Solenoid coil for generating high-uniformity magnetic field and manufacturing method thereof
By designing a three-layer solenoid coil and adjusting the magnetic field gradient using the compensation winding, the problem of difficulty in realizing low magnetic field gradient and long uniform zone in the prior art is solved, the generation of high uniformity magnetic field is achieved, and the error suppression requirements of gravity meter measurement is met.
Patent Information
- Application Number
- CN202411974461.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-05-06
AI Technical Summary
The existing solenoid coils are difficult to meet the requirements of low magnetic field gradients and long uniform areas at the same time, and cannot effectively suppress errors caused by magnetic field gradients in gravitational meter measurements.
By adding compensation windings, a three-layer solenoid coil is designed coaxially from the inside to the outside. The first and second solenoids jointly generate an M-type base magnetic field, and the third solenoid generates an M-type compensation magnetic field, adjusts the number of turns, spacing and distribution distance of the coil, so that the compensation magnetic field coincides with the extreme point position of the base magnetic field, and keeps the gradient ratio constant.
The low gradient distribution and long uniform area of the axial magnetic field are realized, which meets the requirements of the Bias magnetic field gradient of the optical lattice gravity meter, and the proportion of the uniform area can reach 78%.
Smart Images
Figure CN119943521A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of electromagnetic fields, and in particular to a solenoid coil for generating a high-uniformity magnetic field and a manufacturing method thereof. Background Art
[0002] When measuring space gravity information using a cold atom interferometer, the gradient of the bias magnetic field in the atomic interference region of the gravity-sensitive unit is an important factor affecting the system error. Measurement error usually requires the bias magnetic field to be highly uniform. For example, an optical lattice gravimeter based on Bragg diffraction requires the magnetic field gradient to be Caused by When the Bias magnetic field amplitude is In typical experimental situations, the required magnetic field gradient is In addition, the miniaturization of the gravity sensitive unit requires that the length of the uniform area of the bias magnetic field provided by the coil should be proportional to the length of the coil. As high as possible. Usually, When the uniform area of the Bias magnetic field is , it can meet the requirement of completely covering the atomic interference area.
[0003] The solenoid coil is an ideal structure for providing a uniform bias magnetic field. For short and thick solenoids (i.e., the coil aspect ratio is relatively small), the bias magnetic field generated by the solenoid using a single-layer uniform dense winding method or a double-layer differential compensation method cannot simultaneously meet the requirements of low gradient and long uniform area. It is necessary to increase the compensation winding to improve the uniformity of the solenoid axis magnetic field and the length of the uniform area. The coil of the non-uniformly wound compensation winding is symmetrical about the axis center. If the axis center is taken as the coordinate origin, the axis magnetic field size when any two turns of the coil symmetrical about the axis center pass the same direction of current is described by the following function:
[0004] Where R is the coil radius (m), d is the coil spacing (m), z is the distance from the axis center (m), I is the current (A), μ 0 = 4π×10 -7 is the magnetic permeability of air (T·m / A). Summary of the invention
[0005] In view of the technical problems existing in the background technology, the present invention provides a solenoid coil for generating a high uniformity magnetic field and a manufacturing method thereof. By adding a compensation winding, the uniformity of the magnetic field on the axis of the solenoid and the length of its uniform zone are improved, so that the Bias magnetic field generated by the solenoid can simultaneously meet the requirements of low gradient and long uniform zone.
[0006] According to a first aspect of the present invention, there is provided a solenoid coil for generating a high uniformity magnetic field, comprising: three layers of solenoids coaxially arranged from inside to outside: a first solenoid (1), a second solenoid (2) and a third solenoid (3); The first solenoid (1) comprises: a first evenly wound coil (1-1) located in the middle, and a second coil (1-2) and a third coil (1-3) symmetrically arranged at the upper and lower ends; the second solenoid (2) comprises: a fourth evenly wound coil (2-1) located in the middle, and a fifth coil (2-2) and a sixth coil (2-3) symmetrically arranged at the upper and lower ends; the first solenoid and the second solenoid jointly generate an M-type base magnetic field; The third solenoid (3) comprises: a seventh coil (3-1), an eighth coil (3-2), and a ninth coil (3-3) symmetrically arranged in the middle, and a tenth coil (3-4), an eleventh coil (3-5), and a twelfth coil (3-6) symmetrically arranged at upper and lower ends; the third solenoid generates an M-shaped compensation magnetic field; In the solenoid coil, by adjusting the appropriate number of coil turns, spacing, and distribution distance, the positions of the two upper extreme points of the M-type compensation magnetic field can basically coincide with the positions of the two upper extreme points of the M-type base magnetic field, and the ratio between the compensation magnetic field gradient and the base magnetic field gradient remains basically constant within the interval between the two upper extreme points.
[0007] Based on the above technical solution, the present invention can also make the following improvements.
[0008] Optionally, the coils of the first solenoid and the second solenoid are set as base coils, and the coil of the third solenoid is set as a compensation coil; The ratio of the excitation current of the compensation coil and the base coil is adjusted so that the change of the magnetic field gradient between the two upper extreme points of the M-type base magnetic field and the M-type compensation magnetic field does not exceed a set threshold.
[0009] Optionally, when the diameters of the first solenoid (1), the second solenoid (2) and the third solenoid (3) are 320 mm, 330 mm and 340 mm respectively, the current I of the compensation coil is offset The base coil is energized with a current I base The ratio between them is I offset / I base =4.15±0.005.
[0010] Optionally, the current direction of the first evenly wound coil (1-1) is the same as that of the third coil (1-3), and is opposite to that of the second coil (1-2).
[0011] Optionally, when the diameter of the first solenoid (1) is 320 mm: The number of turns of the first evenly wound coil (1-1) is 5, and the spacing between each turn of the coil is 10 mm; The number of turns of the second coil (1-2) is 10, the average spacing between the coils at both ends is 374 mm, and the spacing between each turn of the coil at one end is 1 mm; The number of turns of the third coil (1-3) is 10, the average spacing between the coils at both ends is 392 mm, and the spacing between each turn of the coil at one end is 2 mm.
[0012] Optionally, the fourth evenly wound coil (2-1), the fifth coil (2-2) and the sixth coil (2-3) have the same current direction as the first evenly wound coil (1-1).
[0013] Optionally, when the diameter of the second solenoid (2) is 330 mm: The fourth evenly wound coil (2-1) has 19 turns, and the spacing between each turn of the coil is 1 mm; The number of turns of the fifth coil (2-2) is 76, the average spacing between the coils at both ends is 317 mm, and the spacing between each turn of the coil at one end is 1 mm; The sixth coil (2-3) has 38 turns, the average spacing between the coils at both ends is 380 mm, and the spacing between each turn of the coil at one end is 1 mm.
[0014] Optionally, the eighth coil (3-2), the ninth coil (3-3) and the twelfth coil (3-6) have the same current direction as the first evenly wound coil (1-1), and the seventh coil (3-1), the tenth coil (3-4) and the eleventh coil (3-5) have the opposite current direction as the first evenly wound coil (1-1).
[0015] Optionally, when the diameter of the third solenoid (3) is 340 mm: The seventh coil (3-1) has 12 turns, the average spacing between the coils at both ends is 15 mm, and the spacing between the turns on each side is 1 mm; The eighth coil (3-2) has 10 turns, the average spacing between the coils at both ends is 44 mm, and the spacing between the turns on each side is 1 mm; The number of turns of the ninth coil (3-3) is 8, the average spacing between the coils at both ends is 183 mm, and the spacing between the turns on each side is 1 mm; The number of turns of the tenth coil (3-4) is 38, the average spacing between the coils at both ends is 334 mm, and the spacing between the turns on each side is 1 mm; The number of turns of the eleventh coil (3-5) is 4, the average spacing between the coils at both ends is 369 mm, and the spacing between the turns on each side is 1 mm; The number of turns of the twelfth coil (3-6) is 28, the average spacing between the coils at both ends is 387 mm, and the spacing between the turns on each side is 1 mm.
[0016] According to a second aspect of the present invention, there is provided a method for producing a high uniformity solenoid coil, comprising: Step 1, winding the first solenoid (1), the second solenoid (2) and the third solenoid (3) in sequence from the inside to the outside; Step 2, by allocating appropriate coil turns, spacing, and distribution distance, the positions of the two upper extreme points of the M-type compensation magnetic field are basically coincident with the positions of the two upper extreme points of the M-type base magnetic field, and the ratio between the compensation magnetic field gradient and the base magnetic field gradient remains basically constant within the interval between the two upper extreme points; Step 3, by setting the excitation current of the base coil and the compensation coil with a suitable ratio, the magnetic field gradient between the two upper extreme points of the M-type superimposed magnetic field can be suppressed within a very small variation range.
[0017] The present invention provides a solenoid coil that produces high uniformity and a method for making the same. The method of using the coil axial magnetic field gradient differential to suppress the magnetic field gradient in the extreme point interval can not only ensure the low gradient distribution of the axial magnetic field, but also increase the proportion of the magnetic field uniformity area to the coil length. Under the conditions that the solenoid length is 400mm and the total magnetic field amplitude is ≥20000nT, in the interval [-156mm, 156mm], the axial magnetic field gradient value is ≤19nT / cm, and the proportion of the uniform area that meets the Bias magnetic field gradient requirements of the optical lattice gravimeter in the background technology can reach 78%. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 A schematic diagram of the structure of a solenoid coil for generating a highly uniform magnetic field provided by an embodiment of the present invention; Figure 2 A schematic structural diagram of a first solenoid coil provided in an embodiment of the present invention; Figure 3 A schematic diagram of the structure of a second solenoid coil provided by an embodiment of the present invention; Figure 4 A schematic diagram of the structure of a third solenoid coil provided in an embodiment of the present invention; Figure 5 A distribution diagram of the magnetic field amplitude of each layer of the solenoid axis provided by the embodiment of the present invention; Figure 6 A gradient distribution diagram of the magnetic field along the axis of each layer of the solenoid provided in an embodiment of the present invention. DETAILED DESCRIPTION
[0019] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.
[0020] Figure 1 A structural schematic diagram of a solenoid coil for generating a high uniformity magnetic field provided by an embodiment of the present invention is shown in FIG. Figure 1 As shown, the solenoid coil comprises: three layers of solenoids coaxially arranged from inside to outside: a first solenoid (1), a second solenoid (2) and a third solenoid (3).
[0021] The first solenoid (1) comprises: a first evenly wound coil (1-1) located in the middle, and a second coil (1-2) and a third coil (1-3) symmetrically arranged at the upper and lower ends; the second solenoid (2) comprises: a fourth evenly wound coil (2-1) located in the middle, and a fifth coil (2-2) and a sixth coil (2-3) symmetrically arranged at the upper and lower ends; the first solenoid and the second solenoid jointly generate an M-shaped base magnetic field; The third solenoid comprises: a seventh coil (3-1), an eighth coil (3-2), and a ninth coil (3-3) symmetrically arranged in the middle, and a tenth coil (3-4), an eleventh coil (3-5), and a twelfth coil (3-6) symmetrically arranged at upper and lower ends; the third solenoid generates an M-shaped compensation magnetic field.
[0022] In a specific implementation, the first solenoid (1) and the second solenoid (2) jointly generate an M-type base magnetic field with a larger average amplitude, and the third solenoid (3) generates an M-type compensation magnetic field with a smaller average amplitude. By adjusting the number of coil turns, spacing, and distribution distance, the positions of the two upper extreme points of the M-type compensation magnetic field can be made to substantially coincide with the positions of the two upper extreme points of the M-type base magnetic field, and the ratio between the compensation magnetic field gradient and the base magnetic field gradient can be made to remain substantially constant within the interval between the two upper extreme points.
[0023] Example The present invention provides an embodiment of a solenoid coil for generating a high uniformity magnetic field, wherein the winding length is 400 mm and the aspect ratio is 1.18 to 1.25. Figure 1 As shown, it comprises: three layers of solenoids coaxially arranged from inside to outside: a first solenoid (1), a second solenoid (2) and a third solenoid (3). Figure 2-Figure 4 The diagrams are schematic diagrams of the structures of a first solenoid coil, a second solenoid coil and a third solenoid coil provided in the embodiments of the present invention. The first solenoid (1) comprises: a first evenly wound coil (1-1) located in the middle, and a second coil (1-2) and a third coil (1-3) symmetrically arranged at upper and lower ends; In a specific implementation, the current direction of the first evenly wound coil (1-1) is the same as that of the third coil (1-3), and is opposite to that of the second coil (1-2); In a possible embodiment, when the diameter of the first solenoid (1) is 320 mm: The number of turns of the first evenly wound coil (1-1) is 5, and the spacing between each turn of the coil is 10 mm; The number of turns of the second coil (1-2) is 10, the average spacing between the coils at both ends is 374mm, and the spacing between each turn of the coil at one end is 1mm; The third coil (1-3) has 10 turns, the average spacing between the coils at both ends is 392 mm, and the spacing between each turn of the coil at one end is 2 mm.
[0024] The second solenoid (2) comprises: a fourth evenly wound coil (2-1) located in the middle, and a fifth coil (2-2) and a sixth coil (2-3) symmetrically arranged at the upper and lower ends; In a specific implementation, the current direction of the fourth evenly wound coil (2-1), the fifth coil (2-2) and the sixth coil (2-3) is the same as that of the first evenly wound coil (1-1); In a possible embodiment, when the diameter of the second solenoid (2) is 330 mm: The fourth evenly wound coil (2-1) has 19 turns, and the spacing between each turn of the coil is 1 mm; The fifth coil (2-2) has 76 turns, the average spacing between the coils at both ends is 317 mm, and the spacing between each turn of the coil at one end is 1 mm; The sixth coil (2-3) has 38 turns, the average spacing between the coils at both ends is 380 mm, and the spacing between each turn of the coil at one end is 1 mm.
[0025] The first solenoid (1) and the second solenoid (2) jointly generate an M-type base magnetic field.
[0026] The third solenoid (3) comprises: a seventh coil (3-1), an eighth coil (3-2), and a ninth coil (3-3) symmetrically arranged in the middle, and a tenth coil (3-4), an eleventh coil (3-5), and a twelfth coil (3-6) symmetrically arranged at upper and lower ends; In a specific implementation, the eighth coil (3-2), the ninth coil (3-3) and the twelfth coil (3-6) have the same current direction as the first evenly wound coil (1-1), and the seventh coil (3-1), the tenth coil (3-4) and the eleventh coil (3-5) have the opposite current direction as the first evenly wound coil (1-1).
[0027] In a possible embodiment, when the diameter of the third solenoid (3) is 340 mm: The seventh coil (3-1) has 12 turns, the average spacing between the coils at both ends is 15 mm, and the spacing between the turns on each side is 1 mm; The eighth coil (3-2) has 10 turns, the average spacing between the coils at both ends is 44 mm, and the spacing between the turns on each side is 1 mm; The ninth coil (3-3) has 8 turns, the average spacing between the coils at both ends is 183 mm, and the spacing between the turns on each side is 1 mm; The number of turns of the tenth coil (3-4) is 38, the average spacing between the coils at both ends is 334mm, and the spacing between the turns on each side is 1mm; The number of turns of the eleventh coil (3-5) is 4, the average spacing between the coils at both ends is 369mm, and the spacing between the turns on each side is 1mm; The number of turns of the twelfth coil (3-6) is 28, the average spacing between the coils at both ends is 387mm, and the spacing between the turns on each side is 1mm.
[0028] The third solenoid (3) generates an M-shaped compensation magnetic field.
[0029] In a specific implementation, when the diameters of the first solenoid (1), the second solenoid (2) and the third solenoid (3) are 320 mm, 330 mm and 340 mm respectively, according to the coil parameters of each layer of solenoids specified above, the positions of the two upper extreme points of the "M"-shaped compensation magnetic field jointly generated by the solenoid (1) and the solenoid (2) will basically coincide with the positions of the two upper extreme points of the "M"-shaped compensation magnetic field generated by the solenoid (3), and the ratio between the compensation magnetic field gradient and the base magnetic field gradient between the upper extreme points will basically remain constant within this range.
[0030] By adjusting the ratio of the excitation current of the compensation coil and the base coil, the magnetic field gradient between the two upper extreme points of the M-type superimposed magnetic field can be suppressed within a very small range of variation. In the embodiment, the optimal ratio Ioffset / Ibase between the compensation coil current Ioffset and the base coil current Ibase is approximately 4.15.
[0031] Figure 5 and Figure 6 The amplitude and gradient distribution diagrams of the magnetic field of each layer of the solenoid axis provided by the embodiment of the present invention are respectively Figure 1-Figure 3 It can be seen that the coils of the coaxially nested solenoid (1) and the solenoid (2) are distributed in the same manner. The purpose of the combination of the two is to generate an M-shaped base magnetic field with a large amplitude. The amplitude curve of the magnetic field under the radius conditions given in the embodiment is as follows: Figure 5As shown in "B1+B2" in . When the required parameters are obtained by adjusting the number of turns, spacing and distribution distance of the coils of solenoid (1) and solenoid (2), the distance between the two upper extreme points of the M-type base magnetic field and the center of the axis is approximately ±145mm. The coil distribution method of solenoid (3) is divergently adjusted on the basis of solenoids 1 and 2, the purpose of which is to: 1) make the two upper extreme points of the "M"-type compensation magnetic field generated by solenoid (3) (the distance from the center of the axis is approximately ±144mm) coincide with the two upper extreme points of the "M"-type base magnetic field as much as possible; 2) make the gradient change trend between the two upper extreme points of the "M"-type compensation magnetic field basically consistent with the "M"-type base magnetic field, as shown in FIG. Figure 3 Although it is impossible to make the above two extreme points and the gradient changes between them completely match in the actual coil parameter debugging, from the superposition effect of the "M" type base magnetic field and the "M" type compensation magnetic field, the magnetic field gradient between the two extreme points is suppressed in a very small range, as shown in the "B1+B2" and "-B3" curves in the figure. Figure 3 As shown, under the condition that the total magnetic field amplitude is ≥20000nT, in the interval of [-156mm, 156mm], the magnetic field gradient value is ≤19nT / cm, and the proportion of uniform areas that meet the Bias magnetic field gradient requirements of the optical lattice gravimeter in the background technology can reach 78%.
[0032] It should be noted that in the above embodiments, the description of each embodiment has its own emphasis, and for parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.
[0033] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.
[0034] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded computer, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1A device that provides the functions specified in a block or multiple blocks.
[0035] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.
[0036] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.
[0037] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.
[0038] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.
Claims
1. A solenoid coil for producing high uniformity, characterized in that The solenoid coil comprises: three layers of solenoids coaxially arranged from inside to outside: a first solenoid (1), a second solenoid (2) and a third solenoid (3); The first solenoid (1) comprises: a first evenly wound coil (1-1) located in the middle, and a second coil (1-2) and a third coil (1-3) symmetrically arranged at the upper and lower ends; the second solenoid (2) comprises: a fourth evenly wound coil (2-1) located in the middle, and a fifth coil (2-2) and a sixth coil (2-3) symmetrically arranged at the upper and lower ends; the first solenoid and the second solenoid jointly generate an M-type base magnetic field; The third solenoid (3) comprises: a seventh coil (3-1), an eighth coil (3-2), and a ninth coil (3-3) symmetrically arranged in the middle, and a tenth coil (3-4), an eleventh coil (3-5), and a twelfth coil (3-6) symmetrically arranged at upper and lower ends; the third solenoid generates an M-shaped compensation magnetic field; In the solenoid coil, by adjusting the number of coil turns, spacing, and distribution distance, the position difference between the two upper extreme points of the M-type base magnetic field and the M-type compensation magnetic field is made smaller than a set threshold, and the ratio of the magnetic field gradients of the M-type base magnetic field and the M-type compensation magnetic field between the two upper extreme points changes less than a set value.
2. The solenoid coil according to claim 1, characterized in that The coils of the first solenoid (1) and the second solenoid (2) are arranged as base coils, and the coil of the third solenoid (3) is arranged as a compensation coil; The ratio of the excitation current of the base coil and the compensation coil is adjusted so that the change of the magnetic field gradient difference between the two upper extreme points of the M-type base magnetic field and the M-type compensation magnetic field does not exceed a set threshold.
3. The solenoid coil embodiment according to claim 2, characterized in that When the diameters of the first solenoid (1), the second solenoid (2) and the third solenoid (3) are 320 mm, 330 mm and 340 mm respectively, the current I offset The base coil is energized with a current I base The ratio between them is I offset / I base =4.15±0.
005.
4. The solenoid coil embodiment according to claim 1, characterized in that The current direction of the first evenly wound coil (1-1) is the same as that of the third coil (1-3), and is opposite to that of the second coil (1-2).
5. The solenoid coil embodiment according to claim 4, characterized in that When the diameter of the first solenoid (1) is 320 mm: The number of turns of the first evenly wound coil (1-1) is 5, and the spacing between each turn of the coil is 10 mm; The number of turns of the second coil (1-2) is 10, the average spacing between the coils at both ends is 374 mm, and the spacing between each turn of the coil at one end is 1 mm; The number of turns of the third coil (1-3) is 10, the average spacing between the coils at both ends is 392 mm, and the spacing between each turn of the coil at one end is 2 mm.
6. The solenoid coil embodiment of claim 1, wherein: The fourth evenly wound coil (2-1), the fifth coil (2-2) and the sixth coil (2-3) have the same current direction as the first evenly wound coil (1-1).
7. The solenoid coil embodiment according to claim 6, characterized in that When the diameter of the second solenoid (2) is 320 mm: The fourth evenly wound coil (2-1) has 19 turns, and the spacing between each turn of the coil is 1 mm; The number of turns of the fifth coil (2-2) is 76, the average spacing between the coils at both ends is 317 mm, and the spacing between each turn of the coil at one end is 1 mm; The sixth coil (2-3) has 38 turns, the average spacing between the coils at both ends is 380 mm, and the spacing between each turn of the coil at one end is 1 mm.
8. The solenoid coil embodiment of claim 1, wherein: The seventh coil (3-1), the eighth coil (3-2), the ninth coil (3-3), the tenth coil (3-4), the eleventh coil (3-5) and the twelfth coil (3-6) are all arranged symmetrically in an upper and lower direction; The eighth coil (3-2), the ninth coil (3-3) and the twelfth coil (3-6) have the same current direction as the first evenly wound coil (1-1), and the seventh coil (3-1), the tenth coil (3-4) and the eleventh coil (3-5) have the opposite current direction as the first evenly wound coil (1-1).
9. The solenoid coil embodiment according to claim 8, characterized in that When the diameter of the third solenoid 3 is 340 mm: The seventh coil (3-1) has 12 turns, the average spacing between the coils at both ends is 15 mm, and the spacing between the turns on each side is 1 mm; The eighth coil (3-2) has 10 turns, the average spacing between the coils at both ends is 44 mm, and the spacing between the turns on each side is 1 mm; The number of turns of the ninth coil (3-3) is 8, the average spacing between the coils at both ends is 183 mm, and the spacing between the turns on each side is 1 mm; The number of turns of the tenth coil (3-4) is 38, the average spacing between the coils at both ends is 334 mm, and the spacing between the turns on each side is 1 mm; The number of turns of the eleventh coil (3-5) is 4, the average spacing between the coils at both ends is 369 mm, and the spacing between the turns on each side is 1 mm; The number of turns of the twelfth coil (3-6) is 28, the average spacing between the coils at both ends is 387 mm, and the spacing between the turns on each side is 1 mm.
10. A method for manufacturing a solenoid coil for generating a high uniformity magnetic field according to any one of claims 1 to 9, characterized in that: The production method comprises: Step 1, winding the first solenoid (1), the second solenoid (2) and the third solenoid (3) in sequence from the inside to the outside; Step 2, by allocating appropriate coil turns, spacing, and distribution distance, the position difference between the two upper extreme points of the M-type base magnetic field and the M-type compensation magnetic field is smaller than a set threshold, and the ratio of the magnetic field gradient between the two upper extreme points of the M-type base magnetic field and the M-type compensation magnetic field is smaller than a set value; Step 3, by setting a fixed ratio of excitation currents for the base coil and the compensation coil, the magnetic field gradient change between the two upper extreme points of the M-type superimposed magnetic field is less than the set value.