Bulk Superconductor Magnet Homogenization via Sensorless Thermal Control
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Solution Overview
Problem
Existing superconductor magnet systems face challenges in achieving high magnetic field homogeneity due to the complexity and cost associated with temperature sensors required for controlling the cryogenic cooling system, which limits the system's performance and efficiency.
Innovation Solution
A method that homogenizes the magnetic field profile by controlling heating and cooling powers at the bulk sub-magnets without measuring their temperatures, allowing for a simple and cost-effective design by identifying regions needing current reduction and adjusting temperatures to achieve magnetic saturation or desaturation, thereby redistributing currents for improved field homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If temperature sensors are installed at each bulk sub-magnet to enable precise temperature control, then magnetic field homogeneity can be improved, but device complexity and cost increase significantly
Solution Approach 1:
The system uses self-service by monitoring magnetic field homogeneity directly and allowing the bulk sub-magnets to self-adjust their current distribution through temperature variation. The magnetic field measurement serves as the feedback signal, eliminating the need for separate temperature sensors at each sub-magnet. The system serves itself by using the magnetic field state to control the temperature distribution that achieves the desired homogeneity.
Solution Approach 2:
The invention changes the control parameter from temperature to magnetic field homogeneity. Instead of measuring and controlling temperature at each sub-magnet, the system directly measures magnetic field homogeneity and uses this information to adjust the temperature distribution of bulk sub-magnets. This parameter change eliminates the need for temperature sensors while achieving the same control objective.
2Manufacturing precision
If temperature sensors are installed at each bulk sub-magnet, then magnetic field homogeneity can be improved, but system cost increases
Solution Approach 1:
The system uses a copy of the temperature control functionality through magnetic field measurement. Instead of directly measuring temperature and inferring magnetic field state, the invention directly measures magnetic field homogeneity, which is the ultimate parameter of interest. This copying approach uses the actual performance metric as the control feedback, eliminating intermediate temperature sensors and reducing system cost.
3Manufacturing precision
If temperatures of bulk sub-magnets are varied to redistribute currents for homogeneity, then magnetic field homogeneity improves, but control complexity increases
Solution Approach 1:
The system implements feedback control by continuously monitoring magnetic field homogeneity and using this information to adjust the temperature distribution of bulk sub-magnets. The magnetic field measurement provides direct feedback on the effectiveness of current redistribution, allowing the control system to optimize temperature variation to achieve desired homogeneity while simplifying the control process through direct performance measurement.
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 approach enables the achievement of high magnetic field homogeneity without temperature sensors, simplifying the system design, reducing costs, and enhancing performance by allowing for precise control of the magnetic field profile without the need for temperature monitoring.
Implementation Method 1
for a first part of the bulk sub-magnets, the bulk sub-magnets of this first part are at least almost magnetically saturated, in particular with at least 99% relative magnetic saturation, and for a second part of the bulk sub-magnets, the bulk sub-magnets of this second part are significantly away from magnetic saturation, in particular with at most 95% relative magnetic saturation
Implementation Method 2
Superconductors are materials that may carry an electrical current at practically no ohmic losses. Superconductors are, for example, used to generate magnetic fields of high strength
Implementation Method 3
the superconductor bulk magnet comprises at least N axially stacked bulk sub-magnets... a magnetic field profile of the superconductor bulk magnet based on the final currents is more homogenous
Data Source
AI summary
A method is provided for homogenizing a magnetic field profile of a superconductor magnet system having a cryostat with a room temperature bore, a superconductor bulk magnet with at least three axially stacked bulk sub-magnets, arranged coaxially with the room temperature bore, and a cryogenic cooling system for cooling the superconductor bulk magnet. The cryogenic cooling system independently controls the temperature of each bulk sub-magnet to provide different respective temperatures to the sub-magnets and thereby provide the sub-magnets with different relative currents such that a first subset of the bulk sub-magnets are almost magnetically saturated, and a second subset of the bulk sub-magnets are significantly away from magnetic saturation. By controlling a heating power and/or a cooling power at the bulk sub-magnets without measuring the temperatures of the bulk sub-magnets, the respective currents of the bulk sub-magnets are changed to increase a homogeneity of the field profile.