Superconducting Field Coil Current Segmentation for Magnetic Homogeneity
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Solution Overview
Problem
Existing superconductor magnets face challenges in maintaining stable and homogeneous magnetic fields due to variations in critical current and magnetic field alignment, which can lead to thermal runaway and require additional shim coils for correction.
Innovation Solution
A system with a primary electric current source and a secondary electric current source connected in parallel across a subset of field coils, allowing for additional DC or AC current to be supplied to modify or correct the magnetic field, enhancing stability and homogeneity by adjusting the current distribution and critical current ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single primary current source is used to generate magnetic field, then the system structure is simple, but the magnetic field homogeneity and stability are insufficient
Solution Approach 1:
The patent divides the current source into two independent parts: a primary current source connected across all field coils for basic magnetic field generation, and a secondary current source connected across a subset of field coils for fine-tuning. This segmentation allows each current source to perform its specific function optimally, with the secondary source correcting field non-uniformities without requiring complete system redesign.
Solution Approach 2:
The secondary current source is strategically connected across only a subset of field coils (e.g., end coils) where magnetic field non-uniformities are most pronounced. This local application of additional current provides targeted correction to specific regions of the magnetic field, improving overall homogeneity without unnecessarily complicating the entire system.
2Manufacturing precision
If additional shim coils are added to correct magnetic field variations, then the magnetic field homogeneity improves, but the device complexity and cost increase
Solution Approach 1:
The secondary current source serves multiple functions: it corrects magnetic field non-uniformities, compensates for critical current variations in different field coils, and can adapt to different operating conditions. By making the current source adjustable and programmable, a single device performs what would traditionally require multiple fixed shim coils, reducing overall system complexity.
Solution Approach 2:
Instead of adding fixed structural elements like shim coils, the patent changes the electrical parameters (current magnitude and distribution) dynamically. The secondary current source can vary its output to compensate for different levels of field non-uniformity and critical current variations, providing a flexible software-controlled solution rather than rigid hardware additions.
3Adaptability or versatility
If the critical current ratio between field coils varies significantly, then the magnet can accommodate different operating conditions, but thermal runaway risk increases
Solution Approach 1:
The system incorporates monitoring of critical current ratios between field coils and uses this information to adjust the secondary current source output. When variations in critical current are detected, the control system modifies the additional current distribution to compensate, preventing conditions that could lead to thermal runaway while maintaining adaptability to different operating scenarios.
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
The system enables precise control of magnetic fields, reduces the need for shim coils, and increases stability by optimizing current distribution, ensuring the magnetic field matches design specifications and remains stable under varying conditions.
Implementation Method 1
A superconducting magnet is formed by arranging HTS cables into coils comprising one or more turns. A primary electric current source is connected across the plurality of the field coils for supplying a DC electric current to the field coils to generate a magnetic field.
Implementation Method 2
HTS tapes and other superconducting materials may be characterised by a critical surface of a maximum current, temperature and magnetic field at which the superconductor transitions from a superconducting state to a normal state.
Data Source
AI summary
A superconductor magnet system including a superconductor magnet including a plurality of field coils connected in series, each field coil having a plurality of turns including superconductor material. The system also includes a primary electric current source connected across the plurality of the field coils for supplying a DC electric current to the field coils to generate a magnetic field. The system further includes a secondary electric current source connected in parallel with the primary electric current source across a subset of the field coils for supplying an additional DC electric current to the or each field coil in the subset to modify or correct the magnetic field.