大气压氩等离子体射流的放电特性

Discharge Characteristics of Atmosphere Pressure Plasma Jet in Ar

为了深入地理解大气压等离子体射流放电机理和优化其放电效率,通过对大气压氩等离子体射流的电压电流波形和Lissajous图形等电气特性的测量及发射光谱和发光图像等光学特性诊断,研究了外电极距石英玻璃管口不同距离时,氩等离子体射流放电的放电特性和演变规律。计算放电功率、传输电荷量、电子激发温度、分子振动温度和分子转动温度等主要放电参量后,研究了它们随外加电压增加的变化趋势,并结合放电机理对所得实验结果进行了分析。结果表明,氩等离子体射流主要产生的粒子有OH、N2、Ar和少量的O,随着外电极位置的不同,气体温度在317～395K之间变化,为典型的低温等离子体;外电极位置影响放电模式和放电起始电压,在氩射流阶段,电子激发温度在不同外电极位置条件下相差不大。当外电极距离管口40mm时,外加电压幅值达8kV时,放电功率和传输电荷最大,放电效果和发光强度也最强,由Penning效应产生的OH谱线强度也最强,因此,用于聚合物材料表面改性等应用时,可以采用此运行参数,以达到更好处理效果。

In order to study discharge mechanisms of atmosphere pressure plasma jet （APPJ] in Ar deeply and to optimize its discharge efficiency, the effects of outer electrode position on discharge characteristics and evolutions of APPJ in Ar were studied by means of electrical measurements of voltage and current waveforms and Lissajous figures, and by diagnosing optical properties on optical emission spectra and light-emission pictures. The main discharge parameters such as discharge power, transported charges, electronic excitation temperature, molecular vibrational temperature and molecular rotational temperature were calculated, the changing tendencies of them with applied voltage were studied, and the experimental results were explained by analyzing discharge mechanism. Results show that the effects of outer electrode position on discharge characteristics are mainly reflected in stage of plasma iet, and the electronic excitation＂ temperature changes little with the positions of outer electrode. The generated APPJ in Ar plasm is a typical non-thermal one with gas temperature in the range of 317 K to 395 K, in which the main species are OH, N2, Ar and a little O. The outer electrode positions affect both the mode of the discharge and the breakdown voltage. When the distance from outer electrode to exit of tube is 40 mm and the applied voltage amplitude is 8 kV, the most intensified discharge with large discharge power and transported charges can be obtained, and the intensity of OH spectral line also reaches its peak. Therefore, when it is applied to surface modification of polymeric materials, the most efficient outcome can be achieved under the operation parameters.