大气压等离子体针产生空气均匀放电特性研究

大气压空气放电由于脱离了真空装置,易于实现流水线生产,因而在工业上具有广泛的应用. 采用等离子体针装置在空气中产生了稳定的大气压均匀放电. 利用光谱法对等离子体的相关参数进行了空间分辨率测量,并通过光学方法对放电机理进行了研究. 结果表明,等离子体针产生的放电存在电晕放电和等离子体羽放电两种模式. 在稳定的等离子体羽放电模式中,发光分为强光区和弱光区. 弱光区放电的发展速度远大于强光区的发展速度,电子能量和电子密度均是弱光区比强光区大. 对均匀放电的气体温度和振动温度的研究表明,强光区放电遵循汤生击穿机理而弱光区为流光放电. 这些结果对大气压空气放电的工业应用具有重要意义.关键词：大气压均匀放电等离子体针发射光谱放电机理

Characteristics of atmospheric pressure air uniform discharge generated by a plasma needle

Cold plasma generated by atmospheric air discharge has wide application prospect in industry because it does not need vacuum equipment and mass production is possible. In this paper, a stable uniform discharge is generated in open air by a plasma needle. Discharge mechanism is investigated by optical method, and plasma parameters are given by the spatially resolved measurement of emission spectrum from the discharge. Results show that the discharges have two modes. One is a corona discharge mode and the other is plasma plume mode. In the stable plasma plume mode, a strong emission area and a weak emission one can be distinguished from each other. The development velocity of the weak emission area is much faster than that of the strong emission area. Furthermore, the electron energy and the plasma density in the weak emission area are also bigger than those in the strong emission area. Therefore, the discharge in the strong emission area is dominated by Townsend mechanism, while that in the weak emission area is dominated by streamer discharge. Gas temperature and vibration temperature are also studied in this paper. The experimental results are of great importance to the industrial applications of atmospheric pressure discharge.