Experimental and numerical study on the optimization of pulse-modulated radio-frequency discharges

In this paper we present an experimental and computational study on the optimization of pulse-modulated radio-frequency (rf) discharges at atmospheric pressure. Based on the measured and simulated data, to improve the electron density and electron temperature in a pulse-modulated rf discharge, a lower modulation frequency, smaller than 50 kHz, with a higher duty cycle, usually larger than 30%, should be used. But to reduce the power consumption and lower the gas heating, the duty cycle should be smaller than 60%. On the other hand, to achieve a quasi-continuous rf plasma in a whole modulation cycle, a modulation frequency larger than 100 kHz is preferred. Thus, by choosing an appropriate modulation frequency and duty cycle, the pulsed rf discharge can be effectively optimized to produce a high-density and non-equilibrium atmospheric plasma without the risk of gas heating but with a reduced power consumption. (paper)