Thermal interposer for a cryogenic cooling system
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Solution Overview
Problem
Conventional cryogenic cooling systems face challenges in achieving good thermal contact between the sample sleeve and cooling parts without external pressure or permanent bonding, and existing thermal interposer materials like indium require high pressure and have creep issues, while grease requires flat contact surfaces.
Innovation Solution
A cryogenic cooling system utilizing a gallium indium tin alloy as a thermal interposer between the cooling plate and sample sleeve, allowing for effective thermal contact without external pressure and enabling removable attachment, thereby maintaining low thermal resistance and stability across temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If indium is used as a thermal interposer material, then thermal contact between cooling surfaces is improved, but high pressure must be applied and creep issues occur
Solution Approach 1:
The patent changes the material parameter from pure indium to a gallium-indium-alloy with specific composition ratios (Ga: 60-75 atom%, In: 15-25 atom%). This material parameter change reduces thermal shrinkage during cooling, eliminating the need for high applied pressure while maintaining reliable thermal contact stability across temperature ranges.
Solution Approach 2:
The patent uses a composite alloy material combining gallium and indium in specific proportions. This composite material integrates the advantages of both elements while mitigating their individual drawbacks, providing both thermal contact reliability and resistance to creep without requiring high pressure application.
2Reliability
If pressure is applied to contact surfaces to maintain thermal contact, then thermal resistance is reduced, but detachment and reattachment become difficult
Solution Approach 1:
The patent utilizes the phase transition property of the gallium-indium-alloy, which remains solid at cryogenic temperatures but can be melted by localized heating. This allows the thermal interposer to maintain solid-state thermal contact during operation while enabling easy detachment through controlled melting, resolving the contradiction between contact quality and detachment ease.
3Reliability
If grease is used as a thermal interposer material, then thermal contact is improved, but flat contact surfaces are required
Solution Approach 1:
The gallium-indium-alloy interposer exhibits self-leveling properties due to its soft, malleable nature at room temperature. When pressed between contact surfaces, it automatically conforms to surface irregularities and fills gaps, eliminating the need for precisely flat surfaces while maintaining effective thermal contact. The material essentially performs the surface preparation function itself.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves a minimal thermal difference of less than 0.1K between the sample and cooling medium, ensuring efficient cooling to temperatures below 2K, and allows for easy detachment and reattachment of the sample sleeve, enhancing the reliability and reuse of the cooling system.
Implementation Method 1
The interposer is disposed between at least one of (i) the thermal switch and the cooling plate and (ii) the thermal switch and the sample sleeve. The interposer includes a gallium indium tin alloy.
Implementation Method 2
The cryogenic chamber includes a cryogenic fluid and the cooling plate is disposed in the cryogenic chamber, in contact with the cryogenic fluid.
Implementation Method 3
DNP systems may include liquid cryogen (e.g., liquid helium) baths to cool the sample to very low temperatures, sometimes below four Kelvin.
Implementation Method 4
The thermal switch is disposed between the cooling plate and the sample sleeve.
Data Source
AI summary
A cooling system, an apparatus for producing hyperpolarized samples, where the apparatus includes the cooling system, and a method for assembling and using the cooling system are disclosed. The cooling system includes a cryogenic chamber, a cooling plate, a sample sleeve, a thermal switch, and an interposer. Also, the cryogenic chamber includes a cryogenic fluid and the cooling plate is disposed in the cryogenic chamber, in contact with the cryogenic fluid. Further, the sample sleeve is configured to receive a sample. The sample sleeve is at least partially inserted in the cryogenic chamber. The thermal switch is disposed between the cooling plate and the sample sleeve. Moreover, the interposer is disposed between at least one of (i) the thermal switch and the cooling plate and (ii) the thermal switch and the sample sleeve. The interposer includes a gallium indium tin alloy.