Spatiotemporal measurement of OH density from upstream to downstream in humid helium atmospheric-pressure plasma jet
Spatiotemporal measurement of OH density from upstream to downstream in humid helium atmospheric-pressure plasma jet
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DOI：
10.1088/1361-6595/ab3c75
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发表时间：
2020-03
影响因子：
3.8
通讯作者：
R. Ono;M. Tokuhiro
中科院分区：
文献类型：
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作者：
R. Ono;M. Tokuhiro
利用激光诱导荧光（LIF）技术测量了He/H_2O（10-6000 ppm）大气压等离子体射流中OH浓度从上游到下游的轴向分布和时间演化。用重复正脉冲（7-10 kV，800 ns和1 kHz）产生等离子体。我们研究了（i）OH密度对各种放电参数的依赖性，（ii）OH自由基的产生和损失过程，以及（iii）O2混合物对OH密度的影响。模拟仅包括放电后反应。为了模拟放电脉冲，使用LIF测量的放电脉冲中的OH密度的增加被用作输入参数。结果表明，在等离子体中任意位置处的OH密度近似正比于ε d 0.5f0.4，与H2O浓度无关，其中εd为该位置处的放电能量密度，f为脉冲重复频率。OH主要由H2O + + e → OH + H而不是H2O + e → OH + H + e产生，其中H2O+由Penning电离产生，其主要损失过程为H + OH + M → H2O + M和OH + OH + M → H2 O2 + M
The axial distribution and time evolution of OH density from upstream to downstream in a He/H2O(10–6000 ppm) atmospheric-pressure plasma jet was measured using laser-induced fluorescence (LIF). The plasma was generated with repetitive positive pulses (7–10 kV, 800 ns, and 1 kHz). We investigated (i) the dependence of OH density on various discharge parameters, (ii) the production and loss processes of OH radicals, and (iii) the effect of O2 admixture on OH density with the help of simulations. The simulations included only postdischarge reactions. To simulate the discharge pulse, the increase in the OH density in a discharge pulse measured using LIF was used as an input parameter. The results suggested that the OH density at any position in the plasma was approximately proportional to ε d 0.5 f 0.4 regardless of the H2O concentration, where εd is the discharge energy density at the position and f is the pulse repetition frequency. The results also suggested that OH was mainly produced by H 2 O + + e → OH + H rather than H 2 O + e → OH + H + e , where H 2 O + was produced by Penning ionization, and its main loss processes were H + OH + M → H 2 O + M and OH + OH + M → H 2 O 2 + M .