When a current passes between two electrodes — one thinner than the other — it creates wind in the air between. If enough voltage is applied, the resulting wind can produce a thrust without the help of motors or fuel. This phenomenon, called electrohydrodynamic thrust — or “ionic wind” — was first identified in the 1960s.
There have been few rigorous studies of ionic wind as a viable propulsion system. Some researchers have theorized that ionic thrusters, if used as jet propulsion, would be extremely inefficient, requiring massive amounts of electricity to produce enough thrust to propel a vehicle.
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.
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.
Barrett acknowledges that there is one big obstacle to ionic wind propulsion: thrust density, or the amount of thrust produced per given area. Ionic thrusters depend on the wind produced between electrodes; the larger the space between electrodes, the stronger the thrust produced. That means lifting a small aircraft and its electrical power supply would require a very large air gap.
Ned Allen, chief scientist and senior fellow at Lockheed Martin Corp., says that while ionic thrusters face serious drawbacks — particularly for aerospace applications — the technology “offers nearly miraculous potential.” Lockheed Martin is looking into the technology as a potential means of propulsion.