Modeling of Interaction Between Weakly Ionized Near-Surface Plasmas and Gas Flow

Detailed physical model for asymmetric dielectric barrier discharge (DBD) in air is developed. Modeling of DBD with applied sinusoidal voltage is carried out. The leading role of charging the dielectric surface by electrons in the cathode phase is shown to be critical, acting as a harpoon that pulls positive ions forward and accelerates the gas in the anode phase. The positive ion motion back towards the exposed electrode is shown to be a major source of inefficiency in the sinusoidal or near-sinusoidal voltage cases. Based on understanding of the DBD physics, an optimal voltage waveform is proposed, consisting in high repetition rate short (a few nanoseconds in duration) negative pulses combined with positive dc bias applied to the exposed electrode. The velocity of near-surface gas jet produced by the DBD actuator thus optimized is shown to be considerably (potentially - by 1-2 orders of magnitude) greater than that for a sinusoidal signal with similar parameters.

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