氮气中空心阴极放电条纹的发光特性

The Optical Characteristics of Hollow Cathode Discharge Striations in Nitrogen

利用发射光谱法,在氮气环境下研究了圆柱型空心阴极放电条纹的特性。测量得到了气压为20Pa,放电电流为1.3mA时条纹区的发射光谱,结果表明发射光谱主要为氮分子的第一正带系(B3Пg→A3Пu)和第二正带系(C3Пu→B3Пg)。利用双原子光谱发射理论,计算得到了氮分子振动温度的空间分布特性。结果表明光谱线强度呈周期性分布,明纹中心处的谱线强度高于暗纹中心处的谱线强度。明纹中心处的N2分子振动温度为3 500～4 400K,并且从阴极到阳极,明纹中心处光谱线强度和分子振动温度逐渐下降。同时测量得到了放电电流为1.0和1.5mA时的发光条纹特性,研究了放电电流对条纹特性的影响。随着放电电流的增加,明纹中心处的分子振动温度升高,条纹间距增加。另外,利用测量得到的发光条纹,计算得到了条纹区的平均约化电场强度为44～49m-1·Pa-1,并且由阴极向阳极逐渐降低。对于揭示气体放电中发光条纹的形成机理和促进空心阴极放电的稳定性有重要的参考价值。

The characteristics of striations in cylindrical hollow cathode discharge were investigated experimentally. The spectra of striations were measured at a pressure of 20 Pa in a discharge of 1.3 mA, in which the main spectra are the emission spectrum lines of the N2 first positive band（B3∏g→A3∏a）and second positive hand system （C3∏u→B3∏g）. The spatial characteristics of vibrational temperature of N2 were calculated based on the theory of double molecular spectrum. It is shown that the emission in- tensity exhibits a periodic structure with an unequal magnitude, and the spectral intensity of bright striation is higher than that of dark striations. The vibrational temperature of bright striation is of the value of 3500--4400K, moreover the vibrational temper- ature in the bright regions decreases from the cathode to the anode. In addition, the characteristics of striations at 1.0 mA and 1.5 mA were obtained, and the influence of discharge current on the striations was investigated. It is shown that the vibrational temperature and the distance between two striations increase. Finally the reduced electric field was calculated, which is about 44 -49 m-1. Pa-1 , moreover it decreases with the increase in discharge current. The results are very useful for understanding the mechanism of discharge striations and for improving the stability of hollow cathode discharge.