Multipart Pole Piece Shimming for Halbach Magnet Field Homogeneity
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Solution Overview
Problem
Existing pole pieces for Halbach-type magnet configurations in compact NMR applications fail to effectively shim magnetic fields due to their design limitations in confined spaces, leading to inhomogeneities that affect magnetic field uniformity.
Innovation Solution
A multipartite pole piece comprising a top iron, bottom iron, and an interstitial shim layer, allowing for modification of material content through processes like chemical etching or adding materials to shim the magnetic field, with shimming holes and inserts for precise adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single-piece pole piece design is used, then the structure is simple and easy to manufacture, but the magnetic field homogeneity is insufficient due to inability to effectively shim in confined spaces
Solution Approach 1:
The pole piece is divided into multiple separable components including a body portion and one or more shim layers that can be independently positioned and adjusted. This segmentation allows precise control of magnetic field homogeneity by adjusting the relative positions of the components, while maintaining a relatively simple overall structure that can be manufactured using conventional techniques.
2Volume of moving object
If traditional pole pieces are used in compact NMR applications, then the device size is reduced, but magnetic field inhomogeneities increase due to design limitations in confined spaces
Solution Approach 1:
The invention introduces adjustable shim layers that can be positioned at different distances from the magnet array, adding a dimensional adjustment capability to the pole piece structure. This allows optimization of magnetic field homogeneity along the axial dimension while maintaining a compact overall device size suitable for tabletop NMR applications.
3Manufacturing precision
If the pole piece structure is made complex to achieve better shimming, then magnetic field homogeneity improves, but the ease of manufacture decreases
Solution Approach 1:
The pole piece is divided into multiple separable components including a body portion and one or more shim layers that can be independently positioned and adjusted. This segmentation allows precise control of magnetic field homogeneity by adjusting the relative positions of the components, while maintaining a relatively simple overall structure that can be manufactured using conventional techniques.
Solution Approach 2:
The invention allows adjustment of magnetic field homogeneity by changing the position and configuration of shim layers relative to the magnet array and pole piece body. This parameter adjustment capability enables optimization of field uniformity without requiring complex manufacturing processes, as the same basic structure can be adapted to different requirements by repositioning components.
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
Enhances magnetic field homogeneity by allowing for precise shimming of Halbach-type magnet configurations, improving the performance of compact NMR devices by reducing field inhomogeneities.
Implementation Method 1
a pole piece for use in a Halbach-type magnet configuration... comprising a top iron, a bottom iron, and an interstitial shim layer... for shimming the magnetic field generated by the Halbach-type magnet configuration
Data Source
AI summary
A pole piece for use in a Halbach-type magnet configuration, the pole piece having an elongated body adapted for insertion into the Halbach-type magnet configuration and having at least two parts operably and removably connected to each other. The at least two parts of the pole piece comprise a top iron having a front face and a rear face, a bottom iron having a front face and a rear face, and an interstitial shim layer adapted to be inserted in a shim cavity defined by a depression formed in at least one of: the front face of the top iron and the rear face of the bottom iron. A method for shimming includes modifying a material content of the shim cavity and inserting the pole piece into the central cavity of the Halbach-type magnet configuration for shimming the magnetic field generated.