Being able to generate a remote plasma plume, the atmospheric pressure plasma jet has become an indispensable tool for extensive application fields. A plasma plume usually has a straight column morphology, which results from straight-line or stochastic snake-like propagations of streamers. The snake-like propagation of streamers is unclear in the mechanism. In this paper, a meandering plume is generated for the first time downstream of an argon plasma jet excited by a positively biased sinusoidal voltage, which transits from a straight column plume with an increasing bias voltage (V_b). Results indicate that the wavelength of the meandering plume is inversely proportional to voltage frequency and directly proportional to the gas flow rate. For every voltage cycle, integrated light emission from the meandering plume presents one pulse with low V_b and two pulses with high V_b. Fast photography reveals that the meandering plume results from repeated snake-like propagations of positive streamers due to the influence of ion clouds. To confirm the existence of ion clouds, an opposite argon flow is introduced. With wiping off ion clouds in the argon stream, the meandering plume gradually turns back to a straight column with an increasing opposite flow rate. All these phenomena mentioned above have been explained qualitatively on the basis of ion clouds. These results may shed light on the streamers' dynamics in the atmospheric pressure plasma jet.

中文翻译：

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正偏置正弦电压激发的蜿蜒等离子体羽流中正流光的蛇形传播机制

由于能够产生远程等离子体羽流，常压等离子体射流已成为广泛应用领域不可或缺的工具。等离子羽流通常具有直柱形态，这是由拖缆的直线或随机蛇形传播引起的。流光的蛇形传播机制尚不清楚。在本文中，在正偏置正弦电压激发的氩等离子体射流下游首次产生曲折羽流，该喷射流从具有增加的偏置电压 ( V _b)的直柱状羽流过渡）。结果表明，曲折羽流的波长与电压频率成反比，与气体流速成正比。对于每个电压周期，来自蜿蜒羽流的综合光发射呈现一个低V _b脉冲和两个高V _b脉冲. 快速摄影显示，由于离子云的影响，正流带的重复蛇状传播导致了蜿蜒的羽流。为了确认离子云的存在，引入了相反的氩气流。随着氩气流中的离子云被擦掉，蜿蜒的羽流逐渐变回直柱，并具有增加的相反流速。上面提到的所有这些现象都已经在离子云的基础上得到了定性解释。这些结果可能有助于阐明大气压等离子体射流中的拖缆动力学。