The influence of pulse repetition frequency on reactive oxygen species production in pulsed He+H2O plasmas at atmospheric pressure
The influence of pulse repetition frequency on reactive oxygen species production in pulsed He+H2O plasmas at atmospheric pressure
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DOI：
10.1063/5.0161825
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发表时间：
2023-09
影响因子：
3.2
通讯作者：
B. Harris;E. Wagenaars
中科院分区：
文献类型：
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作者：
B. Harris;E. Wagenaars
由氦气与水蒸气的混合物产生的大气压等离子体在生物医学中有许多应用。重要的是，可以严格控制此类等离子体的化学性质，以便可以根据其预期用途进行定制。在本研究中，计算模型用于在 1-100 kHz 范围内改变纳秒脉冲、针对针 He + 0.25% H2O 放电的脉冲重复频率，以确定脉冲重复频率对活性氧物质密度以及涉及它们的主要反应途径速率的影响。使用 0D 等离子体化学动力学模型 GlobalKin 模拟等离子体。脉冲形状保持恒定。因此，余辉持续时间取决于重复频率。等离子体达到平衡后对本体等离子体化学的分析表明，峰值电子密度仅微弱地依赖于脉冲重复频率。增加脉冲重复频率可以增加 H、O 和 OH 自由基的密度，而重复频率与寿命较长的物质（即 H2O2 和 O3）的密度之间的关系则更为复杂。这些是在余辉过程中形成的，它们的密度取决于反应物种类的可用性、余辉持续时间和背景气体温度。这项工作的结论是，脉冲重复频率不是一个简单的控制参数，特别是对于主要在余辉中产生的物种而言。使用脉冲重复频率精确控制物种密度需要详细的建模。
Atmospheric pressure plasmas generated from a helium gas with admixtures of water vapor have numerous applications in biomedicine. It is important that the chemistry of such plasmas can be tightly controlled so that they may be tailored for their intended use. In this study, computational modeling is used to vary the pulse repetition frequency of a nanosecond-pulsed, pin-to-pin He + 0.25% H2O discharge in the range of 1–100 kHz to determine the influence of the pulse repetition frequency on the resulting densities of reactive oxygen species and the rates of dominant reaction pathways involving them. The plasma is simulated using the 0D plasma-chemical kinetics model GlobalKin. The pulse shape is kept constant. The afterglow duration is, therefore, dependent on the repetition frequency. Analysis of the bulk plasma chemistry after the plasma has reached equilibrium shows that the peak electron density is only weakly dependent on the pulse repetition frequency. Increasing the pulse repetition frequency is shown to increase the density of H, O, and OH radicals, while the relationship between the repetition frequency and the densities of species with longer lifetimes, namely, H2O2 and O3, is found to be more complex. These are formed throughout the afterglow, and their density depends on the availability of reactant species, the afterglow duration, and the background gas temperature. This work concludes that the pulse repetition frequency is not a simple control parameter, especially for species that are predominantly produced in the afterglow. Detailed modeling is required for accurate control of species densities using the pulse repetition frequency.