大气压下绝缘毛细管内等离子体放电及其特性研究

Characteristics of the plasma discharge generated in dielectric capillary at atmospheric pressure

在石英毛细管内利用两个边缘锋利的中空针型电极间的放电形成了63cm长的大气压弧光等离子体.通过记录放电图片和测量电流-电压特征波形及伏安特性曲线的方法对管内等离子体从反常辉光状态过渡至超长弧光状态的过程做了细致的研究,发现管内等离子体在弧光状态下的电子密度不低于1014cm-3.另外,还进一步考察了两电极的间距和电源工作频率对放电伏安特性的影响以及通过发射光谱法测得的等离子体气体温度随外加电压的变化规律.当活性气体(氧气)按一定比例混合到氩等离子体中时,通过光化线强度测定法研究了放电产生氧原子的含量随氧气流量与总气体流量之比的变化趋势,结果发现虽然氧气流量与总气体流量之比逐渐增大,但产生的氧原子含量却基本维持不变.

An atmospheric-pressure argon plasma discharge with a length of 63 cm is generated in a quartz capillary by using a pair of hollow needle electrodes. The discharge mode transition from abnormal glow to arc is investigated by means of electrical measurement and optical emission spectroscopy. The effects of the distance between two needle electrodes and the operating frequency of power supply on the voltage-current characteristics are discussed. The plasma electron density was estimated to be the order of 1014 cm-3 in the arc discharge. Moreover,the variation of gas temperature with the applied voltage is also studied,which is closely associated with the power dissipation. Furthermore,in measuring the oxygen atoms generated in argon/oxygen arc plasma discharge by optical actinometry,we found that the amount of oxygen atoms almost does not change with the rise of oxygen concentration.