分子发射光谱法测量微波等离子体气体温度

摘要

通过O H自由基A2Σ+→ X2Πr 电子带系分子发射光谱测温法,实现了对氩气、氮气、空气三种大气压微波等离子体气体温度的测量.探究了不同微波功率、不同气体流量下气体温度的变化规律,测量了氮气、空气微波等离子体羽流的轴向温度分布.实验结果表明,不同工作条件下微波等离子体核心温度普遍超过2000 K,空气微波等离子体可超过6000 K;同样工作条件下三种微波等离子体气体温度满足:TAr< TN2< TAir;气体温度总体上随微波功率增加而小幅增加,随气体流量下降而小幅降低;氮气与空气等离子体羽流温度沿轴向迅速降低.为验证分子发射光谱测温法的准确性,以热电偶测温作为比对,对温度较低的介质阻挡放电氩气等离子体进行了温度测量,实验表明,分子发射光谱法与热电偶所测结果十分接近.%In this study,gas temperature measurements of argon,nitrogen,and air microwave plasmas are achieved by the molecular emission spectrometry of the A2Σ+→ X2Πr electronic system of OH radical.The gas temperatures at different microwave powers or gas flow rates were explored,and the axial temperature distri-butions of nitrogen and air microwave plasma plumes were measured.The experimental results showed that temperatures in the core region of microwave plasma were higher than 2000 K at different working conditions, even up to over 6 000 K in air microwave plasma.At the same working condition,the three kinds of micro-wave plasma gas temperatures meet:TAr< TN2 < TAir.The gas temperature increased slightly with the increase of microwave power,and decreased slightly with the decrease of gas flow rate overall.The gas temperatures of nitrogen and air microwave plasma plumes reduced quickly along the axial direction.In order to verify the accu-racy of molecular emission spectrometry,the thermocouple was used as a comparison to take the temperature of the dielectric barrier discharge argon plasma.Experiments showed that the temperature measurements of molecular emission spectrometry and thermocouple are fairly consistent.