Normalized Electronegative Species Effects in the Dielectric-Barrier-Discharge Plasma Actuator

Time-resolved and time-averaged net force (electrohydrodynamic force plus viscous drag) are presented for a dielectric-barrier-discharge-based aerodynamic plasma actuator operated in artificial atmospheres composed of nitrogen (N-2) with various concentrations of electronegative gasses: 1-20% oxygen (O-2) and 0.01-0.34% sulfur hexafluoride (SF6). It is possible to deconvolve and isolate the role of oxygen to the negative-going or forward stroke of the discharge and to the region of parameter space with high E/n: a change in oxygen content by a factor of 20 yields only a 20% increase in force produced when 12 kV AC is applied to the system but yields a 170% increase when the voltage amplitude is increased by less than a factor of 2, to 20 kV applied. It is shown that substituting SF6 for O-2 produces a mild net increase in force production that saturates at very low SF6 concentrations (0.1%) and that the increase is limited because of substantial (50%) losses of the momentum to drag even though the momentum input is increased by a factor of 2.