Cryogenic Cooling Circuit Layout to Prevent Helium Vapor Lock
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Solution Overview
Problem
Superconducting magnet systems operating in AC environments face significant AC losses due to eddy currents induced in metal components, which generate heat and hinder efficient cooling, particularly in magnetic resonance (MR) systems where maintaining low temperatures is crucial.
Innovation Solution
A cold mass design for superconducting magnet systems incorporates a cryogenic cooling circuit with a conductive coupler that channels liquid helium in an inlet path to avoid direct thermal engagement and directs vapor helium upward for efficient heat removal, minimizing AC losses and preventing helium vapor lock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If liquid helium inlet path directly thermally engages with conductive coupler, then heat removal efficiency is improved, but helium vapor lock occurs and cooling efficiency deteriorates
Solution Approach 1:
The cooling circuit is segmented into distinct inlet and outlet paths with different thermal engagement characteristics. The inlet path avoids direct thermal engagement with the coupler to prevent vapor lock, while the outlet path engages directly for efficient heat removal. This segmentation allows each path to be optimized for its specific function without compromising the other.
Solution Approach 2:
Different thermal engagement qualities are applied to different parts of the cooling circuit. The inlet path portion near the coupler is designed with minimal thermal engagement to maintain liquid helium flow, while the outlet path is designed with maximal thermal engagement to the coupler for efficient heat removal. This local differentiation resolves the contradiction between preventing vapor lock and maximizing heat removal.
2Strength
If metal components are used in cold mass, then structural strength is improved, but eddy currents are induced and AC losses increase
Solution Approach 1:
The coupler is designed with localized conductive properties only where needed for thermal management, rather than being entirely conductive. This allows the structure to maintain necessary strength while minimizing the volume of conductive material exposed to AC fields, thereby reducing eddy current losses.
Solution Approach 2:
The cold mass employs composite construction combining conductive materials for thermal coupling with non-conductive or low-conductivity materials for structural support. This composite approach allows the system to achieve required mechanical strength without excessive AC losses from eddy currents in large metal components.
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 design reduces AC losses and enhances cooling efficiency by minimizing direct thermal engagement during helium flow, maintaining the superconducting magnet at low temperatures while preventing helium vapor accumulation, thus optimizing the operation of MR systems.
Implementation Method 1
The inlet path avoids direct conductive thermal engagement with the substantially conductive coupler
Implementation Method 2
The substantially upward outlet path comprises direct conductive thermal engagement with the substantially conductive coupler
Implementation Method 3
a substantially conductive coupler that serves to couple the superconducting magnet and the cryogenic cooling circuit
Implementation Method 4
Liquid helium contained in the helium vessel provides cooling for the superconducting magnet and maintains the superconducting magnet at a low temperature
Implementation Method 5
When the superconducting magnet for the MR system operates in an AC field environment, eddy current is induced in the metal of the cold mass. Eddy currents are induced in a relatively large metal component of the helium vessel
Implementation Method 6
a superconducting magnet operating in an alternating current (AC) environment
Data Source
AI summary
A cold mass for a superconducting magnet system in one example comprises a superconducting magnet, a cryogenic cooling circuit, and a magnet and cooling circuit support. The magnet and cooling circuit support comprises a substantially conductive coupler that serves to couple the superconducting magnet and the cryogenic cooling circuit. The cryogenic cooling circuit comprises an inlet path and a substantially upward outlet path. The inlet path avoids direct conductive thermal engagement with the substantially conductive coupler. The substantially upward outlet path comprises direct conductive thermal engagement with the substantially conductive coupler.