This work presents a systematic numerical investigation on the behaviors of electrons in the bullet in the Ar/O ₂ plasma jet in changing oxygen concentration and the applied voltage, based on a needle-plate discharge configuration and a 1-D particle-in-cell Monte-Carlo collision (PIC-MCC) method. The increase in oxygen concentration allows more electrons to be scattered toward the target, i.e., more electrons to most probably interact with the target, and induces a dramatic increase of reactive oxygen species (ROS), but leads to the decrease of the bullet velocity and average electron energy. In addition, there is a weak correlation between the electron density and ROS generation. When increasing the applied voltage, the electrons scattered toward the target decrease, however, the majority of these electrons, above 70%, are of energy higher than the threshold inducing a dissociative electron attachment (DEA) to water molecule, and meanwhile, there is an evident increase of high-energy electrons being able to excite water molecules. Also, there is a strong correlation between the electron density and ROS generation. The present results are also compared with those in the Ar/H ₂ O plasma jets, indicating qualitative and quantitative differences.

中文翻译：

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改变氧浓度和外加电压的 Ar/O₂ 等离子体射流中电子的行为

这项工作对 Ar/O ₂中子弹中电子的行为进行了系统的数值研究。 基于针板放电配置和一维粒子在细胞内蒙特卡罗碰撞 (PIC-MCC) 方法，等离子体射流改变氧浓度和施加的电压。氧浓度的增加允许更多的电子向目标散射，即更多的电子最有可能与目标相互作用，并导致活性氧 (ROS) 急剧增加，但导致子弹速度和平均电子能量。此外，电子密度与 ROS 生成之间存在弱相关性。当增加施加的电压时，向目标散射的电子会减少，但是，这些电子中的大多数（超过 70%）的能量高于阈值，从而诱导离解电子附着 (DEA) 到水分子，同时，能够激发水分子的高能电子明显增加。此外，电子密度和 ROS 生成之间存在很强的相关性。目前的结果也与 Ar/H ₂ O 等离子体射流，表明质量和数量上的差异。