Self-consistent two-dimensional modeling of cold atmospheric-pressure plasma jets/bullets
Self-consistent two-dimensional modeling of cold atmospheric-pressure plasma jets/bullets
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DOI：
10.1088/0963-0252/21/3/034011
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发表时间：
2012-06-01
影响因子：
3.8
通讯作者：
Raja, L. L.
中科院分区：
文献类型：
--
作者：
Breden, D.;Miki, K.;Raja, L. L.
提出了环境空气中冷、大气压、氦射流中流光传播的计算模型研究。使用具有详细的有限速率化学和光电离效应的自洽、多物种、多温度等离子体模型来提供对流光的结构和动力学的基本见解。对流注特性作为重要放电几何和操作条件的函数进行了参数研究。氦射流核心和环境空气之间的流体机械混合层有助于引导流光的传播方向，并使等离子体射流具有明显的准直外观。驱动流光传播的关键化学反应是氦中性分子和氮分子的电子轰击电离。光电离在提高流光的传播速度方面发挥着作用，但不是维持流光所必需的。流注通过流注头部和主体的化学反应产生大量的自由基浓度。流注传播速度随着氦射流半径的减小和氦-空气混合层宽度的增加而增加。氦射流中的杂质通过光电离导致管内的放电传播速度显着增加，但在流光传播到开放的环境区域之后却不会。还观察到，较薄的电极会产生更强的电场集中，这会增加管内的放电传播速度，但在放电以流光形式从管中出现后对放电的影响较小。
A computational modeling study of streamer propagation in a cold, atmospheric-pressure, helium jet in ambient air is presented. A self-consistent, multi-species, multi-temperature plasma model with detailed finite-rate chemistry and photoionization effects is used to provide fundamental insights into the structure and dynamics of the streamers. A parametric study of the streamer properties as a function of important discharge geometric and operating conditions is performed. The fluid mechanical mixing layer between the helium jet core and the ambient air is instrumental in guiding the propagation direction of the streamer and gives the plasma jet a visibly collimated appearance. The key chemical reactions which drive the streamer propagation are electron-impact ionization of helium neutral and nitrogen molecules. Photoionization plays a role in enhancing the propagation speed of the streamer, but is not necessary to sustain the streamer. The streamer yields a large radical concentration through chemical reactions in the streamer head and the body. The streamer propagation speed increases with reduced helium jet radius and increased helium-air mixing layer width. Impurities in the helium jet result in a significant increase in the discharge propagation speed within the tube through photoionization, but not after the streamer propagates into the open ambient region. It is also observed that thinner electrodes produce stronger electric-field concentrations that increase discharge propagation speeds within the tube but have a smaller influence on the discharge after it emerges out of the tube as a streamer.