Study the formation mechanism of plasma effluent gas turbulence and its dynamics at different plasma configurations help to manipulate and optimize the plasma for relevant applications. In this article, the dynamics of the turbulent front (TF) of the jet plasma effluent gas at three-electrode configuration driven by pulsed dc and ac power sources was studied experimentally for the first time. The TF formed by helium plasma jet was imaging by Schlieren technics. Moreover, the high-speed camera was utilized to capture the time evolution of the TF formation, and the contribution of ac and pulsed dc on the turbulent formation was studied and repeated for different initial phases of ac sinusoidal waveform. The results show that the pulsed dc is more effective on diminishing the laminar length, whereas ac power affects on laminar fluctuations which is resulted from the formation of trains of the fast TF. The transverse turbulent is also observed resulted from the speed change of consecutive TF. The study of the bullet propagation at different initial phases of ac power showed that although bullet propagation dynamics alters drastically due to changes of electric field distribution, there is no experimental evidence observed to prove that TF fluctuations follow the bullet propagation dynamics.

中文翻译：

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由脉冲直流和交流电源双源驱动的等离子体射流废气湍流前沿的动力学：实验研究

研究等离子体流出气体湍流的形成机制及其在不同等离子体配置下的动力学有助于操纵和优化相关应用的等离子体。在本文中，首次通过实验研究了由脉冲直流和交流电源驱动的三电极配置下喷射等离子体废气的湍​​流前沿 (TF) 动力学。氦等离子体射流形成的 TF 由 Schlieren technics 成像。此外，利用高速相机捕捉挠场形成的时间演变，研究了交流和脉冲直流对湍流形成的贡献，并针对交流正弦波形的不同初始相位进行了重复。结果表明，脉冲直流对减少层流长度更有效，而交流电源会影响层流波动，这是由快速 TF 序列的形成引起的。横向湍流也是由连续 TF 的速度变化引起的。对交流电源不同初始阶段子弹传播的研究表明，虽然子弹传播动力学因电场分布的变化而发生剧烈变化，但没有观察到实验证据证明TF波动跟随子弹传播动力学。