Enhanced oxygen dissociation in a propagating constricted discharge formed in a self-pulsing atmospheric pressure microplasma jet
Enhanced oxygen dissociation in a propagating constricted discharge formed in a self-pulsing atmospheric pressure microplasma jet
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DOI：
10.1088/0022-3727/46/46/464003
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发表时间：
2013-10
期刊：
影响因子：
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通讯作者：
D. Schröder;S. Burhenn;D. Kirchheim;V. D. Gathen
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文献类型：
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作者：
D. Schröder;S. Burhenn;D. Kirchheim;V. D. Gathen
我们报告了在周围空气环境中，在氦气和 0.075 vol% 分子氧混合物中运行的重复自脉冲微等离子体射流中收缩放电特征的传播。收缩放电宽度约为 1 mm，在楔形电极配置中的最小电极距离点处重复点燃，通过放电通道向喷嘴传播，熄灭，并以 kHz 范围内的频率在入口处重新点燃。它与均匀的、体积主导的低温 (T ⋍ 300 K) α 模式辉光共存。氮分子 C 态和氮分子离子 B 态发射带的时间分辨测量表明，收缩放电内的旋转温度在 50 µs 内增加到约 600 K。通过相位分辨诊断确定其传播速度与气体速度相似，约为 40 m s−1。与自脉冲同步的双光子吸收激光诱导荧光光谱揭示了氧原子密度增加的空间区域与收缩放电特征共同传播。产生的氧脉冲密度比共存的均质 α 模式高约十倍。在喷嘴处平均温度为 450 K 时，密度达到约 1.5 × 1016 cm−3。这种约 80% 的增强解离归因于收缩放电与共传播气体体积的连续相互作用。
We report on the propagation of a constricted discharge feature in a repetitively self-pulsing microplasma jet operated in helium with a 0.075 vol% molecular oxygen admixture in ambient air environment. The constricted discharge is about 1 mm in width and repetitively ignites at the point of smallest electrode distance in a wedge-shaped electrode configuration, propagates through the discharge channel towards the nozzle, extinguishes, and re-ignites at the inlet at frequencies in the kHz range. It co-exists with a homogeneous, volume-dominated low temperature (T ⋍ 300 K) α-mode glow. Time-resolved measurements of nitrogen molecule C-state and nitrogen molecule ion B-state emission bands reveal an increase of the rotational temperature within the constricted discharge to about 600 K within 50 µs. Its propagation velocity was determined by phase-resolved diagnostics to be similar to the gas velocity, in the order of 40 m s−1. Two-photon absorption laser-induced fluorescence spectroscopy synchronized to the self-pulsing reveals spatial regions of increased oxygen atom densities co-propagating with the constricted discharge feature. The generated oxygen pulse density is about ten times higher than in the co-existing homogeneous α-mode. Densities reach about 1.5 × 1016 cm−3 at average temperatures of 450 K at the nozzle. This enhanced dissociation of about 80% is attributed to the continuous interaction of the constricted discharge to the co-propagating gas volume.