Superconducting Magnet Thermal Switch Using Differential Expansion
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Solution Overview
Problem
Existing superconducting magnet devices face challenges in efficiently switching a permanent current switch between superconducting and normal conducting states due to increased heat incursion and refrigerant consumption, particularly when using high temperature superconducting materials, as they require external driving mechanisms and large electric heater capacities.
Innovation Solution
A superconducting magnet device design that includes a permanent current switch, a first electric heater, a support member with a high thermal expansion coefficient, and a second electric heater, along with a cooling member and columnar members to manage thermal conductivity and heat transfer paths within the vacuum case, allowing for rapid switching without external driving mechanisms and reduced refrigerant consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a thermal switch with external driving mechanism is used to decouple the permanent current switch from the cooling stage, then the electric heater capacity can be decreased, but the amount of heat incursion into the cooling stage increases and refrigerant consumption increases
Solution Approach 1:
The patent removes the external driving mechanism from the system entirely. The permanent current switch is integrated directly into the cooling stage structure, eliminating the need for separate thermal switches and external actuators. This extraction of the external mechanism prevents heat incursion from outside the vacuum environment while maintaining effective thermal coupling through the integrated design.
Solution Approach 2:
The patent merges the permanent current switch with the cooling stage by providing a through-hole structure that allows direct thermal and electrical connection. The switch is positioned to extend through the cooling stage, combining the switching function with the cooling function in a single integrated structure, thereby eliminating intermediate thermal paths that would cause heat incursion.
2Use of energy by moving object
If a thermal switch with external driving mechanism is used to decouple the permanent current switch from the cooling stage, then the electric heater capacity can be decreased, but the device complexity increases due to vacuum sealing requirements
Solution Approach 1:
The patent extracts the driving mechanism from outside the vacuum environment and eliminates it completely. The permanent current switch is actuated by thermal fields generated within the vacuum environment itself, removing the need for bellows, flexures, or other vacuum-compatible mechanical actuators that would complicate the design.
Solution Approach 2:
The system uses the cold field from the cooling stage itself to actuate the permanent current switch, rather than requiring external mechanical actuators. The thermal contraction of components at cryogenic temperatures provides the necessary movement to open or close the switch, making the system self-actuating and eliminating complex vacuum sealing requirements.
3Ease of operation
If a heat transfer plate cooled continuously from the cooling stage is used, then external driving mechanisms are unnecessary, but the electric heater capacity increases and switching speed decreases
Solution Approach 1:
The patent creates a dynamic thermal coupling system where the heat transfer path is not continuous but variable. The permanent current switch can be thermally decoupled from the cooling stage by utilizing the thermal expansion/contraction of components at different temperatures, dynamically opening or closing the heat transfer path as needed for rapid switching.
Solution Approach 2:
The patent exploits thermal expansion and contraction of materials at cryogenic temperatures to control the thermal coupling between the permanent current switch and the cooling stage. As components cool down, differential contraction creates gaps or contact conditions that control heat flow, enabling rapid switching without continuous thermal conduction.
4Ease of operation
If a heat transfer plate cooled continuously from the cooling stage is used, then external driving mechanisms are unnecessary, but the refrigerant consumption increases
Solution Approach 1:
The patent extracts the continuous thermal conduction path and replaces it with a controlled, intermittent thermal coupling. By using the vacuum environment and thermal expansion effects, the system eliminates the need for a continuously cooled heat transfer plate, reducing the cooling load and refrigerant consumption while maintaining operational capability.
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
Enables high-speed operation of the permanent current switch with reduced electric heater capacity and refrigerant consumption, maintaining the superconducting coil at extremely low temperatures while minimizing heat incursion and optimizing cooling and heating performance.
Implementation Method 1
The support member has a coefficient of thermal expansion that is higher than the coefficient of thermal expansion of the first columnar member
Implementation Method 2
a first electric heater which is laid on the permanent current switch
Implementation Method 3
a second electric heater which is laid on the support member
Implementation Method 4
a first cooling member which is cooled by a refrigerant or a refrigerator
Data Source
AI summary
The present invention addresses a challenge of providing a superconducting magnet device that enables it to realize an operation of opening and closing a permanent current switch of the superconducting magnet device at high speed with small electric heater capacity, avoiding an increase in the amount of heat incursion into the superconducting coil by not providing a driving mechanism from outside while enabling it to reduce refrigerant consumption or electric power consumed by a refrigerator, or an MRI apparatus using it having means for obtaining good image quality. The superconducting magnet device including a superconducting coil and a permanent current switch to enable it to realize permanent current flowing with the permanent current switch operated by an electric heater or an MRI apparatus using it has a heat transfer member to cool the permanent current switch from a cooling stage with solid conductivity and a thermal switch, and the thermal switch generates a gap in a heat transfer path including the heat transfer member for cooling and a refrigerator by thermal expansion when an electric heater is electrified.