US4876510A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for nuclear spin tomography having superconducting base field magnetic coils and a radiation shield
Assignee: Siemens AG
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Filing: 1988-05-12
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Granted: 1989-10-24
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Expires: 2008-05-12
Abstract
Abstract Magnet coil system for nuclear spin tomography has superconducting coils for generating a homogeneous magnetic base field and nonsuperconducting coils within an interior region defined by the base field coils for developing magnetic field gradients. At least one cooled radiation shield of electrically and thermally conductive material is arranged between the gradient coils and the superconducting base field coils. To prevent eddy currents started in the radiation shield from distorting the gradient fields, the radiation field contains superconducting material of a "second kind" that is a high temperature superconductor. The superconductor is in a nonsuperconducting state at the start of an excitation process for the base field coils and in a superconducting state during the undisturbed operation of the magnet coil system.
Inventors
- 👤 Horst Siebold
- 👤 Gunter Ries
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 01:21
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/28; G01R33/42; G01R33/421; G01R33/38; G01R33/381; G01R33/3815; Y; Y10; Y10S; Y10S505/00; Y10S505/825; Y10S505/85
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
110 words
A magnet coil system for a nuclear spin tomography apparatus comprising; superconducting base field coils for generating a homogeneous magnetic base field, said superconducting base field coils defining an interior region; gradient coils that are not superconducting positioned within said interior region for developing magnetic field gradients; at least one cooled radiation shield that is electrically and thermally conducting and comprises a superconducting material of a second kind having a high superconducting transition temperature; and said shield is positioned between said gradient coils and said superconducting base field coils and has a nonsuperconducting state during a starting process and a superconducting state during undisturbed operation of the magnetic coil system.
Claim 2
Dependent Claim
110 words
A magnet coil system for a nuclear spin tomography apparatus comprising; superconducting base field coils for generating a homogeneous magnetic base field, said superconducting base field coils defining an interior region; gradient coils that are not superconducting positioned within said interior region for developing magnetic field gradients; at least one cooled radiation shield that is electrically and thermally conducting and comprises a superconducting material of a second kind having a high superconducting transition temperature; and said shield is positioned between said gradient coils and said superconducting base field coils and has a nonsuperconducting state during a starting process and a superconducting state during undisturbed operation of the magnetic coil system.
Claim 3
Dependent Claim
29 words
A magnet system as claimed in claim 1, wherein said superconducting material is applied as a thin layer or coating on the inside or outside of said radiation shield.
Claim 4
Dependent Claim
24 words
A magnet system as claimed in claim 2, wherein said superconducting layer or coating of said radiation shield has the structure of a mesh.
Claim 5
Dependent Claim
29 words
A magnet system as claimed in claim 3, wherein said mesh structure comprises superconducting wires or ribbons that are connected to each other in a highly electrically conducting manner.
Claim 6
Dependent Claim
23 words
A magnet system as claimed in claim 2, wherein said superconducting layer or coating of said radiation shield comprises several prefabricated planar elements.
Claim 7
Dependent Claim
29 words
A magnet system as claimed in claim 5, wherein said planar elements of said superconducting layer or coating are plates or foils that are coated with said superconducting material.
Claim 8
Dependent Claim
17 words
A magnet system as claimed in claim 5, wherein said planar elements overlap in narrow edge strips.
Claim 9
Dependent Claim
17 words
A magnet system as claimed in claim 6, wherein said planar elements overlap in narrow edge strips.
Claim 10
Dependent Claim
35 words
A magnet system as claimed in claim 1, further comprising means for heating said radiation shield to heat said superconductive material above its critical transition temperature during the starting process for said base field coils.
Claim 11
Dependent Claim
44 words
A magnet system as claimed in claim 1 wherein said superconducting material has dimensions chosen so that, during the starting process of said base field coils and before an operating current is reached, a critical current carrying capacity of the superconducting material is exceeded.
Claim 12
Dependent Claim
32 words
A magnet system as claimed in claim 1, further comprising means for cooling said base field coils; and means for disconnecting said radiation shield from said cooling means during said starting process.
Claim 13
Dependent Claim
21 words
A magnet system as claimed in claim 1, wherein said radiation shield comprises a longitudinally slotted design formed from metallic parts.
Claim 14
Dependent Claim
43 words
A magnet system as claimed in claim 1, wherein said radiation shield further comprises thin walled coolant tubes that are arranged in an axial direction of the shield parallel to each other and connected to each other in a poorly electrically conducting manner.
Claim 15
Dependent Claim
54 words
A magnet system as claimed in claim 1, wherein said radiation shield contains thin metal strips of thermally highly conducting material that are arranged in an axial direction of the shield parallel to each other and overlap as seen in a circumferential direction of the shield while they are insulated electrically from each other.
Claim 16
Dependent Claim
17 words
A magnet system as claimed in claim 1, wherein said superconducting material contains a superconducting Y-Ba-Cu-O phase.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-10-23 | 1993-04-24 | 1993-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-23 | 1997-04-24 | 1997-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-23 | 2001-04-24 | 2001-10-24 | $7700.00 | Window Closed / Lapsed |