H_2O/N_2脉冲流光放电和介质阻挡放电发射光谱比较

Compare of H_2O/N_2 emission spectrum between pulsed stream discharge and dielectric barrier discharge

本文采用脉冲流光放电和介质阻挡放电两种放电形式分别获得了H_2O/N_2等离子体的发射光谱.OH(A^2∑^+→X^2Ⅱ)荧光辐射在两种放电等离子体中均出现,而H_a荧光辐射仅存在于脉冲流光放电等离子体中.实验还对脉冲流光放电条件下OH、H_a荧光信号进行了时间分辨测量,结果显示H_a荧光信号滞后OH荧光信号约10ns.综合时间分辨测量结果以及水分子解离的相关文献可知等离子体内水分子分解的主要产物是基电子态的H原子和OH自由基,H_a荧光辐射源于快电子对H原子的次级碰撞激发.介质阻挡放电等离子体的放电脉冲宽度较窄,不能对基态H原子进行有效地次级碰撞激发,所以H_2O/N_2介质阻挡放电等离子体发射光谱中没有出现H_a荧光辐射.实验结论证明放电脉冲宽度对放电等离子体内次级碰撞激发过程有影响.

H_2O/N_2 plasmas emission spectrum were acquired using pulsed streamer discharge and dielectric barrier discharge,respectively.OH(A^2Σ^+→X^2Ⅱ)fluorescence emission appeared in both plasmas while H_α fluorescence emission was found only in pulsed stream discharge plasma.Time-resolve measurement of OH,H_α fluorescence signals showed that H_α signal appeared about 10 ns after OH signal's appearance in the pulsed streamer discharge.Based on time-resolve results and some water dissociation references, it was found out that H atom at ground electronic state and OH are main products of water dissociation in the plasma,and H_α signal resulted from H atom second collision and excitation by fast electrons. H atom was not excited efficiently during the second collision and excitation process in dielectric barrier discharge due to its narrower discharge pulse width,so there was no H_α signal in its emission spectrum.The conclusions of this experiment verified the fact that discharge pulse width could influence second collision and excitation process in discharge plasma.