Numerical study on the gas heating mechanism in pulse-modulated radio-frequency glow discharge**Project supported by the National Natural Science Foundation of China (Granted Nos. 11405022 and 11475040) and Dalian High Level Talent Innovation Support Plan, China (Grant No. 2015R050).

Abstract

The gas heating mechanism in the pulse-modulated radio-frequency (rf) discharge at atmospheric pressure was investigated with a one-dimensional two-temperature fluid model. Firstly, the spatiotemporal profiles of the gas temperature () in both consistent rf discharge and pulse-modulated rf discharge were compared. The results indicated that decreases considerably with the pulse-modulated power, and the elastic collision mechanism plays a more important role in the gas heating change. Secondly, the influences of the duty cycle on the discharge parameters, especially on the , were studied. It was found that decreases almost linearly with the reduction of the duty cycle, and there exists one ideal value of the duty cycle, by which both the can be adjusted and the glow mode can be sustained. Thirdly, the discharge mode changing from α to γ mode in the pulse-modulated rf discharge was investigated, the spatial distributions of in the two modes show different features and the ion Joule heating is more important during the mode transition.