Superconducting Magnet System for High-Field NMR
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Solution Overview
Problem
Current superconducting magnet systems for nuclear magnetic resonance imaging (MRI) have limitations in achieving high magnetic field intensity and homogeneity, which restricts the sensitivity and resolution of MRI images, making it challenging to handle and integrate massive information for rapid and accurate diagnosis.
Innovation Solution
A superconducting magnet system with a compact structure, low operating cost, and high magnetic field homogeneity is developed, comprising a main coil, magnetic field homogeneity compensating coil, and a refrigeration system, using NbTi/Cu superconducting wires and 6061-T6 aluminum alloy for structural support, with a ferro-magnetic shielding system to reduce stray magnetic fields and enhance electromagnetic compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If superconducting magnet systems are designed to achieve high magnetic field intensity, then the magnetic field strength increases, but the magnetic field homogeneity deteriorates
Solution Approach 1:
The magnet system is divided into multiple independent coil assemblies (first, second, third, and fourth coil assemblies) arranged coaxially. Each assembly can be optimized and adjusted independently, allowing high magnetic field intensity to be achieved through cumulative effect while maintaining homogeneity through individual coil optimization and positioning.
Solution Approach 2:
Different coil assemblies have different structural characteristics and winding configurations tailored to specific regions. The coils are designed with varying turn densities, radii, and axial positions to locally optimize the magnetic field distribution, achieving both high intensity and homogeneity in the target imaging region.
2Manufacturing precision
If complex coil structures are used to achieve high magnetic field homogeneity, then the magnetic field uniformity improves, but the device complexity increases
Solution Approach 1:
The complex coil structure is segmented into four distinct coil assemblies, each with a relatively simple individual design. This modular approach distributes the complexity across multiple manageable units rather than requiring one extremely complex single coil, facilitating manufacturing and adjustment while achieving the required homogeneity.
Solution Approach 2:
Multiple coil assemblies with individually simpler structures are combined coaxially to create the overall magnet system. The cumulative effect of these merged simple structures achieves the magnetic field homogeneity that would require excessive complexity in a single coil design.
3Use of energy by moving object
If more coil assemblies are added to increase magnetic field intensity, then the magnetic field strength increases, but the system complexity and operating cost increase
Solution Approach 1:
The system uses four coil assemblies instead of one massive coil, allowing the magnetic field intensity to be built up incrementally through each assembly. This segmentation enables scalable intensity adjustment by optimizing each assembly independently while keeping overall system complexity manageable through standardized modular design.
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 generates a magnetic flux intensity ranging from 9.4 T to 11.75 T with a degree of non-homogeneity less than 0.1 ppm within 300 mm, enabling high-resolution imaging and improving diagnostic capabilities with reduced temperature rise and enhanced safety.
Implementation Method 1
using NbTi/Cu superconducting wires
Implementation Method 2
and a refrigeration system
Data Source
AI summary
A superconducting magnet system for nuclear magnetic resonance with a high magnetic field and a high degree of homogeneity of magnetic field is provided. The system comprises a main coil and a magnetic field homogeneity compensating coil having a combination of a forward current and a reverse current, and is composed of 24 superconducting coils formed by winding NbTi/Cu low-temperature superconducting wires. The system can produce a magnetic field of 9.4 T within a room-temperature space of 800 mm and can obtain a degree of non-homogeneity of magnetic field less than 0.1 ppm within a spherical volume of 300 mm. The system is equipped with a superconducting magnet inside, and a low-temperature vessel for liquid helium provides a low-temperature environment of 4K which is required for the normal operation of the superconducting magnet. A ferro-magnetic shielding system enables the system to have a good electromagnetic compatibility.