Early helium liquefier, c 1932-1936.
© Science Museum / Science & Society Picture Library
The helium liquefier was originated by Simon in 1932. Helium gas is compresed to a presure of about 100 atmospheres and then allowed to expand to atmospheric presure. It is initially cooled to about 12 degrees Kelvin and the further cooling produced by the adiabatic (non-heat involving) expansion is sufficient to liquefy a large proportion of the helium at once. The apparatus illustrated is intended for use with the magnetic method of producing still lower temperatures.