Time-resolved radial uniformity of pulse-modulated inductively coupled O₂/Ar plasma has been investigated by means of a Langmuir probe as well as an optical probe in this paper. The radial uniformity of plasma has been discussed through analyzing the nonuniformity factor β (calculated by the measured n _e, lower β means higher plasma radial uniformity). The results show that during the active-glow period, the radial distribution of n _e exhibits an almost flat profile at the beginning phase, but it converts into a parabola-like profile during the steady state. The consequent evolution for β is that when the power is turned on, it declines to a minimum at first, and then it increases to a maximum, after that, it decays until it keeps constant. This phenomenon can be explained by the fact that the ionization gradually becomes stronger at the plasma center and meanwhile the rebuilt electric field (plasma potential and ambipolar potential) will confine the electrons at the plasma center as well. Besides, the mean electron energy (〈 ε 〉_on) at the pulse beginning decreases with the increasing duty cycle. This will postpone the plasma ignition after the power is turned on. This phenomenon has been verified by the emission intensity of Ar (; = 750.4 nm). During the after-glow period, it is interesting to find that the electrons have a large depletion rate at the plasma center. Consequently, n _e forms a hollow distribution in the radial direction at the late stage of after-glow. Therefore, β exhibits a maximum at the same time. This can be attributed to the formation of negative oxygen ion (O⁻) at the plasma center when the power has been turned off.

本文采用朗缪尔探针和光学探针研究了脉冲调制电感耦合O _{2 /Ar等离子体的时间分辨径向均匀性。}等离子体径向均匀性通过分析非均匀性因子β（由测量的n _e计算， β越低表示等离子体径向均匀性越高）讨论。结果表明，在主动辉光阶段，n _e的径向分布在开始阶段呈现出几乎平坦的轮廓，但在稳定状态下转变为抛物线状轮廓。β的后续演化就是通电时，先下降到最小值，然后上升到最大值，之后衰减，直到保持不变。这种现象可以解释为电离在等离子体中心逐渐变强，同时重建的电场（等离子体电势和双极电势）也将电子限制在等离子体中心。此外，脉冲开始时的平均电子能量（< ε > _on）随着占空比的增加而减小。这将在打开电源后推迟等离子点火。这一现象已通过 Ar ( ;= 750.4 纳米）。在余辉期间，有趣的是发现电子在等离子体中心具有很大的耗尽率。因此，n _e在余辉后期形成径向中空分布。因此，β同时表现出最大值。这可以归因于当电源关闭时在等离子体中心形成负氧离子（O ^{- ）。}