大气压氩气/空气针-环式介质阻挡放电发射光谱诊断

为了更加深入地了解氩气/空气等离子体射流内的电子输运过程及化学反应过程，通过针-环式介质阻挡等离子体发生器在放电频率10 kHz，一个大气压条件下对氩气/空气混合气进行电离并产生了稳定的等离子体射流。通过发射光谱法对不同峰值电压下氩气/空气等离子体射流的活性粒子种类、电子激发温度及振动温度进行了诊断。结果表明，射流中的主要活性粒子为N₂的第二正带系、Ar Ⅰ原子以及少量的氧原子，其中N₂的第二正带系的相对光谱强度最强、最清晰，在本试验的发射光谱中没有发现N+₂的第一负带系谱线，这说明在氩气/空气等离子体射流中几乎没有电子能量高于18.76 eV的自由电子。利用Ar Ⅰ原子激发能差较大的5条谱线做最小二乘线性拟合对等离子体射流的电子激发温度进行了计算，得到大气压氩气/空气等离子体射流的电子激发温度在7 000~11 000 K之间。随峰值电压的增大，电子激发温度表现出先增大后减小的变化趋势，这说明电子激发温度并不总是随峰值电压的增长单调变化的。通过N₂的第二正带系对等离子体振动温度进行了诊断，发现大气压氩气/空气等离子体射流振动温度在3 000~4 500 K之间，其随峰值电压的增大而减小，这意味着虽然峰值电压的提高可有效提高自由电子的动能，但当电子动能较大时自由电子与氮分子之间的相互作用时间将会缩短，进而二者之间的碰撞能量转移截面将会减小，从而导致等离子体振动温度的降低。

Diagnosis of Atmospheric Pressure Argon/Air Needle-Ring Dielectric Barrier Discharge Emission Spectrum

To gain a deeper understanding of the electron transport process and chemical reaction process in the plasma jet. A needle-ring plasma generator generated a stable plasma jet- at a discharge frequency of 10 kHz and an atmospheric pressure. The types of active particles, electron excitation temperature and plasma vibration temperature of atmospheric pressure argon/air plasma jet under different applied peak voltages were diagnosed by emission spectroscopy. The results show that the main active particles in the atmospheric pressure argon/air plasma jet are the second positive band system of N₂, Ar Ⅰ atoms and a small number of oxygen atoms, and the relative spectral intensity of the second positive band system of N₂ is the strongest and the most clear. The first negative band line of N+₂ was not found in the emission spectrum of this experiment, which shows that there are almost no free electrons with electron energy higher than 18.76eV in the argon/air plasma jet. Plasma electron excitation temperature was calculated using5 spectral lines with a large difference in excitation energy of Ar Ⅰ atoms. The electron excitation temperature was between 7 000 and 11 000 K. With the increase of the applied peak voltage, the electron excitation temperature showed a trend of increasing first and then decreasing. The plasma vibration temperature was diagnosed by the second positive band system of N₂, and it was found that the vibration temperature of the atmospheric pressure argon/air plasma jet was between 3 000 and 4 500 K, which decreased with the increase of the applied peak voltage. This means that although the increase in peak voltage can effectively increase the kinetic energy of free electrons, when the electron kinetic energy is large, the interaction time between free electrons and nitrogen molecules will be shortened, and the collision energy transfer cross section between the two will be reduced. So the plasma vibration temperature shows a downward trend.