Plasma Structure in the Aerodynamic Plasma Actuator

Abstract

The aerodynamic plasma actuator is a surface discharge configuration dielectric barrier discharge (DBD) plasma using a highly asymmetric electrode configuration with one electrode exposed to air and the other encapsulated by dielectric material, driven by a high voltage (5-10 kV) AC waveform (2-10 kHz). The discharge appears over the surface of the dielectric above the encapsulated electrode, and is capable of coupling momentum into the surrounding air sufficient to substantially affect the airflow around aerodynamic surfaces. We describe the results of a series of optical measurements that reveal the rich temporal and spatial structure of the plasma. We show that the structure of the plasma is substantially different in both space and time on the negative-going versus the positive-going half-cycles of the applied voltage waveform. We demonstrate that the plasma initiates near the edge of the exposed electrode once each half-cycle, and that subsequent to this sudden initiation event, the discharge sweeps over the dielectric surface at a relatively constant rate. At the extrema of the voltage waveform, the discharge quenches entirely, and we show that the speed of this quenching is related to the plasma chemistry of the ionized air.