High repetition frequency pulse strong magnet

Abstract

The invention provides a high repetition frequency pulsed strong magnet, which belongs to the technical field of pulsed strong magnetic fields and comprises a magnetic collector and a solenoid magnet coil. The magnetic collector is of a hollow structure, and a non-hollow part of the magnetic collector is provided with a slit penetrating through the side wall of a magnetic collector body in the radial direction. The magnetic collector comprises an inner magnetic collector and an outer magnetic collector which are nested; wherein the diameter of the inner magnetic collector is equal to the aperture of the outer magnetic collector; the mechanical strength of the inner magnetic collector is higher than that of the outer magnetic collector; the conductivity of the outer magnetic collector is higher than that of the inner magnetic collector; the inner magnetic collector and the outer magnetic collector are made of metal materials; the magnetic collector is used for introducing eddy current induced by the pulsed magnetic field on the outer wall into the inner wall through the slit and generating a high-repetition-frequency pulsed high-intensity magnetic field in the hollow area; wherein the high repetition frequency is a frequency higher than 1Hz. According to the invention, the heating value can be reduced while the magnet is ensured to bear huge electromagnetic force brought by a strong magnetic field, so that a high-repetition-frequency pulsed strong magnetic field is generated.

Description

Technical Field

[0001] The present application belongs to the technical field of pulsed strong magnetic field, and more specifically, relates to a high repetition frequency pulsed strong magnet. Background Art

[0002] Pulsed strong magnetic field is an important extreme experimental condition in modern scientific research. With the development of science and technology, some scientific experiments, such as room temperature magnetic refrigeration, high-power microwaves and neutron scattering, have put forward the need for repeated pulsed strong magnetic fields, that is, to continuously generate pulsed strong magnetic fields at a higher frequency.

[0003] The main challenge in designing high-repetition-rate pulsed strong magnets is to make the magnets withstand high electromagnetic stress while ensuring that the large amount of Joule heat energy generated in a short period of time is promptly transferred to the external environment to avoid insulation and conductor damage. In order to solve this problem, the existing technology draws on the structure of steady-state magnets and uses Bitter disk stacking to generate repetitive pulsed strong magnetic fields of 20T / 0.5Hz and 30T / 2Hz respectively. Although the use of Bitter magnets can generate steady-state strong magnetic fields, the biggest difference between pulsed magnetic fields and steady-state magnetic fields is that the former is time-varying and has a serious skin effect. The pulse current is concentrated in a very small part of the Bitter disk, and the heat generated is concentrated, huge, and extremely difficult to dissipate in time within a discharge cycle. This is also the reason why the repetition frequency of the Bitter disk solution is low.

[0004] Therefore, there is an urgent need to develop a magnet with low heat generation and strong heat dissipation capacity for generating repetitive pulsed strong magnetic fields. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of this application is to provide a high repetition rate pulse strong magnet, aiming to solve the problem that the existing pulse magnetic field has a skin effect, resulting in concentrated heat generation, which is difficult to dissipate in time within a discharge cycle, thereby resulting in a low repetition frequency.

[0006] To achieve the above-mentioned purpose, the present application provides a high repetition frequency pulse strong magnet, comprising a magnetism collector and a solenoid magnet coil; the magnetism collector is coaxially arranged inside the solenoid magnet coil;

[0007] The magnetism collector is a hollow structure, and a slit is provided in the non-hollow part of the magnetism collector, which radially penetrates the side wall of the magnetism collector body; it is a passage between the hollow structure and the outer wall of the magnetism collector; the hollow structure is a structure with wide sides and narrow middle from top to bottom, and the magnetism collector includes a nested inner magnetism collector and an outer magnetism collector; wherein the diameter of the inner magnetism collector is equal to the aperture of the outer magnetism collector; the mechanical strength of the inner magnetism collector is higher than that of the outer magnetism collector; the electrical conductivity of the outer magnetism collector is higher than that of the inner magnetism collector; the inner magnetism collector and the outer magnetism collector are both made of metal materials;

[0008] The solenoid magnet coil is coaxially wound with a conductor;

[0009] The solenoid magnet coil is used to generate a pulsed magnetic field under the action of a high repetition frequency pulsed current;

[0010] The magnetic collector is used to introduce the eddy current induced by the pulsed magnetic field on the outer wall into the inner wall through the slit, and generate a high repetition frequency pulsed strong magnetic field in the hollow area; wherein the high repetition frequency is a frequency higher than 1 Hz. Further preferably, the hollow structure is a hollow cylindrical tube-shaped structure, and the hollow structure is provided with a first through hole, a second through hole and a third through hole from top to bottom; the first through hole is truncated cone-shaped, and the diameter of the upper surface of the first through hole is larger than the lower surface, the second through hole is cylindrical, and the upper surface of the second through hole is the lower surface of the first through hole; the third through hole is truncated cone-shaped, and the diameter of the upper surface of the third through hole is smaller than the lower surface, and the upper surface of the third through hole is the lower surface of the second through hole.

[0011] Further preferably, a distance is maintained between the inner wall of the solenoid magnet coil and the outer wall of the magnetism collector so as to increase the heat dissipation area.

[0012] Further preferably, the solenoid magnet coil is wound with copper wire.

[0013] Further preferably, the radius of the inner magnetic collector is 20 mm, and it is made of copper-chromium-zirconium alloy; the radius of the outer magnetic collector is 100 mm, and it is made of red copper.

[0014] Further preferably, the high repetition rate pulsed strong magnet is immersed in liquid nitrogen during operation.

[0015] Further preferably, pulse capacitor discharge is used to provide a high repetition frequency pulse current to the solenoid magnet coil.

[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 high repetition rate pulsed strong magnet, which gathers the time-varying electromagnetic field generated by the solenoid magnet coil into a smaller area through a magnet collector (a slit radially penetrating the side wall of the magnet collector body is provided in the non-hollow part of the magnet collector to introduce eddy currents into the inner wall, thereby generating a high repetition rate pulsed strong magnetic field in the hollow area). Compared with traditional pulsed strong magnets that generate the same peak magnetic field, the resistance is reduced and the required energy is significantly reduced (the present application adopts general pulse current to obtain a high repetition rate pulsed strong magnet), thereby reducing the heat generation of the magnet and increasing the heat dissipation area and heat capacity.

[0018] The present application provides a high repetition frequency pulsed strong magnet, which adopts a nested structure of an inner magnet collector with relatively higher mechanical strength and an outer magnet collector with relatively higher conductivity, ensuring that the central area of ​​the magnet collector is sufficient to withstand the electromagnetic force caused by the strong magnetic field, while further reducing the magnet resistance and heat generation. At the same time, the present application sets a certain distance between the inner wall of the solenoid magnet coil and the outer wall of the magnet collector, thereby increasing the heat dissipation area. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a half-section diagram of the structure of a high repetition rate pulsed strong magnet provided in an embodiment of the present application;

[0020] Figure 2 It is a top view of a high repetition rate pulsed strong magnet provided in an embodiment of the present application;

[0021] FIG3( a ) is a waveform diagram of a 10 Hz magnetic field generated by a 25 T high repetition rate pulsed strong magnet provided in an embodiment of the present application;

[0022] FIG3( b ) is a waveform diagram of a 10 Hz magnetic field generated by a 25 T high repetition rate pulsed strong magnet provided in an embodiment of the present application within a discharge cycle;

[0023] Figure 4 This is a diagram of the maximum temperature change of the 25T high repetition rate pulsed strong magnet provided in an embodiment of the present application after reaching a thermal equilibrium state. DETAILED DESCRIPTION

[0024] For ease of understanding, the English abbreviations and related technical terms involved in the embodiments of the present application are explained and described below.

[0025] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0026] like Figure 1 and Figure 2 As shown, a high repetition frequency pulsed strong magnet comprises a magnet collector 1 and a solenoid magnet coil 2;

[0027] The magnetism collector 1 is a hollow cylindrical structure, and is provided with a slit 4 which radially penetrates the side wall of the magnetism collector body; the hollow structure is a structure which is wide at both sides and narrow in the middle;

[0028] The solenoid magnet coil 2 is coaxially wound by multiple layers of conductor;

[0029] The magnetic collector 1 is formed by nesting an inner magnetic collector 1-1 and an outer magnetic collector 1-2, wherein the diameter of the inner magnetic collector 1-1 is equal to the aperture of the outer magnetic collector 1-2;

[0030] Further preferably, the inner magnetic collector 1-1 is made of a metal material with high strength and high conductivity; the outer magnetic collector 1-2 is made of a metal material with relatively higher conductivity;

[0031] After a high repetition frequency pulse current is passed through the solenoid magnet coil 2 , an induced current is generated on the outer wall of the magnet collector 1 according to Lenz's law, and flows into the inner wall along the slit, thereby generating a high repetition frequency pulse strong magnetic field near the center hole 3 .

[0032] Further preferably, the magnetic collector 1 is provided with a first through hole, a second through hole and a third through hole which are arranged from top to bottom, the first through hole is truncated cone-shaped, and the diameter of the upper surface of the first through hole is larger than the lower surface, the second through hole is cylindrical, and the upper surface of the second through hole is the lower surface of the first through hole; the third through hole is truncated cone-shaped, and the diameter of the upper surface of the third through hole is smaller than the lower surface, and the upper surface of the third through hole is the lower surface of the second through hole.

[0033] Further preferably, the magnetism collector 1 is placed in the center hole of the solenoid magnet coil 2, coaxial with the magnetism collector 1, and a certain distance is kept between the inner wall of the solenoid magnet coil 2 and the outer wall of the magnetism collector 1 to increase the heat dissipation area.

[0034] Example

[0035] In the embodiment of the present application, the solenoid magnet coil 2 is wound with copper wire, the inner magnet collector 1-1 of the magnet collector 1 has a radius of 20 mm and is made of copper-chromium-zirconium alloy, and the outer magnet collector 1-2 has a radius of 100 mm and is made of red copper;

[0036] In the embodiment of the present application, a 25T high repetition rate pulsed strong magnet is designed by the method of the present application, and its repetition rate reaches 10 Hz, as shown in FIG3(a); the high repetition rate pulsed strong magnet is powered by a pulse capacitor, and the pulse current flow path is:

[0037] The pulse capacitor discharges, generating a pulse current flowing through the solenoid magnet coil 2. The pulse magnetic field brought by the pulse current passes through the outer wall of the magnet collector 1. According to Lenz's law, an induced eddy current is generated on the outer wall. Due to the influence of the skin effect, the eddy current converges on the outer wall of the magnet collector 1.

[0038] The eddy current at the outer wall of the magnetic collector 1 flows toward the inner wall through the slit 4;

[0039] The eddy current on the inner wall of the magnetic collector 1 generates a strong magnetic field of 25T at the center hole 3.

[0040] In this embodiment, the high repetition rate pulsed strong magnet is immersed in liquid nitrogen during operation, and the magnetic collector concentrates the magnetic field in the space near the central hole 3, thereby reducing energy consumption and heat generation; at the same time, all surfaces of the magnetic collector 1 are in contact with the liquid nitrogen over a large area, so that the Joule heat generated by the 10Hz high-frequency discharge in the magnetic collector 1 can be dissipated promptly and efficiently.

[0041] like Figure 3(a) and 3(b) As shown, the generated repetitive pulse magnetic field has a pulse width of 0.2 ms and a frequency of 10 Hz.

[0042] like Figure 4 As shown, after the high repetition rate pulsed strong magnet reaches thermal equilibrium, the maximum temperature during discharge is 480K, and the maximum temperature before discharge is 249.5K.

[0043] In summary, compared with the prior art, the present application has the following advantages:

[0044] The present application provides a high repetition frequency pulsed strong magnet, which gathers the time-varying electromagnetic field generated by the coil into a smaller area through a magnetic collector. Compared with the traditional pulsed strong magnet that generates the same peak magnetic field, the resistance is reduced and the required energy is significantly reduced, thereby reducing the heat generated by the magnet, while increasing the heat dissipation area and heat capacity. The structure of nesting an inner magnetic collector with relatively higher mechanical strength and an outer magnetic collector with relatively higher conductivity is adopted to ensure that the central area of ​​the magnetic collector is sufficient to withstand the electromagnetic force caused by the strong magnetic field, while further reducing the resistance of the magnet and reducing the heat generated.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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 high repetition rate pulsed strong magnet, characterized in that: It includes a magnetism collector and a solenoid magnet coil; the magnetism collector is coaxially arranged inside the solenoid magnet coil; The magnetism collector is a hollow structure, and a slit is arranged in the non-hollow part of the magnetism collector, which is radially penetrated through the side wall of the magnetism collector body and serves as a passage between the hollow structure and the outer wall of the magnetism collector; the hollow structure is a structure with wide sides and narrow middle from top to bottom, and the magnetism collector includes a nested inner magnetism collector and an outer magnetism collector; wherein the diameter of the inner magnetism collector is equal to the aperture of the outer magnetism collector; the mechanical strength of the inner magnetism collector is higher than that of the outer magnetism collector; the electrical conductivity of the outer magnetism collector is higher than that of the inner magnetism collector; and both the inner magnetism collector and the outer magnetism collector are made of metal materials; The solenoid magnet coil is coaxially wound by a conductor; the solenoid magnet coil is used to generate a pulse magnetic field under the action of a high repetition frequency pulse current; The magnetic collector is used to introduce the eddy current induced by the pulse magnetic field on the outer wall into the inner wall through the slit, so as to generate a high repetition frequency pulse strong magnetic field in the hollow area; wherein the high repetition frequency is a frequency higher than 1 Hz.

2. The high repetition rate pulsed strong magnet according to claim 1, characterized in that: The hollow structure is a hollow cylindrical structure, and a first through hole, a second through hole and a third through hole are arranged through the hollow structure from top to bottom; the first through hole is a truncated cone, and the diameter of the upper surface of the first through hole is larger than the lower surface; the second through hole is a cylindrical shape, and the upper surface of the second through hole is the lower surface of the first through hole; the third through hole is a truncated cone, and the diameter of the upper surface of the third through hole is smaller than the lower surface, and the upper surface of the third through hole is the lower surface of the second through hole.

3. The high repetition rate pulsed strong magnet according to claim 1 or 2, characterized in that: The inner wall of the solenoid magnet coil is kept at a distance from the outer wall of the magnet collector so as to increase the heat dissipation area.

4. The high repetition rate pulsed strong magnet according to claim 1 or 2, characterized in that: The solenoid magnet coil is wound with copper wire.

5. The high repetition rate pulsed strong magnet according to claim 4, characterized in that: The radius of the inner magnetic collector is 20 mm and it is made of copper-chromium-zirconium alloy; the radius of the outer magnetic collector is 100 mm and it is made of red copper.

6. The high repetition rate pulsed strong magnet according to claim 1, characterized in that: The high repetition rate pulsed strong magnet is immersed in liquid nitrogen during operation.

7. The high repetition rate pulsed strong magnet according to claim 1 or 6, characterized in that: Pulse capacitor discharge is used to provide high repetition frequency pulse current to the solenoid magnet coil.

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