Conduction cold superconducting magnet

Abstract

The utility model relates to the technical field of superconducting magnets, in particular to a conduction cold superconducting magnet. A conduction cold superconducting magnet comprises an outer shell which is a Dewar container, and is characterized in that a refrigerating machine, a cold shield, a cooling plate, a current lead and a superconducting coil are arranged in the outer shell, the superconducting coil is arranged in the cooling plate, the two ends of the superconducting coil are connected with superconducting connectors respectively, and the superconducting connectors are connected with the cold shield and the outer shell through the current lead respectively; the cooling plate is connected with a refrigerator through a cold guide assembly. Compared with the prior art, the conduction cold superconducting magnet is provided, heat insulation is mainly carried out on the superconducting magnet through the large-thermal-resistance high-temperature superconducting current lead, the superconducting connector is completely located in a superconducting state area, and therefore the superconducting state area does not generate heat.

Description

Technical Field

[0001] The utility model relates to the technical field of superconducting magnets, in particular to a conductive cold superconducting magnet. Background Art

[0002] Superconducting magnets are devices that use the special property of superconducting materials with zero resistance to generate strong magnetic fields. They can achieve zero dissipation, high energy efficiency, and occupy less space than traditional magnets. The magnetic field they generate has the characteristics of high stability, high uniformity, and high field strength, and is used in many fields. For example, in the medical field: nuclear magnetic resonance (NMR), medical imaging (MRI), and special medical research, mainly used in medical diagnosis, biological reactions and biological effects under strong magnetic fields, etc.; in the industrial field: magnetic pulling of single crystals, superconducting power, control of fluids, high-energy accelerators, etc.

[0003] The superconducting wire windings of superconducting magnets usually require a very low temperature working environment to achieve superconductivity. To reduce the temperature of the superconducting magnet system to a very low temperature and stabilize it at low temperature, the superconducting magnet is usually placed in a dewar tank, cooled with liquid nitrogen, and then cooled with a refrigerator, and the magnet is stabilized in the required low temperature zone to achieve superconductivity. With the development of technology, there are various forms of superconducting magnet cooling, the most common of which are liquid helium cooling, micro-liquid helium siphon cooling, and liquid helium-free conduction cooling.

[0004] When the existing excitation system that is matched with the superconducting magnet is energized, Joule heat will be generated due to the resistance of the low-temperature end joint of the high-temperature superconducting current lead and the fact that the temperature of the low-temperature end joint cannot be reduced to below the superconducting critical temperature, thereby causing the superconducting temperature zone to heat up. The greater the current, the greater the Joule heat generated, and the higher the temperature rise of the superconducting temperature zone. Once the temperature of the superconducting temperature zone exceeds the superconducting critical temperature, it will lose superconductivity. Therefore, high-current superconducting magnets are difficult to achieve and require huge costs, especially in conduction-cooled superconducting magnets. Because there is no liquid helium phase transition in the 4K temperature zone of the conduction-cooled superconducting magnet, its temperature rise is particularly obvious. Therefore, this problem needs to be solved urgently. Summary of the invention

[0005] The utility model provides a conductive cold superconducting magnet to overcome the deficiencies of the prior art. The superconducting magnet is mainly insulated by high-temperature superconducting current leads with large thermal resistance, so that the superconducting joint is completely in the superconducting state area, thereby achieving the goal of no heat generation in the superconducting state area.

[0006] To achieve the above purpose, a conduction-cooled superconducting magnet is designed, comprising an outer shell, wherein the outer shell is a Dewar container, and is characterized in that a refrigerator, a cold shield, a cooling plate, a current lead, and a superconducting coil are arranged in the outer shell, a superconducting coil is arranged in the cooling plate, two ends of the superconducting coil are respectively connected to superconducting joints, and the superconducting joints are respectively connected to the cold shield and the outer shell through the current lead; the cooling plate is connected to the refrigerator through a cold conduction component.

[0007] The current lead is composed of two sections, one end of the upper section of the current lead is located outside the outer shell, and one end of the upper section of the current lead is connected to an external power supply, and the other end of the upper section of the current lead is connected to the cold shield through a first thermal connection component; one end of the lower section of the current lead is connected to the cold shield through the first thermal connection component, and the other end of the lower section of the current lead is connected to the superconducting coil through a superconducting joint.

[0008] The middle part of the upper section of the current lead is sealed and connected to the outer shell through a sealing component.

[0009] The lower section of the current lead is a high-temperature superconducting current lead with large thermal resistance.

[0010] The lower section of the current lead is a soft high-temperature superconducting tape, and is serpentine-shaped. The length of the lower section of the current lead is 900 mm. The lower section of the current lead is installed on the serpentine plate.

[0011] The upper end of the serpentine plate is fixed on the first thermal connection component, and the lower end of the serpentine plate is fixed on the superconducting joint.

[0012] The refrigerator is a GM type two-stage refrigerator.

[0013] The refrigerator is installed on the outer shell, the first-level cold head of the refrigerator is connected to the cold screen through the second thermal connection component, and the second-level cold head of the refrigerator is connected to the cooling plate through the cooling conduction component.

[0014] The outer shell is 300K.

[0015] The cold shield is 50K.

[0016] Compared with the prior art, the utility model provides a conductive cold superconducting magnet, which is mainly insulated by high-temperature superconducting current leads with large thermal resistance, so that the superconducting joint is completely in the superconducting state area, thereby achieving the goal of no heat generation in the superconducting state area.

[0017] The structure of the utility model can reduce the heat conductivity of the superconducting state area and the Joule heat generated during the excitation process, reduce the heat load of the superconducting state area, increase the excitation current, increase the magnetic field of the superconducting coil, and also reduce the superconducting wire material of the superconducting coil, thereby saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a connection diagram of the utility model.

[0019] Figure 2 It is a schematic diagram of the lower section of the current lead in the utility model.

[0020] See also Figure 1 , Figure 2, 1 is an outer shell, 2 is a refrigerator, 3 is a cold shield, 4 is a sealing component, 5 is a first thermal connection component, 6 is a superconducting joint, 7 is a current lead, 7-1 is an upper segment of the current lead, 7-2 is a lower segment of the current lead, 8 is a second thermal connection component, 9 is a superconducting coil, 10 is a cold conduction component, 11 is a cooling plate, and 12 is a serpentine plate. DETAILED DESCRIPTION

[0021] The utility model is further described below with reference to the accompanying drawings.

[0022] like Figure 1 , Figure 2 As shown, a refrigerator, a cold shield, a cooling plate, a current lead, and a superconducting coil are arranged in the outer shell 1. A superconducting coil 9 is arranged in the cooling plate 11. Both ends of the superconducting coil 9 are respectively connected to superconducting joints 6. The superconducting joints 6 are respectively connected to the cold shield 3 and the outer shell 1 through the current lead 7; the cooling plate 11 is connected to the refrigerator 2 through the cooling component 10.

[0023] The current lead 7 consists of two sections, one end of the current lead upper section 7-1 is located outside the outer shell 1, and one end of the current lead upper section 7-1 is connected to an external power supply, and the other end of the current lead upper section 7-1 is connected to the cold shield 3 through a first thermal connection component 5; one end of the current lead lower section 7-2 is connected to the cold shield 3 through the first thermal connection component 5, and the other end of the current lead lower section 7-2 is connected to the superconducting coil 9 through a superconducting joint 6.

[0024] The middle portion of the upper segment 7 - 1 of the current lead is sealed and connected to the outer shell 1 via a sealing assembly 4 .

[0025] The lower segment 7-2 of the current lead is a high-temperature superconducting current lead with large thermal resistance.

[0026] The lower segment 7 - 2 of the current lead is a soft high-temperature superconducting tape, and is serpentine-shaped. The length of the lower segment 7 - 2 of the current lead is 900 mm. The lower segment 7 - 2 of the current lead is installed on the serpentine plate 12 .

[0027] The upper end of the serpentine plate 12 is fixed on the first thermal connection component 5 , and the lower end of the serpentine plate 12 is fixed on the superconducting joint 6 .

[0028] Refrigerator 2 is a GM type two-stage refrigerator.

[0029] The refrigerator 2 is mounted on the outer shell 1 , the primary cold head of the refrigerator 2 is connected to the cold shield 3 via the second thermal connection component 8 , and the secondary cold head of the refrigerator 2 is connected to the cooling plate 11 via the cooling conduction component 10 .

[0030] The outer shell 1 is 300K.

[0031] Cold Screen 3 is 50K.

[0032] like Figure 1 As shown, it includes a Dewar container, a superconducting coil 9 located in the Dewar container, a refrigerator 2, a thermal connection component, a current lead 7, a cooling component 10, a cooling plate 11, and a superconducting joint 6. The outer shell 1 is designed to be 300K, and the cold shield 3 is 50K.

[0033] The refrigerator 2 is installed in the outer shell 1 , and its first-level cold head is connected to the cold shield 3 through the second thermal connection component 8 , and its second-level cold head is connected to the cooling plate 11 through the cooling conduction component 10 .

[0034] The current lead 7 is divided into two sections. The upper end of the current lead upper section 7-1 is outside the outer shell 1 and connected to an external power supply. The other end of the current lead upper section 7-1 is connected to the cold shield 3 through the first thermal connection component 5, and the middle is connected to the outer shell 1 through the sealing component 4. The current lead lower section 7-2 is a high-temperature superconducting current lead with large thermal resistance, the upper end of which is connected to the cold shield 3 through the first thermal connection component 5, and the lower end is connected to the superconducting coil 9 through the superconducting joint 6.

[0035] The refrigerator 2 is a GM type two-stage refrigerator. The first-stage cold head of the refrigerator 2 cools the cold shield 3 through the second thermal connection component 8, and the second-stage cold head cools the cooling plate 11 through the cold conduction component 10, and then indirectly cools the superconducting coil 9 and the superconducting joint 6. The shape of the high-temperature superconducting current lead of the general conduction cold superconducting magnet is straight, and the length of the high-temperature superconducting current lead is limited by the space of the Dewar container. Generally, the two terminals of the high-temperature superconducting current lead are connected with copper, and the temperature of the end connected to the superconducting wire is also above the superconducting critical temperature, so there is resistance. This has little effect on the excitation of the superconducting coil if a small current is passed during excitation. However, as the excitation current increases, the Joule heat also increases. When it reaches a certain value, the temperature of the superconducting coil and the superconducting joint 6 connected thereto will exceed the critical temperature, causing it to quench and prevent the current from being excited.

[0036] In order to ensure that the large current of the superconducting magnet can be effectively realized, the utility model uses the current lead lower segment 7-2 of the soft high-temperature superconducting tape. In order to make the thermal resistance of the current lead lower segment 7-2 large enough to enable the superconducting joint 6 to reach the superconducting critical temperature, the length of the current lead lower segment 7-2 is lengthened, and the length of the current lead lower segment 7-2 is about 900mm. In order to put the extra-long current lead lower segment 7-2 into a limited space, the current lead lower segment 7-2 of the soft high-temperature superconducting tape is fixed on a serpentine plate 12, such as Figure 2 shown.

[0037] The upper end of the serpentine plate 12 is fixed on the first thermal connection component 5, and the lower end of the serpentine plate 12 is fixed on the superconducting joint 6. In order to make the superconducting joint 6 reach the superconducting state, the superconducting part of the superconducting wire and the superconducting surface of the current lead lower segment 7-2 are first hung with melted indium, and the superconducting part of the superconducting wire and the superconducting surface of the current lead lower segment 7-2 are closely contacted and pressed, and after the indium solidifies, they are placed in the superconducting joint 6 and filled with Wood's alloy solution, and when it solidifies, it can reach the superconducting state in a low temperature environment. In this way, during the excitation process, the current lead lower segment 7-2, the superconducting joint 6, and the superconducting coil 9 are in the superconducting state without generating any heat, and a large current can be excited, thereby increasing the magnetic field of the magnet and reducing the material of the superconducting coil.

Claims

1. A conductive cold superconducting magnet, comprising an outer shell, wherein the outer shell is a Dewar container, characterized in that: The outer shell (1) is provided with a refrigerator, a cold shield, a cooling plate, a current lead, and a superconducting coil. The cooling plate (11) is provided with a superconducting coil (9). Both ends of the superconducting coil (9) are respectively connected to superconducting joints (6). The superconducting joints (6) are respectively connected to the cold shield (3) and the outer shell (1) through the current lead (7). The cooling plate (11) is connected to the refrigerator (2) through a cold conduction component (10).

2. A conductive cold superconducting magnet according to claim 1, characterized in that: The current lead (7) is composed of two sections, one end of the current lead upper section (7-1) is located outside the outer shell (1), and one end of the current lead upper section (7-1) is connected to an external power supply, and the other end of the current lead upper section (7-1) is connected to the cold shield (3) through a first thermal connection component (5); one end of the current lead lower section (7-2) is connected to the cold shield (3) through the first thermal connection component (5), and the other end of the current lead lower section (7-2) is connected to the superconducting coil (9) through a superconducting joint (6).

3. A conductive cold superconducting magnet according to claim 2, characterized in that: The middle portion of the upper segment (7-1) of the current lead is sealedly connected to the outer shell (1) via a sealing component (4).

4. A conductive cold superconducting magnet according to claim 2, characterized in that: The lower section (7-2) of the current lead is a high-temperature superconducting current lead with large thermal resistance.

5. A conductive cold superconducting magnet according to claim 2 or 4, characterized in that: The current lead lower segment (7-2) is a soft high-temperature superconducting tape, and is serpentine-shaped. The length of the current lead lower segment (7-2) is 900 mm. The current lead lower segment (7-2) is mounted on the serpentine plate (12).

6. A conductive cold superconducting magnet according to claim 5, characterized in that: The upper end of the serpentine plate (12) is fixed on the first thermal connection component (5), and the lower end of the serpentine plate (12) is fixed on the superconducting joint (6).

7. A conductive cold superconducting magnet according to claim 1, characterized in that: The refrigerator (2) is a GM type two-stage refrigerator.

8. A conductive cold superconducting magnet according to claim 1 or 7, characterized in that: The refrigerator (2) is mounted on the outer shell (1); the primary cold head of the refrigerator (2) is connected to the cold shield (3) via a second thermal connection component (8); and the secondary cold head of the refrigerator (2) is connected to the cooling plate (11) via a cooling conduction component (10).

9. A conductive cold superconducting magnet according to claim 1, characterized in that: The outer shell (1) is 300K.

10. A conductive cold superconducting magnet according to claim 1, characterized in that: The cold shield (3) is 50K.

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