Magnetic Ball Valve Cooling for Persistent Current Switch Heat Control
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Solution Overview
Problem
Existing superconducting magnet systems face challenges in managing the heat generated by persistent current switches, which can overwhelm the cooling system, especially in cryogen-free systems, requiring a solution to control temperature efficiently without straining the cooling system.
Innovation Solution
A thermal switch system incorporating a heat exchanger, loop tube, and ball valves with electromagnets is used to control the flow of coolant, allowing for rapid temperature adjustments of the persistent current switch, thereby isolating it from the cryostat and managing heat effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the persistent current switch is thermally connected to the cooling system, then the cooling capacity is sufficient to handle heat, but the temperature control speed is too slow and the system cannot respond rapidly to temperature changes
Solution Approach 1:
The cooling system is segmented into two independent pathways: a main cooling system for the superconducting coils and a separate thermal switch system for the persistent current switch. This segmentation allows each subsystem to be optimized independently - the main cooling system maintains stable low temperature while the thermal switch system provides rapid temperature control capability.
Solution Approach 2:
A thermal switch acts as an intermediary between the persistent current switch and the cooling system. This intermediary component enables rapid thermal connection and disconnection, allowing the system to quickly respond to temperature control needs without continuously straining the main cooling system.
2Ease of operation
If the persistent current switch generates heat during operation, then the switching function is achieved, but the heat overload overwhelms the cooling system capacity
Solution Approach 1:
The thermal management of the persistent current switch is extracted from the main cooling system. By using a separate thermal switch system, the heat generated during switching operations is isolated and managed independently, preventing it from overwhelming the main cooling system that maintains the superconducting state.
Solution Approach 2:
The heat generated by the persistent current switch during operation, which would normally be harmful, is converted into a controllable parameter. The rapid thermal switch system allows this heat to be managed on-demand, transforming the harmful thermal load into a controllable aspect of the switching operation.
3Device complexity
If a cryogen-free system is used, then the system simplicity is improved, but the heat absorption capacity is limited and cannot cope with additional heat from the PCS
Solution Approach 1:
The thermal connection between the persistent current switch and the cooling system is made dynamic rather than static. The thermal switch can rapidly change the thermal connection state, allowing the system to adapt its heat absorption capacity on-demand. This dynamic capability enables the cryogen-free system to handle variable heat loads without requiring excessive cooling capacity.
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
This system enables efficient cooling of the persistent current switch, preventing heat overload on the cryostat and allowing the switch to maintain the necessary temperature for persistent current mode operation, while minimizing energy consumption and heat input.
Implementation Method 1
The heat exchanger is configured to disperse heat
Implementation Method 2
The loop tube is configured to enable flow of coolant to convectively transfer thermal energy generated by the persistent current switch to the heat exchanger
Implementation Method 3
Energizing a first electromagnet of the multiple electromagnets magnetically moves the ferromagnetic ball to a first position opening the loop tube and enabling the flow of the coolant
Data Source
AI summary
A system (100) for controlling temperature of a persistent current switch (120) operating in a background magnetic field includes a heat exchanger (138), a loop tube (135), a ball valve (245) and multiple electromagnets (251, 252). The heat exchanger disperses heat to a cryocooler (106). The loop tube enables flow of coolant to convectively transfer thermal energy generated by the persistent current switch to the heat exchanger. The ball valve is integrated with the loop tube between the persistent current switch and the heat exchanger, and contains a ferromagnetic ball (250). The electromagnets are positioned outside the loop tube adjacent to the ball valve, where energizing a first electromagnet of the multiple electromagnets magnetically moves the ferromagnetic ball to a first position opening the loop tube and enabling the flow of the coolant, and energizing a second electromagnets magnetically moves the ferromagnetic ball to a second position closing the loop tube and blocking the flow of the coolant.