Systems and methods for cryogenic refrigeration

Abstract

Systems and methods for improving the performance of dilution refrigeration systems are described. Filters and traps employed in the helium circuit of a dilution refrigerator may be modified to improve performance. Some traps may be designed to harness cryocondensation as opposed to cryoadsorption. A cryocondensation trap employs a cryocondensation surface having a high thermal conductivity and a high specific heat with a binding energy that preferably matches at least one contaminant but does not match helium. Multiple traps may be coupled in series in the helium circuit, with each trap designed to trap a specific contaminant or set of contaminants. Both cryocondensation and cryoadsorption may be exploited among multiple traps.

Description

BACKGROUNDField[0001]The present systems and methods generally relate to cryogenic refrigeration technology, and particularly relate to cryogenic trapping systems and methods for removing contaminants from cryogen circuits.Description of the Related Art[0002]Refrigeration[0003]Temperature is a property that can have a great impact on the state and evolution of a physical system. For instance, environments of extreme heat can cause even the strongest and most solid materials to melt away or disperse as gas. Likewise, a system that is cooled to cryogenic temperatures may enter into a regime where physical properties and behavior differ substantially from what is observed at room temperature. In many technologies, it can be advantageous to operate in this cryogenic regime and harness the physical behaviors that are realized in the realm of cold. The various embodiments of the systems, methods and apparatus described herein may be used to provide and maintain the cryogenic environments ...

AI Technical Summary

Problems solved by technology

For instance, environments of extreme heat can cause even the strongest and most solid materials to melt away or disperse as gas.

The pumps and compressors used are large, expensive, noisy, in need of periodic maintenance, and they inevitably add contaminants, such as air (i.e., nitrogen, oxygen, carbon dioxide, argon, etc.) to the helium.

These contaminants typically have higher freezing points than the helium and so may solidify in the helium fluid channels, creating blockages.

Such blockages may plug fine capillaries in the dilution refrigerator, causing problems with reliability.

The procedure of warming and subsequently cooling back down to operating temperatures can take several days.

Filters and cold traps can be used to reduce the frequency of plugging by removing contaminants from the helium, but current filters and traps used in the art are of limited effectiveness.

Thus, plugging due to contaminants remains a serious technical challenge in cryogenic refrigeration technology affecting fridge performance, and there remains a need in the art for improved systems and methods for contaminant filtering and / or trapping in cryogenic refrigeration systems.

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