US4983922A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic shim for magnetic field correction
Assignee: Mitsubishi Electric Corp
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Filing: 1989-06-02
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Granted: 1991-01-08
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Expires: 2009-06-02
Abstract
Abstract A magnetic shim for correcting the n-th order harmonic of the Z-axis component of the main magnetic field of an NMR device has its end surfaces disposed such that each of the (n+2)-order harmonics of the magnetic fields generated by the end surfaces are nonzero and such that the sum of the (n+2)-order harmonics is equal to zero.
Inventors
- 👤 Yasuyuki Tahara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 02:32
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/28; G01R33/38; G01R33/387; G01R33/3873
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
177 words
A magnetic field correcting magnetic shim for a superconducting magnet apparatus having a superconducting main coil for generating a uniform magnetic field in the vicinity of a central region thereof, a cryostat containing said superconducting main coil therein, and a magnetic field correcting apparatus having a magnetic field correcting shim disposed on a cylindrical surface substantially concentric to said main coil, characterized by: said magnetic field correcting magnetic shim having two axially spaced end surfaces oriented perpendicular to an axial direction of the coil, a magnetic field generated by a magnetic charge appearing on said end surfaces having a component contributing to an nth-power term of a spherical harmonization function development representing the magnetic field in the axial direction of the coil, and the position of said two end surfaces being selected such that a component contributing to an (n+2)-power term generated by the magnetic charge on each of said end surfaces is non-zero, but the sum of the components contributing to the (n+2)-power term generated by the magnetic charge on said two end surfaces is zero.
Claim 2
Dependent Claim
177 words
A magnetic field correcting magnetic shim for a superconducting magnet apparatus having a superconducting main coil for generating a uniform magnetic field in the vicinity of a central region thereof, a cryostat containing said superconducting main coil therein, and a magnetic field correcting apparatus having a magnetic field correcting shim disposed on a cylindrical surface substantially concentric to said main coil, characterized by: said magnetic field correcting magnetic shim having two axially spaced end surfaces oriented perpendicular to an axial direction of the coil, a magnetic field generated by a magnetic charge appearing on said end surfaces having a component contributing to an nth-power term of a spherical harmonization function development representing the magnetic field in the axial direction of the coil, and the position of said two end surfaces being selected such that a component contributing to an (n+2)-power term generated by the magnetic charge on each of said end surfaces is non-zero, but the sum of the components contributing to the (n+2)-power term generated by the magnetic charge on said two end surfaces is zero.
Claim 3
Dependent Claim
16 words
A magnetic field correcting shim as claimed in claim 1, wherein said magnetic shim is cylindrical.
Claim 4
Dependent Claim
21 words
A magnetic field correcting shim as claimed in claim 1, wherein said magnetic shim comprises a plurality of circumferentially divided sections.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-01-07 | 1994-07-09 | 1995-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-01-07 | 1998-07-09 | 1999-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-01-07 | 2002-07-09 | 2003-01-08 | $7700.00 | Window Closed / Lapsed |