发射光谱研究大气压等离子体射流的气体温度

采用介质阻挡放电等离子体喷枪装置,在大气压下流动氩气中产生了射流等离子体。利用光电倍增管,对射流等离子体进行了时空分辨测量,分析了等离子体喷枪内介质阻挡放电和外部等离子体羽的放电特性。利用高分辨率光谱仪采集等离子体羽处的发射光谱,通过对发射光谱中OH(A2Σ+→X2Π,307.7～308.9nm)及N2+的第一负系(B2Σ+u→X2Π+g,390～391.6nm)谱线拟合得到了射流等离子体的转动温度,拟合得到的转动温度分别为443和450K。在5%的误差范围内,这2种方法得到的结果是一致的。由于在大气压下,转动温度近似等于产生气体放电的气体温度,所以可以确定大气压射流等离子体气体温度。利用该方法研究了不同电压下的气体温度,发现气体温度随着外加电压增加而增大。

Investigation on the gas temperature of a plasma jet at atmospheric pressure by emission spectrum

A plasma jet of a dielectric barrier discharge in coaxial electrode was used to produce plasma plume in atmospheric pressure argon. Spatially and temporally resolved measurement was carried out by photomultiplier tubes. The light emission signals both from the dielectric barrier discharge and from the plasma plume were analyzed. Furthermore, emission spectrum from the plasma plume was collected by high-resolution optical spectrometer. The emission spectra of OH (A 2sigma + --> X2 II, 307.7-308.9 nm) and the first negative band of N2+ (B2 sigma u+ --> X2 IIg+, 390-391.6 nm) were used to estimate the rotational temperature of the plasma plume by fitting the experimental spectra to the simulated spectra. The rotational temperature obtained is about 443 K by fitting the emission spectrum from the OH, and that from the first negative band of N2+ is about 450 K. The rotational temperatures obtained by the two method are consistent within 5% error band. The gas temperature of the plasma plume at atmospheric pressure was obtained because rotational temperature equals to gas temperature approximately in gas discharge at atmospheric pressure. Results show that gas temperature increases with increasing the applied voltage.