Superconducting Magnet Device with Inter-Winding Magnetic Rings
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Solution Overview
Problem
Existing superconducting magnet devices for NMR and MRI applications face challenges in producing intense and homogeneous magnetic fields within a compact design, often requiring additional ferromagnetic rings that increase weight and reduce free space, making them bulky and costly.
Innovation Solution
A compact superconducting magnet device utilizing axisymmetric windings with a circumspherical configuration of coaxial solenoids and strategically placed magnetic rings to cancel specific harmonic terms, optimizing homogeneity while minimizing external field leakage and maintaining free space within the volume of interest.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ferromagnetic rings are added to improve magnetic field homogeneity, then homogeneity is improved, but weight increases and free space in the volume of interest is reduced
Solution Approach 1:
The patent extracts the ferromagnetic rings from the volume of interest and relocates them to the space between the solenoid windings. This allows the rings to perform their homogeneity-improving function while being removed from the region where they would otherwise occupy useful space and add unwanted weight to the active volume.
Solution Approach 2:
The ferromagnetic rings are nested within the structure of the magnet device, specifically positioned in the annular space between the inner and outer solenoid windings. This nested arrangement allows the rings to be integrated into the device structure without increasing the external dimensions or encroaching on the volume of interest.
2Measurement precision
If ferromagnetic rings are added to improve magnetic field homogeneity, then homogeneity is improved, but the device becomes bulkier and production cost increases
Solution Approach 1:
The patent utilizes the radial dimension by placing ferromagnetic rings in the annular space between windings, rather than adding them axially or radially outward. This dimensional arrangement improves homogeneity without increasing the overall footprint or compromising compactness in the volume of interest.
3Volume of moving object
If the volume of interest is maintained, then free space is preserved, but adding ferromagnetic rings requires increasing coil diameter which harms compactness
Solution Approach 1:
The ferromagnetic rings are extracted from the volume of interest and repositioned in the inter-winding space, allowing the volume of interest to remain unchanged while still incorporating the homogeneity-improving elements into the overall device structure.
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 achieves a highly homogeneous magnetic field with reduced superconductor volume and no encroachment on the volume of interest, allowing for intense fields like 11 Tesla with improved compactness and cost-effectiveness.
Implementation Method 1
at least two windings (1, 2) coaxial superconducting helicals... Azimuthal current densities (j1, j2) of said helical windings (1, 2)... alternately have opposite signs
Implementation Method 2
Rings (4) made of magnetic material... magnetized to saturation with a magnetization in the opposite direction to that of the field created at the center O
Implementation Method 3
Rings (4) made of magnetic material centered on the axis Oz... interposed between the first and second windings (1, 2)
Data Source
AI summary
The invention relates to a compact superconducting magnet device for generating a strong, uniform magnetic field component Bz along an axis Oz in an area of interest ZI, including, in series starting from the axis Oz, at least two coaxial superconducting helical windings (1, 2) provided around circular cylindrical wafers (10, 20) having an axis Oz, said cylindrical wafers being delimited by end circles (10A, 10B, 20A, 20B). The side ends of the helical windings (1, 2) are arranged at the bodies of the adjacent windings and near a single sphere (5) having a radius c, the center O of said sphere being placed on the axis Oz at the center of the area of interest ZI, wherein said sphere encompasses the entirety of the magnet device. The azimuthal current densities j1, j2 of the helical windings (1, 2) have opposite signs. The lengths (2b1, 2b2) of the helical windings (1, 2) are decreasing. Rings (4) made of magnetic material, which are centered on the axis Oz and symmetrical relative to a median plane xOy passing through the center O of the sphere (5) and perpendicular to the axis Oz, are positioned between the first and second windings (1, 2) inside the sphere (5), and are saturation-magnetized by means of a magnetization, the direction of which is opposite that of the magnetization of the field created at the center O of the sphere (5).