微空心阴极放电或微放电是一种能够实现高气压下放电的有效方法。利用不锈钢空心针作阴极,不锈钢网作阳极,进行了大气压氩直流微放电实验研究。测量了大气压氩微放电光谱,发现氩气的发射谱线主要集中在690~860nm范围,且全部为氩原子4p-4s的跃迁。实验研究了不同放电电流、气体压强、气体流量与谱线强度之间的关系,发现谱线强度随放电电流、气体流量增加均增加,而谱线强度随压强变化呈现不同特征:谱线强度随压强的增加先增加后降低,在13.3kPa时强度最大。此外,选用跃迁波长为763.51和772.42nm的两条光谱线,利用发射谱线强度比值法测量了氩气微放电等离子体的电子激发温度。结果显示,其电子激发温度处于2000-2800K之间,且随放电电流的增加而增加,随气体压强和气体流量的增加而降低。
Microhollow cathode discharge or microdischarge is an efficient method to generate plasma in a high pressure gas. In the present work, the emission spectra were observed in an atmospheric pressure argon direct current microdischarge apparatus, using a stainless steel capillary as the cathode, and a stainless steel mesh as the anode. It was shown that all of the seventeen argon spectral lines arose from electronically excited argon atom 4p-4s transition in the wavelength range of 690-860 nm. The depenadences of emission intensity on the discharge current, gas pressure and argon flow rate were investigated. The experimental results show that the emission intensity increased with discharge current from 1 to 6 mA and argon flow rate from 100 to 700 mL·min^-1. The dependence of emission intensity on gas pressure exhibited different characteristics, i.e. spectral signal increased with the gas pressure, but reached the intensity maximum at 13.3 kPa, and decreased afterwards. The argon atom spectral lines 763.51 and 772.42 nm were chosen to measure the electron excitation temperature by the intensity ratio of two spectral lines. The electron excitation temperature was determined to be in the range of 2 000 to 2 800 K in the atmospheric pressure argon microdischarge. The changes in electron excitation temperature with discharge current, gas pressure and argon flow rate were ex plored, indicating that the electron excited temperature increased with the discharge current, but decreased when gas flow rate or argon pressure increased.