Permanent magnet quadrupole magnet with ultrahigh magnetic field gradient

Abstract

The utility model relates to a permanent magnet quadrupole magnet with ultrahigh magnetic field gradient, which belongs to the technical field of permanent magnet quadrupole magnets, and comprises a shell and a Halbach magnet ring arranged in the shell and formed by connecting a plurality of magnetic steels end to end in a Halbach array form, wherein the magnetic steel, of which the extension line of the polarity direction passes through the center of the Halbach magnetic ring, in the plurality of magnetic steel is polar magnetic steel, and the pole head, close to the center of the Halbach magnetic ring, of the polar magnetic steel is replaced by a soft magnetic material block. The pole heads, close to the center of the Halbach magnet ring, of the pole-oriented magnetic steel are replaced by the soft magnetic material blocks, the soft magnetic material blocks have higher magnetic permeability and saturation magnetization than the magnetic steel at the original position, magnetic lines of the magnetic steel on three sides are easily concentrated, the directions of the magnetic lines are changed, the magnetic field intensity of the pole faces of the permanent magnet quadrupole magnet is remarkably improved, and the permanent magnet quadrupole magnet is more stable and reliable. Therefore, the magnetic field gradient of the permanent-magnet quadrupole magnet is remarkably improved.

Description

Technical Field

[0001] The utility model relates to the technical field of permanent quadrupole magnets, in particular to a permanent quadrupole magnet with an ultra-high magnetic field gradient. Background Art

[0002] Quadrupole magnets are the focusing elements of charged particle beams. Permanent-magnet quadrupole magnets offer advantages such as compact structure, no need for power or water supply, and stable magnetic fields, helping accelerators achieve higher acceleration efficiencies. Besides accelerators, they are also suitable for other beam focusing systems requiring compact, highly stable magnetic fields.

[0003] The permanent magnetic quadrupole iron of the prior art Figure 1 , Figure 2 As shown, it can be composed of 12 or 16 magnets with different magnetization directions, or it can be composed of any 4n magnets (n ≥ 2) with different magnetization directions. However, the magnetic field intensity of the existing quadrupole iron pole surface is difficult to reach the remanence Br of the material itself, and its magnetic field gradient is limited. Improving the magnetic field gradient of the quadrupole magnet is of great significance for the development of low-emissivity diffraction limit loops, and it is necessary to develop permanent quadrupole magnets with higher magnetic field gradients. Utility Model Content

[0004] In order to develop a permanent quadrupole magnet with a higher magnetic field gradient, the utility model provides a permanent quadrupole magnet with an ultra-high magnetic field gradient.

[0005] The purpose of the utility model can be achieved through the following technical solutions:

[0006] A permanent quadrupole magnet with an ultra-high magnetic field gradient comprises a shell, and:

[0007] Halbach magnetic rings are made up of multiple magnets connected end to end in a Halbach array;

[0008] Among them, the magnetic steels whose extension lines of polarity directions pass through the center of the Halbach magnetic ring are polar magnetic steels, and the pole heads of the polar magnetic steels near the center of the Halbach magnetic ring are replaced with soft magnetic material blocks.

[0009] Furthermore, the soft magnetic material block is one of the magnetic conductive materials such as iron-cobalt alloy block, pure iron block or low carbon steel block.

[0010] Furthermore, the cavity surrounded by the Halbach magnetic ring is a working cavity. When the charged particle beam passes through the working cavity, it is affected by the magnetic field gradient of the quadrupole magnet, and the cross-sectional shape of the beam changes.

[0011] Furthermore, the plurality of magnetic steels has 4n pieces, n≥2. Preferably, the plurality of magnetic steels has 8 pieces, 12 pieces, 16 pieces, or even more pieces.

[0012] Furthermore, the plurality of magnets are all rare earth permanent magnets; preferably, the magnets are high-performance NdFeB permanent magnets.

[0013] Furthermore, the shell is provided with fixing holes for fixing the plurality of magnets and other accessories.

[0014] Furthermore, the fixing hole is a through hole or a threaded hole.

[0015] Furthermore, the outer cross-section of the shell is a regular octagon, and the inner cross-section is a circle.

[0016] Furthermore, the shell is a ferromagnetic material shell.

[0017] Compared with the prior art, the present invention replaces the pole head of the polo magnet near the center of the Halbach magnetic ring with a block of soft magnetic material. This material has higher magnetic permeability and saturation magnetization intensity than the original position magnet, and can easily concentrate the magnetic lines of force of the three-sided magnets and change the direction of the magnetic lines of force, thereby significantly improving the magnetic field strength of the pole surface of the permanent quadrupole magnet, thereby significantly improving the magnetic field gradient of the permanent quadrupole magnet. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of the magnetic distribution of a Halbach quadrupole magnet consisting of 12 magnets in the prior art;

[0019] Figure 2 A schematic diagram of the magnetic distribution of a Halbach quadrupole magnet consisting of 16 magnets in the prior art;

[0020] Figure 3 Schematic diagram of a permanent quadrupole magnet with ultra-high magnetic field gradient in an embodiment;

[0021] The numbers in the figure are as follows: 1-working chamber; 2-pole head; 3-polar magnetic steel; 4-first oblique magnetic steel; 5-second oblique magnetic steel; 6-housing; 7-fixing hole. DETAILED DESCRIPTION

[0022] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments. Example

[0023] In order to provide a permanent quadrupole magnet with a higher magnetic field gradient, this embodiment provides a permanent quadrupole magnet with an ultra-high magnetic field gradient. The specific structure is shown in Figure 1 , comprising a housing 6, and disposed within the housing 6:

[0024] Halbach magnetic rings are made up of multiple magnets connected end to end in a Halbach array;

[0025] Among them, the magnetic steel whose extension line of the polar direction passes through the center of the Halbach magnetic ring is a polar magnetic steel, and the pole head of the polar magnetic steel near the center of the Halbach magnetic ring is replaced by a soft magnetic material block, and the soft magnetic material block is one of the magnetic conductive materials such as iron-cobalt alloy block, pure iron block or low-carbon steel block. Preferably, the soft magnetic material block is an iron-cobalt alloy block.

[0026] Specifically, the pole head 2 is a block of soft magnetic material with extremely high saturation magnetization and high magnetic permeability. Using this material, a surface magnetic field strength of more than 2T can be obtained, and an ultra-high magnetic field gradient of more than 400T / m can be achieved. In this embodiment, a surface magnetic field strength of 2T and a magnetic field gradient of 400T / m are achieved.

[0027] Please see again Figure 3 In this embodiment, the cavity surrounded by the Halbach magnetic ring is the working cavity 1. Specifically, the working cavity 1 is a straight hole, which is a channel for the beam and a working gap of the multipolar magnetic field. In this working gap, the beam is affected by the magnetic field and changes its motion trajectory.

[0028] In this embodiment, there are 4n pieces of the plurality of magnetic steels, where n≥2; preferably, there are 12 pieces of the plurality of magnetic steels.

[0029] In this embodiment, the plurality of magnets are all rare earth permanent magnets, which have strong magnetic force and serve as the power source for the permanent quadrupole magnets in this embodiment. The permanent quadrupole magnets are arranged in a Halbach pattern to provide long-term stable magnetic field strength. Preferably, the rare earth permanent magnets are neodymium iron boron permanent magnets.

[0030] Please see again Figure 1 In this embodiment, the housing 6 is provided with a fixing hole 7, which is preferably a through hole or a threaded hole. The fixing hole 7 is mainly used to fix the housing to the front and rear end plates, brackets, or other components.

[0031] Please see again Figure 1 In this embodiment, the outer cross-section of the shell 6 is a regular octagon and the inner cross-section is a circle.

[0032] In this embodiment, the housing 6 can be made of either ferromagnetic or non-magnetic material. When the housing is made of ferromagnetic material, it provides a certain degree of magnetic shielding, but suffers from slight magnetic loss. When the housing is made of non-magnetic material, it exhibits a strong magnetic property but lacks magnetic shielding, resulting in significant magnetic flux leakage. The appropriate housing can be selected based on actual needs.

[0033] Working principle:

[0034] The magnetic field gradient of a permanent quadrupole magnet = the magnetic field strength of the pole face / the pole face radius. Under the condition of a certain pole face radius, the only way to increase the gradient of a permanent quadrupole magnet is to increase the magnetic field strength.

[0035] This embodiment is directed to a permanent quadrupole magnet made of a Halbach arrangement (4n magnets, n ≥ 2). When the surface magnetic field strength of the permanent quadrupole magnet is greater than the residual magnetism of the magnetic material, the magnet structure of this embodiment should be considered.

[0036] The surface magnetic field strength of a magnet made of permanent magnet material is difficult to achieve, even with the remanent magnetism of the permanent magnet. However, when the pole head 2 of the polar magnet is made of a material with extremely high saturation magnetization and high magnetic permeability, this material can concentrate the magnetic lines of force transmitted from other surfaces, redirect them, and radiate them on the desired surface, thereby increasing the magnetic field strength on that surface to over 2T.

[0037] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation thereto. Any person skilled in the art may utilize the above disclosure to modify or remodel the present invention into equivalent embodiments. However, any simple modification, equivalent variation, or modification of the above embodiment that does not depart from the technical content of the present invention and is based on the technical essence of the present invention shall still fall within the scope of protection of the present invention.

Claims

1. A permanent quadrupole magnet with ultra-high magnetic field gradient, characterized in that: The invention comprises a housing, and disposed in the housing: Halbach magnetic rings are made up of multiple magnets connected end to end in a Halbach array; Among them, the magnetic steels whose extension lines of polarity directions pass through the center of the Halbach magnetic ring are polar magnetic steels, and the pole heads of the polar magnetic steels near the center of the Halbach magnetic ring are replaced with soft magnetic material blocks.

2. The permanent quadrupole magnet with ultra-high magnetic field gradient according to claim 1, characterized in that: The soft magnetic material block is one of an iron-cobalt alloy block, a pure iron block or a low-carbon steel block.

3. The permanent quadrupole magnet with ultra-high magnetic field gradient according to claim 1, characterized in that: There are 4n pieces of the plurality of magnetic steels, where n≥2.

4. The permanent quadrupole magnet with ultra-high magnetic field gradient according to claim 1, characterized in that: The plurality of magnets are all rare earth permanent magnets.

5. The permanent quadrupole magnet with ultra-high magnetic field gradient according to claim 4, characterized in that: The rare earth permanent magnet steel is neodymium iron boron permanent magnet steel.

6. The permanent quadrupole magnet with ultra-high magnetic field gradient according to claim 1, characterized in that: The shell is provided with a fixing hole.

7. The permanent quadrupole magnet with ultra-high magnetic field gradient according to claim 6, characterized in that: The fixing hole is a through hole or a threaded hole.

8. The permanent quadrupole magnet with ultra-high magnetic field gradient according to claim 1, characterized in that: The shell is made of ferromagnetic material or non-magnetic material.

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