Tunable segmented ring magnet and method of manufacture
First Claim
1. A tunable segmented ring magnet extending along a magnet axis perpendicular to the plane of the ring configuration thereof, and defining a torus surrounding an interior space, said magnet producing a preselected magnetic field within said interior space transverse to said magnet axis, said magnet comprisingA. a first plurality of inner magnet segments, each of said inner magnet segments being formed of a permanant magnetic material having essentially linear behavior in the second quadrant of the B-H curve and having an easy axis of magnetization in a predetermined orientation,B. a second plurality of outer magnet segments located radially outward from said inner magnet segments, each of said outer magnet segments being formed of a permanant magnetic material having essentially linear behavior in the second quadrant of the B-H curve and having an easy axis of magnetization in a predetermined orientation, andC. tuning means for moving at least one said magnet segment radially relative to said ring to produce a preselected transverse magnetic field in said interior space.
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Accused Products
Abstract
A segmented permanent ring magnet which is tunable to provide a preselected transverse magnetic field within the magnet interior is disclosed. The permanent magnet is constructed of material which has essentially linear behavior in the second quadrant of the B-H curve. The invention includes a method of tuning a segmented permanent ring magnet and a method of manufacture for the blocks of magnetic material which make up the magnet. The magnets of the present invention are particularly adapted for use as bias magnets in NMR imaging systems.
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Citations
24 Claims
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1. A tunable segmented ring magnet extending along a magnet axis perpendicular to the plane of the ring configuration thereof, and defining a torus surrounding an interior space, said magnet producing a preselected magnetic field within said interior space transverse to said magnet axis, said magnet comprising
A. a first plurality of inner magnet segments, each of said inner magnet segments being formed of a permanant magnetic material having essentially linear behavior in the second quadrant of the B-H curve and having an easy axis of magnetization in a predetermined orientation, B. a second plurality of outer magnet segments located radially outward from said inner magnet segments, each of said outer magnet segments being formed of a permanant magnetic material having essentially linear behavior in the second quadrant of the B-H curve and having an easy axis of magnetization in a predetermined orientation, and C. tuning means for moving at least one said magnet segment radially relative to said ring to produce a preselected transverse magnetic field in said interior space.
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14. A method of tuning a segmented permanent ring magnet to achieve a preselected transverse magnetic field in the interior of said ring, said magnet having a ring of N substantially uniform inner magnet segments, each of said inner magnet segments formed of a permanant magnetic material having essentially linear behavior in the second quadrant of the B-H curve and having an easy axis of magnetization in a predetermined orientation, said method comprising the steps of
providing M substantially uniform further magnet segments located radially outward of said inner magnet segments, and adjusting the location of at least one of said magnet segments to achieve said preselected transverse magnetic field.
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20. A method for fabricating a multipart rectangular-shaped permanent magnet having an easy axis of magnetization oriented in a selected angle relative to the easy axis of magnetization of its constituent parts, said method comprising the steps of:
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A. providing a rectangular-shaped magnet with an easy axis of magnetization parallel to a first surface thereof, B. cutting said magnet through an edge of said first surface at a selected angle relative to the easy axis of magnetization of said rectangular-shaped magnet thereby forming a first element and a second element from said rectangular-shaped magnet, each element including a portion of said first surface, C. cutting said first element through said portion of said first surface at an angle perpendicular to the surface formed by the first cut to form a third element and a fourth element, said cut also passing through an edge of said magnet; and D. reassembling said second, third and fourth elements to form a new rectangular-shaped magnet having an easy axis of magnetization rotated by said selected angle relative to the easy axis of magnetization relative to the original rectangular-shaped magnet. - View Dependent Claims (22, 24)
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Specification