Cylindrical NMR bias magnet apparatus employing permanent magnets and methods therefor
First Claim
1. Magnetic bias apparatus comprising:
- a plurality of elongated sleeves each having a longitudinal axis and being disposed parallel to each other, said sleeves arranged around a closed curvilinear space to define a bore therein, each of said plurality of sleeves being rotatable about its longitudinal axis; and
a plurality of rectangular permanent magnet slabs mounted in each of said plurality of sleeves, each of said plurality of permanent magnet slabs having a length, width and thickness dimension and being stacked in the thickness dimension within each of said plurality of sleeves with said length dimension parallel to the longitudinal axis, each of said plurality of rectangular permanent magnet slabs having an anisotropic axis of magnetic orientation parallel to said thickness direction and stacked in a magnetically aiding relation in said thickness direction whereby the magnetic field exhibited through at least a portion of said bore may be maximized and rendered more uniform by rotation of said sleeves to a selected orientation.
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Abstract
NMR bias magnet apparatus employing permanent magnets and methods therefor are provided in accordance with the teachings of the present invention. According to the present invention a plurality of insulating sleeves which may be rotated are disposed about the periphery of a structure having a curvilinear cross section such as a cylinder. Each of the plurality of insulating sleeves are filled with stacks of slabs of permanent magnet material forming slugs and having an anisotropic axis of magnetic orientation aligned at an azimuth corresponding to a=2φ. The length of slug sections or even of individual slabs within each sleeve may be varied for purposes of introducing desired harmonics, as may the manner in which each sleeve is filled, so long as quadrature symmetry is maintained.
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Citations
35 Claims
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1. Magnetic bias apparatus comprising:
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a plurality of elongated sleeves each having a longitudinal axis and being disposed parallel to each other, said sleeves arranged around a closed curvilinear space to define a bore therein, each of said plurality of sleeves being rotatable about its longitudinal axis; and a plurality of rectangular permanent magnet slabs mounted in each of said plurality of sleeves, each of said plurality of permanent magnet slabs having a length, width and thickness dimension and being stacked in the thickness dimension within each of said plurality of sleeves with said length dimension parallel to the longitudinal axis, each of said plurality of rectangular permanent magnet slabs having an anisotropic axis of magnetic orientation parallel to said thickness direction and stacked in a magnetically aiding relation in said thickness direction whereby the magnetic field exhibited through at least a portion of said bore may be maximized and rendered more uniform by rotation of said sleeves to a selected orientation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. Magnetic bias apparatus comprising:
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N nonconductive elongated sleeves each having a longitudinal axis, said sleeves disposed parallel to each other and arranged around a closed curvilinear space to define a bore therein, each of said N sleeves being rotatable about an axis parallel to said longitudinal axis; nonconductive permanent magnet material mounted in each of said N sleeves, said permanent magnet material having a length, width and thickness dimension and exhibiting an anisotropic axis of magnetic orientation parallel to said thickness direction, said nonconductive permanent magnet material being segmented in said length dimension to provide for introduction of selected magnetic harmonics whereby the magnetic field exhibited through at least a portion of said bore may be maximized and rendered more uniform by rotation of said sleeves to a selected orientation; and where N and N/4 are whole numbers and the magnetic characteristics of each sleeve within a grouping of N/4 sleeves may vary and the magnetic characteristics of each grouping of N/4 sleeves are substantially the same. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31)
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32. A method of fabricating a magnetic bias assembly comprising the steps of:
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configuring a plurality of sleeves; disposing a plurality of rectangular permanent magnet slabs in each of said plurality of sleeves, each of said plurality of rectangular permanent magnet slabs having a length, width and thickness dimension and being stacked in the thickness dimension within each said sleeve, said plurality of rectangular permanent magnet slabs each having an anisotropic axis of magnetic orientation parallel to said thickness direction and stacked in a magnetically aiding relation in said thickness direction within each sleeve; placing the plurality of sleeves parallel to each other than forming them around a curvilinear space to enclose a bore; rotatably mounting said plurality of sleeves in said curvilinear space to arrange each of said plurality of sleeves rotatable about an axis parallel to the longitudinal axis of the sleeve; and maximizing the magnetic field exhibited through at least a portion of said bore by rotation of said sleeves to a selected orientation. - View Dependent Claims (33, 34, 35)
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Specification