Halbach Ring Magnet Segments for Homogeneous NMR Fields
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Solution Overview
Problem
Existing magnet systems for generating homogeneous magnetic fields in MR applications face challenges in material efficiency and flux density due to the need for multiple segment types with different magnetization directions, leading to complex manufacturing processes and increased costs.
Innovation Solution
The use of identical, convex, regular pentagonal or heptagonal magnet segments in a Halbach configuration allows for a compact and lightweight magnet system with improved material efficiency and flux density, achieved by rotating segments to vary magnetization direction, enabling a single type of segment to form a Halbach ring with enhanced magnetic field homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple segment types with different magnetization directions are used to form a Halbach ring, then the magnetic field homogeneity is improved, but the manufacturing complexity and material variety increase
Solution Approach 1:
The patent applies homogeneity by using identical magnet segments with the same geometry and magnetization direction throughout the entire Halbach ring. This uniform approach simplifies manufacturing while the specific pentagonal or heptagonal geometry with particular magnetization orientations achieves the required magnetic field homogeneity without requiring multiple segment types.
Solution Approach 2:
The patent changes geometric parameters by using regular pentagonal or heptagonal cross-sections instead of conventional circular or rectangular segments. This parameter change in the segment geometry, combined with specific magnetization directions, enables the Halbach configuration to achieve field homogeneity using identical segments, thereby reducing manufacturing complexity.
2Ease of manufacture
If traditional circular cylinder or trapezoidal segments are used, then the Halbach configuration can be approximated, but material efficiency and flux density are reduced
Solution Approach 1:
The patent applies curvature principles by using regular pentagonal or heptagonal cross-sections that more closely approximate circular geometry than trapezoidal segments. This curved-like geometry improves material packing efficiency and flux density while maintaining manufacturability through standardized regular polygon shapes.
Solution Approach 2:
The patent changes the geometric parameters of the magnet segments from conventional trapezoidal or cylindrical shapes to regular pentagonal or heptagonal cross-sections. This parameter change optimizes the space utilization and magnetic flux density while maintaining ease of manufacture through standardized geometries.
3Ease of manufacture
If identical polygonal segments are used throughout the Halbach ring, then manufacturing is simplified, but achieving precise Halbach magnetization becomes more difficult
Solution Approach 1:
The patent applies local quality by assigning specific magnetization directions to segments at different angular positions around the Halbach ring. While all segments are geometrically identical, each segment is magnetized in a specific direction according to the Halbach configuration requirements, achieving precise magnetization control through localized orientation specification rather than segment geometry variation.
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 simplifies the manufacturing process, reduces material usage, and increases magnetic flux density while maintaining field homogeneity, offering a more efficient and cost-effective solution compared to traditional methods.
Implementation Method 1
at least one ring-shaped magnetic element with magnetic material in a ring plane, which has a number n of individual magnet segments arranged next to one another in a Halbach configuration and each with surface contact, which have changing magnetization directions as they revolve around the ring-shaped magnetic element according to the rules of a Halbach arrangement, which together generate a magnetic dipole field in the ring plane
Data Source
Figure 1a~1b
Figure 2~3b
Figure 4
AI summary
The invention relates to a permanent magnet system having a magnet array (1) which is arranged annularly about a z axis in order to produce a homogeneous magnetic field in a direction perpendicular to the z axis in a measuring volume (0) inside the annular magnet array, said array having at least one annular magnet element (2) with magnetic material in a plane of the ring, and having, in a Halbach configuration, a number n of juxtaposed individual magnet segments (3), each in surface contact, which according to the rules of a Halbach array have changing magnetization directions when rotating about the annular magnet element and which together produce a magnetic dipole field in the plane of the ring of the annular magnet array, and that each have the same polyhedron geometry and that each have an identical, convex, regular polygonal cross-section. Such a permanent magnet system is characterized in that in the plane of the ring each magnet segment has a convex, regular pentagonal or heptagonal or octagonal cross-section that is identical among them. The permanent magnet system is manufactured in a streamlined and automated method, with considerably improved material efficiency and magnetic flux density being produced by means of the Halbach ring.