Cryostat, and method for cooling a cryostat
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Solution Overview
Problem
Existing cryostats face challenges in managing increased heat loads when scaled up, leading to complex and expensive solutions, and require frequent access while maintaining reliability and ease of servicing.
Innovation Solution
A cryostat design featuring a vacuum enclosure with nested radiation shields and a thermally conductive layer cooled by a compressor-driven refrigerator, allowing for scalable and efficient heat load reduction without complicating the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If the size of the cryostat is scaled up, then the cooling capacity and volume are improved, but the heat load increases significantly
Solution Approach 1:
The patent implements a nested structure with multiple radiation shields (first radiation shield, second radiation shield, third radiation shield) placed concentrically within the vacuum enclosure. Each shield is positioned at different radial distances from the central axis, creating a layered防护 system that intercepts thermal radiation at multiple stages, thereby reducing the heat load on the cooled space while maintaining large volume capacity.
Solution Approach 2:
The patent introduces a thermally conductive layer as an intermediary component between the radiation shields and the vacuum enclosure wall. This layer provides a controlled thermal pathway that allows heat interception while maintaining structural integrity and vacuum sealing, effectively mediating the thermal interaction between the external environment and the internal cooled space.
2Loss of energy
If multi-layer superinsulation is used to reduce heat load, then the heat load reduction is effective, but the assembly becomes cumbersome and time-consuming
Solution Approach 1:
The patent divides the thermal protection system into distinct modular segments: the vacuum enclosure wall, the first radiation shield, the second radiation shield, the third radiation shield, and the thermally conductive layer. Each segment can be manufactured and positioned independently, simplifying the assembly process compared to traditional multi-layer superinsulation that requires layer-by-layer installation of numerous thin foils.
Solution Approach 2:
The patent employs a composite structure combining radiation shields (for radiative heat interception) with a thermally conductive layer (for controlled heat transfer and structural support). This composite approach integrates the functions of multiple insulating layers into a fewer number of components with optimized material properties, reducing assembly complexity while maintaining effective heat load reduction.
3Ease of manufacture
If air is trapped between superinsulation layers, then vacuum conditions become more difficult to achieve, but the structure remains simple
Solution Approach 1:
The patent applies thermal protection through a subset of components (three radiation shields and a thermally conductive layer) rather than using extensive multi-layer superinsulation. This partial approach reduces the number of interfaces where air trapping can occur, making it easier to achieve and maintain vacuum conditions while still providing effective heat load reduction through the nested radiation shield configuration.
4Ease of operation
If frequent access to the inside is needed, then multi-layer superinsulation becomes unattractive, but thermal protection is still required
Solution Approach 1:
The patent creates a segmented thermal protection system where the vacuum enclosure and radiation shields form a robust outer structure that can be opened or accessed without compromising the thermal protection of the internal components. The nested radiation shields remain in place during access operations, maintaining thermal protection while allowing convenient access to the cooled space.
Solution Approach 2:
The thermally conductive layer automatically provides thermal protection and structural support without requiring additional active components or complex assembly procedures during access operations. The nested radiation shields self-adjust to maintain their protective function even when the vacuum enclosure is opened for access, eliminating the need for reassembly or reconfiguration during maintenance or operation.
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
Significantly reduces radiated heat load on nested radiation shields using a simple and affordable cooling apparatus, enabling easy access and servicing of large cryostats.
Implementation Method 1
The purpose of the radiation shields is to reduce the heat load to the colder parts inside, by intercepting radiated heat from warmer parts outside
Implementation Method 2
A cryostat according to the invention comprises a vacuum enclosure
Implementation Method 3
Radiation shields, each thermally coupled to the respective temperature stage, form a nested structure in which each colder temperature stage is surrounded by the radiation shield of the previous, warmer temperature stage. The purpose of the radiation shields is to reduce the heat load to the colder parts inside, by intercepting radiated heat from warmer parts outside
Data Source
Figure 1~3
Figure 4
AI summary
A cryostat comprises a vacuum enclosure (101) and, inside said vacuum enclosure, a plurality of nested radiation shields (102, 103). Stages of a cryogen-free cooling system (104) are thermally coupled with and configured to cool respective ones of said plurality of nested radiation shields (102, 103). Inside said vacuum enclosure (101) is a thermally conductive layer (201), at least partly surrounding said plurality of nested radiation shields (102, 103). A compressor-driven refrigerator (202) is thermally coupled with said thermally conductive layer (201) and configured to cool said thermally conductive layer (201).