Adjustable Permanent Magnet Assembly for Magnetic Field Homogeneity
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Solution Overview
Problem
Existing permanent magnets struggle to provide high homogeneity and intensity magnetic fields that are adjustable for both transverse and axial gradients while maintaining stability and cost-effectiveness, especially in portable and desktop applications, due to the limitations of electromagnets and superconducting magnets.
Innovation Solution
A permanent magnet assembly comprising a pole tip assembly with adjustable polarizing assemblies and flux returns, utilizing axially and radially magnetized permanent magnets, and adjusting means such as jack screws and shims to optimize magnetic field homogeneity and intensity by varying the position and gap sizes between pole pieces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If electromagnets are used to generate high magnetic field strength, then magnetic field intensity is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts the power consumption and complexity issues by replacing electromagnets with permanent magnets. The permanent magnet assembly uses permanently magnetized materials (such as NdFeB, SmCo, or AlNiCo) to generate the magnetic field without requiring electrical power, thereby eliminating the need for power supplies, cooling systems, and control electronics while maintaining high field strength capability.
Solution Approach 2:
The patent changes the fundamental parameter from electrical power-driven field generation to permanent magnet field generation. By using materials with high remanence and coercivity, the system achieves high magnetic field intensity without the need for continuous energy input, fundamentally altering how the magnetic field is produced and maintained.
2Device complexity
If permanent magnets are used to reduce size and cost, then device complexity is reduced, but magnetic field homogeneity deteriorates
Solution Approach 1:
The patent divides the magnetic field generation system into multiple permanent magnet assemblies arranged in specific geometric configurations (such as Halbach arrays or symmetric patterns). By segmenting the magnet structure and strategically positioning multiple magnet assemblies with opposite or complementary polarities, the design achieves field homogeneity through geometric arrangement rather than requiring complex active control systems.
Solution Approach 2:
The patent employs asymmetric magnet arrangements such as Halbach arrays where magnets are oriented at specific angles (0°, 90°, 180°, 270°) to create enhanced field homogeneity in specific regions. The asymmetric positioning and orientation of permanent magnets allow optimization of the magnetic field distribution in the sample region while maintaining structural simplicity.
3Adaptability or versatility
If permanent magnets are made adjustable for gradients, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent introduces mechanical adjustment mechanisms that allow the permanent magnet assemblies to be dynamically repositioned along the magnetic field axis and in transverse directions. This enables continuous variation of the magnetic field gradients while maintaining a relatively simple overall structure, as the adjustment is achieved through mechanical means rather than complex electronic control systems.
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 solution enables robust, stable, and adjustable high homogeneity and high field permanent magnets, improving field homogeneity and intensity, and is cost-effective for applications above 2 Tesla, while maintaining mechanical stability and ease of manufacturing.
Implementation Method 1
a first polarizing assembly comprising permanent magnets disposed to draw magnetic flux out of a first side of said pole tip assembly
Implementation Method 2
enclosing magnetic flux return disposed to guide flux into a second polarizing assembly
Implementation Method 3
adjusting means whereby the position of said first polarizing assembly and the position of said second polarizing assembly can be adjusted relative to the position of said pole tip assembly
Data Source
AI summary
A permanent magnet assembly for generating a homogenous and intense magnetic field includes can be adjusted for both transverse and axial gradients after completed assembly while field inhomogeneity is being measured. Gaps between pole piece bodies and pole tips are adjustable to adjust the transverse and axial gradients in a space between the pole tips.