This Rapid Communication reports on the observation of an interesting phenomenon: the shape, especially the length, of a microwave plasma jet (MPJ) can be clearly influenced by simply placing a conductor near the plasma source, particularly when the nearby conductor is in contact with the external conductor of the coaxial microwave plasma generator, accompanied by a significant change in microwave reflection power from the terminal. To further investigate this discovery, the relationships between the length of the plume and some important factors, such as the conductivity and length of the nearby conductor, microwave input power, and gas flow velocity, are analyzed, and we find nonlinear rules of influence of these factors on the jet. Measurements of the electric potential around the jet reveal the nonuniform and non-neutral charge distribution inside the visible plasma plume, which plays a vital role in uncovering the mechanism underlying this phenomenon. The results are helpful for providing a deeper understanding of microwave plasma jet characteristics. More importantly, it provides guidelines to control the MPJ using simple structures.

中文翻译：

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附近导体对微波等离子体射流的形状和长度的影响

这份快速通讯报道了对一个有趣现象的观察：只要将导体放在等离子源附近，就可以明显地影响微波等离子体射流（MPJ）的形状，尤其是长度，特别是当附近的导体与等离子体源接触时。同轴微波等离子体发生器的外部导体，伴随着来自终端的微波反射功率的显着变化。为了进一步研究这一发现，分析了羽流长度与一些重要因素之间的关系，例如附近导体的电导率和长度，微波输入功率和气体流速，并发现了影响羽化的非线性规则。这些因素对喷气机来说。对射流周围电势的测量揭示了可见等离子羽流内部的不均匀和非中性电荷分布，这在揭示该现象背后的机理中起着至关重要的作用。结果有助于深入了解微波等离子流的特性。更重要的是，它提供了使用简单结构控制MPJ的准则。