Abstract
Summary form only given. Many experimental and theoretical studies show that the shape of excitation voltage waveform is a crucial factor in generating uniform atmospheric-pressure plasmas1–4. In this paper, we compare the characteristic of pulsed and sinusoidal dielectric-barrier discharges (DBDs) in atmospheric N 2 by numerical simulations based on a one-dimensional fluid model. The results show that, different from the sinusoidal atmospheric nitrogen discharges which usually operate in Townsend discharge mode, the pulsed atmospheric nitrogen discharge can exist in two different modes, namely glow mode and Townsend mode depending on the rise time of the applied voltage pulse. Under the same voltage amplitude, when the rise time is longer, the discharge operates in Townsend mode, otherwise glow discharge occurs. In the Townsend discharge mode, the density of N 2 + is some orders of magnitude lower than that of N 4 +, but is much higher than N 4 + density in the glow mode, implying the penning ionizations between two metastable molecules play a dominate role in Townsend discharge, whereas the direct ionization of N 2 by electron impact is the primary ionization mechanism in the glow discharge. The effects of other parameters (such as pulse width, frequency, etc.) on the behaviors of pulsed DBD in atmospheric N 2 are also studied. In addition, the pulsed nitrogen discharge with multiple current peaks during the rise phase of the applied voltage pulse are also discussed and analyzed. For many practical applications, the atmospheric nitrogen plasma is more attractive due to its low cost and active reaction chemistry, and therefore, the detailed study of N 2 atmospheric DBDs under different electrical excitation is very necessary.
Published Version
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