Superconducting magnet support structure suitable for cold transport

Abstract

The present invention discloses a superconducting magnet support structure suitable for cold transport, including a support tube inserted into a sealed transport port, wherein: the support tube has a room temperature end connection part, a cold shield heat interception ring and a cold end connection tube arranged in sequence from outside to inside; the room temperature end connection part is pressed and fixed on the outside of the low temperature Dewar shell, and a sealed channel is also provided between the inner wall and the cold shield heat interception ring; the outer wall of the cold shield heat interception ring is sealed and connected to the cold shield, and a cold end connection tube is provided on the inner wall; a hollow cavity is provided inside the cold end connection tube; a bellows is fixed in the sealed channel; one end of the bellows is fixed to the inner wall of the low temperature Dewar shell, and the other end freely extends to the room temperature end connection part of the support tube, and a support tube pad is provided between the inner wall of the room temperature end connection part and the outer side of the low temperature Dewar shell. The superconducting magnet support structure of the present invention realizes that the vacuum stability of the superconducting magnet can be maintained for transportation without first heating up and releasing liquid helium to destroy the vacuum, thereby saving the transportation cost of the superconducting magnet.

Description

Technical Field

[0001] The invention relates to the technical field of superconducting magnets, in particular to a superconducting magnet supporting structure suitable for cold transport. Background Art

[0002] In the structure of ordinary superconducting magnets, the magnetic field is generated by the current in the superconducting coil. In order to maintain the superconducting state of the coil wire, the coil must be kept at an extremely low temperature, which is generally maintained at a stable low temperature by liquid helium and the cold head of the cryogenic refrigerator. The superconducting coil is immersed in the liquid helium of the liquid helium container of the cryogenic dewar. In order to effectively prevent the external heat from being transferred to the liquid helium dewar through conduction, convection or radiation, causing the evaporation of liquid helium, the superconducting coil and the cryogenic container of the dewar must be placed inside the vacuum chamber and the radiation-proof cold shield and multi-layer heat radiation-proof film wrapped therein. The vacuum is maintained by the room temperature container of the dewar. However, no matter how good the cryogenic system is, it cannot completely eliminate the external heat entering the liquid helium container. The remaining thermal radiation and the suspension system of the liquid helium container in the vacuum are the main heat leakage channels. The role of the cold head is to remove the heat leaked from the supporting original and the remaining radiation, which can also be said to be to liquefy the helium gas evaporated by the heat leakage and return it to liquid state.

[0003] Since the temperature of the superconducting magnet is close to absolute zero at 4.2K, a large amount of heat energy in the surrounding environment tends to be transferred to the interior of the cryogenic dewar, and part of the heat is transferred through the magnet suspension system. The liquid helium dewar and the coil inside the magnet for general magnetic resonance weigh from several hundred kilograms to several tons. The cryogenic dewar is suspended in a vacuum through a carefully designed suspension mechanism. An overly strong suspension mechanism may increase heat leakage. The current suspension mechanism is mainly made of fiberglass, carbon fiber, or alloy materials. The common characteristics of these materials are high mechanical strength, high tensile strength, and low thermal conductivity. Long-term stability and non-volatile gas components in vacuum are also necessary properties. Even with such excellent performance materials, heat conduction cannot be completely eliminated. If these heat leaks are close to or greater than the cooling power of the cryogenic cold head, liquid helium may be volatilized and consumed, which will hinder the long-term stable operation of the magnet. Therefore, the fine suspension mechanism design usually selects an appropriate safety factor to make the magnet safe during transportation, and the heat leakage is small enough to be cooled by a cryogenic cold head.

[0004] However, as the size of the magnet or the magnetic field increases, such as a 7T (Tesla) magnet, the weight of the magnetic field coil and the cryogenic dewar will increase, requiring a more robust suspension mechanism, which means that the suspension mechanism will cause greater heat leakage. When the cooling power of a cold head is not enough to balance this heat leakage, the liquid helium will begin to be consumed.

[0005] One way to re-balance is to add a cold head. This is a relatively expensive solution. The cold head and the helium compressor that go with it are expensive, and they require an additional water or air cooling system, which also increases power consumption.

[0006] Another way to re-achieve balance is not to increase the strength of the suspension mechanism. At this time, the magnet is only safe when it is stationary. During transportation, the magnet must be fixed by an additional support mechanism to protect the suspension mechanism. There are four pairs of concentric holes on the magnet vacuum shell and cold screen. At the same position, there are four screw holes on the end face of the innermost liquid helium container. Under normal circumstances, the four holes on the vacuum shell are covered and sealed by four vacuum blind plates and sealing rings to maintain vacuum. When transporting magnets with additional transport supports, the transport holes are installed with transport support cylinders, and are fastened to the liquid helium dewar inside and the vacuum shell outside with screws.

[0007] This transport support mechanism effectively transfers the weight of the coil and cryogenic dewar and the impact force during transportation to the outer shell through a more solid support tube. It effectively protects the original insulation support of the magnet. The disadvantage of this solution is that it needs to break the vacuum to completely restore the magnet to room temperature. The temperature recovery of the magnet not only wastes a lot of liquid helium, but also takes a lot of time. Summary of the invention

[0008] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a superconducting magnet support structure that allows the coil and the cryogenic dewar to be effectively supported without destroying the vacuum, and the heat leakage is controlled within the allowable range, so that the magnet can be transported in a cold state. Without increasing too much heat leakage, the support of the shell to the cryogenic dewar and the coil inside it can be increased to effectively resist the mechanical impact that may be generated during transportation, and protect the suspension mechanism inside the superconducting magnet, which is suitable for cold transportation.

[0009] The technical solution adopted by the present invention is: a superconducting magnet support structure suitable for cold transportation is connected to the sealed transportation port of the low-temperature Dewar shell, used to support and seal the transportation port, including a support cylinder inserted into the sealed transportation port, wherein:

[0010] The support tube has a room temperature end connection portion, a cold shield heat interception ring and a cold end connection tube which are sequentially arranged from outside to inside;

[0011] The room temperature end connection part is pressed and fixed on the outer side of the low temperature Dewar shell, and a sealing channel is also provided between the inner wall and the cold shield heat interception ring;

[0012] The outer wall of the cold shield heat interception ring is sealed with the cold shield, and the inner wall is provided with a cold end connection tube;

[0013] The cold end connecting tube has a hollow cavity inside, which is used for plugging and unplugging the support shaft of the liquid helium container;

[0014] A bellows is fixed in the sealing channel;

[0015] The bellows has one end fixed to the inner wall of the low-temperature Dewar shell and the other end freely extending to the room-temperature end connection portion of the support tube, thereby achieving stability when the support tube moves, ensuring that the cold air in the superconducting magnet tube does not leak;

[0016] When transporting supermagnetic conductors, a support cylinder pad is provided between the inner wall of the room temperature end connection and the outer side of the low temperature Dewar shell.

[0017] Preferably, during normal operation of the superconducting magnet, the room temperature end connection portion is tightly fixed to the outer side of the low temperature Dewar housing.

[0018] Preferably, a sealing reinforcement tube is also provided on the outer side where the cold shield heat interception ring is connected to the cold shield.

[0019] Preferably, the sealing enhancement tube is fixed on the cold shield, and when the support tube is separated from the liquid helium container, it will not be driven to separate, which can improve the separation efficiency of the cold shield heat interception ring on the one hand, and avoid the generation of heat loss on the other hand.

[0020] The bellows has a bellows connection portion and a bellows expansion tube, wherein:

[0021] A corrugated connection part, one end of which is fixed to the inner wall of the low-temperature Dewar shell, and the other end of which is fixedly connected to the corrugated expansion pipe;

[0022] The bellows expansion tube is placed in the support tube and freely extends toward the room temperature end connection portion of the support tube.

[0023] Preferably, the portion where the corrugated connection part is connected to the interior of the low-temperature Dewar shell is fixedly connected by welding.

[0024] Preferably, the length of the bellows of the bellows is less than the total thickness of the low-temperature Dewar shell, the support tube pad and the room-temperature end connection portion.

[0025] Preferably, the length of the cold shield heat interception ring is greater than the sum of the compressed length of the bellows and the length from the inner wall of the low-temperature Dewar shell to the inner wall of the cold shield.

[0026] Preferably, the support tube is located between the cold end connecting tube and the cold shield heat interception ring and is also provided with a lightening groove.

[0027] Preferably, the room temperature end connection portion is pressed and fixed to the outer side of the low temperature Dewar shell by a plurality of screws.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: the support structure of the superconducting magnet suitable for cold transportation of the present invention can maintain the vacuum stability of the superconducting magnet for transportation without first heating up the temperature to release liquid helium to destroy the vacuum, thereby saving the transportation cost of the superconducting magnet.

[0029] Specifically, after using the support structure of the present invention, the transportation of superconducting magnets is more convenient. It is not necessary to heat up and release liquid helium to destroy the vacuum first. It is only necessary to set a support tube pad between the inner wall of the room temperature end connection part and the outer side of the low temperature Dewar shell, so that the cold end connection tube of the support tube is separated from the outer side of the support shaft of the liquid helium container, and at this time the sealing channel becomes longer, and the bellows changes from the compressed state during operation to a free expansion state. When the entire superconducting magnet is moved, even if it is collided or shaken, the bellows will absorb the vibration energy, and will not cause damage to the low temperature Dewar shell, cold shield, liquid helium container, etc. of the superconducting magnet, and can ensure the normal sealing of the entire superconducting magnet without heat leakage.

[0030] As a result, before the use of this support structure, the transportation time of superconducting magnets was relatively long. First, it took about ten days to restore the superconducting magnets to room temperature before transportation, and they needed to be refilled with new liquid helium after transportation. Now they can be transported with liquid helium, which not only saves transportation time and liquid helium resources. Specifically, the cost of transporting a set of superconducting magnets is about 300 yuan per liter of liquid helium, and a superconducting magnet requires about 1000L of liquid helium, so the transportation cost of a set of superconducting magnets can save hundreds of thousands.

[0031] In summary, the support structure of the superconducting magnet suitable for cold transportation of the present invention has a thermal insulation support mechanism that enables the coil and the low-temperature dewar to be effectively supported without destroying the vacuum, and the heat leakage is controlled within the allowable range, which not only saves transportation costs but also shortens the transportation cycle, and has great application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A structural diagram of a support structure for a superconducting magnet suitable for cold transport;

[0033] Figure 2 for Figure 1 AA cross-sectional view;

[0034] Figure 3 for Figure 2 A is an enlarged view of A in the transport state;

[0035] Figure 4 for Figure 2 A is an enlarged view of the superconducting magnet in normal working state;

[0036] Among them: 1- low temperature Dewar shell, 2- cold shield, 3- liquid helium container, 31- support shaft; 4- support tube, 41- room temperature end connection part, 42- cold shield heat interception ring, 43- cold end connection tube, 431- hollow cavity; 44- sealing channel, 45- lightening groove; 5- bellows, 51- bellows connection part, 52- bellows telescopic tube; 6- support tube gasket, 7- sealing reinforcement tube, 8- screw, 9- sealing transport port, 10- first stage cold head. DETAILED DESCRIPTION

[0037] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0038] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the combination or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, in the description of the embodiments of the present invention, the device positional relationships such as "up", "down", "front", "back", "left", "right" and the like in all the drawings are based on the positions or positional relationships shown in the accompanying drawings. Figure 1 As standard.

[0039] like Figure 1 and Figure 2 , Figure 3 As shown, a superconducting magnet support structure suitable for cold transport is connected to the sealed transport port 9 of the cryogenic Dewar housing 1, and is used to support and seal the transport port 9, including a support cylinder 4 inserted into the sealed transport port 9, wherein:

[0040] The support tube 4 has a room temperature end connection part 41, a cold shield heat interception ring 42 and a cold end connection tube 43 which are arranged in sequence from the outside to the inside;

[0041] like Figure 3 and Figure 4 As shown, the room temperature end connection part 41 is pressed and fixed on the outer side of the low temperature Dewar shell 1, and a sealing channel 44 is provided between the inner wall and the cold shield heat interception ring 42;

[0042] The cold shield heat interception ring 42 has an outer wall that is sealed and connected to the cold shield 2, and plays a role in heat interception. Most of the heat leaking into the magnet from the hot end is conducted to the cold shield, and is finally cooled by the first-stage cold head 10. A cold end connecting tube 43 is also provided on the inner wall;

[0043] The cold end connecting tube 43 has a hollow cavity 431 inside, which is used for plugging and unplugging the support shaft 31 of the liquid helium container 3;

[0044] A bellows 5 is fixed in the sealing channel 44;

[0045] The bellows 5 has one end fixed to the inner wall of the low-temperature Dewar shell 1 and the other end freely extends to the room temperature end connection portion 41 of the support tube 4, thereby achieving that when the support tube moves, it can still maintain its stability and ensure that the cold air in the superconducting magnet tube does not leak;

[0046] When the supermagnetic conductor is transported, a support tube pad 6 is arranged between the inner wall of the room temperature end connection part 41 and the outer side of the low temperature Dewar shell 1, so that the cold end connection tube 43 of the support tube is separated from the outer side of the support shaft of the liquid helium container 3 to reduce heat leakage. At this time, the sealing channel 44 becomes longer, and the bellows 5 changes from the compressed state during operation to a free expansion state. When the entire superconducting magnet is moved, even if it is collided or shaken, the bellows will absorb the vibration energy, and will not cause damage to the low temperature Dewar shell, cold shield, liquid helium container, etc. of the superconducting magnet, and can ensure the normal sealing of the entire superconducting magnet and reduce heat leakage.

[0047] However, during daily operation of the superconducting magnet, the room temperature end connection part 41 is tightly fixed to the outer side of the low temperature Dewar shell 1, and the normal operation of the superconducting magnet can be achieved without using any extra parts. Moreover, during transportation, only the support cylinder gasket needs to be added, and other parts do not need to be changed, which makes transportation and use convenient.

[0048] After the transportation of the superconducting magnet is completed, the support tube pad is pulled out or removed, and the hollow cavity 431 of the cold end connecting tube 43 is inserted into the support shaft 31 of the liquid helium container to maintain normal operation. At the same time, the bellows 5 is compressed and sealed normally, and the outer wall of the cold shield heat interception ring 42 is sealed and connected with the cold shield 2 to play a heat interception role.

[0049] A sealing enhancement tube 7 is also provided on the outer side of the cold shield heat interception ring 42 of the superconducting magnet support structure connected to the cold shield 2, which is used to enhance the sealing performance between the cold shield heat interception ring 42 and the cold shield, and at the same time enhance the supporting strength performance of the support tube.

[0050] The sealing enhancement tube 7 is fixed on the cold shield 2, and will not be driven to separate when the support tube separates from the liquid helium container. This can improve the separation efficiency of the cold shield heat interception ring on the one hand, and avoid heat loss on the other hand.

[0051] The bellows 5 of the superconducting magnet support structure has a bellows connection portion 51 and a bellows expansion tube 52, wherein:

[0052] The bellows connection part 51 has one end fixed to the inner wall of the cryogenic Dewar shell 1 and the other end fixedly connected to the bellows expansion tube 52. The advantage of this design is that since the welded bellows is very soft and has good sealing performance, the vacuum will not be damaged when the position of the additional support cylinder for heat insulation transportation is changed. The bellows expansion tube is fixedly connected to the cryogenic Dewar shell by the bellows connection part 51, thereby achieving the purpose of enhancing the connection strength of the bellows, improving the damage to the bellows caused by frequent vibration or fluctuation during transportation, and extending the service life of the bellows;

[0053] The bellows expansion tube 52 is placed in the support tube 4 and freely extends toward the room temperature end connection portion 41 of the support tube 4 .

[0054] A more preferred embodiment is that the corrugated connection part 51 of the superconducting magnet support structure is connected to the part connected inside the cryogenic Dewar shell 1 by welding to achieve a fixed connection, which can save manufacturing costs and ensure that the corrugated connection part and the cryogenic Dewar shell have good integrity. In addition, the length of the corrugated telescopic tube 52 of the bellows 5 can also be designed to be less than the total thickness of the cryogenic Dewar shell 1, the support tube pad 6 and the room temperature end connection part 41, but greater than the total thickness of the cryogenic Dewar shell 1 and the support tube pad 6, thereby ensuring that the bellows has good telescopic performance when in use.

[0055] The length of the cold shield heat interception ring 42 of the superconducting magnet support structure is greater than the sum of the compressed length of the bellows 5 plus the length from the inner wall of the low-temperature Dewar shell 1 to the inner wall of the cold shield 2, thereby ensuring that when the superconducting magnet is working, the cold shield heat interception ring 42 can fully contact the cold shield, thereby improving the cooling capacity.

[0056] The support tube 4 of the superconducting magnet support structure is located between the cold end connection tube 43 and the cold shield heat interception ring 42 and is also provided with a lightening groove 45 to reduce the overall mass of the support tube. At the same time, due to the large number of ribs inside the support tube, it can ensure good strength. The room temperature end connection part 41 is pressed and fixed to the outside of the low temperature Dewar shell 1 by a plurality of screws 8, but does not completely penetrate the outer wall of the low temperature Dewar shell 1. Such a fixing method can keep the heat inside the superconducting magnet from leaking, and the outside can be well fixed and connected.

[0057] The embodiments of the present invention disclose preferred embodiments, but are not limited thereto. A person skilled in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. However, as long as they do not deviate from the spirit of the present invention, they are all within the protection scope of the present invention.

Claims

1. A superconducting magnet support structure suitable for cold transport, connected to a sealed transport port (9) of a cryogenic Dewar housing (1), used to support and seal the sealed transport port (9), characterized in that: It comprises a support cylinder (4) inserted into a sealed transport port (9), wherein: A support tube (4) having a room temperature end connection portion (41), a cold shield heat interception ring (42), and a cold end connection tube (43) which are arranged in sequence from the outside to the inside; The room temperature end connection portion (41) is pressed and fixed to the outer side of the low temperature Dewar housing (1), and a sealing channel (44) is provided between the inner wall and the cold shield heat interception ring (42); A cold shield heat interception ring (42), the outer wall of which is sealedly connected to the cold shield (2), and the inner wall of which is provided with a cold end connecting tube (43); The cold end connecting cylinder (43) has a hollow cavity (431) inside, which is used for plugging and unplugging the support shaft (31) of the liquid helium container (3); A bellows (5) is fixed in the sealing passage (44); A bellows (5) having one end fixed to the inner wall of the low-temperature Dewar housing (1) and the other end freely extending toward the room-temperature end connection portion (41) of the support tube (4); When the supermagnetic conductor is transported, a support cylinder pad (6) is provided between the inner wall of the room temperature end connection portion (41) and the outer side of the low temperature Dewar shell (1).

2. The superconducting magnet support structure suitable for cold transportation according to claim 1, characterized in that: During normal operation of the superconducting magnet, the room temperature end connection portion (41) is tightly fixed to the outer side of the low temperature Dewar housing (1).

3. The superconducting magnet support structure suitable for cold transportation according to claim 1, characterized in that: A sealing enhancement tube (7) is also provided on the outer side where the cold shield heat interception ring (42) is connected to the cold shield (2).

4. The superconducting magnet support structure suitable for cold transportation according to claim 3, characterized in that: The sealing reinforcement cylinder (7) is fixed on the cold screen (2).

5. The superconducting magnet support structure suitable for cold transportation according to claim 1, characterized in that: The bellows (5) comprises a bellows connection portion (51) and a bellows expansion tube (52), wherein: A corrugated connecting portion (51), one end of which is fixed to the inner wall of the low-temperature Dewar housing (1), and the other end of which is fixedly connected to the corrugated telescopic tube (52); The bellows expansion tube (52) is placed in the support tube (4) and freely extends toward the room temperature end connection portion (41) of the support tube (4).

6. The superconducting magnet support structure suitable for cold transportation according to claim 5, characterized in that: The portion where the corrugated connection portion (51) is connected to the interior of the low-temperature Dewar shell (1) is fixedly connected by welding.

7. The superconducting magnet support structure suitable for cold transportation according to claim 5, characterized in that: The length of the bellows expansion tube (52) of the bellows (5) is less than the total thickness of the low-temperature Dewar shell (1), the support tube pad (6) and the room-temperature end connection portion (41), but greater than the total thickness of the low-temperature Dewar shell (1) and the support tube pad (6).

8. The superconducting magnet support structure suitable for cold transportation according to claim 1, characterized in that: The length of the cold shield heat interception ring (42) is greater than the sum of the compressed length of the bellows (5) and the length from the inner wall of the low-temperature Dewar shell (1) to the inner wall of the cold shield (2).

9. The superconducting magnet support structure suitable for cold transportation according to claim 1, characterized in that: The support tube (4) is located between the cold end connection tube (43) and the cold shield heat interception ring (42) and is further provided with a lightening groove (45).

10. The superconducting magnet support structure suitable for cold transportation according to any one of claims 1 to 9, characterized in that: The room temperature end connection portion (41) is pressed and fixed to the outside of the low temperature Dewar housing (1) by a plurality of screw rods (8).

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