Comparative Study of the Surface Cleaning for Ar-/He-Based Plasma Jets at Atmospheric Pressure

In this study, an atmospheric-pressure He/O₂ or Ar/O₂ plasma jet is generated by a specially designed equipment with two coaxial quartz tubes and double power electrodes to remove lubricants from the surfaces of metals. The experimental results indicate that the cleaning performance is much better in the Ar/O₂ plasma jet than in the He/O₂ plasma jet under the same input power and O₂ mixing ratio. It is found that more electron, more atomic oxygen, and more metastable Ar atoms generated in the Ar/O₂ plasma jet result in better cleaning performance. In the He/O₂ plasma jet or the Ar/O₂ plasma jet, there exists an optimum O₂ mixing ratio for a certain input power, at which the desirable cleaning performance can be received. And the highest removing rate is 1259.8 ng/s when the 2.1% O₂ in the Ar plasma jet at an input power of 6 W. It is considered that atomic oxygen can be generated most efficiently under this optimum O₂ mixing ratio.