Role of the Static Pressure in Experiments on Flow Control by Means of Surface Capacitor Discharges

The effect of the static pressure on the reaction force exerted on a plate above whose surface a gas flow has been induced by exciting a capacitor (barrier) discharge is investigated. In the experiments the discharge was restructured so that the reaction force and the corresponding momentum entrained by the neutral flow increased when the pressure was reduced from atmospheric pressure to 200 Torr, the power supplied to the discharge being fixed. The charge exchange effect is of importance for the formation of the resulting gas flow. It is shown that under the experimental conditions the effect of an increase in the force with decrease in pressure is associated with an increase in the plasma volume ahead of the electrodes and the total number of ions in this volume.