Magnet structure with background magnetic field

Abstract

The invention relates to the technical field of superconducting magnet fault arc testing, and discloses a magnet structure with a background magnetic field, and the magnet structure comprises a fireproof part, a first fixed part, and a first magnet coil and a second magnet coil which are connected in series. Wherein the first magnet coil and the second magnet coil are coaxially arranged, and a magnetic field is formed in combustion spaces inside the first magnet coil and the second magnet coil; a test gap is arranged between the first magnet coil and the second magnet coil. The fireproof part is arranged in the combustion space, heat insulation spaces are formed between the fireproof part and the inner side wall of the first magnet coil and between the fireproof part and the inner side wall of the second magnet coil, and the fireproof part is further provided with a sample piece penetrating channel aligned with the test gap; the first fixing piece comprises a plurality of clamps used for fixing test samples which sequentially penetrate through the test gap and the sample insertion channel; the magnet structure can provide a stable background magnetic field for a test of simulating the spatial propagation characteristics of a fault arc in a fusion device.

Description

Technical Field

[0001] This invention relates to the field of superconducting magnet fault arc testing technology, and in particular to a magnet structure with a background magnetic field. Background Technology

[0002] During the operation of a fusion device, an electric arc fault, as a sudden high-energy release phenomenon, can easily cause serious damage to the superconducting magnet system. Every detail, such as the spatial propagation path of the arc and the energy deposition method, will affect the final arc fault.

[0003] However, existing electric arc test platforms only focus on simulating electric arc phenomena to obtain conclusions on "current / voltage drive, thermal equilibrium, morphological stability," but such test platforms cannot test the propagation behavior of electric arcs such as deflection, contraction, rotation, and extinction under magnetic fields, which is not conducive to supporting experimental research on electric arc behavior in nuclear fusion devices. Summary of the Invention

[0004] This invention provides a magnet structure with a background magnetic field, which solves the problem that existing arc testing platforms cannot test the spatial propagation characteristics of fault arcs in a background field.

[0005] To solve the above-mentioned technical problems, the present invention provides a magnet structure with a background magnetic field, including a fireproof component, a first fixing component, and a first magnet coil and a second magnet coil connected in series; wherein, The first magnet coil and the second magnet coil are coaxially arranged, forming a magnetic field in the combustion space inside them; a test gap is provided between the first magnet coil and the second magnet coil. The fireproof component is disposed within the combustion space and forms a heat insulation space between itself and the inner wall of the first magnet coil and the inner wall of the second magnet coil. The fireproof component is also provided with a sample insertion channel aligned with the test gap. The first fixing member includes a plurality of clamps for fixing test samples that pass sequentially through the test gap and the sample insertion channel.

[0006] As one preferred embodiment, the magnetic field has a magnetic induction intensity of at least 2000 Gauss; the spatial range of the magnetic field is 500 mm radially and 600 mm axially.

[0007] As one preferred embodiment, the test gap is greater than 100mm; the thickness of the insulation space is 10cm.

[0008] As one preferred embodiment, the fireproof component is further provided with a forward observation window corresponding to the test gap and the combustion space.

[0009] As one preferred embodiment, the magnet structure further includes a top observation window positioned directly above the axis connecting the first magnet coil and the second magnet coil, and aligned with the combustion space.

[0010] As one preferred embodiment, the magnet structure further includes a high-speed camera disposed outside the forward observation window and an infrared thermal imager disposed outside the top observation window.

[0011] As one preferred embodiment, the magnet structure further includes a plurality of second fixing members for fixing the first magnet coil and the second magnet coil; the two ends of the second fixing members are respectively connected to the outer wall of the first magnet coil and the outer wall of the second magnet coil, so that the first magnet coil and the second magnet coil are coaxially aligned.

[0012] As one preferred embodiment, the magnet structure further includes a series busbar; the two ends of the series busbar are respectively connected to the corresponding ends of the first magnet coil and the second magnet coil, so that the first magnet coil and the second magnet coil form a series circuit.

[0013] As one preferred embodiment, the magnet structure further includes an electrode busbar; wherein one end of the electrode busbar is connected to a non-corresponding terminal of the first magnet coil or a non-corresponding terminal of the second magnet coil, and the other end of the electrode busbar is connected to an external magnet power supply.

[0014] As one preferred embodiment, the magnet structure further includes an electrode connecting wire; wherein one end of the electrode connecting wire is connected to the other end of the test sample, and the other end of the electrode connecting wire is connected to an external arc power source.

[0015] Compared with the prior art, the beneficial effects of the embodiments of the present invention are as follows: A stable and uniform background magnetic field is generated by connecting a first magnet coil and a second magnet coil coaxially and separated by a test gap. This meets the stringent requirements of the magnetic field environment for arc testing within the fusion device, providing combustion space and reserving space for sample insertion and observation. A fireproof component, located within the combustion space and forming a heat-insulating space between the inner walls of both magnet coils, and aligned with the test gap to create a sample insertion channel, protects the magnet from direct impact by the high-temperature arc, enhancing test safety. A first fixing component, used to fix the test sample sequentially passing through the test gap and the sample insertion channel, ensures the positional stability of the test sample during testing, avoiding the influence of sample shaking or positional deviation on the test results, thus improving the accuracy and reliability of the test. The magnet structure with a background magnetic field constructed in this invention is suitable for studying the propagation characteristics of various arcs in fusion devices, especially fault arcs, and can be extended to fields such as superconducting magnet safety design and failure mechanism assessment. Attached Figure Description

[0016] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a magnet structure with a background magnetic field provided in a certain embodiment of the present invention; Figure 2 This is a schematic diagram of the magnet structure and test sample installation structure provided in a certain embodiment of the present invention; Figure 3 This is a schematic diagram of the magnet structure and test sample installation structure provided in another embodiment of the present invention; Figure 4 This is a layout diagram of the combustion chamber observation window provided in a certain embodiment of the present invention; Figure label: The components include: 1. Magnet structure; 2. Test sample; 3. Combustion space; 4. Test platform; 20. Fireproof component; 30. Sample fixing assembly; 50. Series busbar; 60. Electrode busbar; 70. Electrode connecting wire; 80. Cold water pipe; 101. First magnet coil; 102. Second magnet coil; 301. Fixture; 302. Support frame; 401. Forward observation window; 402. Top observation window; 4011. Combustion chamber forward observation port; 4021. Combustion chamber top observation port. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings and examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this invention, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to communication within two components. The terms "vertical," "horizontal," "left," "right," "upper," "lower," and similar expressions used herein are for illustrative purposes only and do not indicate or imply that the system or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0021] In the description of this invention, it should be noted that, unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is merely for describing specific embodiments and is not intended to limit the invention. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] In one embodiment, such as Figure 1 As shown, the present invention provides a magnet structure 1 with a background magnetic field, including a fireproof component 20, a first fixing component, and a first magnet coil 101 and a second magnet coil 102 connected in series; wherein, The first magnet coil 101 and the second magnet coil 102 are coaxially arranged, and a magnetic field is formed in the combustion space 3 inside them; a test gap is provided between the first magnet coil 101 and the second magnet coil 102. The fireproof component 20 is disposed within the combustion space 3, and a heat insulation space is formed between it and the inner sidewall of the first magnet coil 101 and the inner sidewall of the second magnet coil 102; the fireproof component 20 is also provided with a sample insertion channel aligned with the test gap. The first fixing component includes a plurality of clamps 301 for fixing the test sample 2 that passes through the test gap and the sample insertion channel in sequence.

[0023] To address the problem that existing arc test platforms only focus on simulating arc phenomena and cannot meet the testing requirements of fusion devices for the spatial propagation characteristics of fault arcs, this invention designs a magnet structure 1 with a background magnetic field and a resistance of 1.15Ω. The magnet structure 1, including the skeleton structure, weighs 1.773kg and is used to provide a stable background magnetic field for testing fault arcs within the fusion device simulated on the constructed arc test platform.

[0024] Specifically, the schematic diagram of the installation structure of magnet structure 1 and test sample 2 is as follows: Figure 2 As shown (front view), the schematic diagram of the installation structure of magnet structure 1 and test sample 2 is as follows. Figure 3 As shown in the top view, the layout of the combustion chamber observation window is as follows: Figure 4 As shown, please refer to Figure 1-4 The magnet structure 1 includes a fireproof component 20, a first fixing component, and a first magnet coil 101 and a second magnet coil 102 connected in series. The first magnet coil 101 and the second magnet coil 102 form a magnetic field generating structure. This structure is a hollow cylinder and includes the first magnet coil 101 and the second magnet coil 102, which are coaxially arranged and connected in series. It is used to generate a magnetic induction intensity of at least 2000 Gauss within the combustion space 3 enclosed by the two magnet coils. The uniformity of the magnetic field is better than 10%, and it meets the experimental conditions for the stable propagation of the electric arc in the background magnetic field. The spatial range of the magnetic field is 500 mm radially and 600 mm axially, so that the entire process of the electric arc propagation can be within the observation range.

[0025] The magnet structure 1 connects two magnet coils via a series busbar 50 (preferably made of copper, which has high conductivity and low resistance). The two ends of the series busbar 50 are connected to the corresponding ends of the first magnet coil 101 and the second magnet coil 102, respectively, so that the first magnet coil 101 and the second magnet coil 102 form a series circuit and ensure that the magnetic fields generated by the two coils can be superimposed in the same direction within the combustion space 3. The busbar connection method adopted in this invention simplifies the coil circuit structure (no need to connect to the power supply separately), reduces wiring complexity, and the thermal conductivity of copper can assist in coil heat dissipation, further controlling the temperature rise.

[0026] Meanwhile, the first magnet coil 101 and the second magnet coil 102 in the magnetic field generating structure are both wound with oxygen-free copper conductors. The cross-section of the oxygen-free copper conductor is 8mm×8mm, and a water-cooling hole with a diameter of 5mm is opened inside the conductor along the length direction. The water-cooling hole is connected to the external water-cooling equipment through the water-cooling pipe 80 of the magnet structure 1, so that the temperature rise of the magnetic field generating structure under an input current of 200A does not exceed 30K. In addition, the first magnet coil 101 and the second magnet coil 102 are both composed of 50 layers of windings, with 10 turns per layer. The number of turns in a single coil is 10 in the R direction and 50 in the Z direction. When the magnetic induction intensity of the background magnetic field generated by this structure reaches 2000 Gauss, the input current is 200A. At the same time, an insulating layer with a thickness of 0.5mm (preferably epoxy glass cloth) is provided between two adjacent coil turns. This insulating layer can withstand a breakdown voltage of not less than 10kV. In addition, the first magnet coil 101 and the second magnet coil 102 in the magnetic field generating structure are arranged opposite each other, with a test gap between them that is greater than 100mm, which provides an observation optical path for the forward observation window 401, and at the same time facilitates the insertion of the test sample 2 and the acquisition of arc images.

[0027] The magnetic field generation structure in the magnet structure 1 proposed in this invention adopts a coaxial series coil + test gap design, which ensures the coaxiality of the magnetic field and reserves space for sample insertion and observation. At the same time, the magnetic field strength and uniformity parameters are completely matched with the real background magnetic field environment in the fusion device, ensuring the consistency of the arc test conditions. The 500mm×600mm magnetic field space covers the entire combustion space 3, ensuring that the fault arc is in a stable magnetic field throughout the entire process from ignition, propagation to extinction, avoiding experimental errors caused by magnetic field boundary effects. The oxygen-free copper conductor material and the design of the water-cooling holes can effectively control the magnet temperature rise, ensuring stable operation for a long time at 200A current, avoiding magnetic field attenuation or equipment damage due to overheating. The insulation layer can improve the electrical insulation performance of the coil, prevent breakdown under high voltage environment, and enhance the safety and durability of the system.

[0028] The fireproof component 20 is a fireproof structure, which is a hollow cylindrical structure made of high-temperature resistant ceramic fiber board (temperature resistance ≥1200℃). This structure is fitted inside the combustion space 3 generated by the magnetic field generating structure. The inner diameter matches the outer diameter of the magnet coil. It is fixed by a positioning bracket and maintains a radial distance of 10cm from the inner sidewalls of the two magnet coils to form a heat insulation space with a thickness of 10cm. This effectively blocks the heat conduction between the combustion space 3 and the magnet structure 1, as well as the damage to the device and electrodes caused by the arc combustion splashes. At the same time, the fireproof component 20 also includes a sample insertion channel (diameter 20mm, and its center line passes through the axis of the fireproof component 20 and is aligned with the central space of the magnet) set for alignment with the test gap.

[0029] The fireproof structure in the magnet structure 1 proposed in this invention adopts a hollow cylindrical shape with radial spacing to achieve thermal isolation between the combustion space 3 and other structural components, avoiding high-temperature damage. At the same time, the 10cm radial spacing forms a composite heat-insulating space of test gas and fireproof partition wall, which can not only block the high temperature of the combustion space 3 from being conducted to the magnetic field generating structure (avoiding the aging of the coil insulation layer), but also intercept arc combustion splashes (such as metal fragments) to prevent them from adhering to the coil surface and causing short circuits, while not affecting the magnetic field penetration (air and the fireproof component 20 material have no obvious shielding effect on the magnetic field).

[0030] The magnet structure 1 also includes a fixing structure, namely a first fixing member, which includes several clamps 301 (made of stainless steel or high-strength alloy) for fixing the test sample 2 that passes through the test gap and the sample insertion channel in sequence, so as to suspend and fix the test sample 2 in the magnet structure 1 and so that the test sample 2 can be located in the combustion space 3 enclosed by the magnet coil. There are at least two clamps 301, which fix the two ends of the test sample 2 respectively, and each clamp 301 is also pre-set with a fixing structure (such as threaded hole, slot) that matches the test sample 2, so that the test sample 2 is fixed on the clamp 301 by threaded connection or snap-fit. One end of the clamp 301 is connected to the test sample 2, and the other end is connected to the test platform 4 (for the acquisition of signals such as volt-ampere signal and electromagnetic wave signal, which is not the focus of this invention and will not be described in detail here), so as to fix the entire magnet structure 1 on the test platform 4, and an insulating plate (preferably made of polytetrafluoroethylene with an insulation resistance ≥10) is provided between the clamp 301 and the test platform 4. 8 Ω) to achieve electrical isolation.

[0031] Meanwhile, the magnet structure 1 also includes several second fixing members for fixing the first magnet coil 101 and the second magnet coil 102. One end of each fixing member is connected to the outer wall of the first magnet coil 101, and the other end is connected to the outer wall of the second magnet coil 102. The second fixing member is a support frame 302 (also made of stainless steel or high-strength alloy, adapted to the weight of the magnet and the experimental stability requirements). There are at least four of them, which are used to support the entire magnet structure 1. The support frames 302 are evenly distributed on the magnetic field generating structure. Each support frame 302 is long and narrow, and is connected to the outer wall of the two magnet coils through the test gap by bolts or welding, so that the two magnet coils are coaxially aligned.

[0032] The magnet structure 1 proposed in this invention adopts a suspended fixing + path guidance design to ensure that the test sample 2 falls accurately into the combustion space 3 (the effective coverage area of ​​the magnetic field), improving the repeatability of the experiment. At the same time, fixing the test sample 2 to the fixture 301 can accommodate test samples 2 of different diameters and materials (such as copper-niobium titanium alloy parts simulating superconducting magnet windings), improving the versatility of the device. The connection between the support frame 302 and the two magnet coils can force them to be coaxially aligned (coaxiality error ≤ 0.5 mm), avoiding coil offset that would lead to a decrease in magnetic field uniformity.

[0033] The magnet structure 1 also includes an observation structure, comprising several forward observation windows 401 (150mm × 200mm in size, evenly distributed on the central axis of the fireproof component 20) corresponding to the test gap and the combustion space 3, and a high-speed camera (such as a Phantom VEO1010L) positioned on its outer side; a top observation window 402 (which can be a circular observation window, DN250) positioned directly above the axis connecting the first magnet coil 101 and the second magnet coil 102, and aligned with the combustion space 3; and an infrared thermal imager or infrared camera (such as a SPARK M200) positioned on its outer side. Please refer to [link to relevant documentation]. Figure 4 The forward observation window 401 corresponds to the forward observation port 4011 of the combustion chamber; the top observation window 402 corresponds to the downward observation port 4021 of the combustion chamber, so that the observation structure can accurately observe the arc propagation phenomenon in the combustion space 3, thereby realizing the comprehensive acquisition and analysis of the propagation morphology and thermal characteristics of the fault arc from multiple perspectives.

[0034] The observation structure in the magnet structure 1 proposed in this invention adopts a forward + top dual-window design, breaking the limitations of the traditional single-view perspective and providing comprehensive data support for the analysis of arc propagation characteristics. At the same time, the forward high-speed camera can capture the dynamic propagation process of the fault arc (such as the deflection, stretching, and extinguishing trajectory of the arc in the magnetic field) and obtain morphological data with millisecond-level time resolution. The top infrared thermal imager can simultaneously collect the temperature distribution of the arc (such as the highest temperature in the core area and temperature gradient changes) and obtain thermal characteristic data, providing direct data for subsequent analysis of the influence of the magnetic field on the energy deposition of the arc.

[0035] In addition, the magnet structure 1 also includes an electrode busbar 60 (such as a 10mm thick copper plate) and an electrode connecting wire 70 (preferably a multi-strand copper core cable with a current carrying capacity ≥10kA). One end of the electrode busbar 60 is connected to the non-identical end of the first magnet coil 101 or the non-identical end of the second magnet coil 102 (the non-identical end can be understood as the side of the coil that is not connected to the series busbar 50). The other end of the electrode busbar 60 is reserved with a standard terminal block to connect to an external magnet power supply (DC regulated power supply, rated current ≥300A, rated voltage ≥250V, current regulation accuracy ≤0.5%), thereby providing current to the first magnet coil 101 and the second magnet coil 102. One end of the electrode connecting line 70 is connected to the other end of the test sample 2, which passes through the test gap and the sample insertion channel in sequence. The other end of the electrode connecting line 70 is connected to an external arc power supply (a DC constant current power supply, which can simulate the change of current during the energy release process of a magnet, and output the loading current through a remote input current-time change function, with a total power of 300kW; the maximum output voltage is 125V when the output current is 1200-2400A; and the maximum output voltage is 300V when the output current is 0-1000A), thereby providing electrical energy for the arc propagation phenomenon generated by the test sample 2.

[0036] The magnet structure 1 proposed in this invention uses an electrode busbar 60 for convenient connection to an external magnet power supply, eliminating the need for on-site welding and improving the assembly efficiency of the device. The busbar adopts a rigid structure, which can withstand the electrodynamic force under high current, avoiding current fluctuations caused by vibration and loosening at the connection point, and ensuring stable magnetic field strength. The electrode connecting wire 70 can be adapted to the high current output of the external arc power supply, preventing the cable from overheating and burning out. One end of the connecting wire is connected to the test sample 2 through a quick connector, which allows for quick replacement of the test sample 2 and shortens the experimental interval. The other end is matched with the output end of the arc power supply to ensure stable arc ignition and improve the success rate of the experiment.

[0037] The magnet structure 1 designed in this invention integrates four major functions—magnetic field generation, thermal protection, sample positioning, and observation and acquisition—into a single structure for the first time. Specifically, it provides a stable and highly uniform background magnetic field in a closed combustion chamber, offering ideal experimental conditions for studying arc propagation behavior. The reasonable coil spacing and structural design enable accurate acquisition of arc images by high-speed imaging equipment and infrared cameras. The fireproof structure effectively insulates against heat, protecting the magnet from the direct impact of high-temperature arcs and enhancing system safety. It solves the problem of fragmented functions in existing platforms and simulates typical arc propagation scenarios in fusion reactors. The acquired images can be used to analyze parameters such as arc path, morphology, and heat distribution, providing data support for subsequent magnet structure protection and fault diagnosis. It achieves the testing of arc propagation characteristics of faulty arcs in superconducting magnets within a background magnetic field environment, and the experimental method is safe and reliable. The overall structure is suitable for studying various arc propagation characteristics in fusion devices, especially faulty arcs, and can be extended to fields such as superconducting magnet safety design and failure mechanism assessment. In addition, it should be noted that the device structure, material and size described in this invention are only one embodiment and can be adjusted or implemented through other solutions according to actual needs, and are not specifically limited here.

[0038] This invention addresses the problem that existing arc testing platforms cannot test the spatial propagation characteristics of fault arcs in a background field. A magnet structure with a background magnetic field is designed, consisting of a first and second magnet coil connected coaxially and separated by a test gap. This generates a stable and uniform background magnetic field, meeting the stringent requirements of the magnetic field environment for arc testing within fusion devices by providing combustion space and reserving space for sample insertion and observation. A fireproof component, located within the combustion space and forming a heat-insulating space between the inner walls of the two magnet coils, and aligned with the test gap to create a sample insertion channel, protects the magnet from direct impact by the high-temperature arc, improving test safety. A first fixing component, used to fix the test sample sequentially passing through the test gap and the sample insertion channel, ensures the positional stability of the test sample during testing, avoiding the influence of sample shaking or positional deviation on the test results, thus improving the accuracy and reliability of the test. The magnet structure with a background magnetic field constructed in this invention is suitable for studying the propagation characteristics of various arcs in fusion devices, especially fault arcs, and can be extended to fields such as superconducting magnet safety design and failure mechanism assessment.

[0039] In summary, this invention relates to the field of superconducting magnet fault arc testing technology, and discloses a magnet structure with a background magnetic field. The magnet structure includes a fireproof component, a first fixing component, and a first magnet coil and a second magnet coil connected in series. The first and second magnet coils are coaxially arranged, forming a magnetic field within their combustion space. A test gap is provided between the first and second magnet coils. The fireproof component is located within the combustion space and forms a heat-insulating space between itself and the inner walls of both the first and second magnet coils. The fireproof component also has a sample insertion channel aligned with the test gap. The first fixing component includes several clamps for fixing test samples that sequentially pass through the test gap and the sample insertion channel. This magnet structure can provide a stable background magnetic field for testing the spatial propagation characteristics of fault arcs within a fusion device.

[0040] The various embodiments in this specification are described in a progressive manner. For directly identical or similar parts of the various embodiments, refer to each other. Each embodiment focuses on its differences from other embodiments. It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as these combinations of technical features do not contradict each other, they should be considered within the scope of this specification.

[0041] The above-described embodiments are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and substitutions without departing from the principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A magnetic structure with a background magnetic field, characterized in that, It includes a fireproof component, a first fixing component, and a first magnet coil and a second magnet coil connected in series; wherein, The first magnet coil and the second magnet coil are coaxially arranged, forming a magnetic field in the combustion space inside them; a test gap is provided between the first magnet coil and the second magnet coil. The fireproof component is disposed within the combustion space and forms a heat insulation space between itself and the inner wall of the first magnet coil and the inner wall of the second magnet coil. The fireproof component is also provided with a sample insertion channel aligned with the test gap. The first fixing member includes a plurality of clamps for fixing test samples that pass sequentially through the test gap and the sample insertion channel.

2. The magnet structure with a background magnetic field according to claim 1, characterized in that, The magnetic field has a magnetic induction intensity of at least 2000 Gauss; the spatial range of the magnetic field is 500 mm radially and 600 mm axially.

3. A magnet structure with a background magnetic field according to claim 1, characterized in that, The test gap is greater than 100mm; the thickness of the insulation space is 10cm.

4. A magnet structure with a background magnetic field according to claim 1, characterized in that, The fireproof component is also provided with a forward observation window corresponding to the test gap and the combustion space.

5. A magnet structure with a background magnetic field according to claim 4, characterized in that, The magnet structure also includes a top observation window positioned directly above the axis connecting the first magnet coil and the second magnet coil, and aligned with the combustion space.

6. A magnet structure with a background magnetic field according to claim 5, characterized in that, The magnet structure also includes a high-speed camera located outside the forward observation window and an infrared thermal imager located outside the top observation window.

7. A magnet structure with a background magnetic field according to claim 1, characterized in that, The magnet structure further includes several second fixing members for fixing the first magnet coil and the second magnet coil; the two ends of the second fixing members are respectively connected to the outer wall of the first magnet coil and the outer wall of the second magnet coil, so that the first magnet coil and the second magnet coil are coaxially aligned.

8. A magnet structure with a background magnetic field according to claim 1, characterized in that, The magnet structure also includes a series busbar; the two ends of the series busbar are respectively connected to the corresponding ends of the first magnet coil and the second magnet coil, so that the first magnet coil and the second magnet coil form a series circuit.

9. A magnet structure with a background magnetic field according to claim 1, characterized in that, The magnet structure further includes an electrode busbar; wherein, one end of the electrode busbar is connected to a non-corresponding end of the first magnet coil or a non-corresponding end of the second magnet coil, and the other end of the electrode busbar is connected to an external magnet power supply.

10. A magnet structure with a background magnetic field according to claim 1, characterized in that, The magnet structure also includes an electrode connecting wire; wherein one end of the electrode connecting wire is connected to the other end of the test sample, and the other end of the electrode connecting wire is connected to an external arc power source.

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