Determination of vibrational and rotational temperatures in highly constricted nitrogen plasmas by fitting the second positive system of N2 molecules
Determination of vibrational and rotational temperatures in highly constricted nitrogen plasmas by fitting the second positive system of N2 molecules
复制标题
通过拟合 N2 分子的第二正系统确定高度压缩氮等离子体中的振动和旋转温度
作者：
Q. Zhang;D. Shi;W. Xu;C. Miao;C. Ma;C. Ren;Chao Zhang;Z. Yi
高度收缩的等离子体是一个活跃的研究领域，因为它们能够产生高活性的等离子体束，在材料加工和薄膜沉积的应用中表现出潜力。在这项研究中，光学发射光谱用于研究低压下产生的高度压缩的氮等离子体。通过拟合氮分子的第二正系统确定了分子的振动和旋转温度。在功率密度高达 7 ∼ 85 W/cm3 和压力 2 ∼ 200 Pa 的条件下，发现确定的旋转温度相对较低，从 350 K 增加到 700 K，振动温度保持在 ∼ 5000 K。耗散功率分析表明，约 80% 的输入功率因氮分子解离和氮分子的产生/损失而耗散。离子在管壁处产生高达 1012 ∼ 1013 cm−3 的等离子体，氮解离度为 2%∼15%。随着放电压力的增加，发现更多的输入功率被氮分子的解离而不是离子的产生所消耗，从而导致自由基的密度更高。
Highly constricted plasmas are an active research area because of their ability to generate high activity of plasma beams, which exhibit potential in applications of material processing and film deposition. In this study, optical emission spectroscopy was used to study the highly constricted nitrogen plasma created at low pressure. The vibrational and rotational temperatures of molecules were determined by fitting the second positive system of nitrogen molecule. Under the conditions of the power densities as high as 7 ∼ 85 W/cm3 and the pressures of 2 ∼ 200 Pa, the determined rotational temperature was found to be relatively low, increasing from 350 to 700 K and the vibrational temperature keeping at ∼ 5000 K. The analysis of dissipated power revealed that ∼ 80 % of input power is dissipated for the nitrogen molecule dissociation and the creation/loss of ions at the tube wall, producing an as high as 1012 ∼ 1013 cm−3 plasma with the nitrogen dissociation degrees of 2%∼15%. With the increase in the discharge pressure, more input power was found to be dissipated in the dissociation of nitrogen molecules instead of creation of ions, resulting in a higher density of radicals.