空心针-板电极大气压氩气辉光放电的特性研究

摘要

Atmosphere pressure uniform plasma has the broad application prospect in the industrial field.Using hollow needle cathode-plate anode device excited by direct-current voltage,a uniform and stable glow discharge is generated at atmospheric pressure in ambient air with argon used as working gas.The influence of the experimental parameters (including gas flow rate and the gas gap width)on discharge has been investigated by optical method.It can be found that a glow-discharge plasma col-umn can bridge the two electrodes.The plasma column is uniform,and no filaments can be discerned.Near the plate electrode, the diameter of the plasma column is largest of all positions.The maximal diameter of the plasma column increases with increas-ing the discharge current or the gas flow rate.Through electrical method,the voltage-current characteristic has been investiga-ted.It has been found that the discharge voltage decreases with increasing the current which is similar with the characteristic of glow discharge in low pressure.It increases with increasing the gas gap width or the gas flow rate.By analyzing the optical emis-sion spectrum scanning from 330 to 450 nm emitted from the direct-current glow discharge,the molecular vibrational tempera-ture and the intensity ratio of spectral lines I 391.4/I 337.1 have been investigated as functions of the gas flow rate and gas gap width. Results indicate that both the vibrational temperature and the intensity ratio of spectral lines I 391.4/I 337.1 decrease with increasing the gas flow rate or the gas gap width.In addition,the molecular vibrational temperature and the intensity ratio of spectral lines I 391.4/I 337.1 have been investigated in spatial resolution along the direction of gas flow(plasma column axial),and give a qualita-tive analysis as well.It is found that the vibrational temperature and the average electron energy increase with increasing the dis-tance from the hollow needle cathode.These results are important to the industrial applications of glow discharge.%大气压均匀放电等离子体在工业领域具有非常广泛的应用前景，它是利用直流电源激励的空心针-板放电装置，以氩气为工作气体在大气压空气中产生均匀稳定的放电。对氩气流量和气隙间距对辉光放电发光特性的关系进行了研究，结果表明放电所产生的等离子体柱连接两个电极，发光较为均匀（观察不到放电丝）。在板电极附近放电等离子体柱直径最大，最大直径随着电流和气流的增大而增大。放电伏安特性研究发现，与低气压辉光放电相类似，两电极间的电压随着电流的增大而减小，并且随气流和气隙间距的增大而增大。对该大气压直流均匀放电在扫描范围为330～450 nm 的光学发射光谱进行分析，获得了放电等离子体的分子振动温度和谱线强度比 I 391．4／I 337．1随氩气流量和气隙间距的变化关系。I 391．4／I 337．1均随流量和气隙间距的增大而降低。对等离子体柱的 I 391．4／I 337．1沿气流方向（等离子体柱轴向）进行了空间分辨测量，并进行了定性分析，结果表明，振动温度及电子平均能量随着远离空心针口距离的增大而增大。这些结果对大气压辉光放电在工业中的应用具有重要意义。