This paper quantitatively characterizes a kHz atmospheric pressure He plasma jet without target powered by a pulse of positive applied voltage. It focuses on a quantitative comparison between experimental measurements and numerical results of a two-dimensional fluid model using the same configuration, for different values of magnitude and width of pulsed applied voltage. Excellent agreement is obtained between experiments and simulations on the gas mixture distribution, the length and velocity of discharge propagation and the electric field in the discharge front. For the first time in the same jet, the experimentally measured increase of the electric field in the plume is confirmed by the simulations. The electron density and temperature, measured behind the high field front, are found to agree qualitatively. Moreover, the comparison with simulations shows that discharge propagation stops when the potential in the discharge head is lower than a certain threshold. Hence, pulse width and magnitude allow to control propagation length. For long pulses (≥1000 ns), the threshold potential in the discharge front is reached during the pulse. For shorter pulses, propagation is determined by the pulse shape, as the threshold is reached around 90-130 ns after the fall of the pulse. The results suggest that this threshold is defined by the gas mixture at the position of the front.

中文翻译：

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kHz 大气压等离子体射流的表征：在没有目标的情况下实验和模拟中放电传播参数的比较

本文定量表征了 kHz 大气压力 He 等离子体射流，该射流没有由正施加电压脉冲供电的目标。它侧重于使用相同配置的二维流体模型的实验测量和数值结果之间的定量比较，对于不同的脉冲施加电压的幅度和宽度值。在气体混合物分布、放电传播的长度和速度以及放电前沿中的电场的实验和模拟之间获得了极好的一致性。模拟首次证实了在同一喷射流中实验测量到的羽流中电场的增加。发现在高场锋后面测量的电子密度和温度在性质上是一致的。而且，与模拟的比较表明，当放电头中的电位低于某个阈值时，放电传播停止。因此，脉冲宽度和幅度允许控制传播长度。对于长脉冲 (≥1000 ns)，在脉冲期间达到放电前沿的阈值电势。对于较短的脉冲，传播由脉冲形状决定，因为在脉冲下降后约 90-130 ns 达到阈值。结果表明，该阈值由前沿位置的气体混合物定义。对于较短的脉冲，传播由脉冲形状决定，因为在脉冲下降后大约 90-130 ns 达到阈值。结果表明，该阈值由前沿位置的气体混合物定义。对于较短的脉冲，传播由脉冲形状决定，因为在脉冲下降后大约 90-130 ns 达到阈值。结果表明，该阈值由前沿位置的气体混合物定义。