Fundamental Processes of DBD Plasma Actuators Operating at High Altitude

Dielectric barrier discharge (DBD) plasma actuators are active flow control devices being investigated for implementation on future aircraft. This paper provides the details of a high altitude analysis done on a plasma actuator operating at altitudes from 0 to 18288 meters (60000 feet) in order to qualitatively determine the fundamental processes that lead to increased power consumption and decreased force production. The actuator is driven with a 5 kHz sine wave with a peak-peak voltage of 13.4 kV at pressures of 760, 429, 321, 226, and 88 Torr. A passive measurement technique called the capacitive V-dot probe is adapted to the actuator in order to resolve the spatiotemporal evolution of the surface potential on the dielectric surface. At low pressures, where there is up to 800% more plasma than at sea level, the electric field is at or very near zero for approximately 80% of the dielectric surface, compared to just 55% at sea level. This implies that at lower pressures increased actuator power is spent making plasma and not accelerating it. Measurements also show that the location of the peak physical charge deposition corresponds closely with the location of the peak surface potential, indicating that the primary mechanism for building potential on the dielectric surface is due to physical charge deposition and not from the capacitive voltage division/polarization effects of the actuator.