On the nature of droplet production in DC glows with a liquid anode: mechanisms and potential applications
On the nature of droplet production in DC glows with a liquid anode: mechanisms and potential applications
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关于液体阳极在直流发光中产生液滴的性质：机制和潜在应用
DOI：
10.1088/1361-6595/ac9c8e
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发表时间：
2022
影响因子：
3.8
通讯作者：
Foster, John
中科院分区：
文献类型：
--
作者：
Yang, Zimu;Kovach, Yao;Wang, Zhehui;Foster, John
等离子体和液体溶液之间的相互作用产生了对许多应用有用的化学反应物质，但界面区域的质量传递通常是有限的，并且尚未完全了解。本文报道了用液体阳极进行单大气辉光放电时等离子体-液界面处液滴喷射的观测和解释。利用光谱学分析了液滴发射对等离子体性能的影响。该过程明显发生在放电过程中，是一种有效的质量和电荷传递机制，构成了放电与液体之间的反馈载体。与众所周知的与液体阴极相关的塔赖尔锥液滴不同，所观察到的液滴是由电解和溶剂化空气引起的气泡产生的，不需要在液体表面有强电场。液滴的大小、初始速度与重力、惯性和毛细作用密切相关。液滴出现在等离子体附着处附近，随后汽化，发出强烈的紫外线和可见光，这是由激发的OH自由基和来自液体电解质的钠产生的。光谱分析证实，破裂液滴通常会降低气体温度，而其对电子密度的影响取决于液体阳极的组成。结果还表明，由于钠离子的电离势较低，NaCl溶液中的液滴增加了等离子体电子密度。这些发现揭示了放电维持和质量传输的新机制，并提出了一种将等离子体活化的液体分散到气相从而增强等离子体-液体相互作用的简单方法。
The interactions between plasma and liquid solutions give rise to the formation of chemically reactive species useful for many applications, but the mass transport in the interfacial region is usually limited and not fully understood. In this work, we report on the observation and explanation of droplet ejection at the plasma–liquid interface of a one-atmosphere glow discharge with the liquid anode. The impact of droplets emission on plasma properties is also analyzed by spectroscopy. The process, which is an efficient mass and charge transport mechanism, apparently occurs during discharge operation and thus constitutes a feedback vehicle between the discharge and the liquid. Distinctive from the well-known Talyor cone droplets associated with liquid cathodes, the observed droplets originate from the bubbles due to electrolysis and solvated air which does not require strong electric field at liquid surface. Instead, the droplets are ejected by bubble cavity rupture at the plasma–liquid interface and their size, initial speed are strongly dependent on the gravity, inertia and capillarity. The droplets emerge near the plasma attachment and are subsequently vaporized, emitting intense UV and visible light, which originated from excited OH radicals and sodium derived from the liquid electrolyte. Spectroscopy analysis confirmed that the bursting droplets generally reduce the gas temperature while their effects on electron density depend on the composition of the liquid anode. Results also show that droplets from NaCl solution increase the plasma electron density due to the lower ionization potential of sodium. These findings reveal a new mechanism for discharge maintenance and mass transport as well as suggest a simple approach to dispersing plasma-activated liquid into the gas phase and thus enhancing plasma–liquid interaction.