The spatial distribution of HO 2 in an atmospheric pressure plasma jet investigated by cavity ring-down spectroscopy
The spatial distribution of HO 2 in an atmospheric pressure plasma jet investigated by cavity ring-down spectroscopy
复制标题
通过腔衰荡光谱研究大气压等离子体射流中HO 2 的空间分布
DOI：
10.1088/1361-6595/aba206
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发表时间：
2020
影响因子：
3.8
通讯作者：
Klose S
中科院分区：
文献类型：
--
作者：
Klose S
大气压冷等离子体射流在材料加工、等离子体医学等领域有着重要的应用。为了优化这些等离子体源的效果，对化学反应网络的详细了解是关键。然而，等离子体射流的小直径使得诊断具有挑战性。一个有前途的方法来获得绝对数密度是利用腔增强吸收光谱法，通过该方法的视线平均密度确定。在这里，我们提出的第一个测量如何在冷大气压等离子体射流的流出物中的HO 2的空间分布可以通过腔衰荡光谱学在一个有效的方式获得。代替记录完全波长分辨的光谱，我们将证明在两个波长处测量吸收系数是足够的，对应于激光器打开和关闭分子共振。通过对直径为1.6mm的喷嘴流出液在不同轴向位置的径向取样，测得在喷嘴下方2 mm和10 mm处，HO 2浓度分布的距离分别为（3.9±0.5）mm和（6.7±0.1）mm。我们进行了阿贝尔反演，以获得HO 2的空间分布，呈现沿着对称轴的流出物。基于最大为（4.8±0.6）<$10 14 cm− 3的局部密度，我们将讨论等离子体区对HO 2产生的重要性。
Cold atmospheric pressure plasma jets make important contributions to a range of fields, such as materials processing and plasma medicine. In order to optimise the effect of those plasma sources, a detailed understanding of the chemical reaction networks is pivotal. However, the small diameter of plasma jets makes diagnostics challenging. A promising approach to obtain absolute number densities is the utilisation of cavity-enhanced absorption spectroscopy methods, by which line-of-sight averaged densities are determined. Here, we present first measurements on how the spatial distribution of HO 2 in the effluent of a cold atmospheric pressure plasma jet can be obtained by cavity ring-down spectroscopy in an efficient way. Instead of recording fully wavelength resolved spectra, we will demonstrate that it is sufficient to measure the absorption coefficient at two wavelengths, corresponding to the laser being on and off the molecular resonance. By sampling the effluent from the 1.6 mm diameter nozzle in the radial direction at various axial positions, we determined that the distances over which the HO 2 density was distributed were (3.9±0.5) mm and (6.7±0.1) mm at a distance of 2 mm and 10 mm below the nozzle of the plasma jet, respectively. We performed an Abel inversion in order to obtain the spatial distribution of HO 2 that is presented along the symmetry axis of the effluent. Based on that localised density, which was (4.8±0.6)⋅ 10 14 cm− 3 at the maximum, we will discuss the importance of the plasma zone for the production of HO 2.