CN101345115A - An open permanent magnet module for magnetic resonance spectrum analyzer - Google Patents

Abstract

An open permanent magnet module for a magnetic resonance spectrum analyzer, which relates to an open permanent magnet module to solve the problem of large volume and weight of superconducting magnets used in existing magnetic resonance spectrum analysis equipment. high cost issue. The upper end face of the upper magnetic core is set on the lower end face of the upper arm of the C-shaped yoke, the magnetization direction of the upper magnetic core is parallel to the vertical direction, the upper end face of the magnetic pole is set on the lower end face of the upper magnetic core, and the lower end face of the magnetic pole is convex and concave Ring structure, the shim coil is arranged in the imaging space near the lower end surface of the magnetic pole, the structure of the lower magnet is the same as that of the upper magnet, and it is symmetrically arranged on the lower end surface of the C-shaped magnetic yoke up and down with the upper magnet. The magnetization direction of the lower core of the magnet is the same as that of the upper core. Compared with superconducting magnets, the invention reduces one to two weight levels, and its volume is only 1/4 to 2/3 of that of ordinary superconducting magnet modules, so that the uniformity in the imaging space can reach 10 ^-6 , meeting the requirements of industrial magnetic resonance spectrum analysis .

Description

An open permanent magnet module for magnetic resonance spectrum analyzer

technical field

The invention relates to an open permanent magnet module.

Background technique

At present, most of the magnet modules used for magnetic resonance spectroscopy use superconducting magnets, because the magnetic field provided by superconducting magnets has the advantage of good uniformity, which can meet the requirements of material structure analysis, but superconducting magnets also have large volume and weight, The disadvantage of higher maintenance costs. At present, the permanent magnet module used in the spectrometer for industrial magnetic resonance analysis cannot meet the high-performance requirements of magnetic resonance spectroscopy because the uniformity of the main magnetic field provided is poorer than that of superconducting magnets.

Contents of the invention

The invention provides an open permanent magnet module for a magnetic resonance spectrum analyzer to solve the problems of large volume and weight and high maintenance cost of the superconducting magnet used in the existing magnetic resonance spectrum analysis equipment. The invention includes a C-shaped magnetic yoke, an upper magnet and a lower magnet. The upper magnet includes an upper magnetic core, a magnetic pole and a shim coil. The upper end surface of the upper magnetic core is arranged on the lower end surface of the upper arm of the C-shaped magnetic yoke. The upper magnetic core The magnetization direction of the magnetic pole is parallel to the vertical direction, the upper end surface of the magnetic pole is arranged on the lower end surface of the upper magnetic core, the lower end surface of the magnetic pole is a convex-concave ring structure, and the shim coil is arranged on the position close to the lower end surface of the magnetic pole in the imaging space, The structure of the lower magnet is the same as that of the upper magnet, and it is vertically symmetrically arranged on the lower end surface of the C-shaped yoke. The magnetization direction of the lower core of the lower magnet is the same as that of the upper core.

Beneficial effects: the permanent magnet module of the present invention has the advantages of light weight and small volume, and its weight is only tens of kilograms, which can be reduced by one to two weight levels compared with superconducting magnets, and its volume is only that of ordinary superconducting magnet modules 1/4 to 2/3, due to the comprehensive optimization design of the end faces of the magnetic poles, shim coils and gradient coils, the uniformity in the imaging space can reach 10 ^-6 , which can meet the requirements of industrial magnetic resonance spectrum analysis; in addition, the present invention The cost of the permanent magnet module is relatively low, only 1/6 or less of that of the ordinary superconducting magnet module, and its maintenance cost is negligible compared with the superconducting magnet.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the present invention; Fig. 2 is a schematic diagram of the structure of the magnetic pole 2-2.

Detailed ways

Specific embodiment 1: Referring to Fig. 1, this embodiment consists of a C-shaped yoke 1, an upper magnet 2 and a lower magnet 3, and the upper magnet 2 consists of an upper magnetic core 2-1, a magnetic pole 2-2 and a shim coil 2 -3, the upper end surface of the upper magnetic core 2-1 is arranged on the lower end surface of the upper arm of the C-shaped yoke 1, the magnetization direction of the upper magnetic core 2-1 is parallel to the vertical direction, and the upper end surface of the magnetic pole 2-2 is arranged on On the lower end surface of the upper magnetic core 2-1, the lower end surface of the magnetic pole 2-2 is a convex-concave annular structure, and the shim coil 2-3 is arranged in the imaging space 4 near the lower end surface of the magnetic pole 2-2. The structure of the lower magnet 3 is the same as that of the upper magnet 2, and it is symmetrically arranged on the lower end face of the C-shaped yoke 1 with the upper magnet 2. The magnetization direction of the lower magnetic core 3-1 of the lower magnet 3 is the same as that of the upper magnetic core 2-1. 1 have the same magnetization direction. When the shape of the cross-section of the convex ring of the pole 2-2 is a rectangle or trapezoid, the shape of the corresponding concave ring is a rectangle or a triangle; the shape of the cross-section of the upper magnet 2 and the lower magnet 3 can be a regular polygon, a circle, or a hollow regular polygon or circular ring; both the upper magnetic core 2-1 and the lower magnetic core 3-1 can adopt the structure of multilayer magnetic material, and the multilayer magnetic material can also be divided into multiple parts on average along the geometric center of the cross section; shim coil 2- 3. A flat-plate shim coil can be used, and some non-magnetic materials can be filled between the shim coil 2-3 and the magnetic pole 2-2.

The magnetic field lines emitted by the upper magnetic core 2-1 form a preliminary uniform magnetic field in the imaging space 4 of the C-shaped magnetic yoke 1 made of high magnetic permeability material, but this magnetic field cannot meet the needs of magnetic resonance imaging and spectral analysis; Comprehensive design of magnetic poles, shimming coils and gradient coils: firstly, the preliminary shimming of the magnetic field can be realized by processing the magnetic pole 2-2 into a convex-concave ring structure, and further fine shimming can be achieved through the shimming coil 2-3, so that the entire The uniformity of the main magnetic field in the imaging space reaches 10 ^-6 , thereby meeting the requirements of industrial magnetic resonance spectrum analysis.

Specific embodiment two: referring to Fig. 1, the upper magnet 2 and the lower magnet 3 of the present embodiment respectively increase the gradient coil 2-4 on the basis of the specific embodiment one, and the two gradient coils 2-4 are respectively arranged in the imaging space 4 In the position close to the magnetic pole surface. Part of the shimming function of the shimming coil can be realized by the gradient coil 2-4, the shimming coil 2-3 and the gradient coil 2-4 are all arranged in the imaging space 4 near the magnetic pole surface, and the shimming coil 2- 3 Relatively close to the magnetic pole 2-2 or the gradient coil 2-4 relatively close to the magnetic pole 2-2 can increase the shimming accuracy, and some non-magnetic conductive materials can be filled between the gradient coil 2-4 and the shimming coil 2-3 substance.

Embodiment 3: Referring to FIG. 2 , this embodiment adds a plurality of magnetic sheets 5 on the basis of Embodiment 1, and each magnetic sheet 5 is respectively arranged on the surface of the magnetic pole 2 - 2 near the end of the imaging space 4 . The magnetic sheet 5 is used for shimming, and the magnetic sheet 5 may be partially or completely replaced by an iron sheet.

Claims (7)

1. An open permanent magnet module for a magnetic resonance spectrum analyzer, comprising a C-shaped yoke (1), an upper magnet (2) and a lower magnet (3), characterized in that the upper magnet (2) Including an upper magnetic core (2-1), a magnetic pole (2-2) and a shim coil (2-3), the upper end surface of the upper magnetic core (2-1) is arranged on the lower end surface of the upper arm of the C-shaped yoke (1) On, the magnetization direction of the upper magnetic core (2-1) is parallel to the vertical direction, the upper end surface of the magnetic pole (2-2) is arranged on the lower end surface of the upper magnetic core (2-1), and the magnetic pole (2-2) The lower end surface is a convex-concave annular structure, and the shim coil (2-3) is arranged on the position near the lower end surface of the magnetic pole (2-2) in the imaging space (4), and the structure of the lower magnet (3) is the same as that of the upper magnet ( 2) are the same, and are arranged symmetrically with the upper magnet (2) up and down on the lower end face of the C-shaped yoke (1), and the magnetization direction of the lower magnetic core (3-1) of the lower magnet (3) is the same as that of the upper magnetic core ( 2-1) have the same magnetization direction. 2. An open permanent magnet module for a magnetic resonance spectrum analyzer according to claim 1, characterized in that when the shape of the convex ring cross-section of the magnetic pole (2-2) is rectangular, the shape of the concave ring is The shape is a rectangle, and when the shape of the convex ring cross section of the magnetic pole (2-2) is a trapezoid, the shape of the concave ring is a triangle. 3. An open permanent magnet module for a magnetic resonance spectrum analyzer according to claim 1, characterized in that the cross-sections of the upper magnet (2) and the lower magnet (3) are shaped as regular polygons, circles, Hollow regular polygon or circular ring. 4. An open permanent magnet module for a magnetic resonance spectrum analyzer according to claim 1, characterized in that both the upper magnetic core (2-1) and the lower magnetic core (3-1) adopt multilayer magnetic The structure of the material, the multilayer magnetic material is equally divided into multiple parts along the geometric center of the cross section. 5. An open permanent magnet module for a magnetic resonance spectrum analyzer according to claim 1, characterized in that the upper magnet (2) and the lower magnet (3) are respectively increased with gradient coils (2-4), The two gradient coils (2-4) are respectively arranged in the imaging space (4) at positions close to the pole surfaces of the magnetic poles. 6. An open permanent magnet module for a magnetic resonance spectrum analyzer according to claim 1, characterized in that it adds a plurality of magnetic sheets (5), and each magnetic sheet (5) is respectively arranged on The magnetic pole (2-2) is on the surface near the end of the imaging space (4). 7. An open permanent magnet module for a magnetic resonance spectrum analyzer according to claim 6, characterized in that the material of the magnetic sheet (5) is iron.

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