AQUITAINE, France, Aug. 11 (Brooks Hays) — Researchers in France have levitated a liquid droplet using a stream of electricity, creating a thin layer of plasma beneath.
The phenomenon is similar to the Leidenfrost effect, in which floating droplets are propped up by a layers of hot vapor. Instead of hot air, the droplets are buoyed by a charge of radiation.
Scientists, who detailed their recent discovery in the journal Applied Physics Letters, say the tecnique offers a simple, new way to generate freely movable microplasma. The levitating droplets may help researchers answer fundamental questions of physics.
“This method is probably an easy and original way to make a plasma,” Cedric Poulain, a physicist at the French Alternative Energies and Atomic Energy Commission, said in a press release.
The most common real world example of the Leidenfrost effect, or Leidenfrost levitation, is when water droplets bounce of a piping hot kitchen pan. If not quite hot enough, the water will hit the pan and begin to vaporize. But if the pan is very hot, a layer of vapor forms and causes droplets to levitate.
“This is a classical ‘grandmother’ trick to test the temperature of a pan,” Poulain explained.
To see if electricity could have a similar effect, researchers ran a charge with conductive droplets and filmed them using a high speed camera. When the electricity first pulsed through the droplet, a weak hydrochloric acid, the solution began to vaporize into hydrogen and oxygen.
But when the voltage topped 50, the droplet’s underside began to spark and levitated above the charged hot plate. A faint blue light emanated from the gap between the plate and levitated droplet.
Researchers say the gap appears to be a thin layer of two types of plasma not well understood.
“Although fifty volts is a relatively low voltage,” researchers explained, “the tiny gap between the droplet and the metal plate is what gives rise to the very high electric field necessary to generate a long-term and dense plasma with little energy.”
Poulain and his colleagues are now working to better understand the composition of the proto-plasmic layer.