Jet shape analysis and removal function optimization of atmospheric plasma processing applied in optical fabrication

When inductively coupled plasma (ICP) is used as a machining tool, its chemical etching-based processing method has the advantage of no contact stress between the tool and the material, thus without any mechanical damage. In recent years, this issue has been widely concerned in optical fabrication. However, there are many differences between low power ICP jet and conventional ICP jet, one of which is that the former does not easily form a rotation-symmetric removal function due to its obvious pinch effect. In this research, the electromagnetism principle of the plasma pinch effect was analyzed firstly, and the jet shape under the pinch effect was classified. Then, experiment was carried out to investigate the plasma jet shape under the pure Ar and mixed gas of CF₄-Ar, and the influence law of the reaction gas on the jet propagation shape was analyzed. Finally, the rotational symmetry of the removal function of plasma jet processing was optimized, and the nozzle design criteria were proposed based on pinch effect.