大气压氦氩混合气体介质阻挡放电电学和光谱特性研究

以聚对苯二甲酸乙二醇酯作为介质，在大气压下产生氦氩混合气体放电等离子体。利用电压电流探头、数字示波器和数码相机研究了聚对苯二甲酸乙二醇酯介质阻挡氦氩混合气体放电的电学特性和发光特性。发现随氩气含量增加，每半个电压周期出现一个或多个电流脉冲，放电由均匀放电转变为斑图放电。利用衍射光栅和CCD探测器组成的光谱系统测量了氩原子谱线（696.54, 763.13, 772.09, 811.17和911.81 nm）光谱强度。研究了氩气含量、峰值电压对氩原子谱线光谱强度的影响。实验结果表明：在峰值电压较低时，上述五条氩原子谱线光谱强度随氩气含量的增加均呈现先增强-后减弱-再增强的变化规律；在峰值电压较高时，波长为696.54, 763.13和772.09 nm三条谱线光谱强度增强，波长为811.17和911.81 nm谱线光谱强度减弱。上述情况表明：在低峰值电压下，上述五条氩原子谱线光谱强度的变化规律是由于在放电过程中放电模式发生了变化；而在髙峰值电压下，五条谱线强度变化与气体激发机制有关。在氩气含量低于30%或高于80%时，氩原子谱线光谱强度随峰值电压的增加先保持不变，再增强到稳定值；在氩气含量介于30%～80%之间时，氩原子谱线光谱强度随峰值电压的增加也呈现先增强-后减弱-再增强的变化规律；利用玻尔兹曼图形法计算了氩原子放电的电子激发温度，得到了不同峰值电压下电子激发温度随氦气/氩气比例变化的规律：高峰值电压下电子激发温度明显高于低峰值电压下电子激发温度；电子激发温度随氩气含量增加而减小。出现上述变化规律的原因主要是由于电子与氦原子碰撞截面小，电子与氩原子碰撞截面大，而氦气扩散系数大于氩气扩散系数。

Studies on the Electrical and Spectrum Characteristics in Atmospheric Dielectric Barrier Discharge in Helium-Argon Mixture

The polyethylene terephthalate (PET) was used for dielectric to produce the atmospheric pressure helium-argon mixture discharge plasma. The electrical and luminescence properties of PET dielectric barrier discharge were studied using a voltage probe, a current probe, a digital oscilloscope and a digital camera. It found that one or more current pulses appear in every half voltage cycle, and the discharge transits from uniform to pattern discharge with the increase of argon content. Argon atomic spectra intensities (696.54, 763.13, 772.09, 811.17 and 911.81 nm) were measured using a spectral system composed of the diffraction grating and a CCD detector. The influences of argon content and peak voltage (V_p) on the spectra intensity were researched. The results show that: at lower V_p, the above five argon spectra intensities enhance slowly, then weaken sharply, and enhance rapidly again with the increase of argon content；at higher V_p, the intensities of spectral line 696.54, 763.13 and 772.09 nm enhance and the intensities of argon spectral line 811.17 and 911.81 nm weaken. The discharge mode plays an important role in the spectra intensity variation at lower V_p, but the ionization mechanism makes a dominant contribution to the spectra intensity at higher V_p. At argon content ≤30% or ≥80%, the above argon spectra intensities almost remain unchanged, then increase to the stable value with the increasing V_p; at 30%≤argon content≤80%, the above five argon spectra intensities enhance slowly, then weaken sharply, and enhance rapidly again. The electron excitation temperature (T_exc) was calculated using the Boltzmann graph method, and the variation of T_exc with the ratio of helium to argon was obtained under different V_p. The results show that: the T_exc at high V_p is higher than that at low V_p, and the T_exc decreases with the increasing argon content. The reason is to maintain the balance between the ionization process and ion escape loss because the electron-helium collision section is much smaller than the electron-argon collision section, but helium has a larger diffusion coefficient than argon.