Development of a plasma actuator with arc breakdown in a magnetic field

Ongoing research is presented on the development of an innovative plasma-based flow control actuation technique in which a high-voltage plasma arc is generated across a coaxial pair of electrodes positioned within the field of a strong rare-earth magnet. Generation of the plasma arc within a magnetic field perpendicular to its current path results in a Lorentz force on the charged particles, causing the arc breakdown position to sweep about the center of the coax, forming an apparent plasma disc. Having similarities in concept to microwavegenerating cyclotron elements, this new actuator concept has been designated as a “Cyclotronic Plasma Actuator”. A key aspect of this concept is the coupling of the thermal actuation of the plasma arc along with the induced swirl component produced by the angular velocity of the Lorentz-forced particles. This concept has potential use in boundarylayer flow control, by embedding span-wise arrays in an aerodynamic surface. The purpose of the device is to alleviate turbulent flow separation, serving as a controllable vortex generator that can be enabled on-demand during particular flight segments (e.g., during takeoff and landing), and disabled during high-speed cruise segments, eliminating the parasitic drag associated with conventional (vane-type) vortex generators. Demonstration and maturation of this technology in the current research and development program pioneers a class of plasma actuators aimed at addressing a well-known problem in active flow control. The recent experimental progress and near-term objectives are overviewed.