Patent JPS59141802A successfully refreshed from Google Patents.
US4723116A
Expired / Lapsed
US
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Electromagnet system for nuclear spin tomography
Assignee: Bruker Biospin GmbH
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Filing: 1987-05-11
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Granted: 1988-02-02
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Expires: 2007-05-11
Abstract
Abstract An electromagnet system for nuclear spin tomography comprises a ferromagnetic yoke (41), two pole pieces (42, 43) arranged on the said yoke (41) with their pole faces (51, 52) facing each other, and at least one excitation coil (47, 48). The pole pieces (42, 43) delimit an air gap (44) having a diameter-to-width ratio of less than 2.5. There is arranged in the area of each of the pole faces (51, 52) formed by the pole pieces (42, 43) at least one substantially two-dimensional supplementary coil (55, 56, 57, 58) whose number of ampere turns is between 0.1% and 10% of the number of ampere turns of the excitation coil (47, 48). The excitation and supplementary coils generate together in the air gap (44) a magnetic field (B) which exhibits a homogeneity better than 10 -4 in a spherical volume having a diameter equal to half the value of the width (H) of the air gap.
Inventors
- 👤 Wolfgang Muller
- 👤 Gunther R. Laukien
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 20:16
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/28; G01R33/38; G01R33/383; G01R33/387; G01R33/3875
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
172 words
Electromagnet system for nuclear spin tomography comprising a ferromagnetic yoke, two pole pieces arranged on the said yoke with their pole faces facing each other, the said pole pieces defining between them an air gap of a width H, and comprising further at least one excitation coil, wherein the diameter D of the said pole faces is at the most equal to 2.5 times the value of the width H of the said air gap and wherein at least one substantially two-dimensional supplementary coil is arranged in the area of the plane of each of the said pole faces, whose number of ampere turns is between 0.1% and 10% of the number of ampere turns of the excitation coil and whose field, added to the field generated by the excitation coil, leads in the air gap to a resulting magnetic field (B) which, in a spherical volume having a diameter equal to half the value of the width (H) of the air gap, exhibits a homogeneity theoretically better than 10 -4 .
Claim 2
Dependent Claim
172 words
Electromagnet system for nuclear spin tomography comprising a ferromagnetic yoke, two pole pieces arranged on the said yoke with their pole faces facing each other, the said pole pieces defining between them an air gap of a width H, and comprising further at least one excitation coil, wherein the diameter D of the said pole faces is at the most equal to 2.5 times the value of the width H of the said air gap and wherein at least one substantially two-dimensional supplementary coil is arranged in the area of the plane of each of the said pole faces, whose number of ampere turns is between 0.1% and 10% of the number of ampere turns of the excitation coil and whose field, added to the field generated by the excitation coil, leads in the air gap to a resulting magnetic field (B) which, in a spherical volume having a diameter equal to half the value of the width (H) of the air gap, exhibits a homogeneity theoretically better than 10 -4 .
Claim 3
Dependent Claim
26 words
Electromagnet system according to claim 1, wherein the fields of the supplementary coils are non-orthogonal relative to the magnetic field (B) of the said excitation coil.
Claim 4
Dependent Claim
26 words
Electromagnet system according to claim 1, wherein the said supplementary coils and the said excitation coils are connected in series to a common power supply unit.
Claim 5
Dependent Claim
20 words
Electromagnet system according to claim 1, wherein the said supplementary coils are arranged on top of the said pole surface.
Claim 6
Dependent Claim
23 words
Electromagnet system according to claim 1, wherein the said pole faces are each provided with a central recess receiving the said supplementary coil.
Claim 7
Dependent Claim
29 words
Electromagnet system according to claim 1, wherein the said pole pieces are embraced by the said supplementary coil in the area of the plane of the said pole faces.
Claim 8
Dependent Claim
29 words
Electromagnet system according to claim 1, wherein the said pole pieces are provided with a ferromagnetic shim ring in the area of the plane of the said pole faces.
Claim 9
Dependent Claim
18 words
Electromagnet system according to claim 1, wherein the said pole pieces taper conically toward the said pole face.
Claim 10
Dependent Claim
23 words
Electromagnet system according to claim 1, wherein the current (I) flowing through the said supplementary coils has a value of some 100 amperes.
Claim 11
Dependent Claim
33 words
Electromagnet system according to claim 1, wherein the said pole pieces and the said supplementary coils exhibit a rectangular cross-section in a plane extending perpendicularly to the direction of the magnetic field (B).
References Cited (Backward Citations)
DE1292885B
Cited
US3513422A
Cited
US3622869A
Cited
US4318043A
Cited
US4672346A
Cited
DE3418812A1
Cited
US4656449A
Cited
US4658229A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-02-01 | 1991-08-03 | 1992-02-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-01 | 1995-08-03 | 1996-02-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-01 | 1999-08-03 | 2000-02-02 | $7700.00 | Window Closed / Lapsed |