Storm Layer In Helium Superfluid Discovered
The discovery of helium superfluid in the 20th century is considered as one of the major achievements in physics. Kamerlingh Onnes, renowned Dutch physicist, was the first person to liquefy helium.
Further studies of the liquid helium revealed that it possesses characteristics that are entirely different from normal liquid state. No open surface could contain the superfluid as it would flow up and spill out. Owing to its lack of viscosity and its difficulty to swirl in the form of tiny tornadoes, the liquid state of helium was categorized as "superfluidity."
Scientists believed that since the superfluid lacks viscosity, if someone swirls it in a cup, then unlike the morning tea that stops swirling on its own, helium superfluid will continue to do so indefinitely. Much to the surprise of physicists, the theory was recently proved wrong.
George Stagg, a mathematician from the Newcastle University, has an article published in the journal Physical Review Letters. It indicated that the theory of "eternal flow" of superfluids has always been wrong. When Stagg and his team studied the behavior of the superfluids, they found that the superfluid stops swirling due to the roughness of surrounding surface even if it is in the range of nanometers, Cosmos Magazine reported.
Further analysis revealed that the reason behind the anomaly was the presence of a storm layer of small intertwined tornadoes of the superfluid. What happens is that when the superfluid comes in contact with the microscopic peaks and depressions present on the surface of the surrounding material, they get displaced and take the form of minute tornadoes. This intervening layer of superfluid storm slows down the movement of the superfluid, Phys.org reported.
Stagg and his colleagues explained that the phenomenon could not be studied before because all related experiments were performed with materials with extremely smooth surfaces. The anomaly was detected when the researchers at Lancaster University were trying to study the flow of helium superfluid through a metal rod.
The new revelations will help in the development of improved superfluid cooling systems much like the one that has been created to deep freeze the 27-kilometer-long ring of the Large Hadron Collider.