Cold atmospheric pressure plasma jets (CAPJs) are an emerging technology for the localised treatment of heat sensitive surfaces. Adding humidity to the CAPJ’s feed gas yields an effective production of highly reactive intermediate species, such as hydrogen atoms, oxygen atoms, and hydroxyl radicals, among others, which are key species for biomedical applications. This study focusses on the effluent of the CAPJ kINPen, which was operated with argon feed gas and a humidity admixture of 3000 ppm, while a gas curtain was used to limit the diffusion of ambient air into the effluent. The axial and radial density distribution of O and H atoms is measured by means of picosecond two-photon absorption laser induced fluorescence spectroscopy (ps-TALIF). A maximum O atom density of (3.8 0.7) 10¹⁵ cm⁻³ and a maximum H atom density of (3.5 0.7) 10¹⁵ cm⁻³ are found at the nozzle of the plasma jet. The experimental results are compared to a two-dimensional reacting flow model that is coupled with a local zero-dimensional plasma chemical model. With this model, the main H and O atom production mechanisms are determined to be the dissociation of H₂O and O₂ in the plasma zone of the plasma jet. The latter indicates, that a significant amount of oxygen (1%) was present inside the device. The reaction of OH with O atoms represents the main consumption pathway for O atoms and is at the same time a significant production pathway for H atoms. The main consumption of H atoms is through a three-body reaction including O₂ to form HO₂, which consumes more H and O atoms to form OH. It is pointed out, that most of the species are produced in the plasma zone, and that O and H atoms, OH and HO₂ radicals, and O₂ and H₂O molecules are strongly connected.

冷大气压等离子射流（CAPJ）是一种用于对热敏感表面进行局部处理的新兴技术。向CAPJ的进料气中增加湿度可有效生产高反应性的中间物种，例如氢原子，氧原子和羟基自由基，这是生物医学应用中的关键物种。这项研究集中于CAPJ kINPen的废水，该废水是在使用氩气进料和3000 ppm的湿度混合气下运行的，同时使用气幕来限制环境空气向废水中的扩散。O和H原子的轴向和径向密度分布是通过皮秒双光子吸收激光诱导荧光光谱法（ps-TALIF）测量的。最大O原子密度为（3.8 0.7）10 ¹⁵ cm ^-3在等离子流的喷嘴处发现的最大H原子密度为（3.5 0.7）10 ¹⁵ cm ^-3。将实验结果与二维反应流模型进行了比较，该模型与局部零维等离子体化学模型耦合。使用此模型，主要的H和O原子产生机理被确定为H ₂ O和O ₂在等离子流的等离子区中的解离。后者表明设备内部存在大量氧气（1％）。OH与O原子的反应代表O原子的主要消耗途径，同时也是H原子的重要生产途径。H原子的主要消耗是通过包括O ₂的三体反应形成HO ₂，HO ₂消耗更多的H和O原子形成OH。要指出的是，大多数物种是在等离子体区中产生的，并且O和H原子，OH和HO ₂自由基以及O ₂和H ₂ O分子是牢固连接的。