Numerical Simulation of 50 Hz/5 kHz Dual-Frequency Dielectric Barrier Discharge in Atmospheric-Pressure Air

A dual-frequency (DF) excitation, where the low-frequency voltage (ULF) is introduced into a stable intermediate-frequency (IF) discharge, is proposed to improve discharge. A one-dimensional (1D) plasma fluid model has been developed to investigate the effect of the ULF and IF voltage (UIF) on the current pulse amplitude, electron density, and dielectric surface charge. The simulated results show that the current pulse amplitude, the maximal electron density of the breakdown, and the dielectric surface charge are modulated by the ULF and vary periodically with the ULF magnitude. When the ULF transits from positive to negative polarity, the maximum current pulse amplitude and electron density of the breakdown process is observed within a DF cycle. The maximum electron density of the breakdown within a DF cycle is enhanced by increasing the ULF. In the DF discharge with a ULF of 12 kV, the maximum electron density of the breakdown within a DF cycle is 17.91% higher than that at the same time in the single IF discharge. This is due to the residual voltage between the gap enhanced by the increase of ULF, which causes more charged particles to accumulate on the dielectric surface, thereby increasing the discharge intensity. The distribution range of the current pulse amplitude expands as the UIF amplitude increases. When the UIF is 12 kV, the distribution range of the current pulse amplitude is expanded by 37.5% compared with that when the UIF is 9 kV. This is caused by the generating more transferred charges at the higher UIF.