等离子体喷枪是一种重要的等离子体源, 已成为近几年低温等离子体研究的一个重要课题。 本文利用钨针-钨丝网电极制作了直流喷枪装置, 在大气压空气中产生了稳定的等离子体羽, 并采用发射光谱的方法, 对等离子体羽的等离子体参数进行了研究。 在钨针电极与钨丝网电极之间放出耀眼的白光, 钨丝网电极出口的气流下游有火苗形状的等离子体羽喷出。 在电压保持不变的条件下(13.5 kV), 等离子体羽长度随气体流量增加而增大; 在气体流量保持不变的条件下(10 L·min-1), 羽长度随外加电压的增大而增大。 在气体流量一定的条件下, 放电电压和放电电流呈反比例关系, 即电压随着电流的增大而减小, 说明放电属于辉光放电。 采集了该喷枪在300～800 nm范围内的放电发射光谱, 通过玻尔兹曼方法对放电等离子体电子激发温度进行了测量。 结果表明, 电子的激发温度随外加电压的增大而降低, 随着工作气体流量的减小而升高。 利用放电的基本理论对上述现象做了解释。 这些研究结果对大气压均匀放电等离子体源的研制和工业应用具有重要意义。

Plasma jet is a kind of important plasma source at atmospheric pressure. In recent years, it becomes an important hot topic in the field of low temperature plasma. In this paper, using a tungsten needle and a tungsten wire mesh, a direct-current excited jet is developed to operate in argon at atmospheric pressure. In the atmospheric pressure argon, the plasma jet can produce a stable plasma plume. By using the method of emission spectroscopy, the parameters of the plasma plume are investigated. The discharge emits dazzling white light from the area between the tungsten needle electrode and the wire mesh electrode. A plasma plume with a flame shape appears outside the tungsten wire mesh electrode. For a constant value of voltage(U=13.5 kV), the length of the plasma plume increases with the gas flow rate. For a constant value of the gas flow rate(10 L·min-1), the length of the plasma plume increases with the voltage. The voltage is inversely proportional to the current under the constant gas flow rate. In other words, the voltage decreases with the discharge current, which indicates that a glow discharge is formed in the plasma jet. Optical emission spectrum in 300 to 800 nm is collected from the direct-current excited plasma jet. By Boltzmann plot method, the excited electron temperature of the plasma plume is investigated as a function of the applied voltage or the gas flow rate. Results show that the excited electron temperature increases with decreasing applied voltage under the constant gas flow. Moreover, it increases with decreasing the gas flow under the constant voltage. Based on the discharge theory, these experimental phenomena are explained qualitatively. These results are of great importance to the development of atmospheric pressure uniform discharge plasma source and its application in industrial field.