A dilution refrigerator (DR) is the most common precooling stage for sub-millikelvin demagnetization experiments. The usefulness of the DR comes from its ability to provide cooling at 0.02–0.04 K for long periods of time while the heat of magnetization is being rejected by the demagnetization stage. In order to make these advantages of the DR available to researchers who need the microgravity of space for their experiments, we are developing a continuously-operating DR that will function in microgravity.
We have previously demonstrated that the liquid helium of the DR can be controlled by the use of capillary forces in sintered metal sponges. We have found, however, that the small pores needed to control large heights of liquid on the ground are too small to allow sufficient liquid flow for effective cooling.
We have built a shallow single-cycle version of the refrigerator that does not require large heights of liquid to be supported by capillary forces. The liquid chambers are next to each other and are filled with sinter with relatively open pores; these pores will allow much freer flow of the helium. The gravity independence of this design will be tested by tilting the system so that one chamber is slightly above or below the other and by inverting both chambers. The operation of the refrigerator should be unaffected by tilts of 5–10 degrees or by the inversion of the chambers.
A design for a continuously-operating dilution refrigerator is presented. It includes all the advantages of the single-cycle refrigerator while adding the large advantage of continuous cooling for long periods of time.
Development of a Dilution Refrigerator for Low-Temperature Microgravity Experiments
Cryocoolers 10 ; Chapter : 77 ; 647-653
2002-01-01
7 pages
Article/Chapter (Book)
Electronic Resource
English
Development of a Dilution Refrigerator for Low-Temperature Microgravity Experiments
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