How plasma actuators work at low pressure

What is it about?

Plasma actuators are devices that use electric fields to create a gentle “wind” of charged air—without any moving parts—to control airflow over surfaces like airplane wings. It can help reduce drag, prevent stalls, or even stop ice from forming. Most existing plasma actuators affect only a small area. Still, a newer design, the sliding discharge plasma actuator, uses three electrodes to spread the effect over a much wider region, making it more useful for real aircraft. In this study, we tested how well this three-electrode actuator works at lower air pressures—like those found at high altitudes where planes fly. We found that as pressure drops, the plasma becomes stronger and spreads farther, which is good—up to a point. At very low pressures (around 38 kPa, similar to 7–8 km altitude), the discharge starts to form intense, narrow channels that behave almost like tiny sparks (called “potential-arc-discharge”). It causes uneven heating and actually reduces the airflow the actuator can produce. Our results show that sliding-discharge actuators perform best at moderately low pressures (around 54 kPa) and highlight a key challenge: preventing the discharge from collapsing into unstable spark-like channels at very low pressures. This insight helps guide future designs for practical aerospace applications.

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Photo by Dmitry Khotsinskiy on Unsplash

Photo by Dmitry Khotsinskiy on Unsplash