Compact Superconducting Magnet for NMR Using Nested Helical Windings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing superconducting magnet devices for NMR and MRI applications face challenges in achieving a compact, easy-to-produce design that generates intense and homogeneous magnetic fields while minimizing external field leakage and maintaining free space within the volume of interest.
Innovation Solution
A compact superconducting magnet device comprising multiple coaxial helical windings with specific radii and lengths, arranged such that their lateral ends are near a common sphere, with alternating current densities, and replaced by axisymmetric superconducting helical windings with a rectangular half-axial section to optimize homogeneity and reduce external field leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ferromagnetic rings are arranged within the interior volume defined by the main superconducting coil to improve homogeneity, then the homogeneity of the magnetic field is improved, but the free space in the volume of interest is restricted and the overall dimensions must be increased
Solution Approach 1:
The invention extracts the ferromagnetic rings from the interior volume of the main coil and replaces them with auxiliary superconducting coils positioned outside the volume of interest. This removes the obstruction to free space while maintaining field homogeneity through the auxiliary coils' magnetic field contribution.
Solution Approach 2:
The solution moves the homogeneity-adjusting elements from the radial dimension (inside the coil where they would block space) to the axial dimension (outside the coil at the ends). The auxiliary coils are positioned at the ends of the main coil along the axial direction, providing field control without occupying the radial free space needed for the volume of interest.
2Volume of moving object
If the diameter of superconducting coils is increased to maintain the same free space, then the free space is preserved, but compactness is harmed and production cost increases
Solution Approach 1:
The auxiliary superconducting coils are nested at the ends of the main superconducting coil, sharing the same cylindrical space along the axial direction. This nested arrangement allows multiple functional coils to occupy a compact overall volume without increasing the radial dimensions, thereby preserving compactness while maintaining free space within the volume of interest.
3Power
If a main superconducting coil is used to generate the magnetic field, then an intense magnetic field is produced, but external field leakage occurs
Solution Approach 1:
The auxiliary superconducting coils are configured to generate magnetic fields that oppose and cancel the external leakage fields produced by the main coil. By positioning auxiliary coils at the ends with appropriate current directions, their fields counteract the straying magnetic flux lines, reducing external field leakage while preserving the intense field within the volume of interest.
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 the creation of intense and homogeneous magnetic fields within a compact device, improving homogeneity and reducing external field leakage without the need for ferromagnetic rings, thus maintaining a larger free volume and reducing production costs.
Implementation Method 1
A compact superconducting magnet device for generating a homogeneous magnetic field component Bz along an axis Oz in a zone of interest ZI
Implementation Method 2
at least one first superconducting helical winding produced around a first slice of circular cylinder
Data Source
Figure 1~2
Figure 3~4B
AI summary
The invention relates to a compact superconducting magnet device for generating an intense and 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 three coaxial superconducting helical windings (1, 2, 3) provided around circular cylindrical wafers (10, 20, 30) comprising axis Oz and delimited by end circles (10A, 10B, 20A, 20B, 30A, 30B). The side ends of the helical windings (1, 2, 3) are arranged, give or take the value of the thickness of the windings, in the vicinity of a single sphere (5) which has a radius c and the center O of which is placed on the axis Oz at the center of the area of interest ZI, wherein said sphere encompasses the entire magnet device. The azimuthal current densities j1, j2, j3 of the helical windings (1, 2, 3) have alternately opposite signs. The lengths (2b1, 2b2, 2b3) of the helical windings (1, 2, 3) are decreasing. The outer radius (a32) of the outermost superconducting helical winding (3) is substantially equal to the half-length (b1) of the innermost superconducting helical winding (1), and the outer radius (a12) of the innermost superconducting helical winding (1) is substantially equal to the half-length (b3; b4) of the outermost superconducting helical winding (3).