阅读说明：本技术 一种无液氦超导磁体系统 (Liquid helium-free superconducting magnet system ) 是由 贝嘉仪 莫磊 王苏聪 梁平 李璟 于 2020-05-15 设计创作，主要内容包括：本发明公开了一种无液氦超导磁体系统,解决了现阶段的超导磁体系统依赖液氦的问题。其技术方案要点是一种无液氦超导磁体系统,包括室温真空筒、超导磁体、低温系统；室温真空筒包括室温外筒、室温内筒、第一室温环和第二室温环；低温系统包括制冷机、第一隔热筒、冷屏筒、第二隔热筒、第一冷屏环和第二冷屏环和支撑环；第二隔热筒一端固定于第一室温环且另一端固定于第一冷屏环；第一隔热筒的一端固定于第一冷屏环且另一端固定于支撑环；制冷机的一级冷头与冷屏筒热连接,制冷机的二级冷头与超导磁体的超导线圈热连接,所述无液氦超导磁体系统内部没有设计液氦杜瓦,对液氦的依赖较小,确漏热量较小,且结构强度较高。(The invention discloses a liquid helium-free superconducting magnet system, which solves the problem that the superconducting magnet system at the present stage depends on liquid helium. The key point of the technical scheme is a liquid-helium-free superconducting magnet system, which comprises a room-temperature vacuum cylinder, a superconducting magnet and a low-temperature system; the room-temperature vacuum cylinder comprises a room-temperature outer cylinder, a room-temperature inner cylinder, a first room-temperature ring and a second room-temperature ring; the low-temperature system comprises a refrigerator, a first heat insulation cylinder, a cold screen cylinder, a second heat insulation cylinder, a first cold screen ring, a second cold screen ring and a support ring; one end of the second heat insulation cylinder is fixed on the first room temperature ring, and the other end of the second heat insulation cylinder is fixed on the first cold shield ring; one end of the first heat insulation cylinder is fixed on the first cold shield ring, and the other end of the first heat insulation cylinder is fixed on the support ring; the primary cold head of the refrigerator is thermally connected with the cold screen cylinder, the secondary cold head of the refrigerator is thermally connected with the superconducting coil of the superconducting magnet, and the liquid helium dewar is not designed in the liquid helium-free superconducting magnet system, so that the dependence on liquid helium is small, the heat leakage is small, and the structural strength is high.)

1. A liquid-helium-free superconducting magnet system comprises a room temperature vacuum cylinder (1), a superconducting magnet (2) and a low temperature system; the room-temperature vacuum cylinder (1) comprises a room-temperature outer cylinder (11), a room-temperature inner cylinder (12), a first room-temperature ring (13) and a second room-temperature ring (14); characterized in that the cryogenic system comprises a refrigerator (3), a first heat-insulating cylinder (41), a cold-shielding cylinder (42) and a second heat-insulating cylinder (43); the superconducting magnet (2), the first heat insulation cylinder (41), the cold shield cylinder (42) and the second heat insulation cylinder (43) are sequentially arranged from inside to outside; a first cold shield ring (44) and a second cold shield ring (45) for mounting the cold shield cylinder (42) are respectively arranged at two ends of the cold shield cylinder (42); one end of the second heat insulation cylinder (43) is fixed on the first room temperature ring (13) and the other end is fixed on the first cold shield ring (44); the end part of the superconducting magnet (2) far away from the first cold shield ring (44) is provided with a support ring (46); one end of the first heat insulation cylinder (41) is fixed on the first cold shield ring (44) and the other end is fixed on the support ring (46); the primary cold head (31) of the refrigerator (3) is thermally connected with the cold shielding barrel (42), and the secondary cold head (32) of the refrigerator (3) is thermally connected with the superconducting coil (22) of the superconducting magnet (2).

2. A liquid-helium-free superconducting magnet system according to claim 1, wherein the superconducting magnet (2) comprises a mounting frame (21) and superconducting coils (22) mounted to the mounting frame (21); the mounting frame (21) comprises support pieces arranged at intervals, and mounting gaps for mounting the superconducting coils (22) are formed between the adjacent support pieces; the supporting piece is also provided with a limit convex ring which is supported on the side wall of the inner ring of the superconducting coil (22).

3. The fluidless helium superconducting magnet system according to claim 2, wherein the support member comprises end support members (211) at both ends and an intermediate support member disposed between the two end support members (211); the mounting rack (21) is characterized in that guide pillars (2113) are fixed on the two end supporting pieces (211), the middle supporting piece is provided with a guide sliding sleeve matched with the guide pillars (2113), and the guide sliding sleeve is fixed on the guide pillars (2113).

4. A liquid-free helium superconducting magnet system according to claim 3 wherein the intermediate support comprises a first support (212); the first support member (212) includes two first support rings (2121) and at least three first support blocks (2122) circumferentially disposed between the two first support rings (2121).

5. The liquid-helium-free superconducting magnet system of claim 2, wherein the cryogenic system further comprises a refrigeration platform (5), a cryogenic sleeve assembly and a heat conduction assembly located within the first thermally insulated cylinder (41) and in communication with the superconducting coils (22); the low-temperature sleeve assembly comprises a first-stage low-temperature sleeve (61) which penetrates through the room-temperature cylinder in a sealing mode and is positioned on the outer side of a first-stage cold head (31) of the refrigerator (3), a second-stage low-temperature sleeve (62) which is positioned on the outer side of a second-stage cold head (32) and is installed on the refrigerating platform (5) at the bottom, and a connecting ring (63) which is used for connecting the first low-temperature sleeve and the second-stage low-temperature sleeve (62) in a; the connecting ring (63) is thermally connected to the cold shield cylinder (42); the heat conduction assembly comprises a primary low-temperature conduction piece (71) thermally connected with the connecting ring (63) and the primary cold head (31) of the refrigerator (3), and a secondary low-temperature conduction piece (72) thermally connected with the secondary cold head (32) of the refrigerator (3) and the refrigeration platform (5).

6. The liquid-helium-free superconducting magnet system according to claim 5, wherein the primary cryogenic sleeve (61) has a mounting bottom ring (612) at the bottom, the connecting ring (63) has a first sealing ring groove at the side facing the mounting bottom ring (612) and a first sealing element (632) is arranged in the first sealing ring groove and is in sealing contact with the mounting bottom ring (612) and the connecting ring (63); the top of second grade low temperature sleeve pipe (62) has the second collar (621) that supplies the installation of go-between (63), second collar (621) towards the side of go-between (63) has seted up the second seal ring groove and is in be equipped with in the second seal ring groove seal butt in second collar (621) with the second sealing member (6211) of go-between (63).

7. The mounting structure of the refrigerator (3) of the liquid-helium-free superconducting magnet (2) according to claim 6, wherein the cold shield cylinder (42) is provided with a copper receiving flange (421) supported on the bottom surface of the mounting bottom ring (612), and the top of the copper receiving flange (421) is provided with a mounting ring groove (4211) for mounting the connecting ring (63); the mounting bottom ring (612) is mounted on the copper bearing flange (421) through a fixing screw (6121); the connecting ring (63) is fixed in the mounting ring groove (4211) through a first screw (631); the connection ring (63) is fixed to the second mounting ring (621) by a second screw (633).

8. The liquid helium free superconducting magnet system of claim 5 wherein the primary cryogenic sleeve (61) has a first bellows section (613); the secondary cryogenic sleeve (62) has a second bellows section (622).

9. The liquid helium free superconducting magnet system of claim 2, wherein the cryogenic system further comprises a first copper strip (81) helically applied to an inner wall of the superconducting coil (22) and a second copper strip (82) helically applied to an outer wall of the superconducting coil (22); the first copper strip (81) and the second copper strip (82) are both thermally connected to the secondary cold head (32) of the refrigerator (3).

10. The liquid-helium-free superconducting magnet system according to claim 9, wherein the first copper strip (81) has a first cooling channel (811), and both ends of the first copper strip (81) are provided with first air joints (812); the second copper strip (82) is provided with a second cooling channel (821), and two ends of the second copper strip (82) are provided with second ventilation joints (822); the outside of the cold screen cylinder (42) is also provided with a third copper strip (83) in a winding manner, the third copper strip (83) is provided with a third cooling channel (831), the two ends of the third copper strip (83) are respectively provided with a third air joint (832), and the third copper strip (83) is thermally connected with a first-stage cold head (31) of the refrigerator (3).

Technical Field

The invention relates to the field of nuclear magnetic resonance instruments, in particular to a liquid-helium-free superconducting magnet system.

Background

Disclosure of Invention

In view of the deficiencies of the prior art, it is an object of the present invention to provide a liquid helium free superconducting magnet system.

The above object of the present invention is achieved by the following technical solutions:

a liquid-helium-free superconducting magnet system comprises a room-temperature vacuum cylinder, a superconducting magnet and a low-temperature system; the room-temperature vacuum cylinder comprises a room-temperature outer cylinder, a room-temperature inner cylinder, a first room-temperature ring and a second room-temperature ring; the low-temperature system comprises a refrigerator, a first heat insulation cylinder, a cold screen cylinder and a second heat insulation cylinder; the superconducting magnet, the first heat insulation cylinder, the cold shield cylinder and the second heat insulation cylinder are sequentially arranged from inside to outside; a first cold shield ring and a second cold shield ring for mounting the cold shield cylinder are respectively arranged at two ends of the cold shield cylinder; one end of the second heat insulation cylinder is fixed on the first room temperature ring, and the other end of the second heat insulation cylinder is fixed on the first cold shield ring; a support ring is arranged at the end part of the superconducting magnet far away from the first cold shield ring; one end of the first heat insulation cylinder is fixed on the first cold shield ring, and the other end of the first heat insulation cylinder is fixed on the support ring; the primary cold head of the refrigerator is thermally connected with the cold shielding barrel, and the secondary cold head of the refrigerator is thermally connected with the superconducting coil of the superconducting magnet.

By adopting the technical scheme, the working principle of the liquid-helium-free superconducting magnet system is as follows: the secondary cold head of the refrigerator has a 4K refrigeration effect, so that the superconducting magnet can be at a temperature below 7K, and a superconducting coil of the superconducting magnet has a condition of realizing a superconducting state at an ambient temperature; the primary cold head of the refrigerator has a 40K refrigeration effect, so that the cold screen cylinder, the first cold screen ring and the second cold screen ring are at a temperature of about 50K; meanwhile, the first heat insulation cylinder and the second heat insulation cylinder reduce the transfer of heat among the superconducting magnet, the cold shielding cylinder and the room temperature cylinder, and the liquid-free helium superconducting magnet system is internally provided with a stepped arrangement of a secondary low temperature (4.2K-8K), a primary low temperature (38K-55K) and a room temperature, so that a superconducting coil of the superconducting magnet is in a superconducting state. In the liquid-free helium superconducting magnet system, the cylindrical supporting structure is adopted, so that the heat leakage quantity in the liquid-free helium superconducting magnet system is reduced, and the structural strength inside the liquid-free helium superconducting magnet system is improved.

The invention further provides that the superconducting magnet comprises a mounting frame and a superconducting coil arranged on the mounting frame; the mounting frame comprises supporting pieces arranged at intervals, and mounting gaps for mounting the superconducting coils are formed between the adjacent supporting pieces; the supporting piece is also provided with a limiting convex ring which is supported on the side wall of the inner ring of the superconducting coil.

By adopting the technical scheme, the production mode of the superconducting magnet is as follows: 1. placing the support member of the mounting frame on the mounting plane; 2. mounting a superconducting coil on a top surface of a support; 3. placing another support member on a surface of the superconducting coil; and repeating the steps 2 and 3 until the installation of all the superconducting coils is completed. The supporting piece is provided with a limiting convex ring which is supported on the side wall of the inner ring of the adjacent superconducting coil, so that the superconducting coil is radially limited in the installation process, and the installation accuracy of the superconducting coil on the installation frame is improved. Compared with a mode of winding a superconducting coil on a framework, the structure and the production mode of the superconducting magnet are beneficial to reducing the loss of the superconducting wire in the superconducting magnet production process.

The frameless structure in the invention does not mean that the superconducting magnet has no structural setting of a support, but is different from the traditional structure that a superconducting wire is wound on the superconducting magnet framework. The traditional superconducting coil is produced by winding a superconducting wire in a skeleton wire groove of a superconducting magnet skeleton, and the superconducting magnet skeleton can always radially support the superconducting coil in the production process, so that the superconducting magnet skeleton has the function of a skeleton. However, the superconducting coil is produced independently through a die on a winding machine, demoulding is carried out after winding is completed, and the mounting frame does not provide any support for forming the superconducting coil, so that the mounting frame does not have the function of a framework of the coil. Although the mounting frame is also provided with a limit convex ring supported on the side wall of the inner ring of the superconducting coil, the limit convex ring is only convenient for positioning the superconducting coil on the supporting piece for limiting.

The invention further provides that the support member comprises end support members at both ends and a middle support member arranged between the two end support members; the mounting frame is two the tip supporting member is fixed with the direction pillar, middle supporting member have with direction pillar complex direction sliding sleeve, the direction sliding sleeve is fixed in the direction pillar.

Through adopting above-mentioned technical scheme, when installing superconducting coil to the mounting bracket, place superconducting coil on an end support, middle support slides through the cooperation of guide sliding sleeve and guide pillar and installs the top to superconducting coil. The installation mode facilitates the installation and the positioning of the middle supporting piece, so that the middle supporting piece is not easy to deviate in the installation process.

The invention further provides that the intermediate support comprises a first support; the first supporting member comprises two first supporting rings and at least three first supporting blocks circumferentially arranged between the two first supporting rings.

By adopting the technical scheme, the positions of the superconducting coils in the superconducting magnet are fixed, and the distance between two adjacent superconducting coils is different, so that the structure of the first supporting piece can be adopted when the distance between two adjacent superconducting coils is larger. The first support member includes two first support rings and at least three first support blocks, which are lighter in weight than a solid support member structure.

The invention is further configured that the cryogenic system further comprises a refrigeration platform, a cryogenic sleeve assembly and a heat conduction assembly, wherein the refrigeration platform, the cryogenic sleeve assembly and the heat conduction assembly are positioned in the first heat insulation cylinder and are connected with the superconducting coil; the low-temperature sleeve assembly comprises a first-stage low-temperature sleeve which penetrates through the room-temperature cylinder in a sealing mode and is positioned on the outer side of a first-stage cold head of the refrigerating machine, a second-stage low-temperature sleeve which is positioned on the outer side of a second-stage cold head and is installed on the refrigerating platform at the bottom, and a connecting ring which is used for connecting the first low-temperature sleeve and the second low-temperature sleeve in a sealing mode; the connecting ring is thermally connected with the cold shield cylinder; the heat conduction assembly comprises a primary low-temperature conduction piece thermally connected with the connecting ring and the primary cold head of the refrigerator and a secondary low-temperature conduction piece thermally connected with the secondary cold head of the refrigerator and the refrigeration platform.

By adopting the technical scheme, the matching of the first-stage low-temperature sleeve, the second-stage low-temperature sleeve and the connecting ring in the low-temperature sleeve assembly enables the installation cavity of the refrigerator to be isolated from the inner cavity of the superconducting magnet, the inner cavity of the superconducting magnet can keep a vacuum state in the dismounting and mounting process of the refrigerator, the superconducting magnet is kept in a low-temperature state after the refrigerator is dismounted, and the energy loss caused in the dismounting and maintenance process of the refrigerator is reduced. The primary cold head of the refrigerator can keep the temperature of the cold shielding barrel at about 50K through the primary low-temperature conducting piece and the connecting ring, and the secondary cold head of the refrigerator is connected with the refrigerating platform through the secondary low-temperature conducting piece, so that the temperature of the refrigerating platform can be kept below 7K, and the superconducting state of a superconducting coil in the liquid-helium-free superconducting magnet is guaranteed.

The invention is further provided that the bottom of the primary low-temperature sleeve is provided with an installation bottom ring, the connecting ring is provided with a first sealing ring groove on the side surface facing the installation bottom ring, and a first sealing element which is in sealing butt joint with the installation bottom ring and the connecting ring is arranged in the first sealing ring groove; the top of second grade low temperature sheathed tube has the confession the second collar of go-between installation, the second collar is in orientation the sealed annular of second has been seted up to the side of go-between and has just been in be equipped with sealed butt in the sealed annular of second in the second collar with the second sealing member of go-between.

By adopting the technical scheme, the first sealing element is in sealing and abutting connection between the mounting bottom ring and the connecting ring, and sealing between the mounting bottom ring and the connecting ring is realized. The provision of the first sealing ring groove facilitates the positional mounting of the first seal on the connecting ring. The second sealing element is in sealing abutting connection between the second mounting ring and the connecting ring, and sealing between the second mounting ring and the connecting ring is achieved. The provision of the second seal ring groove facilitates the secure mounting of the second seal on the second mounting ring.

The invention is further provided that the cold shield cylinder is provided with a copper receiving flange supported on the bottom surface of the mounting bottom ring, and the top of the copper receiving flange is provided with a mounting ring groove for mounting the connecting ring; the mounting bottom ring is mounted on the copper bearing flange through a fixing screw; the connecting ring is fixed in the mounting ring groove through a first screw; the connecting ring is fixed to the second mounting ring by a second screw.

By adopting the technical scheme, the installation of the first-stage low-temperature sleeve, the second-stage low-temperature sleeve and the connecting ring can be facilitated by the setting of the bearing copper flange, so that the first-stage low-temperature sleeve, the second-stage low-temperature sleeve and the connecting ring can be conveniently taken down from the superconducting magnet system when the whole of the subsequent liquid-helium-free superconducting magnet system is disassembled.

The invention further provides that the primary cryogenic sleeve has a first bellows section; the secondary cryogenic bushing has a second bellows section.

Through adopting above-mentioned technical scheme, one-level low temperature sheathed tube bottom is installed on accepting the flange, and the temperature of this department keeps about 50K, and one-level low temperature sheathed tube top is with external contact, and the temperature of this department keeps about 290K for there is obvious temperature difference in its direction of height in the lateral wall of whole one-level low temperature sheathed tube, and one-level low temperature sheathed tube is from last to lower temperature gradually reducing. Because the top of one-level cryogenic cannula installs on room temperature neck pipe, the bottom is installed on accepting the flange, after the refrigerator starts, there is the difference in temperature at one-level cryogenic cannula's both ends, one-level cryogenic cannula's bottom is by cold shrink, the shrink force is along with one-level cryogenic cannula's pipe wall transmission to one-level cryogenic cannula's top, make one-level cryogenic cannula's top also take place the internal contraction, the setting for of first bellows section can weaken the power of the internal contraction in one-level cryogenic cannula's top, the bellows allows the radial movement in the certain extent simultaneously, help keeping one-level cryogenic cannula's top and room temperature neck pipe, refrigerator adapter flange's connection stability.

The second corrugated pipe section arranged in the secondary low-temperature sleeve pipe can help to weaken the force of inward contraction of the top of the secondary low-temperature sleeve pipe caused by different temperatures at two ends of the secondary low-temperature sleeve pipe, and helps to stabilize the installation of the secondary low-temperature sleeve pipe on the connecting ring and the refrigeration platform. Meanwhile, the secondary low-temperature sleeve is provided with a second corrugated pipe section, so that the second corrugated pipe section can be compressed in the installation process, and the secondary low-temperature sleeve and the connecting ring can be conveniently and fixedly installed.

The invention is further arranged that the low-temperature system also comprises a first copper strip spirally attached to the inner wall of the superconducting coil and a second copper strip spirally attached to the outer wall of the superconducting coil; the first copper strip and the second copper strip are both in thermal connection with a secondary cold head of the refrigerator.

Through adopting above-mentioned technical scheme, through first copper strips and second copper strips, can take off the heat that superconducting magnet produced through the one-level cold head of refrigerator. Because the traditional conduction type cooling superconducting magnet only winds the copper strip on the outer surface of the superconducting coil and connects the copper strip with the refrigeration platform, the superconducting magnet is cooled, but because the superconducting coil is brushed with a layer of thinner epoxy resin on each layer in the production process, the part of the superconducting coil positioned on the inner side often cannot reach a more ideal low-temperature state. The superconducting magnet in this application does not set up the skeleton texture for the second copper strips can contact with superconducting coil's inner wall, thereby promotes the cooling effect to superconducting coil.

The invention is further provided that the first copper strip is provided with a first cooling channel, and two ends of the first copper strip are provided with first ventilation joints; the second copper strip is provided with a second cooling channel, and two ends of the second copper strip are provided with second ventilation joints; and a third copper strip is also arranged on the outer side of the cold shielding cylinder in a winding manner, the third copper strip is provided with a third cooling channel, third air connectors are arranged at two ends of the third copper strip, and the third copper strip is thermally connected with a primary cold head of the refrigerator.

By adopting the technical scheme, the first cooling channel in the first copper strip, the second cooling channel in the second copper strip and the third cooling channel in the third copper strip are set to be used for primarily cooling the liquid-helium-free superconducting magnet system, and liquid nitrogen is injected into the first cooling channel, the second cooling channel and the third cooling channel to reduce the temperature of the superconducting coil and the cold shielding cylinder in the superconducting magnet system to 77K; and then, because the two ends of the first copper strip and the second copper strip are connected with the secondary cold head of the refrigerator, and the two ends of the third copper strip are connected with the cold head and the refrigerator, the superconducting coil is continuously reduced to below 7K through the refrigerator. The structure is set, so that the initial cooling time of the liquid-free helium superconducting magnet system is saved, and the electric energy consumed on the refrigerating machine is saved.

In summary, the invention includes at least one of the following beneficial technical effects:

1. a liquid-helium-free superconducting magnet system comprises a room temperature vacuum cylinder, a superconducting magnet and a cryogenic system, wherein the cryogenic system comprises a refrigerator, a first heat insulation cylinder, a cold screen cylinder and a second heat insulation cylinder, a secondary cold head of the refrigerator enables the superconducting magnet to be at a temperature below 7K, a primary cold head of the refrigerator enables the cold screen cylinder, a first cold screen ring and a second cold screen ring to be at a temperature of 50K, meanwhile, the first heat insulation cylinder and the second heat insulation cylinder are set, so that the heat transfer among the superconducting magnet, the cold screen cylinder and the room temperature cylinder is reduced, a secondary low temperature (4.2K-7K), a primary low temperature (38K-55K) and a room temperature ladder arrangement are arranged in the liquid-helium-free superconducting magnet system, and a superconducting coil of the superconducting magnet is in a superconducting state;

2. the superconducting magnet comprises a mounting frame and a superconducting coil, the framework is removed, and the loss of a superconducting wire in the production process of the superconducting magnet is facilitated;

3. the installation cavity of the refrigerator is isolated from the inner cavity of the superconducting magnet by arranging the primary low-temperature sleeve, the secondary low-temperature sleeve and the connecting ring which is hermetically connected between the primary low-temperature sleeve and the secondary low-temperature sleeve, so that the inner cavity of the superconducting magnet can be kept in a vacuum state in the process of dismounting and mounting the refrigerator, the superconducting magnet can be kept in a low-temperature state after the refrigerator is dismounted, and the energy loss caused in the process of dismounting and maintaining the refrigerator is reduced;

4. the first-stage low-temperature sleeve is provided with a first corrugated pipe section, and the second-stage low-temperature sleeve is provided with a second corrugated pipe section, so that the mounting stability of the first-stage low-temperature sleeve on a room-temperature neck pipe and a refrigerator adapter flange is facilitated, and the mounting stability of the second-stage low-temperature sleeve on a refrigeration platform and a connecting ring is facilitated;

5. the low-temperature system also comprises a first copper strip and a second copper strip, so that the inner wall and the outer wall of the superconducting coil can be synchronously cooled, and the cooling effect of the superconducting coil is improved;

6. through set up first cooling channel on first copper strips, set up second cooling channel on the second copper strips, set up third cooling channel on the third copper strips, thereby in no liquid helium superconducting magnet system's primary cooling, can adopt to first cooling channel, let in liquid nitrogen in second cooling channel and the third cooling channel, make superconducting coil and cold shield section of thick bamboo's temperature reduce earlier to 77K, rethread refrigerator cooling superconducting coil and cold shield section of thick bamboo, make it reach the design temperature, the settlement of this kind of structure helps reducing the initial cooling time of no liquid helium superconducting magnet system and reduces the power consumption of refrigerator in no liquid helium superconducting magnet system's primary cooling.

Drawings

Fig. 1 is a schematic diagram of the structure of a liquid helium free superconducting magnet system.

Fig. 2 is a schematic view of the structure of a room temperature neck tube of a room temperature vacuum cylinder.

Fig. 3 is a schematic diagram of a superconducting magnet.

Fig. 4 is a schematic cross-sectional view of a superconducting magnet.

Fig. 5 is an enlarged view at a in fig. 4.

Fig. 6 is a schematic structural view of the first supporting member.

Fig. 7 is an enlarged view at B in fig. 4.

Fig. 8 is a schematic structural view of the second support member.

Fig. 9 is an enlarged view at C in fig. 3.

Fig. 10 is a schematic configuration diagram of the refrigerator.

Fig. 11 is a schematic view of the refrigerator mounted on a room temperature vacuum drum.

FIG. 12 is a schematic view of the installation of the copper receiving flange in the cold shield cylinder.

Fig. 13 is an enlarged view at D in fig. 11.

Fig. 14 is an enlarged view at E in fig. 11.

Fig. 15 is an enlarged view at F in fig. 11.

FIG. 16 is a schematic diagram of the mating of the superconducting coils, the first copper strip, and the second copper strip.

FIG. 17 is a schematic view of the mating of the cold platen and the third copper strip.

In the figure: 1. a room temperature vacuum cylinder; 11. an outer cylinder at room temperature; 12. inner cylinder at room temperature; 13. a first room temperature ring; 14. a second room temperature ring; 15. a room temperature neck tube; 151. installing a ring at room temperature; 1511. a third seal member; 2. a superconducting magnet; 21. a mounting frame; 211. an end support; 2111. a first ring groove; 2112. a first limit convex ring; 2113. a guide pillar; 212. a first support member; 2121. a first support ring; 21211. a first support groove; 21212. a second limit convex ring; 21213. a first guide sliding sleeve; 2122. a first support block; 2123. a connecting plate; 213. a second support member; 2131. a third limit convex ring; 2132. a second guide sliding sleeve; 214. a support plate; 2141. fixing grooves; 2142. connecting grooves; 215. a fixing ring; 22. a superconducting coil; 3. a refrigerator; 31. a first-stage cold head; 32. a second-stage cold head; 33. a transfer flange; 331. a fourth screw; 41. a first heat insulation cylinder; 42. a cold shield cylinder; 421. receiving a copper flange; 4211. mounting a ring groove; 422. an inner cold shield cylinder; 43. a second heat insulation cylinder; 44. a first cold shield ring; 45. a second cold shield ring; 46. a support ring; 5. a refrigeration platform; 51. a refrigeration support; 61. a first-stage low-temperature sleeve; 611. a first mounting ring; 6111. a third screw; 6112. a fourth seal member; 612. mounting a bottom ring; 6121. a set screw; 613. a first bellows section; 62. a second-stage low-temperature sleeve; 621. a second mounting ring; 6211. a second seal member; 622. a second bellows section; 63. a connecting ring; 631. a first screw; 632. a first seal member; 633. a second screw; 71. a primary low temperature conductor; 72. a secondary low temperature conductor; 81. a first copper strip; 811. a first cooling channel; 82. a second copper strip; 821. a second cooling channel; 83. a third copper strip; 831. a third cooling channel.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

Referring to fig. 1, the liquid helium-free superconducting magnet system disclosed by the invention comprises a room temperature vacuum cylinder 1, a superconducting magnet 2 and a cryogenic system. In the present embodiment, the liquid helium-free superconducting magnet system is applied to a nuclear magnetic resonance apparatus.

Referring to fig. 1, a room temperature vacuum cylinder 1 includes a room temperature outer cylinder 11, a room temperature inner cylinder 12, a first room temperature ring 13, and a second room temperature ring 14. The room temperature vacuum cylinder 1 may be made of stainless steel. Since the liquid helium-free superconducting magnet system is applied to a nuclear magnetic resonance apparatus, the axis of the room-temperature vacuum cylinder 1 is arranged horizontally. The room temperature vacuum cylinder 1 is also provided with a vacuumizing joint for vacuumizing the room temperature vacuum cylinder 1. Since the vacuum pumping joint belongs to the common technology in the field of nuclear magnetic resonance instruments, it is not described in detail in this embodiment.

Referring to fig. 2, a room temperature neck 15 is provided on the top of the outer wall of the room temperature outer tub 11. The room temperature neck tube 15 is in the shape of a hollow circular tube and is arranged in the vertical direction. The bottom of the room temperature neck tube 15 is in sealing welding fit with the room temperature cylinder. The top of the room temperature neck tube 15 is provided with a room temperature installation ring 151, the cross section of the room temperature installation ring 151 in the vertical direction is rectangular, and the top edge of the room temperature neck tube 15 is connected to the middle of the bottom surface of the room temperature installation ring 151.

Referring to fig. 3 and 4, the superconducting magnet 2 includes a mount 21 and seven superconducting coils 22 mounted on the mount 21. In this embodiment, the superconducting coils 22 are wound by a winding machine, and each layer of the superconducting wires is formed by brushing a layer of resin, so that the superconducting coils 22 are cylindrical and are not easily scattered. Adjacent superconducting coils 22 are connected by superconducting joints.

The mounting frame 21 includes eight spaced apart supports. A mounting gap for mounting the superconducting coil 22 is formed between the adjacent supports. Wherein the supports include end supports 211 at both ends of the mounting frame 21 and six intermediate supports between the two end supports 211.

Referring to fig. 4 and 5, the end support 211 is an annular plate structure. The two end supporting pieces 211 are provided with first ring grooves 2111 for placing the superconducting coils 22 on opposite side surfaces of the two end supporting pieces, and first limiting convex rings 2112 for limiting the radial sliding of the superconducting coils 22 are formed at the inner ring edges of the first ring grooves 2111.

Four guide struts 2113 located outside the superconducting coil 22 are further provided between the two end supports 211, and the four guide struts 2113 are uniformly arranged circumferentially with the central axis of the superconducting coil 22. The end support 211 has post insertion holes into which four guide posts 2113 are inserted, the post insertion holes penetrating the end support 211. When assembling the mount 21 and the superconducting coil 22, the end portions of the guide legs 2113 are inserted into the leg insertion holes of the end support 211 and fixed by welding. In this embodiment, the guide post 2113 is a hollow aluminum alloy tube.

Referring to fig. 4, the six intermediate supporting members are of two types, a first supporting member 212 and a second supporting member 213. In this embodiment, the six intermediate supporting members are, from bottom to top, a first supporting member 212, a second supporting member 213, a first supporting member 212, and a first supporting member 212 in this order.

Referring to fig. 6, the first supporting member 212 includes two parallel first supporting rings 2121 and eight first supporting blocks 2122 uniformly supported circumferentially to the two first supporting rings 2121. The first support ring 2121 is formed by welding multiple arc sections, and the first support block 2122 is a hollow square tube structure, and an axis of the first support block 2122 is parallel to an axis direction of the superconducting coil 22.

Referring to fig. 4 and 7, the first supporting ring 2121 has a first supporting groove 21211 at an end surface facing the first supporting block 2122, into which an end edge of the first supporting block 2122 is fitted. The end surface of the first support ring 2121 facing away from the first support block 2122 is circumferentially provided with a second limit convex ring 21212 for limiting the radial sliding of the superconducting coil 22.

Referring to fig. 4 and 6, the outer sidewalls of the two first support rings 2121 are each provided with a first guide runner 21213 that cooperates with four guide struts 2113. After the first support member 212 is positioned on the guide post 2113 by the first guide runner 21213, the first support member 212 is positioned on the mounting bracket 21 by welding the first guide runner 21213 and the guide post 2113.

Referring to fig. 4 and 8, the second support member 213 has a solid ring structure. And third limiting convex rings 2131 for limiting the radial sliding of the superconducting magnet 2 are arranged on the two end faces of the second supporting piece 213 close to the edge of the inner ring.

The second support element 213 is provided with a second guide sleeve 2132 on its outer wall, which cooperates with four guide struts 2113. After the second supporting member 213 is installed and positioned on the guide post 2113 by the second sliding guide sleeve 2132, the second supporting member 213 is installed and positioned on the guide post 2113 by welding the second sliding guide sleeve 2132 and the guide post 2113.

Referring to fig. 3, the mounting bracket 21 is further provided with eight support plates 214 between the two end supports 211. The support plate 214 is parallel to the axis of the superconducting coil 22 and the end faces of the support plate 214 are arranged radially. Wherein, eight supporting plates 214 are in a group of two by two, and two supporting plates 214 of each group of supporting plates 214 are respectively located at two sides of the guiding support 2113.

Referring to fig. 3 and 9, the mounting frame 21 further has four fixing rings 215 fixed to the outer sides of the eight supporting plates 214. The four fixing rings 215 are respectively arranged on the upper part and the lower part of the mounting frame 21 in pairs. The upper and lower portions of the support plate 214 are each provided with a fixing groove 2141 in which the two fixing rings 215 of the same group are mounted. The two fixing rings 215 of the same group are respectively attached and welded to the top surface or the bottom surface of the fixing groove 2141. In which, one end of the fixing ring 215 is opened with a fracture, and after being mounted to the fixing groove 2141 of the support plate 214, the fixing ring 215 is welded at the fracture to maintain the ring structure of the fixing ring 215.

Referring to fig. 3, in order to improve the structural strength of the first supporting member 212, the first supporting member 212 is further provided with connecting plates 2123 corresponding to the supporting plates 214 one to one in a radial direction between the two first supporting rings 2121. The connecting plate 2123 is radially arranged and welded between the two first support rings 2121. The support plate 214 has a connection groove 2142 into which the connection plate 2123 is fitted, and the connection plate 2123 is welded to the support plate 214.

Referring to fig. 1, the cryogenic system includes a refrigerator 3, a cold shield inner cylinder 422 located inside the superconducting magnet 2, a first heat shield cylinder 41 located outside the superconducting magnet 2, a cold shield cylinder 42 located outside the first heat shield cylinder 41, a second heat shield cylinder 43 located outside the cold shield cylinder 42, a refrigeration platform 5 located inside the first heat shield cylinder 41 and above the superconducting magnet 2, a cryogenic sleeve assembly, and a heat conduction assembly.

Referring to fig. 10, the refrigerator 3 has a primary cold head 31, a secondary cold head 32, and an adapter flange 33. The first-stage cold head 31 can achieve the refrigerating effect of 50K, and the second-stage cold head 32 can achieve the refrigerating effect of 4.2K.

Referring to fig. 1, the room temperature inner cylinder 12, the superconducting magnet 2, the first heat insulation cylinder 41, the cold shield cylinder 42, the second heat insulation cylinder 43, and the outdoor outer cylinder are sequentially arranged from inside to outside, and a gap is formed between each two of the two cylinders. The two ends of the cold shield cylinder 42 are respectively provided with a first cold shield ring 44 and a second cold shield ring 45 for installing the cold shield cylinder 42. The inner sides of the first cold shield ring 44 and the second cold shield ring 45 are welded and fixed on the outer wall of the room-temperature inner barrel 12. Wherein, one end of the second heat insulation cylinder 43 is fixed on the first room temperature ring 13, and the other end is fixed on the first cold shield ring 44; the superconducting magnet 2 is provided with a support ring 46 at an end portion far away from the first cold shield ring 44, and one end of the first heat insulation cylinder 41 is fixed to the first cold shield ring 44 and the other end is fixed to the support ring 46. The two ends of the inner cold shield cylinder 422 are respectively connected to the first cold shield ring 44 and the second cold shield ring 45.

Referring to fig. 1, the refrigeration platform 5 has refrigeration brackets 51 respectively fixed to ends of the superconducting magnet 2, so that the refrigeration platform 5 can be horizontally fixed above the superconducting magnet 2.

Referring to fig. 11 and 12, the cold shield cylinder 42 has a copper receiving flange 421 on its top side wall. The outer edge of the copper receiving flange 421 is fixed to the cold shield cylinder 42 by brazing, a flange through hole is formed in the inner side of the copper receiving flange 421, and a mounting ring groove 4211 is formed in the top surface of the copper receiving flange along the edge of the flange through hole. Wherein the copper receiving flange 421 is arranged coaxially with the room temperature neck 15.

Referring to fig. 11 and 13, the cryogenic sleeve assembly includes a primary cryogenic sleeve 61, a secondary cryogenic sleeve 62, and a connecting ring 63 sealingly connected between the primary cryogenic sleeve 61 and the secondary cryogenic sleeve 62.

Referring to fig. 11 and 14, a primary cryogenic sleeve 61 is provided inside the room temperature neck 15, and the primary cryogenic sleeve 61 is made of a material having a low thermal conductivity. The top of the primary cryogenic sleeve 61 is provided with a first mounting ring 611. The first mounting ring 611 has a rectangular cross section in the vertical direction. The top of the primary cryogenic sleeve 61 is attached to the bottom middle of the first mounting ring 611.

The outer side of the bottom surface of the first mounting ring 611 is attached to the top surface of the room temperature mounting ring 151 of the room temperature neck 15, and the first mounting ring 611 and the room temperature mounting ring 151 are fixedly connected by six third screws 6111. Six third screws 6111 are arranged circumferentially and uniformly. The first mounting ring 611 has a third counterbore matched with the third screw 6111, and the room temperature mounting ring 151 has a third threaded hole matched with the third screw 6111.

The room temperature installation ring 151 is provided with a third sealing ring groove on the top surface thereof, and a third sealing member 1511 is arranged in the third sealing ring groove. When the primary cryogenic sleeve 61 is mounted to the room temperature neck 15, the third seal 1511 abuts between the room temperature mounting ring 151 and the first mounting ring 611, thereby sealing therebetween. And the third sealing ring groove is positioned on the inner side of the third threaded hole.

Referring to fig. 11 and 15, the adapter flange 33 of the refrigerator 3 is fixedly connected to the first mounting ring 611 by six fourth screws 331. The six fourth screws 331 are circumferentially uniformly arranged. Wherein the adaptor flange 33 has a fourth counter bore that mates with the fourth screw 331, and the first mounting ring 611 has a fourth threaded bore that threadedly mates with the fourth screw 331.

The first mounting ring 611 has a fourth ring groove formed on the top surface thereof, and a fourth sealing element 6112 is disposed in the fourth ring groove. When the refrigerator 3 is mounted on the first-stage cryogenic jacket 61, the fourth sealing member 6112 is in sealing contact with the first mounting ring 611 and the adapter flange 33, so that sealing between the first mounting ring 611 and the adapter flange 33 is realized. And the fourth sealing ring groove is positioned on the outer side of the fourth threaded hole.

In this embodiment, the third seal 1511 and the fourth seal 6112 are both made of a polymer rubber material.

Referring to fig. 11 and 13, the bottom edge of the primary cryogenic casing 61 has an inwardly extending mounting collar 612 that fits over the top surface of the copper receiving flange. The mounting bottom ring 612 and the receiving copper flange 421 are connected by six set screws 6121. Six fixing screws 6121 are circumferentially and uniformly arranged. The mounting bottom ring 612 has a fixing counter bore matched with the fixing screw 6121, and the receiving copper flange 421 has a fixing threaded hole matched with the fixing screw 6121 in a threaded manner.

The attachment ring 63 is mounted in the mounting ring groove 4211 of the receiving flange by six first screws 631. The six first screws 631 are circumferentially uniformly arranged. The connecting ring 63 has a first counterbore that mates with the first screw 631, and the receiving copper flange 421 has a first threaded hole that threadedly mates with the first screw 631.

The connection ring 63 is provided with a first seal ring groove in the circumferential direction of the top surface thereof, and a first seal 632 is provided in the first seal ring groove. Wherein the first seal 632 is in sealing abutment with the connection ring 63 and the mounting base ring 612 to achieve sealing therebetween.

The bottom of the secondary cryogenic sleeve 62 is hermetically connected to the refrigeration platform 5. In this embodiment, the bottom of the secondary cryogenic sleeve 62 is hermetically welded to the refrigerated platform 5.

The top of secondary cryogenic jacket 62 has a second mounting ring 621. The vertical cross-section of the second mounting ring 621 is rectangular, and the top of the secondary low temperature bushing 62 is connected to the inside of the bottom surface of the second mounting ring 621. The top surface of the second mounting ring 621 is attached to the bottom surface of the connection ring 63, and the connection ring 63 and the second mounting ring 621 are connected by six second screws 633. The six second screws 633 are circumferentially uniformly arranged. The connection ring 63 has a second counterbore to mate with the second screw 633 and the second mounting ring 621 has a second threaded hole to mate with the second screw 633.

The first sealing ring groove is positioned between the first counter bore and the second counter bore.

The top surface of the second mounting ring 621 is provided with a second sealing ring groove outside the second threaded hole, and a second sealing element 6211 is provided in the second sealing ring groove. The second sealing element 6211 sealingly abuts between the attachment ring 63 and the second mounting ring 621, effecting a seal therebetween.

In this embodiment, the first seal 632 and the second seal 6211 are both made of indium. High purity indium is a good quality low temperature seal. In this embodiment, 99.99% indium is used for both the first seal 632 and the second seal 6211.

Referring to fig. 11, in order to reduce the interference of the temperature difference between both ends of the primary cryogenic sleeve 61 with the installation of the primary cryogenic sleeve 61, the primary cryogenic sleeve 61 has a first bellows section 613. To reduce interference of the temperature differential across the secondary cryosleeve 62 with the installation of the secondary cryosleeve 62, the secondary cryosleeve 62 has a second bellows section 622.

Referring to fig. 11, the heat transfer assembly includes a primary low temperature conductor 71 and a secondary low temperature conductor 72. The primary cryogenic conductor 71 is thermally connected to the connection ring 63 and the primary coldhead 31 of the refrigerator 3, so that the primary coldhead 31 of the refrigerator 3 can carry heat on the cold shield 42 away from the liquid-helium-free superconducting magnet 2. Wherein, the primary low temperature conductor 71 and the connecting ring 63 are thermally connected through a copper strip.

The secondary cryogenic conductor 72 is thermally connected to the refrigeration platform 5 and the primary cold head 31 of the refrigerator 3. The secondary low-temperature conductor 72 is screwed to the refrigeration platform 5, so that the primary coldhead 31 of the refrigerator 3 can carry away heat generated by the superconducting coil 22 of the liquid-helium-free superconducting magnet 2 from the superconducting magnet 2.

Referring to fig. 16, the cryogenic system further includes a first copper strip 81 spirally attached to the inner wall of the superconducting coil 22 and a second copper strip 82 spirally attached to the outer wall of the superconducting coil 22; both ends of the first copper belt 81 and both ends of the second copper belt 82 are mounted on the refrigeration platform 5. The first copper strip 81 is provided with a first cooling channel 811, and two ends of the first copper strip 81 are provided with first ventilation joints; the second copper strip 82 has a second cooling passage 821, and both ends of the second copper strip 82 are provided with second vent joints.

Referring to fig. 17, the cryogenic system further includes a third copper strip 83 helically wound around the outside of the cold shield cylinder 42. Third copper strip 83 has a third cooling passage 831. And third air connectors are arranged at two ends of the third copper strip 83.

The first copper strip 81, the second copper strip 82 and the third copper strip 83 can be used for primarily cooling the liquid-helium-free superconducting magnet system, liquid nitrogen is injected into the first cooling channel 811 of the first copper strip 81, the second cooling channel 821 of the second copper strip 82 and the third cooling channel 831 of the third copper strip 83, so that the temperature of the superconducting coil 22 and the temperature of the cold screen cylinder 42 in the superconducting magnet system are reduced to 77K, then, the two ends of the first copper strip 81 and the second copper strip 82 are fixed on the refrigeration platform 5, the two ends of the third copper strip 83 are fixed on the bearing copper flange 421, and the superconducting coil 22 is reduced to 4.2K through the refrigerating machine 3.

The implementation principle of the above-mentioned liquid-helium-free superconducting magnet system is as follows: the secondary cold head 32 of the refrigerator 3 has a refrigerating effect of 4K, and can make the superconducting magnet 2 at a temperature below 4.2K, so that the superconducting coil 22 of the superconducting magnet 2 has a condition of realizing a superconducting state at an ambient temperature; the primary cold head 31 of the refrigerator 3 has a refrigeration effect of 40K, so that the cold screen cylinder 42, the first cold screen ring 44 and the second cold screen ring 45 are at a temperature of about 50K; meanwhile, the first heat insulation cylinder 41 and the second heat insulation cylinder 43 reduce the heat transfer among the superconducting magnet 2, the cold shield cylinder 42 and the room temperature cylinder, and the step arrangement of 4.2K, 50K and room temperature is provided inside the above-mentioned no-liquid-helium no-skeleton superconducting magnet 2 system, which helps to make the superconducting magnet 2 at the set temperature and the superconducting coil 22 in the superconducting state.

The embodiments of the present invention are preferred embodiments of the present invention, and the scope of the present invention is not limited by these embodiments, so: all equivalent changes made according to the structure, shape and principle of the invention are covered by the protection scope of the invention.