针-板电极间的电压。由于伏安特性具有负斜率，且放电电流密度介于10-5～10-4 A·cm-2，说明两种装置中的放电均处于正常辉光放电阶段。在正常辉光放电的范围内比较两种放电的发射光谱, 发现发射光谱中都包含N₂的第二正带系(含波长为337.1 nm的谱线)和N+₂的第一负带系(含波长为391.4 nm的谱线)，但相对强度不同。利用光谱学方法对放电发射谱的谱线强度比I_391.4／I_337.1和振动温度进行了空间分辨测量，发现相同位置处针-水电极放电的谱线强度比要比针-板电极放电的大，并且相同位置处针-水电极放电的振动温度高。

Spectroscopic Characteristics of DC Excited Atmospheric Pressure Glow Discharges Generated in a Needle-Plate Electrode Device and a Needle-Water Electrode One

Glow discharge characteristics in two discharge devices, i.e. in a needle-plate electrode geometry and a needle-water electrode one were compared by using spectroscopic method. Results show that the different emission regions were found in both discharges generated by the two devices. From the cathode to the anode, there are a cathode glow region, cathode dark glow, a positive column, and an anode glow region. The anode dark region can be clearly discerned in the glow discharge in the needle-plate electrode device, while it almost cannot be found in the needle-water electrode discharge. Comparing the current-voltage characteristics of the two glow discharges, it was found that the voltage across the electrodes decreases with increasing the discharge current in both discharge devices, while the voltage in the needle-water glow discharge is higher than that of the needle-plate one at the same current value. The current-voltage curves have a negative slope and their current densities lie in the range from 10-5 to 10-4 A?cm-2, which indicates that a normal glow discharge mechanism was involved in the two discharges. Comparing the optical spectra scanning from 300nm to 800nm and emitted from the whole normal glow discharge in the two electrode devices, similar spectral lines from the two discharges can be found on the optical emission spectrum, including the second positive system of nitrogen molecules (337.1nm) and the first negative system of nitrogen molecular ions (391.4nm). However, the intensity ratio of spectral lines is different. The intensity ratio (391.4nm to 337.1nm) and vibrational temperature were investigated at different locations. It was found that the intensity ratio of the needle-water electrode discharge is larger than that of the needle-plate electrode discharge at the same location. Furthermore, the vibrational temperature in the needle-water electrode discharge is higher than that of the needle-plate one at the same location.