Magnetic assembly for a nuclear magnetic resonance imaging system
First Claim
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1. A magnet assembly having a generally U-shape, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose flux passes through a working volume defined between the arms of the U, and wherein the dimensions of the assembly are chosen such that:
- ##EQU8## where;
Lg is the length of the gap between the arms,Lm is the length of the magnet,Br is the remnant field of the magnet, andBg is the field in the gap.
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Abstract
A magnet assembly has a generally U-shape, the bight of the U including a permanent magnet which generates a magnetic field whose flux passes through a working volume defined between the arms of the U. The dimensions of the assembly are chosen such that: ##EQU1## where: Lg is the length of the gap between the arms,
Lm is the length of the magnet,
Br is the remnant field of the magnet, and
Bg is the field in the gap.
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Citations
18 Claims
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1. A magnet assembly having a generally U-shape, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose flux passes through a working volume defined between the arms of the U, and wherein the dimensions of the assembly are chosen such that:
- ##EQU8## where;
Lg is the length of the gap between the arms,Lm is the length of the magnet, Br is the remnant field of the magnet, and Bg is the field in the gap. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- ##EQU8## where;
- 9. A nuclear magnetic resonance imaging system comprising a generally U-shaped cross-section, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose magnetization direction is substantially parallel with the arms of the U, the magnetic flux passing into a working volume defined within the gap between the arms of the U and returning via the arms, and a ferro-magnetic pole piece provided along the face of the permanent magnet and facing towards the working volume, the pole piece provided with a triangular front aspect.
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12. A nuclear magnetic resonance imaging system comprising a magnet assembly having a generally U-shape, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose flux passes through a working volume defined between the arms of the U, and wherein the dimensions of the assembly are chosen such that:
- ##EQU9## where;
Lg is the length of the gap between the arms,Lm is the length of the magnet, Br is the remnant field of the magnet, and Bg is the field in the gap. - View Dependent Claims (13, 14)
- ##EQU9## where;
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15. A nuclear magnetic resonance imaging system comprising:
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a generally U-shaped cross-section, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose magnetization direction is substantially parallel with the arms of the U, the magnetic flux passing into a working volume defined within the gap between the arms of the U and returning via the arms; and one or more cladding magnets which compensate for flux leakage from the assembly. - View Dependent Claims (16)
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17. A nuclear magnetic resonance imaging system comprising:
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a generally U-shaped cross-section, wherein the bight of the U includes a permanent magnet which generates a magnetic field whose magnetization direction is substantially parallel with the arms of the U, the magnetic flux passing into a working volume defined within the gap between the arms of the U and returning via the arms; and one or more permanent, correction magnets at the ends of the magnet assembly, the direction of magnetization of the correction magnets being substantially parallel with the direction of magnetization of the permanent magnet of the assembly. - View Dependent Claims (18)
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Specification