US4590428A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electromagnet for NMR tomography
Assignee: Bruker Biospin GmbH
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Filing: 1983-12-08
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Granted: 1986-05-20
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Expires: 2003-12-08
Abstract
Abstract An electromagnet for generating the constant magnetic field required in NMR tomography includes a superconductive coil system consisting of at least one circular cylindrical field coil (1) and at least one correction coil (2, 3) concentric with the field coil. The coil system is enclosed in a ferromagnetic cylindrical shell (13) whose influence on the homogeneity of the magnetic field is compensated by the particular dimensioning of the field and correction coils. The magnetic field is produced by the coil system (1, 2, 3) in the interior space defined by it, which space is accessible and suitable to receive the body presented for examination. The cylindrical shell (13) may be closed at its ends by ring-shaped ferromagnetic plates (14). The cylindrical shell (13), complete with plates (14), may directly form the exterior wall of the Dewar.
Inventors
- 👤 Wolfgang Muller
- 👤 Bertold Knuttel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:16
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/28; G01R33/38; G01R33/387; G01R33/3873; G01R33/381; G01R33/3815; G01R33/3875; G01R33/42; G01R33/421; Y; Y10; Y10S; Y10S505/00; Y10S505/825; Y10S505/842; Y10S505/843; Y10S505/844
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
133 words
An electromagnet for producing a constant magnetic field as required for use in NMR tomography of a body to be examined, the electromagnet including a coil system having an axial interior space therein for receiving the body to be examined, the coil system including at least one circular cylindrical field coil and at least one correction coil coaxial with the field coil, the field coil and the correction coil being dimensioned and positioned to produce a substantially homogeneous magnetic field in the interior space, the coil system being superconductive and having a cryogenic coling system including a Dewar container surrounding the coil system, and a ferromagnetic cylindrical shell surrounding the Dewar container and affording a return magnetic path and a magnetic shield for the coil system while affording shielding for the Dewar container.
Claim 2
Dependent Claim
133 words
An electromagnet for producing a constant magnetic field as required for use in NMR tomography of a body to be examined, the electromagnet including a coil system having an axial interior space therein for receiving the body to be examined, the coil system including at least one circular cylindrical field coil and at least one correction coil coaxial with the field coil, the field coil and the correction coil being dimensioned and positioned to produce a substantially homogeneous magnetic field in the interior space, the coil system being superconductive and having a cryogenic coling system including a Dewar container surrounding the coil system, and a ferromagnetic cylindrical shell surrounding the Dewar container and affording a return magnetic path and a magnetic shield for the coil system while affording shielding for the Dewar container.
Claim 3
Dependent Claim
21 words
An electromagnet according to claim 1, in which the ferromagnetic cylindrical shell itself forms the exterior wall of the Dewar container.
Claim 4
Dependent Claim
42 words
An electromagnet according to claim 1, including a pair of ring-shaped ferromagnetic end plates mounted on the opposite ends of the ferromagnetic cylindrical shell and projecting inwardly therefrom for enclosing the corresponding end portions of the coil system and the Dewar container.
Claim 5
Dependent Claim
26 words
An electromagnet according to claim 1, in which the ferromagnetic cylindrical shell is made of a material having a high permeability and a high electrical resistivity.
Claim 6
Dependent Claim
34 words
An electromagnet according to claim 1, in which the ferromagnetic cylindrical shell is provided with at least one slot therein extending in an axial direction for interrupting circumferential eddy current flow in the shell.
Claim 7
Dependent Claim
26 words
An electromagnet according to claim 1, in which the ferromagnetic cylindrical shell is provided with at least one transversely directed slot for interrupting eddy current flow.
Claim 8
Dependent Claim
157 words
An electromagnet for producing a constant magnetic field as required for use in NMR tomography of a body to be examined, the electromagnet including a coil system having an axial interior space therein for receiving the body to be examined, the coil system including at least one circular cylindrical field coil and at least one correction coil coaxial with the field coil, the field coil and the correction coil being dimensioned and positioned to produce a substantially homogeneous magnetic field in the interior space, the coil system being superconductive and having a cryogenic cooling system including a Dewar container surrounding the coil system, and a ferromagnetic cylindrical shell surrounding the Dewar container and affording a return magnetic path and a magnetic shield for the coil system while affording shielding for the Dewar container, the ferromagnetic cylindrical shell being constructed of a plurality of parallel axially extending rods with axially extending slots therebetween to interrupt eddy current flow.
Claim 9
Dependent Claim
157 words
An electromagnet for producing a constant magnetic field as required for use in NMR tomography of a body to be examined, the electromagnet including a coil system having an axial interior space therein for receiving the body to be examined, the coil system including at least one circular cylindrical field coil and at least one correction coil coaxial with the field coil, the field coil and the correction coil being dimensioned and positioned to produce a substantially homogeneous magnetic field in the interior space, the coil system being superconductive and having a cryogenic cooling system including a Dewar container surrounding the coil system, and a ferromagnetic cylindrical shell surrounding the Dewar container and affording a return magnetic path and a magnetic shield for the coil system while affording shielding for the Dewar container, the ferromagnetic cylindrical shell being constructed of a plurality of parallel axially extending rods with axially extending slots therebetween to interrupt eddy current flow.
Claim 10
Dependent Claim
157 words
An electromagnet for producing a constant magnetic field as required for use in NMR tomography of a body to be examined, the electromagnet including a coil system having an axial interior space therein for receiving the body to be examined, the coil system including at least one circular cylindrical field coil and at least one correction coil coaxial with the field coil, the field coil and the correction coil being dimensioned and positioned to produce a substantially homogeneous magnetic field in the interior space, the coil system being superconductive and having a cryogenic cooling system including a Dewar container surrounding the coil system, and a ferromagnetic cylindrical shell surrounding the Dewar container and affording a return magnetic path and a magnetic shield for the coil system while affording shielding for the Dewar container, the ferromagnetic cylindrical shell being constructed of a series of axially disposed ring-shaped discs with transversely directed slots therebetween to interrupt eddy current flow.
Claim 11
Dependent Claim
157 words
An electromagnet for producing a constant magnetic field as required for use in NMR tomography of a body to be examined, the electromagnet including a coil system having an axial interior space therein for receiving the body to be examined, the coil system including at least one circular cylindrical field coil and at least one correction coil coaxial with the field coil, the field coil and the correction coil being dimensioned and positioned to produce a substantially homogeneous magnetic field in the interior space, the coil system being superconductive and having a cryogenic cooling system including a Dewar container surrounding the coil system, and a ferromagnetic cylindrical shell surrounding the Dewar container and affording a return magnetic path and a magnetic shield for the coil system while affording shielding for the Dewar container, the ferromagnetic cylindrical shell being constructed of a series of axially disposed ring-shaped discs with transversely directed slots therebetween to interrupt eddy current flow.
Claim 12
Dependent Claim
21 words
An electromagnet according to claim 8, in which the ring-shaped discs are provided with radial slots to interrupt eddy current flow.
Claim 13
Dependent Claim
25 words
An electromagnet according to claim 8, in which the ring-shaped discs are subdivided into segments with generally radial slots therebetween to interrupt eddy current flow.
Claim 14
Dependent Claim
176 words
An electromagnet for producing a constant magnetic field as required for use in NMR tomography of a body to be examined, the electromagnet including a coil system having an axial interior space therein for receiving the body to be examined, the coil system including at least one circular cylindrical field coil and at least one correction coil coaxial with the field coil, the field coil and the correction coil being dimensioned and positioned to produce a substantially homogeneous magnetic field in the interior space, the coil system being superconductive and having a cryogenic cooling system including a Dewar container surrounding the coil system, and a ferromagnetic cylindrical shell surrounding the Dewar container and affording a return magnetic path and a magnetic shield for the coil system while affording shielding for the Dewar container, the cryogenic cooling system including cooling vessels within the Dewar container, the cooling vessels having walls made at least in part of a wall material having poor electrical conductivity but with inserts of materials having good thermal conductivity embedded in the wall material.
Claim 15
Dependent Claim
176 words
An electromagnet for producing a constant magnetic field as required for use in NMR tomography of a body to be examined, the electromagnet including a coil system having an axial interior space therein for receiving the body to be examined, the coil system including at least one circular cylindrical field coil and at least one correction coil coaxial with the field coil, the field coil and the correction coil being dimensioned and positioned to produce a substantially homogeneous magnetic field in the interior space, the coil system being superconductive and having a cryogenic cooling system including a Dewar container surrounding the coil system, and a ferromagnetic cylindrical shell surrounding the Dewar container and affording a return magnetic path and a magnetic shield for the coil system while affording shielding for the Dewar container, the cryogenic cooling system including cooling vessels within the Dewar container, the cooling vessels having walls made at least in part of a wall material having poor electrical conductivity but with inserts of materials having good thermal conductivity embedded in the wall material.
Claim 16
Dependent Claim
28 words
An electromagnet according to claim 11, in which the wall material is made of glass fiber reinforced plastic, the inserts being made of metal having good thermal conductivity.
Claim 17
Dependent Claim
152 words
An electromagnet for producing a constant magnetic field as required for use in NMR tomography of a body to be examined, the electromagnet including a coil system having an axial interior space therein for receiving the body to be examined, the coil system including at least one circular cylindrical field coil and at least one correction coil coaxial with the field coil, the field coil and the correction coil being dimensioned and positioned to produce a substantially homogeneous magnetic field in the interior space, the coil system being superconductive and having a cryogenic cooling system including a Dewar container surrounding the coil system, the cryogenic cooling system having cooling vessels within the Dewar container, the vessels having walls made at least in part of a wall material having a poor electrical conductivity but with inserts having a good thermal conductivity embedded in the wall material, the wall material inhibiting eddy current flow.
Claim 18
Dependent Claim
152 words
An electromagnet for producing a constant magnetic field as required for use in NMR tomography of a body to be examined, the electromagnet including a coil system having an axial interior space therein for receiving the body to be examined, the coil system including at least one circular cylindrical field coil and at least one correction coil coaxial with the field coil, the field coil and the correction coil being dimensioned and positioned to produce a substantially homogeneous magnetic field in the interior space, the coil system being superconductive and having a cryogenic cooling system including a Dewar container surrounding the coil system, the cryogenic cooling system having cooling vessels within the Dewar container, the vessels having walls made at least in part of a wall material having a poor electrical conductivity but with inserts having a good thermal conductivity embedded in the wall material, the wall material inhibiting eddy current flow.
Claim 19
Dependent Claim
28 words
An electromagnet according to claim 13, in which the wall material is made of glass fiber reinforced plastic, the inserts being made of metal having high heat conductivity.
Claim 20
Dependent Claim
18 words
An electromagnet according to claim 1, including means for circulating a coolant immediately within the ferromagnetic cylindrical shell.
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) | 1989-05-19 | 1989-11-18 | 1990-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-19 | 1993-11-18 | 1994-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-19 | 1997-11-18 | 1998-05-20 | $7700.00 | Window Closed / Lapsed |