Numerical and experimental study of the dynamics of a μs helium plasma gun discharge with various amounts of N2 admixture
Numerical and experimental study of the dynamics of a μs helium plasma gun discharge with various amounts of N2 admixture
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DOI：
10.1088/0963-0252/25/3/035002
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发表时间：
2016-06-01
影响因子：
3.8
通讯作者：
Robert, Eric
中科院分区：
文献类型：
--
作者：
Bourdon, Anne;Darny, Thibault;Robert, Eric
本文采用二维数值模拟和实验相结合的方法，研究了N-2混合气体对等离子体枪10 cm长介质管内He-N-2放电动力学的影响。首先，对电离波阵面在管内的传播速度进行了实验和模拟比较。提出了在模拟中考虑He-N-2混合气体的详细动力学方案的重要性，以获得与实验良好的一致性。对于Mu S驱动的等离子体枪，在电离前沿后面的等离子体柱中发生的二体和三体Penning反应对放电动力学起着关键作用。在实验和模拟中，观察到外加电压的大小对电离前沿传播速度的显著影响。模拟结果表明，当N-2的量变化时，电离前沿速度取决于放电动力学、光致电离和管内放电的二维结构之间的复杂耦合。最后，将设置在管外的电光探头测量的电场轴向和径向分量的时间演化与模拟结果进行了比较。在电场的两个分量上得到了很好的一致。模拟结果表明，在管内，放电轴上的轴向电场大小与N-2的量成反比，与离轴峰值电场的大小成反比。模拟和在管内或在等离子体羽流中的第一次测量都显示出约45kV·cm(-1)的峰值电场。
This paper presents a combined 2D numerical and experimental study of the influence of N-2 admixture on the dynamics of a He-N-2 discharge in the 10 cm long dielectric tube of a plasma gun set-up. First, the comparison between experiments and simulations is carried out on the ionization front propagation velocity in the tube. The importance of taking into account a detailed kinetic scheme for the He-N-2 mixture in the simulations to obtain a good agreement with the experiments is put forward. For the mu s driven plasma gun, the two- and three-body Penning reactions occurring in the plasma column behind the ionization front, are shown to play a key role on the discharge dynamics. In the experiments and simulations, the significant influence of the amplitude of the applied voltage on the ionization front propagation velocity is observed. As the amount of N-2 varies, simulation results show that the ionization front velocity, depends on a complex coupling between the kinetics of the discharge, the photoionization and the 2D structure of the discharge in the tube. Finally, the time evolution of axial and radial components of the electric field measured by an electro-optic probe set outside the tube are compared with simulation results. A good agreement is obtained on both components of the electric field. In the tube, simulations show that the magnitude of the axial electric field on the discharge axis depends weakly on the amount of N-2 conversely to the magnitude of the off-axis peak electric field. Both, simulations and first measurements in the tube or within the plasma plume show peak electric fields of the order of 45 kV.cm(-1).