A Continuous 4He Refrigerator for Use in a Superfluid Helium Bath
Suwen Wang, Dimitri Avaloff, Joel A. Nissen, David A. Stricker, and John A. Lipa
Hansen Experimental Physics Laboratory, Stanford University, Stanford, California, U.S.A.
In cryogenic applications in space, the base temperature of the helium bath in the dewar is typically
determined by the design of the porous plug and the associated plumbing. For certain experiments, the
required operating temperature of the instrument is lower than the base temperature of the helium bath.
In the laboratory, temperatures below 1.2K require very large pumps or the use of 3He systems. We have
demonstrated a 4He refrigerator with a continuous fill line leading to a superfluid helium bath with a
base temperature below 0.9 K, which was more than 0.5 K below the bath temperature. We describe the
operation as well as mechanism of such a refrigerator. For space operation the device would need to be
equipped with sintered plugs to retain the fluid using surface tension forces.
Sorting category: Ea Materials, techniques, and applications
Keywords: refrigeration, helium, superfluid, bath
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