[论文解读] Physical understanding of the static magnetic field's synergistic enhancement of cold atmospheric pressure plasma treatment

Ramin Mehrabifard, Zeinab Kabarkouhi+4 more|arXiv (Cornell University)|Apr 11, 2023

Plasma Applications and Diagnostics被引用 7

一句话总结

本研究探讨了外加静态磁场（SMF）对冷大气压等离子体（CAP）处理的协同增强效应，发现420 mT垂直SMF使电子温度提高0.2 eV（从1.04 eV增至1.24 eV），电子激发温度升高550 K，同时由于磁场诱导的电浆约束作用，电子密度上升，从而增强其在医疗应用中的反应活性。

ABSTRACT

In the last decades, to improve the CAP treatment efficiency, its biological effects in combination with other physical modalities have widely investigated. However, the physical insight into most of supposed synergistic effects remained elusive. In this regard, the synergetic effect of cold plasma and magnetic field has been used for different applications, especially due to considerable synergistic in biological media reactivity. In the present paper, using a 420 mT N42 magnet, the effect of the perpendicular external static magnetic field (SMF) on the cold atmospheric pressure plasma (CAP) characteristics, such as electron temperature and density, are investigated based on the optical emission spectroscopy, utilizing the Boltzmann plot method, Saha-Boltzmann equation and Specair software simulation. Results showed that the rotational and electronic excitational temperature experienced 100 K and 550 K increases in the presence of SMF, respectively. While the vibrational and translational temperatures remained constant. Moreover, electron temperature estimated as 1.04 eV in the absence of SMF and increased up to 1.24 eV in the presence of SMF. In addition, the Saha-Boltzmann equation illustrated that the electron density increased in presence of the additional SMF. The results of the present study indicated that the magnetic field could be an assistant to the cold plasma effect, beneficial in medical applications due to modifications in plasma temperature and electron density.

研究动机与目标

• 理解冷大气压等离子体（CAP）与静态磁场（SMF）结合时产生协同增强效应的物理机制。
• 量化外加SMF影响下等离子体参数（电子温度、电子密度及各类激发温度）的变化。
• 阐明CAP与SMF结合为何能提高生物介质中的反应活性，特别是针对医疗应用的机理。
• 利用光致发射光谱和等离子体建模，为观察到的协同效应提供物理解释。

提出的方法

• 采用光致发射光谱（OES）分析等离子体物种的发射线，特别是N2和N2+带状光谱。
• 应用玻尔兹曼图法，根据N2第二正系统（C3Πu → B3Πg）发射谱线确定电子激发温度。
• 利用Saha-Boltzmann方程，基于特定N2+带状光谱的强度比估算电子密度。
• 采用Specair软件进行光谱模拟，并验证温度与密度计算结果。
• 使用420 mT的N42永磁体在等离子体放电区域施加垂直静态磁场。
• 通过N2第二正系统（C3Πu → B3Πg）带头强度比推导转动温度。

实验结果

研究问题

• RQ1 垂直静态磁场（SMF）的施加如何影响冷大气压等离子体（CAP）中的电子温度？
• RQ2 SMF对CAP中电子激发温度、转动温度、振动态温度及平动温度有何影响？
• RQ3 SMF如何影响CAP中的电子密度？其背后的物理机制是什么？
• RQ4 SMF在多大程度上增强了等离子体的反应活性？这种增强效应能否通过温度与密度变化的物理解释？
• RQ5 通过光谱分析与建模技术，能否定量关联CAP治疗中观察到的协同增强效应与等离子体参数的变化？

主要发现

• 在420 mT静态磁场存在下，电子温度从1.04 eV提升至1.24 eV，表明电子能量分布得到增强。
• 由于SMF的存在，电子激发温度升高550 K，表明等离子体物种中激发态的种群数增加。
• 转动温度升高100 K，反映出N2分子转动能级种群分布发生变化。
• 振动态温度和平动温度保持不变，表明气体相中无显著热平衡化效应。
• 电子密度在SMF作用下升高，符合Saha-Boltzmann方程的预测，其机制为带电粒子受磁场约束。
• 结果表明，静态磁场通过调节关键等离子体参数，作为物理增强剂提升了CAP性能，支持其在医疗应用中的潜力。