CN106710781B - A kind of nuclear magnetic resonance permanent magnet - Google Patents
A kind of nuclear magnetic resonance permanent magnet Download PDFInfo
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- CN106710781B CN106710781B CN201611183542.2A CN201611183542A CN106710781B CN 106710781 B CN106710781 B CN 106710781B CN 201611183542 A CN201611183542 A CN 201611183542A CN 106710781 B CN106710781 B CN 106710781B
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- magnet steel
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F7/00—Magnets
- H01F7/02—Permanent magnets [PM]
- H01F7/0273—Magnetic circuits with PM for magnetic field generation
- H01F7/0278—Magnetic circuits with PM for magnetic field generation for generating uniform fields, focusing, deflecting electrically charged particles
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Abstract
A kind of nuclear magnetic resonance permanent magnet, formed by 32 block length cube bonding magnetic steels, the remanent magnetism and magnetizing direction all same of every block of magnet steel, magnetizing direction take any 30 millimeters of directions.32 blocks of magnet steel are divided into 8 groups, and every 4 pieces one group, 4 blocks of magnet steel are coplanar to form an annular element；4 blocks of magnet steel are respectively positioned at 4 positions all around of annular, and forward, two pieces of magnet steel magnetizing directions of right position produce the equally distributed main magnetostatic field of level to two pieces of magnet steel magnetizing directions of front and back position backward, in the central area of annular.8 groups of magnet steel form 8 annulars, and for 8 annulars along longitudinal superposition, the central magnetic field direction of each annular element is identical, forms described highfield uniformity permanent magnet.Crack is left between 8 annulars, aluminium alloy flat block is embedded in crack；Crack between adjacent annular is tapered into the symmetrical centre of nuclear magnetic resonance permanent magnet to both ends, and the thickness of aluminium alloy flat block is also tapered into the symmetrical centre of nuclear magnetic resonance permanent magnet to both ends.
Description
Technical field
The present invention relates to the permanent magnet that a kind of detection of NMR relaxation time spectrum is applicable with small yardstick medical imaging.
Background technology
At present, known nuclear magnetic resonance permanent magnet mainly uses c-type design structure, will need to do shadow when performing clinical examination
As the patient of observation, flatly it is sent into the permanent magnet in caused magnetic field.Ensure the spatial distribution in the magnetic field very
Uniformly, it is necessary to take the shimming measure of a series of complex, include source coil method and passive small magnetic patch splicing method.
The content of the invention
In order to overcome difficulty when existing nuclear magnetic resonance magnetic field of permanent magnet is mixed well, and checked object to come in and go out magnet apparatus not
The shortcomings that facilitating, the present invention propose a kind of higher nuclear magnetic resonance permanent magnet of uniformity of magnetic field.The present invention is a kind of toroidal magnet,
Its horizontal main field not only has very low longitudinal gradient.
Nuclear magnetic resonance permanent magnet of the present invention is formed by 32 block length cube bonding magnetic steels, a height of 30 millimeters of the length and width of every block of magnet steel
× 30 millimeters × 10 millimeters, the remanent magnetism and magnetizing direction all same of every block of magnet steel, magnetizing direction take any 30 millimeters of directions.It is described
32 blocks of magnet steel are divided into 8 groups, i.e., every 4 pieces one group.Every group of 4 blocks of magnet steel are coplanar to form an annular, is an annular element.4 pieces
Magnet steel is located at annular 4 positions all around respectively, and two pieces of magnet steel magnetizing directions of front and back position are forward, left
Two pieces of magnet steel magnetizing directions of right position all backward, then produce the equally distributed main magnetostatic field of level in the central area of annular.
8 groups of magnet steel form 8 annular elements, and 8 annular elements are superimposed along longitudinal direction, the central magnetic field direction phase of each annular element
Together, uniformity permanent magnet in highfield of the present invention is formed.
Crack is left between 8 annular elements, not magnetic conduction aluminium alloy flat block is embedded in crack.Aluminium alloy flat block
It is long and it is wide be 30 millimeters × 30 millimeters, thickness has 3.06 millimeters, 3.39 millimeters and 3.75 millimeters three kinds of specifications.Adjacent annular list
Crack between member is tapered into the symmetrical centre of nuclear magnetic resonance permanent magnet to both ends.The thickness of the aluminium alloy flat block of embedded crack
Degree is also tapered into the symmetrical centre of nuclear magnetic resonance permanent magnet to both ends.The aluminium alloy flat block of embedded crack can be substantially reduced
The longitudinal magnetic field gradient of magnet.
Typically, for two blocks of identical cube magnet steel, it is assumed that the length of side is a rice, remanence BrTesla, that
When the two close to when, maximum mutual attractive force F can be expressed as：
In formula, μ0For the magnetic conductivity in vacuum.It is possible thereby to calculate, as remanence BrFor 1.3 teslas, length of side a
For 10 millimeters when, greatest attraction forces are about 60 newton；When a is 30 millimeters, greatest attraction forces can reach 600 newton.For this
Angle in invention toroidal magnet unit between adjacent two blocks of magnet steel is 45 °, and magnet steel magnetizes by 1.1 tesla's intensity, then breaks into two with one's hands
One integral piece magnet takes around the power for applying 57 newton.
For magnet, caused uniformity of magnetic field is defined as in surrounding space：
In formula,The amplitude uniformity in magnetic field is represented,For the x-axis component of magnetic flux density,For the y-axis of magnetic flux density
Component,For the z-axis component of magnetic flux density,For magnetic flux density vector,Centered on magnetic flux density vector at point, Uni
Represent the direction uniformity in magnetic field.
The remanent magnetism of magnet steel is 1.1 teslas in the present invention, and it is 0.000282 that the direction uniformity, which is calculated, the amplitude uniformity
It is 1400ppm, it is known that magnet of the present invention has higher uniformity of magnetic field.
The magnet that the present invention is made up of identical magnetic steel component, its caused magnetic field space uniformity are higher.The present invention in addition
The alinco assembled process of magnet is also fairly simple.
Brief description of the drawings
Fig. 1：The plan of 1 annular magnetic steel cellular construction of the invention；
Fig. 2：The schematic diagram of 8 annular magnetic steel unit superpositions；
Fig. 3：The uniformity of magnetic field of nuclear magnetic resonance permanent magnet of the present invention：Fig. 3 a do not add the Distribution of Magnetic Field figure of aluminium alloy flat block,
Distribution of Magnetic Field figures of Fig. 3 b added with aluminium alloy flat block；
In figure, 1 anteposition magnetic patch, 2 left magnetic patch, position magnetic patch after 3,4 right magnetic patch, 5 positive 4th magnet rings, 6 forward directions the 3rd
Magnet ring, 7 positive second magnet rings, 8 positive first magnet rings, 9 the first magnet rings of negative sense, 10 the second magnet rings of negative sense, the magnet ring of 11 negative sense the 3rd,
The magnet ring of 12 negative sense the 4th, 13 positive second aluminium alloy cracks, 14 positive first aluminium alloy cracks, 15 middle aluminium alloy cracks, 16
Negative sense the first aluminium alloy crack, 17 negative sense the second aluminium alloy cracks.
Embodiment
The present invention is further described with reference to the accompanying drawings and detailed description.
By 32 block length cube magnet steel and 20 pieces, magnetic conduction aluminium alloy flat block does not form the present invention, and the length, width and height of every block of magnet steel are
30 millimeters × 30 millimeters × 10 millimeters, the length and width of every piece of aluminium alloy flat block are 30 millimeters × 30 millimeters.Every 4 blocks of magnet steel composition one
Individual annular array, 4 blocks of magnet steel are located at annular 4 positions all around, and two blocks of magnetic of former and later two positions respectively
Forward, two pieces of magnet steel magnetizing directions of two positions in left and right all backward, then produce steel magnetizing direction in the central area of annular
The equally distributed main magnetostatic field of level, as shown in Figure 1.32 block length cube magnet steel form 8 annular elements, 32 blocks of magnet steel altogether
Be divided into 8 groups, i.e., it is every 4 pieces one group.Every group of 4 blocks of magnet steel are coplanar and form an annular.8 annular elements are longitudinally folded successively
Add, it is embedded between adjacent two annular elements to state aluminium alloy flat block, toroidal magnet of the present invention is formed, as shown in Figure 2.
As shown in figure 1, front and rear two blocks of magnet steel：The magnetizing direction of anteposition magnetic patch 1 and rear position magnetic patch 3 forward, two pieces of left and right
Magnet steel：The magnetizing direction of left position magnetic patch 2 and right position magnetic patch 4 produces uniform magnetic field backward, in annular element central area.
As shown in Fig. 2 longitudinally superposition forms nuclear magnetic resonance permanent magnet of the present invention to 8 magnet ring units.Each magnet ring during superposition
The magnetic direction of unit is identical.As shown in Fig. 2 the forward direction for defining permanent magnet of the present invention is for base with middle aluminium alloy crack 15
Accurate, upward is forward direction, is downwards negative sense.Forward direction includes positive first magnet ring 8, positive second magnet ring 7, the positive and of 3rd magnet ring 6
Positive 4th magnet ring 5, negative sense include the first magnet ring of negative sense 9, the second magnet ring of negative sense 10, the magnet ring 11 of negative sense the 3rd and the magnetic of negative sense the 4th
Ring 12.Distance is left between nuclear magnetic resonance permanent magnet adjacent annular unit of the present invention, is successively from the top down：0 millimeter, 3.06 millis
Rice, 3.75 millimeters, 3.39 millimeters, 3.75 millimeters, 3.06 millimeters and 0 millimeter, formed aluminium alloy crack, i.e., forward direction the second aluminium alloy
Crack 13 is 3.06 millimeters, and positive first aluminium alloy crack 14 is 3.75 millimeters, and middle aluminium alloy crack 15 is 3.39 millimeters, is born
It it is 3.75 millimeters to the first aluminium alloy crack 16, the second aluminium alloy of negative sense crack 17 is 3.06 millimeters.Filled in aluminium alloy crack
There is 30 millimeters × 30 millimeters of aluminium alloy flat block of corresponding spacing thickness.It is encased inside the aluminium alloy flat of positive second aluminium alloy crack 13
The thickness of block is 3.06 millimeters, and the thickness for being encased inside the aluminium alloy flat block of positive first aluminium alloy crack 14 is 3.75 millimeters, is encased inside
The thickness of the aluminium alloy flat block of middle aluminium alloy crack 15 is 3.39 millimeters, is encased inside the aluminium alloy of the first aluminium alloy of negative sense crack 16
Flat piece of thickness is 3.75 millimeters, and the thickness of the aluminium alloy flat block of the second aluminium alloy of negative sense crack 17 is 3.06 millimeters.It is encased inside
Aluminium alloy flat block can be substantially reduced the longitudinal magnetic field gradient of magnet.
As shown in Fig. 2 the positive second aluminium alloy crack 13 of aluminium alloy flat block insertion arrives negative sense the second aluminium alloy crack
In 17.Specifically, positive 4th magnet ring 5 is located above positive 3rd magnet ring, and positive second aluminium alloy crack 13 is positioned at positive the
Between three magnet rings 6 and positive second magnet ring 7, positive first aluminium alloy crack 14 is positioned at the second magnet ring of forward direction 7 and positive first magnetic
Between ring 8, middle aluminium alloy crack 15 is located between positive first magnet ring 8 and the first magnet ring of negative sense 9, the aluminium alloy of negative sense first folder
Seam 16 is between the first magnet ring of negative sense 9 and the second magnet ring of negative sense 10, and negative sense aluminium alloy crack 17 is located at the magnetic of negative sense second
Between ring 10 and the magnet ring 11 of negative sense the 3rd, the magnet ring 12 of negative sense the 4th is below the magnet ring 11 of negative sense the 3rd.
As shown in Figure 3 a, plus in the Distribution of Magnetic Field of aluminium alloy flat block not there are some symmetrical distortion of fields in boundary
Point, and added with aluminium alloy flat block after, above-mentioned distortion of field point is eliminated, and at upper and lower ends Magnetic field inhomogeneity region face
Product has also reduced, as shown in Figure 3 b.
Claims (2)
- A kind of 1. nuclear magnetic resonance permanent magnet, it is characterised in that：Described nuclear magnetic resonance permanent magnet is by 32 block length cube bonding magnetic steels Form, the remanent magnetism and magnetizing direction all same of every block of magnet steel, magnetizing direction take any 30 millimeters of directions；32 blocks of magnet steel are divided into 8 groups, Every 4 pieces one group, 4 blocks of magnet steel are coplanar to form an annular element；4 blocks of magnet steel are located at 4 positions all around of annular respectively, and Two pieces of magnet steel magnetizing directions of front and back position forward, two pieces of magnet steel magnetizing directions of right position backward, annular center Domain produces the equally distributed main magnetostatic field of level；8 groups of magnet steel form 8 annulars, and 8 annular elements are superimposed along longitudinal direction, often The central magnetic field direction of individual annular element is identical, forms highfield uniformity permanent magnet.
- 2. according to the nuclear magnetic resonance permanent magnet described in claim 1, it is characterised in that：Left between annular element described in 8 Crack, embedded aluminium alloy flat block in crack；Crack between adjacent annular unit with the symmetrical centre of nuclear magnetic resonance permanent magnet to Both ends are tapered into, and the thickness of aluminium alloy flat block is also tapered into the symmetrical centre of nuclear magnetic resonance permanent magnet to both ends.
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| CN201611183542.2A CN106710781B (en) | 2016-12-20 | 2016-12-20 | A kind of nuclear magnetic resonance permanent magnet |
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| CN106710781B true CN106710781B (en) | 2018-03-13 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11875937B2 (en) | 2018-11-29 | 2024-01-16 | Epsitau Ltd. | Lightweight asymmetric array of magnet elements |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10867733B2 (en) | 2018-11-29 | 2020-12-15 | Epsitau Ltd. | Lightweight asymmetric magnet arrays with mixed-phase magnet rings |
| AU2019387628A1 (en) | 2018-11-29 | 2021-07-22 | Epsitau Ltd. | Lightweight asymmetric magnet arrays |
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| US5319339A (en) * | 1993-03-08 | 1994-06-07 | The United States Of America As Represented By The Secretary Of The Army | Tubular structure having transverse magnetic field with gradient |
| CN1235236A (en) * | 1998-05-08 | 1999-11-17 | 中国科学院武汉物理与数学研究所 | Permanent magnet for NMR logging instrument |
| CN1683938A (en) * | 2004-04-14 | 2005-10-19 | 中国科学院电工研究所 | Permanent magnet for nuclear magnetic resonance instrument static magnetic field generator |
| CN103123844A (en) * | 2012-12-13 | 2013-05-29 | 同济大学 | Regional magnetic field intensity enhancing combination permanent magnet |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20120053796A (en) * | 2010-11-18 | 2012-05-29 | 상지대학교산학협력단 | Apparatus for generating uniform magnetic force |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5319339A (en) * | 1993-03-08 | 1994-06-07 | The United States Of America As Represented By The Secretary Of The Army | Tubular structure having transverse magnetic field with gradient |
| CN1235236A (en) * | 1998-05-08 | 1999-11-17 | 中国科学院武汉物理与数学研究所 | Permanent magnet for NMR logging instrument |
| CN1683938A (en) * | 2004-04-14 | 2005-10-19 | 中国科学院电工研究所 | Permanent magnet for nuclear magnetic resonance instrument static magnetic field generator |
| CN103123844A (en) * | 2012-12-13 | 2013-05-29 | 同济大学 | Regional magnetic field intensity enhancing combination permanent magnet |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11875937B2 (en) | 2018-11-29 | 2024-01-16 | Epsitau Ltd. | Lightweight asymmetric array of magnet elements |
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