# US 5,345,208 A · Pole face design for a C-shaped superconducting magnet

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- Number: US 5,345,208 A
- Document ID: US5345208A
- Status: Granted
- Kind: A
- Application number: 08/067,183
- Filed: 1993-05-26
- Granted: 1994-09-06
- Earliest claimed: 1993-05-26
- Assignees: General Electric Company
- Inventors: Bizhan Dorri; Evangelos T. Laskaris; Gary Bedrosian; Bu-Xin Xu
- Web page: https://patentgrep.com/patent/US5345208A

## CPC

- G01R 33/3873: using ferromagnetic bodies {; Passive shimming}
- G01R 33/3806: {Open magnet assemblies for improved access to the sample, e.g. C-type or U-type magnets}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

This invention relates to a pole face design for superconducting magnets of the type that are C-shaped. Such structures of this type, generally, employ pole faces which homogenize the magnet field within the imaging volume.

## Claims

### Claim 1

A C-shaped superconducting magnet wherein said magnet is comprised of:
a superconducting coil means;
a ferromagnetic core means operatively connected to said coil means, and
first and second pole pieces operatively connected to said core means and which are located at a predetermined distance away from each other to provide a gap between said first and second pole pieces such that said first and second pole pieces are each further comprised of a passive shim means located adjacent to said first and second pole pieces, wherein said passive shim means is further comprised of a ring means including a number greater than two of circumferentially-abutting concentric continuous rings of different thicknesses generally covering the face area of its associated pole piece, and wherein said passive shim means is further comprised of shimming trays attached to said rings and passive shims disposed on top of said rings on said shimming trays.

### Claim 2 (depends on 1)

The magnet of claim 1, wherein said shimming trays are further comprised of a non-ferromagnetic material.

### Claim 3 (depends on 1)

The magnet of claim 1, wherein said passive shims are further comprised of a ferromagnetic material.

### Claim 4 (depends on 3)

The magnet of claim 3, wherein said passive shims are further comprised of iron.