A single-turn coil destructive pulse magnet using eddy current uniform field
By introducing eddy current shim technology into the single-turn coil magnet, the electromagnetic induction and material combination of the inner and outer coils is used to solve the problem of poor magnetic field uniformity of traditional single-turn coil magnets, and a more uniform magnetic field distribution and protection of test samples are achieved.
Patent Information
- Application Number
- CN202410909449.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-08
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2044-07-08
AI Technical Summary
The magnetic field uniformity of traditional single-turn coil magnets is poor, and the magnetic field uniformity cannot be effectively improved by increasing the number of turns or optimizing the current density distribution, resulting in unfavorable experimental impact.
A single-turn coil-type destructive pulse magnet using eddy current shim, including the magnet coil on the outside and the single-turn passive closed coil on the inside, uses electromagnetic induction to generate eddy currents to resist the electromagnetic transient effect of the magnet coil, improve the magnetic field uniformity, and The eddy current and magnetic field gradient are controlled through a combination of low conductivity materials and high modulus materials.
The uniformity of the magnetic field is significantly improved, the uniform magnetic field space volume in the aperture is increased, and the deformation of the coil during discharge is suppressed, ensuring the safety of the test samples.
Smart Images
Figure CN118737616B_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the technical field of pulsed high-intensity magnetic fields, and more specifically, relates to a single-turn coil-type destructive pulse magnet using eddy current uniform field. Background Art
[0002] The single-turn coil is a destructive pulse magnet with a discharge current of several hundred kiloamperes to several megaamperes, which is used to generate an ultra-strong magnetic field. Since the pulse width of the discharge current is only a few microseconds, although the coil is subjected to a huge electromagnetic force, its electromagnetic inertia is smaller than the mechanical inertia, so that the coil has achieved a peak magnetic field before mechanical damage occurs.
[0003] However, for the traditional conventional single-turn coil, since its size is only in the millimeter level, the magnetic field gradient within the aperture is very large and the uniformity is poor. Such magnetic field inhomogeneity will have an adverse effect on the experiment. In addition, the uniform field of the single-turn coil is not easy to achieve through the conventional uniform field technology applied to other similar fields: on the one hand, due to the low impedance requirement of the single-turn coil discharge circuit, the magnetic coil can only have one turn; on the other hand, due to the large amplitude of the discharge current and the small pulse width, the conductor impact deformation and electromagnetic transient effect are obvious during discharge, and the current distribution on the coil cross section is extremely uneven. The above two characteristics make it impossible for the single-turn coil to improve the magnetic field uniformity by increasing the number of coil turns and reasonably arranging the positions of multiple coils, or by optimizing the current density distribution on the coil cross section. Summary of the invention
[0004] In view of the defects of the prior art, the purpose of the present application is to provide a single-turn coil destructive pulse magnet using eddy current uniform field, aiming to solve the problem of poor uniformity of the magnetic field of traditional single-turn coil magnets.
[0005] To achieve the above-mentioned purpose, the present application provides a single-turn coil type destructive pulse magnet using eddy current uniform field, comprising: a discharge electrode plate, a magnet coil, a single-turn passive closed coil and an insulating layer;
[0006] The discharge electrode plate comprises two metal plates arranged in parallel, which are parallel to the axial cross section of the magnetic coil and arranged radially outside the magnetic coil;
[0007] The magnetic coil has only one turn, and the two ends of the magnetic coil are welded to the outer surfaces of two metal plates;
[0008] The axial height of the single-turn passive closed coil is smaller than the axial height of the magnetic coil, and the single-turn passive closed coil is coaxially arranged inside the magnetic coil, with an insulating layer filled between the two.
[0009] The electrical conductivity of the single-turn passive closed coil is smaller than that of the magnetic coil, and the modulus and strength are larger than those of the magnetic coil.
[0010] Preferably, the conductivity of the single-turn passive closed coil is one order of magnitude smaller than the conductivity of the magnetic coil.
[0011] Preferably, the material of the magnetic coil is copper, and the material of the single-turn passive closed coil is tungsten or tantalum.
[0012] Preferably, the outer diameter of the single-turn passive closed coil is 0.5 mm to 2.0 mm smaller than the inner diameter of the magnet coil.
[0013] Preferably, the axial height of the single-turn passive closed coil is 1.0 mm to 5.0 mm smaller than the height of the magnet coil.
[0014] Preferably, the thickness of the single-turn passive closed coil is less than 1 mm.
[0015] Preferably, the insulating layer can withstand temperatures above 1,000°C.
[0016] Preferably, the insulating layer is insulating clay.
[0017] Preferably, the axial height of the single-turn passive closing coil is greater than the radial thickness of the single-turn passive closing coil.
[0018] Preferably, the upper and lower surfaces of the single-turn passive closed coil are equidistant from the upper and lower surfaces of the magnet coil.
[0019] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art:
[0020] The present application proposes a single-turn coil destructive pulse magnet using eddy current uniform field, including a turn of magnet coil installed on the outside and a single-turn passive closed coil installed on the inside. When the pulse capacitor group power supply is discharged, a large current will flow through the magnet coil to generate an ultra-strong magnetic field. At this time, although the impact deformation of the magnet coil is obvious and the electromagnetic transient effect is severe, the single-turn passive closed coil inside the magnet coil can generate eddy currents that resist the electromagnetic transient effect of the magnet coil due to electromagnetic induction, and shield the adverse effects on the uniformity of the magnetic field caused by this, effectively improving the uniformity of the magnetic field. Since the single-turn passive closed coil is made of a material with low electrical conductivity, the eddy current is significantly smaller than the discharge current in the magnet coil, and will not significantly weaken the magnetic field. Instead, it can compensate for the steep magnetic field gradient and control the magnetic field gradient within a relatively gentle range. At the same time, since the single-turn passive closed coil has a high modulus, it can suppress its radial inward deformation during discharge, and preserve the test sample inside it. The present application can significantly increase the uniformity of the magnetic field while less reducing the magnetic field at the center point, and effectively increase the volume of space with a uniform magnetic field within the aperture. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1It is a schematic diagram of the structure of a single-turn coil type destructive pulse magnet using eddy current uniform field provided in an embodiment of the present application.
[0022] Figure 2 It is a schematic diagram comparing the magnetic field uniformity of a traditional single-turn coil and a single-turn passive closed coil provided in an embodiment of the present application. DETAILED DESCRIPTION
[0023] For ease of understanding, the English abbreviations and related technical terms involved in the embodiments of the present application are explained and described below.
[0024] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.
[0025] like Figure 1 As shown, the present application provides a single-turn coil type destructive pulse magnet using eddy current uniform field, comprising: a discharge electrode plate, a magnet coil, a single-turn passive closed coil and an insulating layer (not shown);
[0026] The discharge electrode plate comprises two metal plates arranged in parallel, which are parallel to the axial cross section of the magnetic coil and arranged radially outside the magnetic coil;
[0027] The magnetic coil has only one turn, and the two ends of the magnetic coil are welded to the outer surfaces of two metal plates;
[0028] The axial height of the single-turn passive closed coil is smaller than the axial height of the magnetic coil, and the single-turn passive closed coil is coaxially arranged inside the magnetic coil, with an insulating layer filled between the two.
[0029] The electrical conductivity of the single-turn passive closed coil is smaller than that of the magnetic coil, and the modulus and strength are larger than those of the magnetic coil.
[0030] It should be noted that the direction of the eddy current generated by electromagnetic induction is circumferential and opposite to the direction of the discharge current. The insulating layer is used to prevent the two coils from breaking down.
[0031] Preferably, the conductivity of the single-turn passive closed coil is one order of magnitude smaller than the conductivity of the magnetic coil.
[0032] Preferably, the material of the magnetic coil is copper, and the material of the single-turn passive closed coil is tungsten or tantalum.
[0033] It should be noted that the magnet coil is made of high-conductivity copper, which is conducive to reducing coil resistance and increasing discharge current; the eddy current shim coil is made of high-density, high-modulus, low-conductivity tungsten / tantalum, which is conducive to controlling the eddy current within a reasonable range and preventing it from moving radially inward at high speed and damaging the test sample. The conductivity of the eddy current shim coil cannot be too high or too low, because too high conductivity will make the eddy current too large and thus significantly weaken the magnetic field strength at the center point, while too low conductivity will make the eddy current shim effect insufficient; in addition, the density and modulus of the eddy current shim coil cannot be too low, otherwise the eddy current shim coil may produce obvious radially inward high-speed movement during discharge due to Lenz's law, thereby damaging the internal experimental sample.
[0034] Preferably, the outer diameter of the single-turn passive closed coil is 0.5 mm to 2.0 mm smaller than the inner diameter of the magnet coil.
[0035] Preferably, the axial height of the single-turn passive closed coil is 1.0 mm to 5.0 mm smaller than the height of the magnet coil.
[0036] It should be noted that the inner and outer diameters of the eddy current shim coil cannot be too small, otherwise it will limit the volume of the test sample inside the single-turn coil magnet; the inner and outer diameters of the eddy current shim coil cannot be too large, otherwise it will be too close to the magnet coil, resulting in the clay thickness between the two being too thin, which will be detrimental to electrical insulation between the two.
[0037] Preferably, the thickness of the single-turn passive closed coil is less than 1 mm.
[0038] Preferably, the insulating layer can withstand temperatures above 1,000°C.
[0039] Preferably, the insulating layer is insulating clay, which generally has high impedance.
[0040] Preferably, the axial height of the single-turn passive closing coil is greater than the radial thickness of the single-turn passive closing coil.
[0041] It should be noted that the present application prefers the above design to avoid the axial length of the eddy current shim coil being too large, thereby over-shielding the magnetic field generated by the magnet coil and causing a significant reduction in the magnetic field strength at the center point.
[0042] Preferably, the upper and lower surfaces of the single-turn passive closed coil are equidistant from the upper and lower surfaces of the magnetic coil, that is, the central cross-sections of the two overlap with each other.
[0043] Preferably, the axial height of the magnet coil is equal to the radial thickness of the magnet coil.
[0044] It should be noted that, due to the short discharge time, the current will be concentrated on the upper and lower edges of the inner surface of the magnetic coil due to the skin effect. Designing the magnetic coil in this way can make the current distribution closer to the equivalent Helmholtz coil, thereby improving the shimming effect.
[0045] Example
[0046] In this embodiment, the diameters (including inner diameter and outer diameter) of the magnet coil and the eddy current shim coil are several millimeters. The magnet coil has only one turn, which is perpendicular to the two electrode plates. The two ends of the coil are welded to the two electrode plates respectively and are made of copper. The eddy current shim coil is coaxial with the magnet coil, perpendicular to the two electrode plates, is a one-turn closed conductor, and is made of tungsten. Insulating clay is installed between the two coils. The axial height and radial thickness of the magnet coil are both 3.0 mm, and the axial height and radial thickness of the eddy current shim coil are 2.2 mm and 0.3 mm respectively.
[0047] like Figure 2 As shown in the figure, under the conditions of discharge peak current of 300kA, current peak time of 1.4 microseconds, magnet inner diameter of 6.0mm, and eddy current shim coil outer diameter of 4.6mm, the magnetic field uniformity diagram of the traditional single-turn coil magnet and the shim single-turn coil magnet at 1.4 microseconds; it can be seen that under the conditions of the same discharge current curve, the magnetic field uniformity of the shim single-turn coil magnet has been effectively improved compared with the traditional single-turn coil magnet, and under different magnetic field uniformity conditions, the shim space volume has been increased to 10-25 times the original. At the same time, at 1.4 microseconds, the magnet coil has undergone obvious impact deformation under the action of electromagnetic force, while the deformation of the eddy current shim coil is not obvious.
[0048] It should be understood that expressions such as "including" and "may include" that may be used in the present application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In the present application, terms such as "including" and / or "having" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.
[0049] In addition, in the present application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.
[0050] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the relative position relationship after connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.
[0051] In addition, in the embodiments of the present application, the mathematical concepts mentioned are symmetry, equality, parallelism, verticality, etc. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense, and allow a small amount of deviation, approximation to symmetry, approximation to equality, approximation to parallelism, approximation to verticality, etc. are all possible. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.
[0052] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.
Claims
1. A single-turn coil destructive pulse magnet using eddy current uniform field, characterized in that: include: Discharge electrode plates, magnet coils, single-turn passive closed coils and insulation layers; The discharge electrode plate comprises two metal plates arranged in parallel, which are parallel to the axial cross section of the magnetic coil and arranged radially outside the magnetic coil; The magnetic coil has only one turn, and the two ends of the magnetic coil are welded to the outer surfaces of two metal plates; The axial height of the single-turn passive closed coil is smaller than the axial height of the magnetic coil, and the single-turn passive closed coil is coaxially arranged inside the magnetic coil, with an insulating layer filled between the two. The conductivity of the single-turn passive closed coil is less than the conductivity of the magnetic coil, and the modulus and strength are greater than the modulus and strength of the magnetic coil; The material of the magnetic coil is copper, and the material of the single-turn passive closed coil is tungsten or tantalum.
2. The pulse magnet according to claim 1, characterized in that The conductivity of the single-turn passive closed coil is one order of magnitude smaller than the conductivity of the magnetic coil.
3. The pulse magnet according to claim 1, characterized in that The outer diameter of the single-turn passive closed coil is 0.5mm~2.0mm smaller than the inner diameter of the magnet coil.
4. The pulse magnet according to claim 1, characterized in that The axial height of the single-turn passive closed coil is 1.0 mm to 5.0 mm smaller than the height of the magnet coil.
5. The pulse magnet according to claim 1, characterized in that The thickness of the single-turn passive closed coil is less than 1 mm.
6. The pulse magnet according to claim 1, characterized in that The insulating layer can withstand temperatures above 1,000°C.
7. The pulse magnet according to claim 6, characterized in that The insulating layer is insulating clay.
8. The pulse magnet according to claim 1, characterized in that The axial height of the single-turn passive closed coil is greater than the radial thickness of the single-turn passive closed coil.
9. The pulse magnet according to any one of claims 1 to 8, characterized in that The upper and lower surfaces of the single-turn passive closed coil are equidistant from the upper and lower surfaces of the magnet coil.