Three-Electrode Sliding Nanosecond Dielectric Barrier Discharge Actuator: Modeling and Physics

We present a numerical study of plasma dynamics in a three-electrode sliding nanosecond dielectric barrier discharge flow actuator. A two-dimensional self-consistent plasma model including the effect of detail air plasma chemistry and ultrafast gas heating is used in our studies. When a third electrode is placed downstream of a classical two-electrode nanosecond dialectric barrier discharge actuator and powered by a negative direct-current voltage, a coronalike discharge is formed in its immediately vicinity, which in turn changes the dynamic of the primary streamers propagating from the pulsed electrode. The primary streamer slides and can even extend to the entire interelectrode distance. The potential difference between the third electrode, the positively charged dielectric surface, and the virtual anode formed by the streamer itself is found to be the main reason behind this elongation because of the electric field enhancement at the streamer head. Preionization and charge accumulation from the third electrode also contribute to this behavior. The numerical results also indicate that for high electric fields a negative streamer can be produced at the third electrode that merges with the positive streamer from the pulsed electrode. Consequently, the plasma channel covers the entire interelectrode space. The elongation of the primary streamer leads to an increase of the effective energy release region, which can result in a more efficient flow actuation mechanism.