Correlation between emission, electric, and flow properties of arc-filament plasma actuators

Renewed interest in flow-control devices using various forms of plasmas has motivated the design and systematic investigation of localized arc-filament plasma actuators. This newly constructed system creates electric arcs by generating electric fields in the range of 20 kV/cm between two pin-type electrodes. The potential of the actuator to influence surrounding quiescent air when placed in a5× 2×1.6 mm cavity was investigated using emission imaging, particle image velocimetry,and current and voltage measurements.The emission imaging showed both temporaland spatial variation. The emission was most intense and variable in the first microsecond after breakdown. The particle- image-velocimetry data were acquired for several plasma currents, on times, and actuation frequencies. The data showed characteristic features of a hot gas expansion from acavity,such as rapid gas dilatation exemplified through a blast wave, and cavity refilling from postdischarge cooling. The electric measurements were correlated to their respective emission imaging and particle-image-velocimetry measurements. The plasma voltage was found to alternate between two distinct modes: high-voltage and low-voltage. From the emission imaging, it is theorized that this actually may be the plasma alternating between glow and arc discharge modes as a result of the restricted current.