Cold atmospheric plasmas have great application potential due to their production of diverse types of reactive species, so understanding the production mechanism and then improving the production efficiency of the key reactive species are very important. However, plasma chemistry typically comprises a complex network of chemical species and reactions, which greatly hinders identification of the main production/reduction reactions of the reactive species. Previous studies have identified the main reactions of some plasmas via human experience, but since plasma chemistry is sensitive to discharge conditions, which are much different for different plasmas, widespread application of the experience-dependent method is difficult. In this paper, a method based on graph theory, namely, vital nodes identification, is used for the simplification of plasma chemistry in two ways: (1) holistically identifying the main reactions for all the key reactive species and (2) extracting the main reactions relevant to one key reactive species of interest. This simplification is applied to He + air plasma as a representative, chemically complex plasma, which contains 59 species and 866 chemical reactions, as reported previously. Simplified global models are then developed with the key reactive species and main reactions, and the simulation results are compared with those of the full global model, in which all species and reactions are incorporated. It was found that this simplification reduces the number of reactions by a factor of 8–20 while providing simulation results of the simplified global models, i.e., densities of the key reactive species, which are within a factor of two of the full global model. This finding suggests that the vital nodes identification method can capture the main chemical profile from a chemically complex plasma while greatly reducing the computational load for simulation.

中文翻译：

---

通过重要节点识别简化等离子体化学

冷大气等离子体由于产生多种类型的活性物种而具有巨大的应用潜力，因此了解其产生机理进而提高关键活性物种的生产效率非常重要。然而，等离子体化学通常包括化学物种和反应的复杂网络，这极大地阻碍了活性物种的主要生产/还原反应的识别。以前的研究已经通过人类经验确定了一些等离子体的主要反应，但由于等离子体化学对放电条件敏感，不同等离子体的放电条件大不相同，因此经验依赖方法的广泛应用是困难的。在本文中，一种基于图论的方法，即重要节点识别，用于以两种方式简化等离子体化学：(1) 整体识别所有关键反应物种的主要反应和 (2) 提取与感兴趣的一个关键反应物种相关的主要反应。这种简化适用于 He + 空气等离子体作为具有代表性的化学复杂等离子体，如前所述，它包含 59 种物质和 866 个化学反应。然后使用关键反应物种和主要反应开发简化的全局模型，并将模拟结果与包含所有物种和反应的完整全局模型的结果进行比较。发现这种简化将反应数量减少了 8-20 倍，同时提供了简化的全局模型的模拟结果，即关键反应物种的密度，它们在完整全局模型的两倍之内。这一发现表明，重要节点识别方法可以从化学复杂的等离子体中捕获主要化学特征，同时大大减少模拟的计算量。