The plasma-liquid interaction holds great importance for a number of emerging applications such as plasma biomedicine, yet a main fundamental question remains about the nature of the physiochemical processes occurring at the plasma-liquid interface. In this paper, the interfacial current distribution between helium plasma jet and water solution was measured for the first time by means of the splitting electrode method, which was borrowed from the field of arc plasma. For a plasma plume in continuous mode, it was found that the mean absolute current distribution at the plasma-liquid interface typically had an annular shape. This shape could be affected by regulating the air doping from the surrounding atmosphere, the gas flow rate, the applied voltage and the conductivity of the water solution. However, only the air doping fraction and the water conductivity could fundamentally change the interfacial current distribution from the annular shape to the central maximum shape. It was deduced that a certain amount of ambient air doping (mainly N2 and O2) and a low conductivity (typically < 300 μS/cm) of the treated water were essential for the formation of the annular current distribution at the plasma-liquid interface.

中文翻译：

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氦等离子体射流与水溶液之间的界面电流分布

血浆-液体相互作用对于血浆生物医学等许多新兴应用具有重要意义，但一个主要的基本问题仍然是血浆-液体界面处发生的物理化学过程的性质。本文借鉴电弧等离子体领域的分裂电极法，首次测量了氦等离子体射流与水溶液之间的界面电流分布。对于连续模式的等离子体羽流，发现等离子体-液体界面处的平均绝对电流分布通常具有环形形状。这种形状可以通过调节周围大气中的空气掺杂、气体流速、施加的电压和水溶液的电导率来影响。然而，只有空气掺杂分数和水电导率才能从根本上改变界面电流分布从环形到中心最大形状。推断出一定量的环境空气掺杂（主要是 N2 和 O2）和低电导率（通常 < 300 μS/cm）的处理水对于在等离子体 - 液体界面处形成环形电流分布至关重要。