CN111554467A

CN111554467A - Vector magnet structure

Info

Publication number: CN111554467A
Application number: CN202010418744.0A
Authority: CN
Inventors: 梅恩铭; 吴巍; 梁羽; 陈玉泉
Original assignee: Institute of Modern Physics of CAS
Current assignee: Institute of Modern Physics of CAS
Priority date: 2020-05-18
Filing date: 2020-05-18
Publication date: 2020-08-18

Abstract

The present invention relates to a vector magnet structure comprising a first coil, a second coil and/or a third coil; the first coil adopts a DCT dipolar coil with a pair of pole heads arranged along the X-axis direction and is used for generating a Bx vector magnetic field distributed along the X-axis direction; the second coil adopts DCT two-pole coils with a pair of pole heads arranged along the Y-axis direction and is used for generating a By vector magnetic field distributed along the Y-axis direction, wherein the second coil is arranged outside the first coil, so that the second coil has a structure that the first coil is coated By the second coil in space; and the third coil is used for generating a Bz vector magnetic field distributed along the Z-axis direction. The method is suitable for the scientific research field with high-precision large sample vector field requirements.

Description

Vector magnet structure

Technical Field

The present invention relates to a magnet structure, and more particularly, to a vector field magnet structure.

Background

In the research of material science, the coupled analysis of the physical properties of materials in multiple physical fields is a great hot direction for the multidisciplinary cross research. Along with the development of scientific technology, besides the analysis of the intrinsic mechanical structure characteristics of the material, the electromagnetic coupling analysis is an important branch, which is to provide a background electromagnetic field for the tested sample, and for some materials with magnetic anisotropy, the included angle between the sample and the direction of the magnetic field is usually required to be changed in the research process, and the implementation manner of the process is as follows: fixed direction magnetic field + sample rotation or fixed sample + magnetic field direction rotation.

A vector magnet is a type of magnet that is capable of generating a directionally rotatable magnetic field. The vector magnet achieves rotation of the magnetic field direction by static current control rather than mechanical structure rotation, which offers many possibilities for experimentation. The vector field magnet is formed by combining two pairs or three pairs of dipolar magnets which are not in the same direction in a three-dimensional coordinate system, as shown in fig. 1 to 4, dipolar magnet structures used by the vector magnets in the current market are commonly dipolar magnets consisting of a solenoid pair, a runway coil pair and a saddle-shaped coil pair.

In the process of combining the dipolar magnets of different types, the more complex framework needs to be designed to support the position distribution and assembly among the coils, and the dipolar magnets have the advantages of easy realization, mature technology, large magnet volume, low excitation efficiency, small range of good field area, poor precision and the like

The spiral type dipolar magnet of the cylindrical sample channel has a spherical radius of only 21mm in an area with the field quality better than +/-3.5%, and the area of a runway type dipolar magnet with the sample channel with the same specification is smaller.

Disclosure of Invention

In view of the above problems, the present invention aims to provide a vector field magnet structure with compact structure, large sample space, large good field region and high resolution.

In order to solve the problems, the invention adopts the technical scheme that: a vector magnet structure comprising a first coil, a second coil and/or a third coil;

the first coil adopts a DCT dipolar coil with a pair of pole heads arranged along the X-axis direction and is used for generating a Bx vector magnetic field distributed along the X-axis direction;

the second coil adopts DCT two-pole coils with a pair of pole heads arranged along the Y-axis direction and is used for generating a By vector magnetic field distributed along the Y-axis direction, wherein the second coil is arranged outside the first coil, so that the second coil has a structure that the first coil is coated By the second coil in space;

the third coil is used for generating a Bz vector magnetic field distributed along the Z-axis direction;

the X-axis and the Y-axis are respectively a first axis and a second axis, wherein XYZ is a Cartesian coordinate system, the Z axis is the central axis direction of the DCT dipolar coil, the polar head direction of the DCT dipolar coil is the Y axis, and the direction perpendicular to the Z axis on the inter-polar symmetric plane of the DCT dipolar coil is the X axis.

The above vector magnet structure, further, the third coil is placed outside the second coil to form a vector magnet, and the space structure presents a coil combination sleeved on the first coil and the second coil;

or the third coil, the first coil and the second coil are in the same framework, and the third coil axially holds the first coil and the second coil to form a vector magnet;

or the third coil is embedded in the first coil to form a vector magnet.

In the vector magnet structure, the third coil may be a solenoid magnet, a racetrack magnet, or a saddle magnet.

The vector magnet structure, further, the DCT dipolar coil includes a cylinder magnet wire surrounded by two unipolar coils, the cylinder magnet wire is solidified on the skeleton to form a cylinder magnet structure, and the unipolar coils are connected in series; each unipolar coil comprises N circles of electromagnetic coils which are arranged in a surrounding mode at intervals, wherein N is an integer and is the set total number of electromagnetic wire turns of the unipolar coil.

In the above vector magnet structure, further, the current density J of the cylindrical electromagnetic wire is distributed in the circumferential direction approximately in a cos (θ) regular distribution, that is, J_z＝j₀cos (θ), wherein j₀For passing the current density in the cross-section of the magnet wire, j_zAnd theta refers to an angle of anticlockwise rotation around the Z axis by taking the X axis as a starting axis.

In the above vector magnet structure, the circumferential position distribution of the cylinder-shaped magnet wires satisfies a flow function sin (θ) ═ i-1/2)/N, where i is a magnet wire number and is an arbitrary integer between {1, N }.

The above vector magnet structure, further, the current line angle distribution θ_i＝Arcsin((i-1/2)/N)。

In the above vector magnet structure, the straight-side segment coordinates of each turn of the cylinder-type magnet wire are (Rcos (θ)_i)， Rsin(θ_i) Z), wherein R is the radius of the magnet wire distributed in the polar coordinate system, and the coordinate z of the arc segment required by each turn of the cylindrical magnet wire satisfies the flow function:

cos(π·(z-hl)/(2·he))·sin(θ)＝(i-1/2)/N，

where hl refers to half the length of the straight segment and he refers to the maximum length of the coil arc segment in the z-direction.

In the vector magnet structure, the DCT dipolar coils can be combined in a multi-layer nested manner to meet the requirement of function enhancement, that is, a plurality of coaxial DCT dipolar coils with different R are combined to form a magnet with a set magnetic field requirement, the multi-layer combined DCT dipolar coils can be powered up in series or in parallel, or can be powered up independently, wherein R is the radius of the electromagnetic wire distributed in a polar coordinate system.

In the vector magnet structure, the first coil, the second coil and the third coil are all made of superconducting cables; alternatively, the first coil, the second coil and the third coil are all made of conventional cables with low electric conductivity.

Due to the adoption of the technical scheme, the invention has the following advantages:

1. the invention adopts a vector field magnet consisting of a Discrete Cosine Theta (DCT) type coil and a solenoid, the DCT dipolar coil structure can generate a high-quality dipolar field in a hole region due to the spatial arrangement of current density distributed by a similar trigonometric function, like a DCT type dipolar coil required by a temperature hole region of 200mm, the radius of the region with the field quality better than +/-3.5 percent can reach 50mm, the cylindrical structure of the magnet is easy to realize the function enhancement requirement by multilayer nesting and is also easy to integrate with magnets of other structural types, so that the vector magnet structure has the characteristics of compact structure, large sample space, large good field area, high resolution and the like;

2. the invention can realize high magnetic field and three-dimensional full-space rotating magnetic field by adopting superconducting technology, and can be suitable for the technical field with high-precision large sample vector field requirement.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Like reference numerals refer to like parts throughout the drawings. In the drawings:

FIG. 1 is a schematic diagram of a conventional vector magnet;

FIG. 2 is a schematic view of a magnet of toroidal (solenoid) configuration;

FIG. 3 is a schematic view of a racetrack configuration magnet;

FIGS. 4(a) and (b) are schematic diagrams of magnets in a saddle-shaped configuration;

FIG. 5 is a schematic diagram of the present invention for realizing a desired vector magnetic field by superimposing three sets of vector magnetic fields perpendicular to each other;

fig. 6 is a two-dimensional space vector magnet structure which is formed by combining a first coil and a second coil and can realize a plane rotating vector magnetic field.

Fig. 7 is a three-dimensional space vector magnet structure which is formed by combining a first coil, a second coil and a third coil and can realize a three-dimensional space vector magnetic field.

FIG. 8 is a schematic view of a DCT type structure dipole magnet according to the present invention; wherein the content of the first and second substances,

the reference signs are:

1. a first coil, 11, a unipolar coil, 2, a second coil, 3, a third coil.

Detailed Description

Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only, and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," and "having" are inclusive and therefore specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order described or illustrated, unless specifically identified as an order of performance. It should also be understood that additional or alternative steps may be used.

Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first," "second," and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

For convenience of description, spatially relative terms, such as "inboard", "outboard", "below", "upper" and the like, may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. Such spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures.

In this embodiment, an XYZ coordinate system may adopt a cartesian right-hand coordinate system or a cartesian left-hand coordinate system, and in this embodiment, referring to fig. 8, the Z axis is defined as a central axis direction of a DCT coil cylindrical skeleton in this embodiment, and is also generally a direction in which a sample is placed along a length position, a direction of a DCT diode pole head is a Y axis, and a direction perpendicular to the Z axis on a symmetrical plane between DCT diode poles is an X axis.

As shown in fig. 5 to 7, the vector magnet structure provided in the present embodiment includes a first coil 1, a second coil 2, and/or a third coil 3.

The first coil 1 is a DCT diode coil having a pair of pole heads disposed along the X-axis direction, and located at the innermost side of the vector magnet structure, for generating Bx vector magnetic field distributed along the X-axis direction, wherein the pole heads are certain spatial positions where magnetic lines of force of the multi-pole magnet are concentrated, for example, a solenoid type diode magnet, the pole heads of which are respectively geometric center regions of two solenoids, and the pole head of the DCT diode coil is a region surrounded by an innermost current loop.

The second coil 2 is a DCT (discrete cosine transformation) dipolar coil with a pair of pole heads placed along the Y-axis direction and is arranged outside the first coil 1, and the second coil 2 is in a form of coating the first coil 1 and is used for generating a By vector magnetic field distributed along the Y-axis direction.

The third coil 3 adopts one or more conventional coils to generate a vector magnetic field distributed along the Z-axis direction in the aperture area of the magnet; following the principle of compact structure, the magnetic field generator can be arranged outside the second coil 2 (the coil combination sleeved on the first coil 1 and the second coil 2 appears in a spatial structure), or be arranged on the same framework with the coils of the first coil 1 and the second coil 2 (the first coil 1 and the second coil 2 are additionally supported by two coil structures of a third coil in the Z direction), or be embedded in the first coil Bx for generating a Bz vector magnetic field distributed along the Z-axis direction; preferably, the third coil 3 may be a circular ring type (solenoid), a runway type, a saddle type or other type of magnet as long as a constant direction magnetic field with certain spatial distribution and field quality can be generated in the warm hole area, and the three groups of coils together form a three-dimensional vector magnet structure.

In some embodiments of the present invention, the first coil 1, the second coil 2 and the third coil 3 may be combined two by two to realize a two-dimensional plane vector field magnet, for example, the combination of the first coil 1 and the second coil 2 may obtain a vector magnetic field that changes in rotation in the XY plane; in addition, the vector magnet formed by the first coil 1, the second coil 2 and the third coil 3 can be a three-dimensional vector magnet, and three-dimensional vector magnetic field distribution similar to cuboid distribution can be obtained in the inner hole space.

In some embodiments of the present invention, the first coil 1 and the second coil 2 both adopt DCT two-pole coil structure, and the magnetic field directions of the two coils are generally perpendicular to each other.

As shown in fig. 8, the DCT two-pole coil structure includes two single-pole coils 11 enclosed into a cylinder-type electromagnetic wire, wherein the cylinder-type electromagnetic wire is solidified on a cylindrical skeleton to form a cylinder-type magnet structure, the single-pole coils 11 are connected in series with each other, each single-pole coil 11 includes N turns of electromagnetic coils arranged in a surrounding manner at intervals, where N is a positive integer, which refers to the total number of turns of the electromagnetic wire of the set single-pole coil 11, and the cylinder-type electromagnetic wire distribution is easy to realize nesting of different DCT two-pole coils, i.e., easy to realize performance enhancement or combined function design, i.e., a plurality of coaxial DCT two-pole coils with different R can be combined into a magnet with a set magnetic field requirement, and the multilayer combined DCT two-pole coils can be powered in a series or parallel connection or independently powered, where R.

The DCT coil structure approximates cos (m θ) distribution requirements for current density in a manner that disperses current line positions, where the equivalent current density j of the barrel magnet wire_zDistributed in the circumferential direction approximately in cos (m theta) rule, i.e. j_z＝j₀cos (θ), wherein j₀As current density through the cross-section of the magnet wire, j_zIs the equivalent current density Z component distributed annularly and is the current really needed by a pure 2m pole magnetic field. When the m-finger coil is composed of 2m monopoles and m is equal to 1, an electromagnetic wire can be designedAnd (4) obtaining a DCT dipolar magnetic field distributed by the enclosed (gap) space with higher uniformity, wherein theta refers to an angle of anticlockwise rotation around a Z axis by taking an X axis as an initial axis. The position distribution of the cylinder-type magnet wire in the annular direction (the direction of increasing along theta) meets the flow function sin (m theta) ═ i-1/2)/N, wherein i is the number of the magnet wire and is an arbitrary integer between {1 and N }; theta is a position angle corresponding to the electromagnetic wire of the ith turn. The current line angle distribution theta required by the 2m pole magnetic field can be obtained through the current function_i＝Arcsin((i-1/2)/N)/m。

Thus, the straight-side segment coordinates of each turn of the cylindrical magnet wire are (Rcos (m θ)_i)，Rsin(mθ_i) Z), R is the distribution radius of the electromagnetic wire under polar coordinates; the coordinates z of the arc segment of the cylinder type electromagnetic wire continuously required by each turn satisfy the flow function: cos (pi · (z-hl)/(2 · he)) ·sin (m θ) ═ i-1/2)/N to correct the tail field effect of the infinitely long coil to optimize the overall integrated field quality of the magnet, where hl refers to half the length of the straight-sided segment; he refers to the maximum length of the coil arc segment in the z direction; the position of the arc-segment electromagnetic wire can be set with different flow functions according to requirements, such as uniform spacing distribution of adjacent turns (the spacing between adjacent turns is always consistent) or uniform spacing distribution of the farthest end of the arc-segment (only the spacing of the farthest end turn of the arc-segment is controlled to ensure the optimal turn density without space interference between turns). Of course, parameters such as the layer turn, the operating current, the maximum magnetic field, the coil length, and the like of the coil of the DCT two-pole coil structure are specifically designed according to the physical requirements of the user, as shown in fig. 6, the layer turn N of the DCT two-pole coil is 40, and the current density J is₀＝594A/mm²The radius of the framework is 100mm, the good field magnetic field By is 0.5T, and the length L of the magnet is 500.

In some embodiments of the present invention, the first coil 1, the second coil 2 and the third coil 3 are individually powered, and the user can control the power supply to obtain a vector magnetic field with a desired size and direction according to the manual data calibrated by testing, and can also obtain a desired magnetic field through closed-loop feedback adjustment of the sensor, as shown in fig. 6, the two-dimensional XY plane vector magnet is composed of the first coil 1 and the second coil 2 arranged perpendicular to each other, and it is actually verified that when only the first coil 1 is energized with I equal to 150A current, the vector magnetic field of (0.5T, 0T) can be generated in the central area of the warm hole, and when it is also detected that only the second coil 2 is energized with I equal to 150A current, the vector magnetic field of (0T, 0.5T, 0T) needs to be generated in the central area of the warm hole, so long as to simultaneously energize the first coil 1 and the second coil 2 with I equal to 150A current, taking this as an example, the selection can be made as needed.

In some embodiments of the present invention, the magnet wires of the first coil 1, the second coil 2 and the third coil 3 can be made of conventional copper, aluminum and other low-conductivity wires, and can also be made of NbTi, Nb₃And (3) manufacturing a superconducting cable containing Sn and the like.

In some embodiments of the present invention, the first coil 1, the second coil 2, and the third coil 3 may share the same support frame, or may be separated separately, and finally assembled into a vector magnet, and the specific structure of the support frame is not limited, and may adopt a corresponding structure according to actual situations.

In some embodiments of the present invention, the included angles between the magnetic fields of the three sets of coils may also be non-perpendicular to adapt to the magnet with special magnetic field requirements, which may be determined according to actual requirements.

The above embodiments are only used for illustrating the present invention, and the structure, connection mode, manufacturing process, etc. of the components may be changed, and all equivalent changes and modifications performed on the basis of the technical solution of the present invention should not be excluded from the protection scope of the present invention.

Claims

1. A vector magnet arrangement, characterized in that the magnet arrangement comprises a first coil, a second coil and/or a third coil;

2. The vector magnet structure according to claim 1, wherein the third coil is placed outside the second coil to constitute a vector magnet, and the spatial structure presents a combination of coils nested in the first and second coils;

or the third coil is embedded in the first coil to form a vector magnet.

3. The vector magnet structure of claim 2, wherein the third coil is a solenoid type magnet, a racetrack type magnet, or a saddle type magnet.

4. The vector magnet structure of claim 1, wherein said DCT dipole coils comprise cylinder-shaped magnet wires surrounded by two monopole coils, said cylinder-shaped magnet wires being consolidated on a former to form a cylinder-shaped magnet structure, said monopole coils being connected in series; each unipolar coil comprises N circles of electromagnetic coils which are arranged in a surrounding mode at intervals, wherein N is an integer and is the set total number of electromagnetic wire turns of the unipolar coil.

5. The vector magnet structure of claim 4, wherein the current density J of the cylindrical magnet wires is approximately in a regular cos (θ) distribution in the circumferential direction, i.e., J_z＝j₀cos (θ), wherein j₀For passing the current density in the cross-section of the magnet wire, j_zIs an equivalent current density Z component distributed annularlyThe quantity θ refers to the angle of counterclockwise rotation about the Z axis starting from the X axis.

6. The vector magnet structure according to claim 5, wherein the circumferential position distribution of the cylinder-type magnet wires satisfies a flow function sin (θ) ═ i-1/2)/N, where i is a magnet wire number and is any integer between {1, N }.

7. The vector magnet structure according to claim 6, wherein the current line angular distribution θ_i＝Arcsin((i-1/2)/N)。

8. The vector magnet structure of claim 7, wherein the barrel magnet wire turns have straight segment coordinates of (Rcos (θ))_i)，Rsin(θ_i) Z), wherein R is the radius of the magnet wire distributed in the polar coordinate system, and the coordinate z of the arc segment required by each turn of the cylindrical magnet wire satisfies the flow function:

cos(π·(z-hl)/(2·he))·sin(θ)＝(i-1/2)/N，

9. The vector magnet structure according to claim 1, wherein the DCT dipolar coil can be combined in a multi-layer nested manner to meet the requirement of function enhancement, that is, a plurality of coaxial DCT dipolar coils with different R are combined to form a magnet with the requirement of a set magnetic field, and the multi-layer DCT dipolar coil can be powered in series or in parallel or independently, wherein R is the radius of the electromagnetic wire distributed in the polar coordinate system.

10. The vector magnet structure according to any of claims 1 to 9, wherein the first, second and third coils are all made of superconducting cables;

alternatively, the first coil, the second coil and the third coil are all made of conventional cables with low electric conductivity.