On airplane wings, for example, tiny plasma actuators could help planes fly more safely, more efficiently, and with greater stability and control.
Embedding high-voltage versions of these wind generators-flat, thin-film electrodes-in an airplane’s wings can not only summon artificial St. Elmo’s fire instantly and on command, but it can also send the charged plasma clouds-and air they carry along with them-moving in one direction or another.
Russian engineers later detailed in a magazine article “How plasmas could weaken the shock waves generated during hypersonic flight,” says Jon Poggie of Purdue University, who at the U.S. Air Force Research Laboratory Command in Ohio previously studied plasma control of supersonic flows.
“If plasmas really could reduce drag, it was thought that it might be possible to delay the onset of sonic booms, steer aircraft by applying plasmas selectively to different parts of the vehicle, and even reduce heating around hot spots on an airframe.” In time, the Soviet Union collapsed and émigré Russian researchers arrived in the west, spurring fruitful research on plasma aerodynamics among R&D institutions in Europe, the U.S., and Russia, an extraordinary international collaboration that lasted almost 20 years.
Plasma wind is created by applying an alternating or pulsed current to electrodes to produce “a dynamically changing electric field,” says Steve Wilkinson, an aerodynamicist at NASA Langley, one of a cadre of researchers at government, industry and university labs in the U.S., Europe, Russia and elsewhere who investigate what’s called plasma aerodynamics.
“They blow like weak table fans, only enough to move notebook pages around.” But, paradoxically, if aimed and timed correctly, the breezes blown by these plasma actuator devices can be strong enough to significantly alter how wind flows over wings in beneficial ways, he adds.
Conceptually, Poggie says, researchers envision tiling wings and tail surfaces with arrays of flat plasma actuators that could be individually activated to tweak airflow to improve aerodynamics.