Helium-3 refrigerator
Encyclopedia
A helium-3 refrigerator is a simple device used in experimental physics
for obtaining temperature
s down to about 0.2 kelvin
s. By evaporative cooling of helium-4
(the more common isotope
of helium
), a 1-K pot
liquefies a small amount of helium-3
in a small vessel called a helium-3 pot. Evaporative cooling of the liquid helium-3, usually driven by adsorption
since due to its high price the helium-3 is usually contained in a closed system to avoid losses, cools the helium-3 pot to a fraction of a kelvin.
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
for obtaining temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
s down to about 0.2 kelvin
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...
s. By evaporative cooling of helium-4
Helium-4
Helium-4 is a non-radioactive isotope of helium. It is by far the most abundant of the two naturally occurring isotopes of helium, making up about 99.99986% of the helium on earth. Its nucleus is the same as an alpha particle, consisting of two protons and two neutrons. Alpha decay of heavy...
(the more common isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
of helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...
), a 1-K pot
1-K pot
A 1-K pot is a cryogenic device used to attain temperatures down to approximately 1 kelvin.The 1-K pot is a small vessel in a cryogenic system that is filled with liquid helium. Usually it is a few cubic centimeters in size with a pickup-tube extending into the primary liquid helium bath of the...
liquefies a small amount of helium-3
Helium-3
Helium-3 is a light, non-radioactive isotope of helium with two protons and one neutron. It is rare on Earth, and is sought for use in nuclear fusion research...
in a small vessel called a helium-3 pot. Evaporative cooling of the liquid helium-3, usually driven by adsorption
Adsorption
Adsorption is the adhesion of atoms, ions, biomolecules or molecules of gas, liquid, or dissolved solids to a surface. This process creates a film of the adsorbate on the surface of the adsorbent. It differs from absorption, in which a fluid permeates or is dissolved by a liquid or solid...
since due to its high price the helium-3 is usually contained in a closed system to avoid losses, cools the helium-3 pot to a fraction of a kelvin.