Superconducting Magnet Shim Layout for Stable Field Homogeneity
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Solution Overview
Problem
Conventional superconducting magnet devices face challenges in maintaining magnetic field homogeneity due to difficulties in adjusting the relative position between the magnetic shim and the superconducting coil, leading to instability in the magnetic field homogeneity caused by temperature changes in the installation environment.
Innovation Solution
The superconducting magnet device incorporates a low temperature iron shim held by a winding frame in the low temperature region, which stabilizes the magnetic field homogeneity by correcting both axial and radial components, and a room temperature iron shim for further adjustments, ensuring stability despite temperature fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the magnetic shim is disposed in liquid helium to avoid temperature change effects, then the magnetic field homogeneity is improved, but the adjustment of relative position between the magnetic shim and superconducting coil becomes difficult
Solution Approach 1:
The invention divides the magnetic shim system into two separate components: a low temperature magnetic shim disposed in the liquid helium region (for temperature stability) and a room temperature magnetic shim disposed in the measurement space (for position adjustment). This segmentation allows each component to fulfill its specific function without compromise - the low temperature shim provides thermal stability while the room temperature shim enables easy positional adjustment during manufacturing and operation.
2Ease of manufacture
If the magnetic shim is disposed at room temperature for easy adjustment, then the relative position adjustment becomes easy, but the magnetic field homogeneity becomes unstable due to temperature changes
Solution Approach 1:
The magnetic shim system is segmented into two functional parts located at different temperatures. The room temperature magnetic shim can be easily adjusted during manufacturing and operation, while the low temperature magnetic shim remains in the stable cryogenic environment to provide temperature-independent field homogeneity correction.
3Device complexity
If a single magnetic shim system is used, then the device structure is simple, but the magnetic field homogeneity cannot be stably maintained under temperature variations
Solution Approach 1:
The magnetic shim system is divided into two segments operating at different temperatures with distinct functions. The low temperature magnetic shim (first magnetic shim) is disposed in liquid helium for thermal stability, while the room temperature magnetic shim (second magnetic shim) is disposed in the measurement space for easy adjustment. This segmentation resolves the contradiction by distributing functions across temperature zones.
Solution Approach 2:
The room temperature magnetic shim acts as an intermediary that can be adjusted during manufacturing to compensate for assembly tolerances and positioning errors, while the low temperature magnetic shim provides the primary temperature-stable field correction. This intermediary approach allows the system to achieve both ease of manufacture and stable operation.
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 device maintains stable magnetic field homogeneity by effectively correcting magnetic field components, reducing the impact of temperature changes and ensuring accurate measurements in NMR devices.
Implementation Method 1
a superconducting coil including a superconducting wire wound around an outer periphery of the winding frame, the superconducting coil being excited to generate a magnetic field
Implementation Method 2
a shim coil that is arranged in the sample region and generates a magnetic field by being excited
Implementation Method 3
a low temperature magnetic shim that is held by the winding frame in the low temperature region and enhances homogeneity of a magnetic field of the sample region
Data Source
AI summary
A superconducting magnet device includes a low temperature vessel disposed in a cylindrical shape around a central axis so as to surround a sample region including the central axis, the low temperature vessel internally having a low temperature region, a winding frame having a cylindrical shape centered on the central axis and disposed in the low temperature region, a superconducting coil including a superconducting wire wound around an outer periphery of the winding frame, the superconducting coil being excited to generate a magnetic field, a shim coil that is arranged in the sample region and generates a magnetic field by being excited, a sample region magnetic shim disposed in the sample region and cooperating with the shim coil to increase homogeneity of a magnetic field of the sample region, and a low temperature magnetic shim in the low temperature region and enhances homogeneity of a magnetic field.