|
Superfluid helium in a
vessel does not rotate with it as a normal
fluid does. Instead, a large number of
whirlpools, called vortices, are formed. They
have diameters from 1000 Å to 100,000
Å. The vortices repel each other and form
a hexagonal pattern. The superfluid circulates
around their cores. The circulation is
quantized in a way similar to that of electron
orbits around atomic nuclei.
Several types of vortex
occur in 3He,
depending upon temperature, rotation speed and
magnetic fields. They are being studied with a
rotating cryostat at the Low Temperature
Laboratory in Helsinki, Finland. Such
experiments have been carried out for modelling
phase transitions that might have occured in
the very early Universe, a fraction of a second
after the Big Bang.
1 Ångström
(Å) = 10-10m
|
|
