A single-turn coil type destructive pulse magnet with inner and outer double-layer structure conductors

Abstract

The present application belongs to the field of pulsed high magnetic field technology, and specifically discloses a single-turn coil type destructive pulse magnet with inner and outer double-layer structure conductors. According to the present application, the inner and outer double-layer structure conductors are composed of a copper conductor located in the inner layer and a tungsten conductor located in the outer layer, or, are composed of a copper conductor located in the inner layer and a tantalum conductor located in the outer layer. During discharge, on the one hand, since the electrical conductivity of tungsten or tantalum is much lower than that of copper, the current will be forced to flow through the inner copper conductor as much as possible, and almost all the current is concentrated on the inner copper conductor, and the electromagnetic diffusion effect radially to the outer conductor is suppressed; on the other hand, since the density of tungsten or tantalum is much greater than that of copper, when the inner conductor is subjected to a huge electromagnetic force and undergoes radial outward impact deformation, the outer conductor exerts a mass damping effect on the inner conductor, suppresses the deformation of the inner conductor, and delays the destruction time of the inner conductor. The peak magnetic field of the single-turn coil magnet is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of pulsed high magnetic field, and more specifically, relates to a single-turn coil type destructive pulse magnet with inner and outer double-layer structure conductors. Background Art

[0002] The single-turn coil is a destructive pulse magnet used to generate ultra-strong magnetic fields. Currently, the single-turn coil has been widely used in scientific experiments in the fields of material magnetization and magneto-optical effects. In order to generate ultra-strong magnetic fields, the capacitor pulse power supply system of the single-turn coil magnet is usually extremely large. At the same time, the current-magnetic field conversion efficiency of the single-turn coil is low. In order to achieve a 100T magnetic field, a large current of several hundred kiloamperes is usually required. Therefore, it is of great engineering significance to increase the coil magnetic field and improve the current-magnetic field conversion efficiency through the optimization design of the magnet.

[0003] Without changing the power supply parameters, there are two main reasons that restrict the peak magnetic field size of the traditional single-turn coil magnet: electromagnetic diffusion effect and conductor impact deformation. The so-called electromagnetic diffusion effect means that the traditional single-turn coil is generally made of a turn of pure copper conductor. At the beginning of the discharge, due to the skin effect, the current is mainly concentrated on the inner surface of the conductor, which causes a sharp temperature rise and phase change on the inner surface of the conductor, causing the conductivity to drop rapidly. Affected by the decrease in the conductivity of the inner surface, the current will gradually move from the inner surface of the conductor to the inside of the conductor, so that the distance between the current and the center point of the coil continues to increase as the discharge proceeds; the so-called conductor impact deformation means that due to the extremely large discharge current, the electromagnetic force borne by the conductor far exceeds the yield strength of the conductor, causing the conductor to undergo extremely high-speed radial outward impact deformation, causing the inner diameter of the coil to increase continuously as the discharge proceeds. The above two reasons both weaken the peak magnetic field. In order to improve the peak magnetic field of the single-turn coil magnet without changing the power supply parameters, it is necessary to propose an optimization plan for the magnet based on the above two reasons. 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 with an inner and outer double-layer structure conductor, aiming to solve the problem of low current-magnetic field conversion efficiency of the existing single-turn coil destructive pulse magnet.

[0005] To achieve the above objectives, the present application provides a single-turn coil-type destructive pulse magnet having an inner and outer double-layer structure conductor, wherein the inner and outer double-layer structure conductor is composed of a copper conductor located in the inner layer and a tungsten conductor located in the outer layer, or, is composed of a copper conductor located in the inner layer and a tantalum conductor located in the outer layer.

[0006] Preferably, the conductor located in the inner layer and the conductor located in the outer layer are fastened and connected by welding.

[0007] Preferably, the thickness of the conductor located in the inner layer is smaller than the thickness of the conductor located in the outer layer.

[0008] Preferably, the thickness of the conductor located in the inner layer accounts for 5% to 20% of the total thickness of the magnet coil; the thickness of the conductor located in the outer layer accounts for 80% to 95% of the total thickness of the magnet coil.

[0009] Preferably, liquid nitrogen is used to pre-cool the magnet coils before discharge.

[0010] Preferably, the total radial thickness of the magnet coil is in the millimeter range, and the axial height of the magnet coil is equal to the inner diameter of the magnet coil.

[0011] Preferably, the cross section of the magnet coil is rectangular.

[0012] Preferably, the peak magnetic field of the single-turn coil destructive pulse magnet is 100T-300T.

[0013] Preferably, it also includes: a trapezoidal electrode plate;

[0014] The trapezoidal electrode plate comprises two parallel arranged trapezoidal metal plates, which are parallel to the axial cross section of the magnetic coil and are arranged on one side of the magnetic coil and perpendicular to the two electrode plates;

[0015] The two ends of the magnetic coil are welded to two electrode plates respectively.

[0016] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art:

[0017] The present application provides a single-turn coil type destructive pulse magnet with an inner and outer double-layer structure conductor, wherein the inner and outer double-layer structure conductor is composed of a copper conductor located in the inner layer and a tungsten conductor located in the outer layer, or, is composed of a copper conductor located in the inner layer and a tantalum conductor located in the outer layer. During discharge, on the one hand, since the conductivity of (outer layer) tungsten or tantalum is much lower than the conductivity of (inner layer) solid copper or even liquid copper, the current will be forced to flow through the inner copper conductor as much as possible, and almost all the current is concentrated on the inner copper conductor, and the electromagnetic diffusion effect radially to the outer conductor is suppressed, which is conducive to reducing the distance from the current to the center point of the coil; on the other hand, since the density of (outer layer) tungsten or tantalum is much greater than the density of (inner layer) copper, when the inner copper conductor is subjected to a huge electromagnetic force and undergoes radial outward impact deformation, the outer tungsten or tantalum conductor plays a mass damping role on the inner conductor, suppressing the deformation of the inner conductor under the electromagnetic force, delaying the destruction time of the inner conductor, and suppressing the increase of the inner diameter of the surface coil. Based on the above two characteristics, the peak magnetic field of the single-turn coil magnet is improved. The present invention can effectively increase the peak magnetic field of a single-turn coil magnet without changing the power system parameters. The present application requires fewer accessories, has a simple manufacturing and assembly process, and can achieve the result of increasing the magnetic field of a destructive pulse magnet with a relatively simple process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of a single-turn coil-type destructive pulse magnet with inner and outer double-layer structure conductors provided by the present application.

[0019] Figure 2 It is a half-section diagram of a single-turn coil-type destructive pulse magnet with inner and outer double-layer structure conductors provided by the present application.

[0020] Figure 3 It is a schematic cross-sectional view of the inner and outer double-layer conductor structure provided by the present application.

[0021] Figure 4 It is a schematic diagram of the change of the magnetic field magnitude at the center point of a traditional conventional single-turn coil magnet and a single-turn coil magnet with a double-layer conductor structure over time provided by an embodiment of the present invention.

[0022] Figure 5 It is a comparison diagram of current density between a conventional single-turn coil magnet and a single-turn coil magnet with a double-layer conductor structure provided by an embodiment of the present invention. 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 and Figure 2 As shown, the present application provides a single-turn coil type destructive pulse magnet with an inner and outer double-layer structure conductor, wherein the inner and outer double-layer structure conductor is composed of a copper conductor located in the inner layer and a tungsten conductor located in the outer layer, or, is composed of a copper conductor located in the inner layer and a tantalum conductor located in the outer layer.

[0026] It should be noted that copper conductors have high electrical conductivity and relatively low density, whereas tungsten or tantalum conductors have high density and relatively low electrical conductivity.

[0027] Preferably, the conductor located in the inner layer and the conductor located in the outer layer are fastened and connected by welding.

[0028] It should be noted that the present application is not limited to the connection by welding, as long as the conductor located in the inner layer and the conductor located in the outer layer will not be delaminated or separated during the discharge process.

[0029] Preferably, the thickness of the conductor located in the inner layer is smaller than the thickness of the conductor located in the outer layer.

[0030] It should be noted that in order to minimize the diffusion of current density radially outward and force the current to concentrate on the inner surface of the conductor to increase the magnetic field, the thickness of the inner copper conductor should be thinner. At the same time, in order to avoid premature damage to the inner copper conductor under the action of large current, the thickness of the inner copper conductor should be thicker.

[0031] Preferably, the thickness of the conductor located in the inner layer accounts for 5% to 20% of the total thickness of the magnet coil; the thickness of the conductor located in the outer layer accounts for 80% to 95% of the total thickness of the magnet coil.

[0032] It should be noted that, through the study of the electromagnetic thermal-phase change destruction model of a single-turn coil, when the thickness of the inner copper conductor is about one order of magnitude less than the thickness of the outer tungsten or tantalum conductor, the two requirements of "delaying destruction" and "suppressing the current from spreading radially outward" can be taken into account to the maximum extent. If the copper conductor is too thin and the outer tungsten or tantalum conductor is too thick, the inner copper conductor is prone to premature destruction during discharge, forcing the current to flow through the outer tungsten or tantalum conductor, which is not conducive to improving the magnetic field. If the copper conductor is too thick and the tungsten or tantalum conductor is too thin, it cannot effectively limit the radial outward diffusion of the discharge current, nor is it conducive to the tungsten or tantalum conductor to play the advantage of mass damping of the copper conductor, and it is also not conducive to improving the magnetic field. Therefore, the present application prefers the thickness in the above range.

[0033] Preferably, liquid nitrogen is used to pre-cool the magnet coils before discharge.

[0034] It should be noted that in order to suppress the temperature rise and phase change damage of the inner copper conductor, such as vaporization heat damage during the discharge process, and reduce the resistance of the magnet coil, the present application preferably requires liquid nitrogen pre-cooling of the entire magnet coil before discharge. On the one hand, it can reduce the temperature of the conductor during discharge, and on the other hand, it can reduce the resistance of the coil conductor and maximize the discharge current.

[0035] Preferably, the total radial thickness of the magnet coil is in the millimeter range, and the axial height of the magnet coil is equal to the inner diameter of the magnet coil.

[0036] Preferably, the cross section of the magnet coil is rectangular.

[0037] Preferably, the peak magnetic field of the single-turn coil destructive pulse magnet is 100T-300T.

[0038] Preferably, it also includes: a trapezoidal electrode plate; the trapezoidal electrode plate includes two parallel arranged trapezoidal metal plates, which are parallel to the axial cross section of the magnetic coil and are arranged on one side of the magnetic coil and perpendicular to the two electrode plates;

[0039] The two ends of the magnetic coil are welded to two electrode plates respectively. The inner diameter and outer diameter of the magnetic coil are both in millimeter level and are perpendicular to the electrode plates.

[0040] Example

[0041] This embodiment provides a single-turn coil type destructive pulse magnet with an inner and outer double-layer conductor structure, which is composed of two trapezoidal electrode plates and a turn of a magnet coil with a double-layer conductor structure. The electrode plate includes two parallel metal plates, which are arranged on the outside of the magnet coil and parallel to the axial section of the magnet coil; the inner and outer diameters and heights of the magnet coil are several millimeters, which are perpendicular to the electrode plates and welded to the two electrode plates respectively.

[0042] When the pulse capacitor bank power supply is discharged, a large current will flow through the magnetic coil, generating an ultra-strong magnetic field. Since the inner layer of the conductor coil uses copper with higher conductivity, and the outer layer uses tungsten with lower conductivity and higher density, the current is forced to concentrate near the inner surface of the conductor during discharge, fully suppressing the electromagnetic diffusion phenomenon in the conductor. At the same time, the high-density tungsten in the outer layer will act as a mass damper for the low-density copper in the inner layer, suppressing the impact deformation of the copper conductor during discharge, reducing the real-time aperture of the magnetic coil during discharge, and achieving the effect of increasing the magnetic field.

[0043] In the embodiment of the present invention, Figure 3As shown, the thickness of the conductor is 3mm, and the height of the conductor is equal to the inner diameter of the conductor. In order to limit the electromagnetic diffusion process in the conductor and delay the damage of the inner copper conductor, the thickness of the copper conductor is one tenth of the total thickness of the conductor, that is, 0.3mm. The thickness of the outer tungsten conductor is nine tenths of the total thickness of the conductor, that is, 2.7mm.

[0044] Figure 4 This is a schematic diagram of the change of the magnetic field size at the center point of a conventional single-turn coil magnet and a single-turn coil magnet with a double-layer conductor structure over time provided by an embodiment of the present invention. In this embodiment, the capacitor capacitance is 10.4μF, the external inductance is 80nH, the external resistance is 13mΩ, and the inner diameter of the magnet is 2.5mm. Figure 4 It can be seen that under the same power supply parameter conditions, the magnetic field at the center point of the single-turn coil magnet with a double-layer conductor structure is 10% higher than the magnetic field at the center point of the traditional conventional single-turn coil magnet.

[0045] Figure 5 The current density (A / m) of the conventional single-turn coil magnet provided by the embodiment of the present invention and the single-turn coil magnet with a double-layer conductor structure is 2 ) comparison chart. Figure 5 It can be seen that when the current peak time is 1.4μs, under the same power supply parameter conditions, the current of the single-turn coil with a double-layer structure is almost entirely concentrated near the inner surface of the conductor, while the current density of the conventional single-turn coil has obviously spread to the inside of the conductor. In addition, the maximum current density of the single-turn coil with a double-layer structure is 10% greater than the maximum current density of the conventional single-turn coil at the same time.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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 type destructive pulse magnet having an inner and outer double-layer structure conductor, characterized in that: It includes inner and outer double-layer structure conductors and a trapezoidal electrode plate; The inner and outer double-layer structure conductor is composed of a copper conductor located in the inner layer and a tungsten conductor located in the outer layer, or is composed of a copper conductor located in the inner layer and a tantalum conductor located in the outer layer; The trapezoidal electrode plate comprises two parallel arranged trapezoidal metal plates, which are parallel to the axial cross section of the magnetic coil and are arranged on one side of the magnetic coil and perpendicular to the two electrode plates; The two ends of the magnetic coil are welded to two electrode plates respectively.

2. The single-turn coil destructive pulse magnet according to claim 1, characterized in that: The conductor located at the inner layer and the conductor located at the outer layer are fastened and connected by welding.

3. The single-turn coil destructive pulse magnet according to claim 1, characterized in that: The thickness of the conductor located in the inner layer is smaller than the thickness of the conductor located in the outer layer.

4. The single-turn coil destructive pulse magnet according to claim 3, characterized in that: The thickness of the conductor in the inner layer accounts for 5% to 20% of the total thickness of the magnetic coil; The thickness of the conductor located in the outer layer accounts for 80% to 95% of the total thickness of the magnetic coil.

5. The single-turn coil destructive pulse magnet according to claim 1, characterized in that: Liquid nitrogen was used to pre-cool the magnet coils before discharge.

6. The single-turn coil destructive pulse magnet according to claim 1, characterized in that: The total radial thickness of the magnetic coil is in the millimeter range, and the axial height of the magnetic coil is equal to the inner diameter of the magnetic coil.

7. The single-turn coil destructive pulse magnet according to claim 6, characterized in that: The cross section of the magnetic coil is rectangular.

8. The single-turn coil destructive pulse magnet according to claim 1, characterized in that: The peak magnetic field of the single-turn coil destructive pulse magnet is 100T-300T.

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