Self-organized patterns at the plasma–liquid anode interface in a helium glow discharge: temporal development and mechanisms
Self-organized patterns at the plasma–liquid anode interface in a helium glow discharge: temporal development and mechanisms
复制标题
氦辉光放电中等离子体-液体阳极界面的自组织模式：时间发展和机制
DOI：
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发表时间：
2022
影响因子：
3.8
通讯作者：
P. Bruggeman
中科院分区：
文献类型：
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作者：
T. Srivastava;M. S. Simeni;G. Nayak;P. Bruggeman
在等离子体-液体阳极界面处的自组织是大气压辉光等离子体中常见的现象，导致具有独特形状的图案，例如圆环形、星形和齿轮状结构，主要取决于放电电流和溶液电导率。最近的研究表明，电极间隙距离、用于液体阳极溶液的溶质和气体成分也可以显著影响图案形成。尽管如此，尚未报告与所有实验观察到的趋势一致的关键基本机制的总体模型或解释。我们提出了一个关键的基本机制，使模式形成的动机，由详细的参数研究的模式形成补充的时间发展的模式，并与所有观察到的趋势一致。观察到图案形成在100 μs的时间尺度上，类似于气体加热和蒸发的时间尺度。结果表明，无论NaCl溶液的电导率和气体组成如何，形成图形所需的最小水蒸发速率为（3.5 ± 0.5）× 10−6 kg s−1，正柱的折合电场为16.6 ± 0.4Td。尽管如此，其相应的金属原子具有低电离能的阳离子的存在被确定为图案形成的必要条件。报道的结果表明，在气相中存在少量的金属原子，电离能低，提高了整体的电离率在近阳极区域，触发图案形成。
Self-organization at the plasma–liquid anode interface is a commonly observed phenomenon for atmospheric pressure glow plasmas, resulting in patterns with distinctive shapes such as circular ring, star-shaped, and gear-like structures, depending primarily on the discharge current and solution conductivity. Recent studies have shown that the electrode gap distance, solute used for liquid anode solution, and gas composition can also significantly impact pattern formation. Nonetheless, an overarching model or explanation of the key underlying mechanisms consistent with all experimentally observed trends is not yet reported. We propose a key underlying mechanism enabling pattern formation motivated by a detailed parametric study of pattern formation complemented by the temporal development of patterns and consistent with all observed trends. Pattern formation was observed to be on a time scale of 100 μs, similar to the time scales of gas heating and evaporation. It was found that a minimum water evaporation rate of (3.5 ± 0.5) × 10−6 kg s−1 and reduced electric field in the positive column of 16.6 ± 0.4 Td is required for pattern formation in the investigated cases irrespective of solution conductivity and gas composition for NaCl solutions. Nonetheless, the presence of cations for which the corresponding metal atom has a low ionization energy was identified as a necessary condition for pattern formation. The reported results suggest that the presence of a small amount of metal atoms in the gas phase with low ionization energy enhances the overall ionization rate in the near anode region which triggers pattern formation.