Research facilities at renowned universities and institutes, such as that conducted at CERN in Geneva, the MPI in Greifswald, JLAB in Newportnews, Fermi-Lab near Chicago, MSU in East Lansing, KEK in Tsukuba, ESS in Lund or DESY in Hamburg, require low-temperature cooling that can be delivered by large cryogenic refrigeration units only.
A helium refrigerator is a closed system in which the same quantity of helium constantly circulates. In contrast to the liquefier, the mass flow rates are symmetric. The required low-temperature cooling is assisted by two or more gas-bearing expansion turbines and can be enhanced by precooling to 80 K with liquid nitrogen.
Mostly refrigeration systems are directly connected to the experiment. Like that, they have to be customized to deliver the needed coldness at the right place at the right time. The solution depends primarily on the size of the refrigeration plant.