This work presents the study of the single-dielectric barrier discharge aerodynamic plasma actuator. To model the physics of the plasma discharge, a space-time lumpedelement circuit model was developed. The model solution compared well to some of the characteristic features of the discharge such as the dependence of the sweep velocity and maximum extent of the ionized air as functions of the applied voltage and ac driving frequency. The time-dependent charge distribution obtained from the model was used to provide boundary conditions to the electric field equation that was used to calculate the time dependent electric potential. The was then used to calculate the space-time distribution of the actuator body force. An application of the plasma actuators to the leading-edge separation control on the NACA 0021 airfoil was studied numerically and experimentally. The results were obtained for a range of angles of attack for uncontrolled flow, and steady and unsteady plasma actuators located at the leading edge of the airfoil. The control of the lift stall was of particular interest. Improvement in the airfoil characteristics were observed in the numerical simulations at post-stall angles of attack with the plasma actuators. The computational results corresponded very well with the experiments.