The µ-APPJ is a well-investigated atmospheric pressure RF plasma jet. Up to now, it has mainly been operated using helium as feed gas due to stability restrictions. However, the COST-Jet design including precise electrical probes now offers the stability and reproducibility to create equi-operational plasmas in helium as well as in argon. In this publication, we compare fundamental plasma parameters and physical processes inside the COST reference microplasma jet, a capacitively coupled RF atmospheric pressure plasma jet, under operation in argon and in helium. Differences already observable by the naked eye are reflected in differences in the power-voltage characteristic for both gases. Using an electrical model and a power balance, we calculated the electron density and temperature at 0.6 W to be 9e17 m-3, 1.2 eV and 7.8e16 m-3, 1.7 eV for argon and helium, respectively. In case of helium, a considerable part of the discharge power is dissipated in elastic electron-atom collisions, while for argon most of the input power is used for ionization. Phase-resolved emission spectroscopy reveals differently pronounced heating mechanisms. Whereas bulk heating is more prominent in argon compared to helium, the opposite trend is observed for sheath heating. This also explains the different behavior observed in the power-voltage characteristics.

中文翻译：

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在氩气和氦气中操作的射频等离子体射流中电子加热和能量损失机制的比较

µ-APPJ 是一种经过充分研究的大气压射频等离子射流。到目前为止，由于稳定​​性的限制，它主要使用氦气作为原料气进行操作。然而，包括精确电探针的 COST-Jet 设计现在提供了稳定性和可重复性，以在氦气和氩气中创建等操作的等离子体。在本出版物中，我们比较了在氩气和氦气中运行的 COST 参考微等离子体射流（一种电容耦合射频大气压等离子体射流）内部的基本等离子体参数和物理过程。肉眼已经可以观察到的差异反映在两种气体的电源电压特性的差异上。使用电气模型和功率平衡，我们计算出 0.6 W 时的电子密度和温度为 9e17 m-3、1.2 eV 和 7.8e16 m-3、1。氩气和氦气分别为 7 eV。在氦气的情况下，相当一部分放电功率消耗在弹性电子-原子碰撞中，而对于氩气，大部分输入功率用于电离。相分辨发射光谱揭示了不同显着的加热机制。与氦气相比，氩气中的整体加热更为突出，而鞘层加热则观察到相反的趋势。这也解释了在电源电压特性中观察到的不同行为。与氦气相比，氩气中的整体加热更为突出，而鞘层加热则观察到相反的趋势。这也解释了在电源电压特性中观察到的不同行为。与氦气相比，氩气中的整体加热更为突出，而鞘层加热则观察到相反的趋势。这也解释了在电源电压特性中观察到的不同行为。