Plasma actuator

Plasma actuators are a type of actuator currently being developed for aerodynamic flow control. Plasma actuators impart force in a similar way to ionocraft.

The working of these actuators is based on the formation of a low-temperature plasma between a pair of asymmetric electrodes by application of a high-voltage AC signal across the electrodes. Consequently, air molecules from the air surrounding the electrodes are ionized, and are accelerated through the electric field.

Plasma actuators operating at the atmospheric conditions are promising for flow control, mainly for their physical properties, such as the induced body force by a strong electric field and the generation of heat during an electric arc, and the simplicity of their constructions and placements. In particular, the recent invention of glow discharge plasma actuators by Roth (2003) that can produce sufficient quantities of glow discharge plasma in the atmosphere pressure air helps to yield an increase in flow control performance.

Either a direct current (DC) or an alternating current(AC) power supply or a microwave microdischarge can be used for different configurations of plasma actuators. One schematic of an AC power supply design for a dielectric barrier discharge plasma actuator is given here as an example. The performance of plasma actuators is determined by dielectric materials and power inputs, later is limited by the qualities of MOSFET or IGBT.

The driving waveforms can be optimized to achieve a better actuation (induced flow speed). However, a sinusoidal waveform may be more preferable for the simplicity in power supply construction. The additional benefit is the relatively less electromagnetic interference. Pulse width modulation can be adopted to instantaneously adjust the strength of actuation.

Manipulation of the encapsulated electrode and distributing the encapsulated electrode throughout the dielectric layer has been shown to alter the performance of the dielectric barrier discharge (DBD) plasma actuator. Locating the initial encapsulated electrode closer to the dielectric surface results in induced velocities higher than the baseline case for a given voltage. In addition, Actuators with a shallow initial electrode are able to more efficiently impart momentum and mechanical power into the flow.

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