EP0139308A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Nuclear magnetic resonance apparatus
Assignee: Koninklijke Philips NV
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Filing: 1984-05-30
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Granted: —
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Expires: 2004-05-30
Abstract
Abstract A nuclear magnetic resonance apparatus comprises an electromagnetic system in which a shield of a magnetic material is arranged about the coil system for the homogeneous magnetic field. By providing the magnetic material, for example soft iron, directly about the coil system, a comparatively compact magnetic with an intensified, interference-insensitive homogeneous magnetic field is obtained. Instead of using a closed cylinder, use can alternatively be made of a cylinder which is formed by rods. The latter is notably attractive for shielding at a larger distance, the original field in the coil then being influenced to only a minor extent. A similar shielding can be obtained by means of a Helmholtz coil pair.
Inventors
- 👤 Hinne C/O Int. Octrooibureau B.V. Zijlstra
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 16:22
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/28; G01R33/42; G01R33/421; G01R33/38; G01R33/387; G01R33/3873; Y; Y10; Y10S; Y10S505/00; Y10S505/825; Y10S505/842; Y10S505/843; Y10S505/844; Y10S505/872
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
52 words
A nuclear magnetic resonance apparatus, comprising a magnet which comprises an electromagnetic coil system for generating a homogeneous magnetic field in an examination space which is enclosed by the magnet, characterized in that a shield for the external stray field of the coil system is arranged coaxially about the electromagnetic coil system.
Claim 2
Dependent Claim
52 words
A nuclear magnetic resonance apparatus, comprising a magnet which comprises an electromagnetic coil system for generating a homogeneous magnetic field in an examination space which is enclosed by the magnet, characterized in that a shield for the external stray field of the coil system is arranged coaxially about the electromagnetic coil system.
Claim 3
Dependent Claim
37 words
A nuclear magnetic resonance apparatus as claimed in Claim 1, characterized in that the shield is formed by a sleeve of a material having a comparatively high magnetic permeability which is concentrically arranged about the coil system.
Claim 4
Dependent Claim
60 words
A nuclear magnetic resonance apparatus as claimed in Claim 1, characterized in that the shield comprises a number of rods of a soft magnetic material which are axially directed and uniformly spaced on a cylindrical surface which extends concentrically about the coil system, the length of said rods being at least equal to the axial length of the coil system.
Claim 5
Dependent Claim
31 words
A nuclear magnetic resonance apparatus as claimed in Claim 2 or 3, characterized in that the shielding sleeve is arranged directly about the coil system and forms one integral unit therewith.
Claim 6
Dependent Claim
48 words
A nuclear magnetic resonance apparatus as claimed in Claim 2, 3 or 4, characterized in that the rods, or the cylinder, are provided at their axial ends with radially inwards directed extensions which reach at least as far as the vicinity of the windings of the coil system.
Claim 7
Dependent Claim
41 words
A nuclear magnetic resonance apparatus as claimed in any one of the Claims 2 to 5, characterized in that the shield for external stray fields and superconducting windings of the main magnet are accommodated in a Dewar vessel for liquid helium.
Claim 8
Dependent Claim
26 words
A nuclear magnetic resonance apparatus as claimed in any one of the Claims 2 to 6 characterized in that the shielding soft magnetic material is premagnetized.
Claim 9
Dependent Claim
26 words
A nuclear magnetic resonance apparatus as claimed in Claim 7, characterized in that the sleeve or the rods are provided with a current winding for premagnetization.
Claim 10
Dependent Claim
32 words
A nuclear magnetic resonance apparatus as claimed in Claim 7, characterized in that at least a piece of a permanent magnetic material is added to the sleeve or each of the rods.
Claim 11
Dependent Claim
48 words
A nuclear magnetic resonance apparatus as claimed in Claim 1, characterized in that the shield is formed by a pair of shielding coils which is situated near the axial ends of the coil system and which serves to generate a magnetic field which compensates for the stray field.
Claim 12
Dependent Claim
47 words
A nuclear magnetic resonance apparatus as claimed in any one of the Claims 1 to 10, characterized in that near the axial ends of the shield for external stray fields there is arranged a shielding coil which is also accommodated in a Dewar vessel for liquid helium.
References Cited (Backward Citations)
No citation records indexed.
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