DBD放电中温度特性与OH促进NO氧化过程光谱诊断

Optical study of temperature characteristic and NO oxidization process by OH radicals in DBD by Optical Emission Spectroscopy

利用光谱诊断方法深入研究了介质阻挡放电（DBD）中气体分子温度分布，OH自由基促进NO分子氧化过程的光谱特性，获得了NO（A^2∑^＋→X^2П，0—3，1—4）、N2（C^3Пu→B^3Пg，0—0）和OH（A^2∑^＋→X^2П，0—0）的高分辨率发射光谱。通过拟舍得到NO（A^2∑^＋→X^2П）转动带253—260nm的谱线，将其与实验谱线进行比较，获得了DBD放电区域的气体分子温度；发现在放电通道内气体分子温度分布较为均衡，但靠近内电极气体分子温度约为330K，略高于介质附近的310K。研究了N2与NO谱线强度的一维分布，发现在放电通道中间位置处谱线强度最高，从中间往内外电极方向谱线强度均逐渐降低。随着交流电压的升高，NO与OH谱线强度均升高，高能电子能有效地激发OH与NO基团。随着相对湿度从20％升高到100％，NO谱线强度降低约93％；随着NO浓度升高，OH谱线强度呈现下降的趋势，NO浓度从200mL／m^3升高到600mL／m^3时，OH谱线强度下降约27％。说明OH基团对NO氧化过程中起到重要作用。

The optical spectroscopy characteristic of dielectric barrier discharge （DBD） plasma in NO/H2O/N2 mixture was studied by Optical Emission Spectroscopy （ OES）. DBD plasmas was generated in a 4mm wire-cylinder gap in atmospheric - pressure, spectrum of NO （ A^2 ∑ ＋ → X^2П,0 → 3,1 - 4 ） , N2 （ C^3Пu→B3 Пg, 0 - 0 ） and OH （ A2 ∑^＋ →X2П,0- 0） was observed. The plasma gas temperature was determined by comparing the experimental spectrum and the best fitted spectrum. From the NO（ A^2∑ →X^2П,0 -3,1 -4） rotational transition band, the temperature was about 320K. One-dimensional distribution of NO （ A^2 ∑ ＋ →X^2 П,0 - 3 ） and N2 （ C3 Пu→B^3 П g, 0 - 0） emission intensity was obtained. When RH = 20% , OH emission intensity reached the maximum. As the peak voltage increased, NO （A^2∑ ＋→X^2П ,0- 0） and OH （ A^2∑^＋ →X^2П ,0 -0） emission intensity rised. As the RH increased, NO emission intensity decreased, emission intensity decreased about 93% when RH = 100% compared with RH = 20% ; NO concentration increased, OH emission intensity decreased, emission intensity decreased about 27% at NO concentration of 600mL/m3 compared with NO concentration of 200mL/m3 , which could reveal the importance of OH radicals in NO conversion process.