Thrusters powered by ionic wind may be an efficient alternative to conventional atmospheric propulsion technologies.

When a current passes between two electrodes — one thinner than the other — it creates a wind in the air between. If enough voltage is applied, the resulting wind can produce a thrust without the help of motors or fuel.


Picture source: San Francisco Sentinel.

This phenomenon, called electrohydrodynamic thrust — or, more colloquially, “ionic wind” — was first identified in the 1960s. Since then, ionic wind has largely been limited to science-fair projects and basement experiments; hobbyists have posted hundreds of how-to videos on building “ionocrafts” — lightweight vehicles made of balsa wood, aluminum foil and wire — that lift off and hover with increased voltage.

A basic ionic thruster consists of three parts: a very thin copper electrode, called an emitter; a thicker tube of aluminum, known as a collector; and the air gap in between. A lightweight frame typically supports the wires, which connect to an electrical power source. As voltage is applied, the field gradient strips away electrons from nearby air molecules. These newly ionized molecules are strongly repelled by the corona wire, and strongly attracted to the collector. As this cloud of ions moves toward the collector, it collides with surrounding neutral air molecules, pushing them along and creating a wind, or thrust.

Now researchers at MIT have run their own experiments and found that ionic thrusters may be a far more efficient source of propulsion than conventional jet engines. In their experiments, they found that ionic wind produces 110 newtons of thrust per kilowatt, compared with a jet engine’s 2 newtons per kilowatt. The team has published its results in the Proceedings of the Royal Society.

Steven Barrett, an assistant professor of aeronautics and astronautics at MIT, envisions that ionic wind may be used as a propulsion system for small, lightweight aircraft. In addition to their relatively high efficiency, ionic thrusters are silent, and invisible in infrared, as they give off no heat — ideal traits, he says, for a surveillance vehicle.

“You could imagine all sorts of military or security benefits to having a silent propulsion system with no infrared signature,” says Barrett, who co-authored the paper with graduate student Kento Masuyama.

Source: MIT Media Relations