Numerical study on the gas heating mechanism in pulse-modulated radio-frequency glow discharge

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 (T_g) in both consistent rf discharge and pulse-modulated rf discharge were compared. The results indicated that T_g 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 T_g, were studied. It was found that T_g decreases almost linearly with the reduction of the duty cycle, and there exists one ideal value of the duty cycle, by which both the T_g 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 T_g in the two modes show different features and the ion Joule heating is more important during the mode transition.