Pluggable nitrogen fixation cooling high-temperature superconducting magnet

Abstract

The invention relates to the technical field of high-temperature superconducting magnets, and discloses a pluggable nitrogen fixation cooling high-temperature superconducting magnet. The superconducting magnet comprises a refrigerating machine cold head, a first cold conduction belt, a nitrogen fixation cavity, an outer Dewar, a second cold conduction belt, a superconducting coil and a cold conduction layer, the nitrogen fixation cavity and the superconducting coil are arranged in the outer Dewar, the interior of the outer Dewar is a vacuum environment, the refrigerating machine cold head is connected with the nitrogen fixation cavity through the first cold conduction belt, and the second cold conduction belt is connected with the superconducting coil through the second cold conduction belt. The nitrogen fixation cavity is connected with the superconducting coil through the second cold conduction belt, and the cold conduction layer is arranged on the outer side of the superconducting coil. Therefore, after the refrigerating machine is separated from the superconducting magnet, the low-temperature state of the superconducting coil can be maintained for a long time, the superconducting magnet can be better used in a dynamic environment, and the problems of weight increase and reliability reduction of the refrigerating machine in a motion environment are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of high-temperature superconducting magnets, and in particular to a pluggable nitrogen-fixed cooling high-temperature superconducting magnet. Background Art

[0002] High-temperature superconducting magnets wound with high-temperature superconducting materials can be used in superconducting electric magnetic levitation trains, high-temperature superconducting flywheel energy storage, nuclear magnetic resonance imaging and other fields. They have advantages that conventional magnets and traditional magnet equipment do not have, such as smaller footprint, higher magnetic field strength and current density, etc.

[0003] There are three critical indicators for high-temperature superconducting tapes, namely critical current, critical temperature and critical magnetic field. When all three indicators meet the requirements of the superconducting state, the high-temperature superconducting tape will change from a resistive state to a superconducting state. In practical applications, liquid nitrogen (77K) is usually selected as a refrigerant to cool the high-temperature superconducting magnet so that it can quickly enter the superconducting state. However, in order to bring out the best performance of the high-temperature superconducting magnet, it is necessary to further reduce the temperature of the cryogenic system. For example, the critical current of a high-temperature superconducting tape at 77K is 200A, so when the temperature drops to 20K, its critical current can reach 300A or even higher. As the temperature decreases, the current carrying capacity of the high-temperature superconducting tape continues to increase. Correspondingly, the magnetic field and safety margin generated by the high-temperature superconducting magnet are also improved.

[0004] In order to provide a lower temperature environment for high-temperature superconducting magnets, there are currently two technical solutions: one is to use a refrigerator as a cold source to cool the superconducting magnet, and the other is to directly use liquid helium to cool the superconducting magnet. However, both solutions have certain disadvantages in actual use.

[0005] Using a refrigerator to cool a high-temperature superconducting magnet has the following disadvantages:

[0006] 1. In the application fields of superconducting electric magnetic levitation trains, high-temperature superconducting flywheel energy storage and high-power electromagnetic propulsion, high-temperature superconducting magnets need to be used as moving parts; similarly, refrigerators also need to move with high-temperature superconducting magnets. The reliability and refrigeration performance of refrigerators will be affected in a moving environment.

[0007] 2. The refrigerator is always in working condition, which undoubtedly increases the overall weight of the superconducting magnet system. Once the refrigerator is removed, the temperature of the high-temperature superconducting magnet will rise rapidly without a cold source, and the service life and safety will be greatly reduced.

[0008] 3. The volume of the refrigerator cold head is limited. Most of the existing technical solutions currently use copper cold tape conduction cooling to cool the superconducting magnet. Due to the limited volume of the cold head, the cooling is uneven and the cooling effect is poor, which makes it easy for local superconducting magnets to quench.

[0009] Direct cooling with liquid helium also has the following disadvantages:

[0010] 1. As a strategic material, liquid helium has very limited reserves and its supply cannot be guaranteed, which to a certain extent limits the use scenarios of liquid helium.

[0011] 2. Liquid helium is very expensive. High-temperature superconducting magnets use liquid helium for cooling, which requires a large amount of liquid helium. The cooling cost is very high, and the recovery system for recycling liquid helium is also very complicated and expensive. Summary of the invention

[0012] The invention provides a pluggable nitrogen-fixed cooling high-temperature superconducting magnet, which can solve the technical problems in the prior art.

[0013] The present invention provides a pluggable nitrogen-fixed cooling high-temperature superconducting magnet, wherein the superconducting magnet comprises a refrigerator cold head, a first cold conduction belt, a nitrogen-fixing cavity, an outer dewar, a second cold conduction belt, a superconducting coil and a cold conduction layer, the nitrogen-fixing cavity and the superconducting coil are arranged in the outer dewar, the outer dewar is a vacuum environment, the refrigerator cold head is connected to the nitrogen-fixing cavity through the first cold conduction belt, the nitrogen-fixing cavity is connected to the superconducting coil through the second cold conduction belt, and the cold conduction layer is arranged on the outside of the superconducting coil.

[0014] Preferably, the first cooling belt is made of a metal braided belt.

[0015] Preferably, the second cooling belt is made of a metal braided belt.

[0016] Preferably, the metal is copper.

[0017] Preferably, the superconducting coil is wound with a high-temperature superconducting tape.

[0018] Preferably, the cooling conduction layer is made of metal wire.

[0019] Preferably, the metal wire is a copper wire.

[0020] Through the above technical solution, the nitrogen fixing chamber can be cooled by a refrigerator to further reduce the temperature of nitrogen fixing, and the cold is transferred between the nitrogen fixing chamber and the refrigerator and between the nitrogen fixing chamber and the superconducting coil through the corresponding cold conduction belt. Therefore, after the refrigerator is separated from the superconducting magnet, the low temperature state of the superconducting coil can be maintained for a long time and the use of the superconducting magnet in a dynamic environment can be better realized, reducing the weight increase and reliability reduction of the refrigerator in a moving environment. In addition, by setting a cold conduction layer, the cold capacity of the refrigerator and the nitrogen fixing chamber can be fully utilized, and the cooling of the superconducting coil is more uniform, which can effectively prevent the superconducting coil from losing supersonic due to the increase in local temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 A schematic structural diagram of a pluggable nitrogen-fixed cooling high-temperature superconducting magnet according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0023] It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0025] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0026] Figure 1 A schematic structural diagram of a pluggable nitrogen-fixed cooling high-temperature superconducting magnet according to an embodiment of the present invention is shown.

[0027] like Figure 1 As shown, an embodiment of the present invention provides a pluggable nitrogen-fixed cooling high-temperature superconducting magnet, wherein the superconducting magnet includes a refrigerator cold head 1, a first cold conduction belt 2, a nitrogen-fixing chamber 3, an outer dewar 4, a second cold conduction belt 5, a superconducting coil 6 and a cold conduction layer 7, the nitrogen-fixing chamber 3 and the superconducting coil 6 are arranged in the outer dewar 4, the outer dewar 4 is a vacuum environment, the refrigerator cold head 1 is connected to the nitrogen-fixing chamber 3 through the first cold conduction belt 2, the nitrogen-fixing chamber 3 is connected to the superconducting coil 6 through the second cold conduction belt 5, and the cold conduction layer 7 is arranged on the outside of the superconducting coil 7.

[0028] Among them, the cold head of the refrigerator is a component of the refrigerator that outputs cold energy. During actual refrigeration, the cooling of the nitrogen-fixing chamber is achieved by connecting it to the nitrogen-fixing chamber. A refrigerator is a device that converts electrical energy into cold energy. The nitrogen-fixing chamber is used to store liquid nitrogen. The temperature of liquid nitrogen is 77K. When the cold head of the refrigerator is used to cool it to below 77K, the liquid nitrogen will solidify to form solid nitrogen. Under the cooling of the refrigerator, the temperature of the solid nitrogen can be continuously reduced, for example, to 20K. After the solid nitrogen is formed, the cold energy can be stored similar to ice cubes, and then the solid nitrogen after cooling in the nitrogen-fixing chamber can be used as a cold source to continuously output cold energy to the superconducting coil. The vacuum environment of the external Dewar can greatly reduce the convective heat dissipation of the entire superconducting magnet system.

[0029] Through the above technical solution, the nitrogen fixing chamber can be cooled by a refrigerator to further reduce the temperature of nitrogen fixing, and the cold is transferred between the nitrogen fixing chamber and the refrigerator and between the nitrogen fixing chamber and the superconducting coil through the corresponding cold conduction belt. Therefore, after the refrigerator is separated from the superconducting magnet, the low temperature state of the superconducting coil can be maintained for a long time and the use of the superconducting magnet in a dynamic environment can be better realized, reducing the weight increase and reliability reduction of the refrigerator in a moving environment. In addition, by setting a cold conduction layer, the cold capacity of the refrigerator and the nitrogen fixing chamber can be fully utilized, and the cooling of the superconducting coil is more uniform, which can effectively prevent the superconducting coil from losing supersonic due to the increase in local temperature.

[0030] In the present invention, although the above description uses a refrigerator to cool the nitrogen fixing chamber, the present invention is not limited thereto, and other refrigeration systems such as a cold helium circulation system may also be used to cool the nitrogen fixing chamber.

[0031] According to an embodiment of the present invention, the first cooling belt 2 is made of a metal braided belt.

[0032] That is, the cold head of the refrigerator and the nitrogen fixing chamber are connected by the first cold conduction belt, so as to realize the cold energy transfer between the cold head of the refrigerator and the nitrogen fixing chamber.

[0033] According to an embodiment of the present invention, the second cooling belt 5 is made of a metal braided belt.

[0034] That is, the nitrogen fixing chamber and the superconducting coil are connected by the second cold conducting belt to realize the cold transfer between the nitrogen fixing chamber and the superconducting coil.

[0035] According to an embodiment of the present invention, the metal is copper.

[0036] For example, the first cooling belt and the second cooling belt may be made of a soft copper braided belt.

[0037] Those skilled in the art should understand that the above description of the cooling belt material is merely exemplary and is not intended to limit the present invention.

[0038] According to an embodiment of the present invention, the superconducting coil 6 is wound with a high-temperature superconducting tape.

[0039] Among them, high-temperature superconducting tapes can reach a superconducting state at a liquid nitrogen temperature of 77K, so that large currents can pass through them losslessly to generate a very strong magnetic field.

[0040] According to an embodiment of the present invention, the cooling layer 7 is made of metal wire.

[0041] According to an embodiment of the present invention, the metal wire is a copper wire.

[0042] For example, floc-like thin copper wires can be used to wrap the outside of the superconducting coil to form a cooling layer. At the same time, the thin copper wires are connected to the cooling belt connected to the nitrogen solidifying chamber to achieve cold transfer between the nitrogen solidifying chamber and the superconducting coil. By wrapping the superconducting coil with very dense thin copper wires, uniform cooling of the superconducting coil can be achieved.

[0043] The pluggable nitrogen-fixed cooling high-temperature superconducting magnet of the present invention is described below with reference to examples.

[0044] In actual use, the nitrogen fixation chamber is first filled with liquid nitrogen, and then the refrigerator is turned on to continue cooling the nitrogen in the nitrogen fixation chamber. In this process, the path of cold transfer is:

[0045] Refrigerator cold head 1 → first cooling belt 2 → nitrogen solidification chamber 3 → second cooling belt 5 → cooling layer 7 → high temperature superconducting coil 7.

[0046] After the temperature of the high-temperature superconducting coil drops to a predetermined temperature, the connection between the first cold conductive belt between the cold head of the refrigerator and the nitrogen fixing chamber can be disconnected, thereby realizing the disconnection between the refrigerator and the superconducting magnet. At this time, since the liquid nitrogen in the nitrogen fixing chamber has become solid nitrogen and the specific heat capacity of solid nitrogen is large, to a certain extent, solid nitrogen can serve as a built-in cold source to continuously output cold to the superconducting coil to maintain its low temperature state. Moreover, the thin copper wire wrapped outside the superconducting coil can transmit the cold of the nitrogen fixing chamber very evenly to ensure the consistency of the temperature of the superconducting coil.

[0047] It can be seen from the above embodiments that the pluggable nitrogen-fixed cooling high-temperature superconducting magnet described in the above embodiments of the present invention has at least the following advantages:

[0048] 1. The refrigerator can be separated from the superconducting magnet. After the refrigerator is separated from the superconducting magnet, the fixed nitrogen in the nitrogen fixing chamber becomes a new cold source. At the same time, due to the large specific heat capacity of fixed nitrogen, the low temperature state of the superconducting coil can be maintained for a long time;

[0049] 2. After the refrigerator is separated from the superconducting magnet, the superconducting magnet can be better used in a dynamic environment, reducing the weight increase and reliability reduction of the refrigerator in a moving environment;

[0050] 3. Wrapping the superconducting coil with flocculent copper wire can make full use of the cooling capacity of the refrigerator and the nitrogen fixation chamber, and the cooling of the superconducting coil is more uniform, which can effectively prevent the superconducting coil from losing superconductivity due to the increase of local temperature.

[0051] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0052] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0053] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pluggable nitrogen-cooled high-temperature superconducting magnet, characterized in that: The superconducting magnet comprises a refrigerator cold head (1), a first cold conduction belt (2), a nitrogen fixing chamber (3), an outer dewar (4), a second cold conduction belt (5), a superconducting coil (6) and a cold conduction layer (7); the nitrogen fixing chamber (3) and the superconducting coil (6) are arranged in the outer dewar (4); the outer dewar (4) is in a vacuum environment; the refrigerator cold head (1) is connected to the nitrogen fixing chamber (3) through the first cold conduction belt (2); the nitrogen fixing chamber (3) is connected to the superconducting coil (6) through the second cold conduction belt (5); and the cold conduction layer (7) is arranged outside the superconducting coil (7).

2. The superconducting magnet according to claim 1, characterized in that The first cooling belt (2) is made of a metal braided belt.

3. The superconducting magnet according to claim 2, characterized in that: The second cooling belt (5) is made of a metal braided belt.

4. The superconducting magnet according to claim 3, characterized in that: The metal is copper.

5. The superconducting magnet according to claim 1, characterized in that: The superconducting coil (6) is wound with a high-temperature superconducting tape.

6. The superconducting magnet according to claim 1, characterized in that: The cooling conduction layer (7) is made of metal wire.

7. The superconducting magnet according to claim 6, characterized in that The metal wire is a copper wire.

Images