A high-efficiency microwave atmospheric pressure plasma jet (APPJ) has been developed in previous work. Long and stable plasma filament is excited directly in the open air with 2.45-GHz microwave power and double-channel argon flow by a double-coaxial structure. Unlike those plasma jets that strongly rely on a high flow rate to shape the plasma jet, this method produces a stable filamentous plasma jet at a low flow rate whose length and diameter are in a linear relationship with absorbed microwave power. This study aims to investigate the fundamental parameters of this special plasma filament under different power levels and gas flow rates by optical emission spectroscopy (OES), including the electron temperature and the spectrum. The electron temperature is determined to be 0.71-0.81 eV. It decreases slightly as the power increases, which is different from other high-voltage or radio frequency excited plasma jets under high power. The electron temperature does not change significantly with the change of microwave power and argon flow rate, more manifested as a change in the length, which indicates that this special plasma filament is related to the complex interaction of the microwave field and plasma. This study provides basic parameters for further investigation of this kind of plasma jet for theoretical and numerical simulation.

中文翻译：

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大气压下微波激发等离子体丝的研究


之前的工作已经开发出一种高效微波大气压等离子体射流（APPJ）。采用双同轴结构，采用 2.45 GHz 微波功率和双通道氩气流直接在露天激发长而稳定的等离子体灯丝。与那些强烈依赖高流速来形成等离子体射流的等离子体射流不同，该方法在低流速下产生稳定的丝状等离子体射流，其长度和直径与吸收的微波功率成线性关系。本研究旨在通过光学发射光谱（OES）研究这种特殊等离子体灯丝在不同功率水平和气体流量下的基本参数，包括电子温度和光谱。电子温度确定为0.71-0.81 eV。随着功率的增加，它略有下降，这与其他高压或射频激发等离子体射流在高功率下不同。电子温度随微波功率和氩气流量的变化并不明显，更多地表现为长度的变化，这表明这种特殊的等离子体灯丝与微波场和等离子体的复杂相互作用有关。本研究为进一步研究此类等离子体射流的理论和数值模拟提供了基本参数。