A superconducting magnet cryogenic system

Abstract

The present invention discloses a superconducting magnet low-temperature system, which comprises, from the inside to the outside, a low-temperature insulation container, a medium-temperature insulation container and a normal-temperature insulation container, the medium-temperature insulation container and the normal-temperature insulation container maintaining a vacuum; a refrigerator is sealed and installed on the normal-temperature insulation container, and a cold head of the refrigerator for cooling is located in the vacuum interlayer of the medium-temperature insulation container and the normal-temperature insulation container; a central cooling ring and a coil clamp assembly are arranged inside the low-temperature insulation container, and the two can realize rapid heat transfer; a cooling component is arranged between the cold head of the refrigerator and the central cooling ring, and a cooling component is arranged between the central cooling ring and the coil clamp assembly, and the cold head of the refrigerator transfers cooling to the coil assembly via the central cooling ring and the coil clamp assembly; the present invention transfers cooling by heat transfer, which saves the amount of low-temperature liquids such as liquid helium compared to the refrigeration method of using liquid helium to reach the superconducting temperature.

Description

Technical Field

[0001] The present invention relates to the field of superconducting equipment, and further to a superconducting magnet cryogenic system. Background Art

[0002] The low-temperature superconducting material NbTi requires operating temperatures around 4K. Liquid helium is currently widely used in the superconducting magnet field for cooling. This cooling method, which involves immersing the superconducting wire in liquid helium containers, provides the required low-temperature environment. This method consumes a significant amount of cryogenic liquid during the cooling process to steady-state operation, and the high cost of liquid helium makes it difficult to reduce costs.

[0003] For those skilled in the art, how to reduce the amount of cryogenic liquid used in the superconducting cryogenic environment refrigeration process is a technical problem that needs to be solved at present. Summary of the Invention

[0004] The present invention provides a superconducting magnet cryogenic system that transfers the cooling capacity of the refrigerator by heat conduction. The refrigeration process does not require cryogenic liquid, thereby reducing costs. The specific solution is as follows:

[0005] A superconducting magnet cryogenic system comprises a low-temperature insulation container, a medium-temperature insulation container and a normal-temperature insulation container which are nested layer by layer, wherein the medium-temperature insulation container and the normal-temperature insulation container maintain a vacuum;

[0006] A refrigerator is sealed and installed on the normal temperature thermal insulation container, and a cold head of the refrigerator for conducting cooling is located in the vacuum interlayer between the medium temperature thermal insulation container and the normal temperature thermal insulation container;

[0007] A central cooling ring and a coil clamp assembly are arranged inside the low-temperature insulation container; a cooling component is arranged between the cold head of the refrigerator and the central cooling ring, and a cooling component is arranged between the central cooling ring and the coil clamp assembly. The cold head of the refrigerator transfers cold energy to the coil assembly via the central cooling ring and the coil clamp assembly.

[0008] Optionally, a double-layer sealing groove is provided on the outer wall of the normal temperature thermal insulation container, and a sealing ring is installed in the sealing groove to maintain the seal between the normal temperature thermal insulation container and the refrigerator.

[0009] Optionally, the central cooling ring is installed on a stainless steel frame, and the central cooling ring is symmetrically distributed at the symmetrical center of the low-temperature insulation container; the central cooling ring and the cold head of the refrigerator are thermally connected through a soft copper wire harness.

[0010] Optionally, the central cooling ring is a copper cylinder; the central cooling ring is composed of two semicircular rings spliced ​​together.

[0011] Optionally, the coil hoop assembly is a copper cylinder; the coil hoop assembly is composed of two semicircular rings; 1 to 2 layers of stainless steel wire or aluminum wire are wound around the outer surface of the coil hoop assembly to tighten the coil hoop assembly to the outer surface of the coil assembly.

[0012] Optionally, heat is transferred between the central cooling ring and the coil clamp assembly through a copper foil connection.

[0013] Optionally, an exhaust pipe is provided at the upper portion of the low-temperature insulation container, and the exhaust pipe passes through the medium-temperature insulation container and the normal-temperature insulation container, and can inject cooling medium into the low-temperature insulation container.

[0014] Optionally, the cold head of the refrigerator includes a primary cold head and a secondary cold head, and the secondary cold head is thermally connected to the central cooling ring;

[0015] The first-level cold head is thermally connected to the medium-temperature insulation container via a heat-saturating wire.

[0016] Optionally, a heat-averaging line is connected between the middle of the pipe wall of the exhaust pipe and the medium-temperature insulation container.

[0017] The present invention provides a superconducting magnet cryogenic system, which comprises, from the inside to the outside, a low-temperature insulation container, a medium-temperature insulation container and a normal-temperature insulation container, the medium-temperature insulation container and the normal-temperature insulation container maintain a vacuum; a refrigerator is sealed and installed on the normal-temperature insulation container, and a cold head of the refrigerator for cooling is located in the vacuum interlayer of the medium-temperature insulation container and the normal-temperature insulation container; a central cooling ring and a coil clamp assembly are arranged inside the low-temperature insulation container, and the two can realize rapid heat transfer; a cooling component is arranged between the cold head of the refrigerator and the central cooling ring, and a cooling component is arranged between the central cooling ring and the coil clamp assembly, and the cold head of the refrigerator transfers cooling to the coil assembly via the central cooling ring and the coil clamp assembly; the present invention transfers cooling by heat transfer, which saves the amount of low-temperature liquids such as liquid helium compared to the refrigeration method of using liquid helium to reach the superconducting temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic structural diagram of the superconducting magnet cryogenic system provided by the present invention;

[0020] Figure 2 This is a partial structural diagram of the refrigerator installed on a normal temperature insulated container;

[0021] Figure 3 Schematic diagram of the structure of the central cooling ring;

[0022] Figure 4 This is a schematic diagram of the cooperation between the center cooling ring and the coil clamp assembly.

[0023] The diagram includes:

[0024] Low-temperature insulation container 1, medium-temperature insulation container 2, equalizing line 21, normal-temperature insulation container 3, double-layer sealing groove 31, refrigerator 4, first-level cold head 41, second-level cold head 42, central cooling ring 5, soft copper wire harness 51, coil clamp assembly 6, copper foil 61, coil assembly 7, exhaust pipe 8. DETAILED DESCRIPTION

[0025] The core of the present invention is to provide a superconducting magnet cryogenic system, which transfers the cooling capacity of the refrigerator by heat conduction. The refrigeration process does not require the use of cryogenic liquid, thereby reducing costs.

[0026] In order to enable those skilled in the art to better understand the technical solution of the present invention, the superconducting magnet cryogenic system of the present invention will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0027] like Figure 1 As shown, it is a structural schematic diagram of the superconducting magnet low-temperature system provided by the present invention; the superconducting magnet low-temperature system of the present invention includes a low-temperature insulation container 1, a medium-temperature insulation container 2 and a normal-temperature insulation container 3 which are nested in layers, all of which play a role in insulation. The low-temperature insulation container 1 can be a 4K container, the medium-temperature insulation container 2 can be a 50K container, and the normal-temperature insulation container 3 can be a 300K container.

[0028] The low-temperature insulated container 1 is located inside the medium-temperature insulated container 2, which is in turn located inside the normal-temperature insulated container 3. The medium-temperature insulated container 2 and the normal-temperature insulated container 3 maintain a vacuum, and both maintain a good sealing effect, forming a cylindrical vacuum interlayer between the medium-temperature insulated container 2 and the normal-temperature insulated container 3.

[0029] A refrigerator 4 is sealed and installed on the normal temperature insulated container 3. The flange of the refrigerator 4 is fixedly installed on the wall of the normal temperature insulated container 3. A part of the refrigerator 4 is located outside the normal temperature insulated container 3, and the main part is inside the normal temperature insulated container 3; the cold head of the refrigerator 4 used for conducting cold is located in the vacuum interlayer between the medium temperature insulated container 2 and the normal temperature insulated container 3, and the cold energy is transferred to the interior of the normal temperature insulated container 3 through the cold head of the refrigerator 4 to reduce the temperature.

[0030] A central cooling ring 5 and a coil clamp assembly 6 are installed inside the cryogenically insulated container 1. Both are made of materials with high thermal conductivity, enabling rapid cooling. A cooling component is installed between the cold head of the refrigerator 4 and the central cooling ring 5, and between the central cooling ring 5 and the coil clamp assembly 6. The cold head of the refrigerator 4 transfers cooling energy to the coil assembly 7 via the central cooling ring 5 and the coil clamp assembly 6.

[0031] The coil assembly 7 is placed inside the low-temperature insulation container 1, and is thermally isolated from the outside world by the three-layer insulation structure of the low-temperature insulation container 1, the medium-temperature insulation container 2 and the normal-temperature insulation container 3. When the refrigerator 4 is working, it gradually transfers cold energy to the central cooling ring 5 and the coil clamp assembly 6 through its cold head, gradually reducing the temperature of the coil assembly 7, and finally making the coil assembly 7 reach the temperature required for superconductivity. The present invention adopts the heat conduction structure of the low-temperature insulation container 1, so that the coil assembly 7 can still achieve excitation and long-term steady-state closed-loop operation under the working conditions without liquid helium immersion, saving the amount of low-temperature liquids such as liquid helium. Compared with the traditional refrigeration structure, the present invention eliminates the cold head container and directly extends the cold head of the refrigerator 4 into the low-temperature insulation container 1, which can effectively reduce the heat leakage of the low-temperature insulation container 1 in the medium-temperature insulation container 2.

[0032] On the basis of the above scheme, Figure 2 The figure shows a partial structural diagram of a refrigerator 4 installed on a normal temperature insulated container 3. In the present invention, a double-layer sealing groove 31 is provided on the outer wall of the normal temperature insulated container 3. Each sealing groove 31 is annular. A sealing ring is installed in each sealing groove 31. The double-layer sealing ring maintains the seal between the normal temperature insulated container 3 and the refrigerator 4 to ensure a vacuum sealing effect.

[0033] Specifically, the central cooling ring 5 in the present invention is installed on a stainless steel frame, which provides support for the central cooling ring 5. The central cooling ring 5 can be in contact with the inner surface of the low-temperature insulation container 1 or separated by a distance; the central cooling ring 5 is symmetrically distributed at the symmetrical center of the low-temperature insulation container 1, such as Figure 1 As shown, the central cooling ring 5 is arranged at the center line of the low-temperature insulation container 1, and the distance from the left and right sides is equal, which can ensure that equal heat is transferred to the left and right sides respectively.

[0034] The central cooling ring 5 and the cold head of the refrigerator 4 are thermally connected through a soft copper wire bundle 51. The soft copper wire bundle 51 has good thermal conductivity and a certain deformation ability, which can offset the stress caused by thermal expansion and contraction when the temperature changes.

[0035] like Figure 3Figure 2 shows the structure of the central cooling ring 5. The central cooling ring 5 is a copper cylinder with a high RRR (residual resistivity, the ratio of room-temperature resistance to low-temperature resistance for the same dimensions) and a certain thickness to ensure good thermal conductivity. The central cooling ring 5 is constructed from two semicircular rings for easy installation and removal.

[0036] Correspondingly, the coil clamp assembly 6 of the present invention is a copper cylinder; the coil clamp assembly 6 is composed of two semicircular rings spliced ​​together, and the structure of the coil clamp assembly 6 is similar to that of the central cooling ring 5, and can achieve similar technical effects.

[0037] The outer surface of the coil clamp assembly 6 is wound with 1 to 2 layers of stainless steel wire or aluminum wire to tighten the coil clamp assembly 6 to the outer surface of the coil assembly 7, so that the coil clamp assembly 6 and the coil assembly 7 fit closely to ensure the effect of heat conduction.

[0038] like Figure 4 The figure shows the cooperation between the central cooling ring 5 and the coil clamp assembly 6. Figure 4 Equivalent to Figure 1 Top view; the center cooling ring 5 and the coil clamp assembly 6 are connected by copper foil 61 to transfer heat. The copper foil 61 is a thin copper sheet that can be deformed to a certain extent to offset the stress caused by temperature changes. Figure 4 As shown, a central cooling ring 5 and multiple coil clamp assemblies 6 are provided. Each coil clamp assembly 6 maintains thermal connection with the central cooling ring 5 through multiple copper foils 61 to achieve heat transfer; the copper foil has good thermal conductivity, which allows the cold to be transferred quickly.

[0039] Based on any of the above technical solutions and their mutual combinations, the present invention provides an exhaust pipe 8 connected to the upper part of the low-temperature insulation container 1, the exhaust pipe 8 is connected to the interior of the low-temperature insulation container 1, the exhaust pipe 8 extends outward through the medium-temperature insulation container 2 and the normal-temperature insulation container 3, and is connected to the gas source, so that the cooling medium can be injected into the low-temperature insulation container 1.

[0040] During the pre-cooling stage, if it is necessary to increase the cooling rate, liquid nitrogen can be injected into the low-temperature insulation container 1 through the exhaust pipe 8, so that the coil assembly 7 is in contact with the liquid nitrogen to complete the process of cooling from 300K to 77K; when liquid helium needs to be injected, the coil assembly 7 is made to complete the process of cooling from 77K to 4K, thereby accelerating the cooling rate; when the coil assembly 7 is excited in the absence of liquid helium, the low-temperature insulation container 1 can be evacuated to below 10Pa through the exhaust pipe 8 in the 40K temperature zone, and the coil assembly 7 operates in a vacuum state.

[0041] The cold head of the refrigerator 4 in the present invention includes a primary cold head 41 and a secondary cold head 42. The secondary cold head 42 is thermally connected to the central cooling ring 5. A low-temperature glue of the type Apizon N is evenly applied between the soft copper wire bundle 51 and the secondary cold head 42 to improve thermal contact. Figure 1 As shown, the first-level cold head 41 is heat-conductingly connected to the medium-temperature insulation container 2 through the heat-averaging line 21, and cools the medium-temperature insulation container 2, so that the medium-temperature insulation container 2 maintains a low temperature of 50K.

[0042] A heat averaging line 21 is connected between the middle of the exhaust pipe 8 and the medium-temperature insulation container 2. The heat averaging line 21 keeps the middle of the exhaust pipe 8 at a low temperature, thereby reducing the impact of the external temperature on the internal temperature of the low-temperature insulation container 1 through the exhaust pipe 8.

[0043] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A superconducting magnet cryogenic system, characterized in that: It comprises a low-temperature thermal insulation container (1), a medium-temperature thermal insulation container (2) and a normal-temperature thermal insulation container (3) which are nested layer by layer, wherein the medium-temperature thermal insulation container (2) and the normal-temperature thermal insulation container (3) maintain a vacuum; A refrigerator (4) is sealed and mounted on the normal temperature insulation container (3), and a cold head of the refrigerator (4) for conducting cooling is located in a vacuum interlayer between the medium temperature insulation container (2) and the normal temperature insulation container (3); A central cooling ring (5) and a coil clamp assembly (6) are provided inside the low-temperature heat-insulating container (1); a cooling component is provided between the cold head of the refrigerator (4) and the central cooling ring (5), and a cooling component is provided between the central cooling ring (5) and the coil clamp assembly (6); the cold head of the refrigerator (4) transfers cooling energy to the coil assembly (7) via the central cooling ring (5) and the coil clamp assembly (6); The central cooling ring (5) and the cold head of the refrigerator (4) are thermally connected via a soft copper wire bundle (51); The central cooling ring (5) is a copper cylinder; the central cooling ring (5) is composed of two semicircular rings spliced ​​together; The coil hoop assembly (6) is a copper cylinder; the coil hoop assembly (6) is composed of two semicircular rings spliced ​​together; the outer surface of the coil hoop assembly (6) is wound with 1 to 2 layers of stainless steel wire or aluminum wire to tighten the coil hoop assembly (6) to the outer surface of the coil assembly (7); The central cooling ring (5) and the coil clamp assembly (6) are connected via copper foil (61) to transfer heat; The central cooling ring (5) is mounted on a stainless steel frame, and the central cooling ring (5) is symmetrically distributed at the symmetrical center of the low-temperature insulation container (1).

2. The superconducting magnet cryogenic system according to claim 1, characterized in that: A double-layer sealing groove (31) is provided on the outer wall of the normal temperature insulation container (3), and a sealing ring is installed in the sealing groove (31) to maintain the seal between the normal temperature insulation container (3) and the refrigerator (4).

3. The superconducting magnet cryogenic system according to claim 1 or 2, characterized in that: An exhaust pipe (8) is provided at the upper portion of the low-temperature thermal insulation container (1), and the exhaust pipe (8) passes through the medium-temperature thermal insulation container (2) and the normal-temperature thermal insulation container (3), and is capable of injecting a cooling medium into the low-temperature thermal insulation container (1).

4. The superconducting magnet cryogenic system according to claim 3, characterized in that: The cold head of the refrigerator (4) comprises a primary cold head (41) and a secondary cold head (42), and the secondary cold head (42) is heat-conductingly connected to the central cooling ring (5); The first-level cold head (41) is heat-conductingly connected to the medium-temperature insulation container (2) via a heat-equalizing line (21).

5. The superconducting magnet cryogenic system according to claim 4, characterized in that: A heat averaging line (21) is connected between the middle portion of the wall of the exhaust pipe (8) and the medium-temperature insulation container (2).

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