WO2023134265A1

WO2023134265A1 - Gas-cooled current lead and superconducting magnet system

Info

Publication number: WO2023134265A1
Application number: PCT/CN2022/128166
Authority: WO
Inventors: 姚海锋; 乐志良; 郑杰; 朱雪松; 刘照泉; 许建益; 袁金辉
Original assignee: 宁波健信超导科技股份有限公司
Priority date: 2022-01-11
Filing date: 2022-10-28
Publication date: 2023-07-20
Also published as: CN114038645A; CN114038645B

Abstract

A gas-cooled current lead and superconducting magnet system. The system comprises: a 4K container filled with liquid helium and a superconducting coil, a heater for heating the liquid helium, a cold head apparatus having a cooling function, a current lead, and a control apparatus, wherein an upper end of the current lead can be connected to a positive connector electrode and a negative connector electrode of an external power source by means of excitation cables, and a lower end of the current lead can be respectively connected to a positive connector electrode and a negative connector electrode of the superconducting coil by means of 4K inner cables; the heater, the cold head apparatus and the external power source are all connected to the control apparatus; the current lead has a tubular structure, and the top thereof is provided with a vent tube for venting helium; the current lead and the cold head apparatus are fixed in the 4K container by means of the same metal flange; an insulation member is sandwiched between the current lead and the metal flange; and a high-temperature superconducting tape is attached in the tubular structure of the current lead located below the metal flange. The apparatus can reduce the heat leakage of a current lead during steady-state operation of a magnet, and simplify an excitation operation.

Description

An air-cooled current lead and superconducting magnet system

This application claims the priority of the Chinese patent application with the application number 202210024160.4 and the title of the invention "An air-cooled current lead and superconducting magnet system" submitted to the China Patent Office on January 11, 2022, the entire contents of which are incorporated by reference in this application.

technical field

The invention relates to the technical field of superconducting magnets, in particular to an air-cooled current lead and a superconducting magnet system.

Background technique

In the prior art, the traditional MRI liquid helium soaked zero-volatile superconducting magnet has a structure as shown in Figure 1, including a 300K container 01, a 4K cold head 02 installed on the 300K container 01, a 50K container 03, and a 50K container Cold head level 04 on 03, 4K container 05, cold head level 2 06 and condenser 07 on 4K container 05, superconducting coil 08 and liquid helium 09 in 4K container 05, used for heating liquid Helium 09 heater 010 and current lead 011, the upper end of the current lead 011 is respectively connected to the positive pole and negative pole of the external power supply 013 through the excitation cable 012, and the lower end of the current lead 011 is respectively connected to the superconducting coil 08 through the 4K inner cable 014. The positive pole of the connector and the negative pole of the joint are connected, the end of the current lead 011 is provided with an exhaust port 015 for discharging cold helium gas 018, the end of the current lead 011 is provided with a female connector 017, and the end of the 4K inner cable 014 is provided with a male connector 016.

Before the magnet is excited or demagnetized, the female end 017 of the current lead 011 needs to be inserted into the male end 016 of the 4K internal cable 014. During the plugging process, the magnet needs to be depressurized and exhausted, which will lose liquid helium 09. In order to ensure good contact between the female end 017 of the current lead 011 and the male end 016 of the 4K inner cable 014 when plugging and unplugging, it is necessary to use a tool to tap the top of the current lead 011, and after the female end 017 and the male end 016 are in good contact, then insert the The upper end of the current lead 011 is connected with the positive cable and the negative cable, so that the excitation power supply and the superconducting coil 08 form a loop. During this period, the heater 010 can be heated to change the liquid helium 09 into cold helium gas 018, and the cold helium gas 018 flows upward through the inner cavity of the current lead 011, thereby cooling the current lead 011, and finally from the exhaust Port 015 is discharged. Wherein, the schematic diagram of conventional magnet air-cooled current lead 011 is as shown in Figure 2, and the direction of the arrow in the figure is the flow direction of cold helium gas 018. Because the material of the current lead 011 is usually copper or brass, the heat generated during excitation is large, and the liquid helium 09 consumes a lot.

Moreover, in the process of plugging and unplugging the lead wire, if the plugging operation is improper, it is easy to cause air to flow into the magnet 4K container 05, causing the magnet to freeze and affecting the normal operation of the magnet. Frost. After plugging and unplugging, the contact resistance between the current lead 011 and the internal electrical connector of the magnet has high requirements and is difficult to control. When the contact is poor, it needs to be pulled out, resulting in the need to repeatedly plug and pull the current lead 011. The operation efficiency is low and the operation is difficult.

To sum up, how to improve the excitation operation effect of a superconducting magnet is an urgent problem to be solved by those skilled in the art.

Contents of the invention

In view of this, the purpose of the present invention is to provide an air-cooled current lead and superconducting magnet system, which can effectively improve the excitation operation effect of the superconducting magnet.

In order to achieve the above object, the present invention provides the following technical solutions:

An air-cooled current lead and superconducting magnet system, including: a 4K container with liquid helium and a superconducting coil, a heater for heating the liquid helium, a cold head device with a cooling function, a current lead and a control device, the upper end of the current lead can be respectively connected to the positive pole and negative pole of the joint of the external power supply through the excitation cable, and the lower end of the current lead can be connected to the positive pole and negative pole of the joint of the superconducting coil through the 4K inner cable respectively, The heater, the cold head device and the external power supply are all connected to the control device;

The current lead is a tubular structure, and the top is provided with an exhaust pipe for discharging helium. The current lead and the cold head device are fixed in the 4K container through the same metal flange. The current lead and the An insulator is sandwiched between the metal flanges, and a high temperature superconducting tape is pasted in the tubular structure of the current lead below the metal flanges.

Preferably, the current lead includes two symmetrically distributed lead pipes, the tops of the two lead pipes are connected, the top of the connection of the lead pipes is provided with the exhaust pipe, and the outer periphery of the connection is covered with A transition ring is provided, and the transition ring is an insulating material.

Preferably, the lead tube connected to the metal flange is a middle pipeline, and the lead tube above the metal flange is an upper pipeline, and the upper pipeline is made of stainless steel, brass or The pure copper part, the middle pipeline is a pure copper part, and the upper pipeline and the middle pipeline are connected by vacuum brazing or soldering.

Preferably, the lead tube located below the metal flange is a lower pipeline, and the lower pipeline is made of epoxy material or stainless steel, and the lower pipeline is connected to the middle pipeline through resin curing or soldered connections.

Preferably, the inner wall of the lower pipeline is axially provided with at least one groove for installing the high-temperature superconducting strip, and the high-temperature superconducting strip is connected to the groove through resin curing.

Preferably, the bottom of the lower pipeline is provided with a lead base, and the lead base is made of pure copper.

Preferably, the lead base and the 4K inner cable are connected by soldering.

Preferably, ventilation holes are provided on the walls of the upper pipeline and the lower pipeline.

Preferably, the insulator includes a filling block sandwiched between the middle pipeline and the metal flange, and the filling block is made of aluminum nitride.

Preferably, a solid resin part is provided at the connection between the middle pipeline and the metal flange.

When using the air-cooled current lead wire and superconducting magnet system provided by the present invention, the current lead wire as a whole is fixed on the metal flange through the insulator, so that the metal flange is cold and non-conductive to the current lead wire, and the upper end of the current lead wire can pass through The excitation cable is respectively connected to the positive pole and negative pole of the connector of the external power supply, and the lower end of the current lead can be connected to the positive pole and negative pole of the connector of the superconducting coil through a 4K inner cable to form an external power supply, excitation cable, current lead, and 4K inner cable. , The circulation circuit of the superconducting coil. The control device can perform excitation or demagnetization operation in real time by controlling whether the external power supply is energized, without manually plugging and unplugging the current leads.

When the magnet is running in a steady state, that is, when the magnet is not in the process of excitation or demagnetization, the cold head device can cool the metal flange to a temperature range of 50K, and through the cooling effect of the metal flange, it can ensure that the middle section of the current lead is also in the 50K temperature zone to reduce the heat leakage phenomenon of the current lead from the upper high temperature zone to the lower 4K temperature zone during the steady state operation of the magnet. When the magnet is in the excitation or demagnetization operation, since the upper end temperature of the high-temperature superconducting strip is in the 50K temperature range, the high-temperature superconducting strip is in a superconducting state as a whole, and, when the magnet is excited or demagnetized, the heater can be controlled by the control device The liquid helium is heated to generate a sufficient amount of cold helium gas, which flows upwards to fully cool the inside and outside of the current lead, and is discharged from the exhaust pipe. This device can not only ensure the stable operation of the magnet, but also effectively reduce the heat leakage phenomenon of the current lead, and make the excitation operation of the magnet simpler, without repeatedly plugging and pulling the lead, avoiding various risks of plugging and pulling the lead, and can also Automated excitation or demagnetization of magnets.

To sum up, the air-cooled current leads and the superconducting magnet system provided by the present invention can effectively improve the excitation operation effect of the superconducting magnet.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings on the premise of not paying creative efforts.

Fig. 1 is the structural representation of the zero-volatile superconducting magnet soaked in MRI liquid helium in the prior art;

Fig. 2 is the schematic diagram of conventional magnet air-cooled current lead;

Fig. 3 is the structural representation of air-cooled current lead wire and superconducting magnet system provided by the present invention;

Fig. 4 is a structural schematic diagram of a current lead;

Fig. 5 is a partial enlarged view of place A in Fig. 4;

Fig. 6 is the structural representation of lead tube;

Fig. 7 is a schematic diagram of the assembly of the high-temperature superconducting strip and the lower pipeline.

In Figure 1 and Figure 2:

01 is 300K container, 02 is 4K cold head, 03 is 50K container, 04 is the first stage of cold head, 05 is 4K container, 06 is the second stage of cold head, 07 is condenser, 08 is superconducting coil, 09 is liquid helium , 010 is the heater, 011 is the current lead, 012 is the excitation cable, 013 is the external power supply, 014 is the 4K inner cable, 015 is the exhaust port, 016 is the male connector, 017 is the female connector, 018 is the cold helium gas;

In Figure 3-Figure 7:

1 is liquid helium, 2 is superconducting coil, 3 is 4K container, 4 is heater, 5 is cold head device, 6 is current lead, 7 is control device, 8 is excitation cable, 9 is external power supply, 10 is 4K Inner cable, 11 is the exhaust pipe, 12 is the metal flange, 13 is the insulator, 14 is the high temperature superconducting strip, 15 is the lead tube, 16 is the transition ring, 17 is the middle pipeline, 18 is the upper pipeline, 19 20 is a lead base, 21 is a vent hole, 22 is a solid resin piece, and 23 is helium.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The core of the invention is to provide an air-cooled current lead and a superconducting magnet system, which can effectively improve the excitation operation effect of the superconducting magnet.

Please refer to Fig. 3 to Fig. 7, wherein, Fig. 3 is the structural representation of the air-cooled current lead wire and the superconducting magnet system provided by the present invention; Fig. 4 is the structural representation of the current lead wire; Fig. 5 is the part of A place in Fig. 4 Enlarged view; Figure 6 is a schematic structural view of the lead pipe; Figure 7 is a schematic view of the assembly of the high-temperature superconducting strip and the lower pipeline.

This specific embodiment provides an air-cooled current lead and a superconducting magnet system, including: a 4K container 3 equipped with liquid helium 1 and a superconducting coil 2, a heater 4 for heating the liquid helium 1, and a cooling function The cold head device 5, the current lead wire 6 and the control device 7, the upper end of the current lead wire 6 can be respectively connected with the positive pole and the negative pole of the joint of the external power supply 9 through the excitation cable 8, and the lower end of the current lead wire 6 can be respectively connected with the external power supply 9 through the 4K internal cable 10. The positive pole and negative pole of the joint of the superconducting coil 2 are connected, the heater 4, the cold head device 5 and the external power supply 9 are all connected to the control device 7; the current lead 6 is a tubular structure, and the top is provided with an exhaust gas for discharging helium The tube 11, the current lead 6 and the cold head device 5 are fixed in the 4K container 3 through the same metal flange 12, an insulating member 13 is interposed between the current lead 6 and the metal flange 12, and the current lead 6 is located on the metal flange 12 A high temperature superconducting strip 14 is pasted inside the lower tubular structure.

It should be noted that the superconducting magnet system usually includes a 300K container, a 4K cold head arranged on the 300K container, a 50K container, a cold head first stage arranged on the 50K container, a 4K container 3, and a cold head installed on the 4K container 3. The cold head stage 2 and the condenser, the cold head device 5 of this device includes a cold head stage 1 and a cold head stage 2, the current lead 6 located at the metal flange 12 is in a temperature zone of 50K, and the current lead 6 located above the metal flange 12 The lead wire 6 is in the temperature range of 50K-300K, and the current lead wire 6 located under the metal flange 12 is in the temperature range of 4K-50K. Among them, the operating power of the first stage of the cold head is large, and the cooling effect is better. The first stage of the cold head can cool the metal flange 12 to a temperature range of 50K, and the metal flange 12 can conduct cooling to the current lead 6, so that the metal flange 12 The junction with the current lead 6 is also in the 50K temperature range. The second stage of the cold head has low operating power and relatively poor cooling effect, so the device is attached with a high-temperature superconducting strip 14 in the tubular structure below the metal flange 12 to reduce heat leakage of the magnet.

In the actual application process, according to the actual situation and actual needs, the 4K container 3, the heater 4, the cold head device 5, the current lead 6, the control device 7, the excitation cable 8, the external power supply 9, the 4K inner cable 10, the metal The shape, structure, size, position, material, etc. of the flange 12, the insulator 13, and the high-temperature superconducting strip 14 are determined.

When using the air-cooled current lead and the superconducting magnet system provided by the present invention, the current lead 6 is integrally fixed on the metal flange 12 through the insulator 13, so that the metal flange 12 conducts cooling and non-conduction to the current lead 6, and the current The upper end of the lead wire 6 can be respectively connected to the positive pole and the negative pole of the joint of the external power supply 9 through the excitation cable 8, and the lower end of the current lead 6 can be respectively connected to the positive pole and the negative pole of the joint of the superconducting coil 2 through the 4K internal cable 10 to form an external connection. Power supply 9, excitation cable 8, current lead wire 6, 4K internal cable 10, circulation loop of superconducting coil 2. The control device 7 can perform the excitation or demagnetization operation in real time by controlling whether the external power supply 9 is energized, without manually plugging and unplugging the current lead 6 .

When the magnet operates in a steady state, that is, when the magnet is not in the process of excitation or demagnetization, the first stage of the cold head can cool the metal flange 12 to a temperature range of 50K, and through the cooling effect of the metal flange 12, the current lead 6 can be guaranteed The middle section is also in the 50K temperature zone to reduce the heat leakage phenomenon of the current lead 6 from the upper high temperature zone to the lower 4K temperature zone when the magnet operates in a steady state. When the magnet is in the excitation or demagnetization operation, because the temperature of the upper end of the high-temperature superconducting strip 14 is in the 50K temperature range, the high-temperature superconducting strip 14 is in a superconducting state as a whole. The heater 4 is controlled to heat the liquid helium 1 to generate a sufficient amount of helium gas 23 , and the helium gas 23 flows upward to fully cool the inside and outside of the current lead 6 and is discharged from the exhaust pipe 11 . This device can not only ensure the stable operation of the magnet, but also effectively reduce the heat leakage phenomenon of the current lead wire 6, and make the excitation operation of the magnet simpler, without repeatedly inserting and pulling out the lead wire, avoiding various risks of plugging and pulling out the lead wire, and also The magnet can be automatically excited or demagnetized.

On the basis of the above-mentioned embodiments, preferably, the current lead 6 includes two symmetrically distributed lead tubes 15, the tops of the two lead tubes 15 are connected, and the top of the connection of the lead tubes 15 is provided with an exhaust pipe 11, and the top of the connected part A transition ring 16 is sheathed on the outer periphery, and the transition ring 16 is made of insulating material.

It should be noted that the structure of the current lead 6 is shown in FIG. 4 , and the direction of the arrow in FIG. 4 is the flow direction of the helium gas 23 . The lead tube 15 on the left can be set as the positive current lead 6 and the lead tube 15 on the right can be set as the negative current lead 6 . A transition ring 16 is sheathed on the outer periphery of the connecting part of the lead pipe 15, so that the lead pipe 15 is divided into upper and lower parts, and the upper and lower parts are electrically insulated. For example, the transition ring 16 can be set as a solid resin material Afterwards, the upper end of the annealed copper wire can be connected to the joint of the external power supply 9, and the lower end of the annealed copper wire is connected to the upper section of the current lead 6 and the position below the transition ring 16 to ensure the connection of the current loop.

The shape, structure, position, etc. of the transition ring 16 can be determined according to the actual situation and actual needs during actual operation.

Preferably, the lead pipe 15 connected to the metal flange 12 is the middle pipe 17, the lead pipe 15 above the metal flange 12 is the upper pipe 18, and the upper pipe 18 is made of stainless steel, brass or pure copper , the middle pipeline 17 is a pure copper piece, and the upper pipeline 18 and the middle pipeline 17 are connected by vacuum brazing or soldering. The material of the upper pipeline 18 can be selected according to the operating current of the magnet.

Preferably, the lead pipe 15 located below the metal flange 12 is a lower pipeline 19, and the lower pipeline 19 is made of epoxy material or stainless steel, and the lower pipeline 19 and the middle pipeline 17 are connected by resin curing or brazing .

It should be noted that the connection mode between the middle pipeline 17 and the lower pipeline 19 depends on the material of the lower pipeline 19, and the lower pipeline 19 can be set as a thin-walled pipe. When the material of the thin-walled pipe is epoxy, it can be The thin-walled tube is solidified on the middle pipeline 17 by using liquid resin or solid resin. When the material of the thin-walled tube is stainless steel, the above-mentioned resin curing method can be used for fixing, and the thin-walled tube can be fixed on the middle pipeline 17 by brazing.

Preferably, the inner wall of the lower pipeline 19 is axially provided with at least one groove for installing the high-temperature superconducting strip 14 , and the high-temperature superconducting strip 14 and the groove are connected by resin curing.

It should be noted that the connection between the lower pipeline 19 and the high-temperature superconducting strip 14 can be cured by epoxy resin, so that the high-temperature superconducting strip 14 and the thin-walled tube become an integral body, and the thin-walled tube is connected to the high-temperature superconducting strip. 14 has mechanical protection. As shown in Figure 7, the high-temperature superconducting strips 14 can be uniformly distributed on the thin-walled tube, and the quantity of the high-temperature superconducting strips 14 is not limited to 4, and the actual number of the high-temperature superconducting strips 14 depends on the operation of the magnet. Current size. That is to say, the shape, position, number, etc. of the grooves can be determined according to the actual situation and actual needs in the actual application process.

On the basis of the above embodiments, preferably, the bottom of the lower pipeline 19 is provided with a lead base 20, and the lead base 20 is made of pure copper. The lead base 20 can effectively fix the current lead 6 . Moreover, the connection mode between the lower pipeline 19 and the lead base 20 is the same as the connection mode between the lower pipeline 19 and the middle pipeline 17, that is, the specific connection mode between the lower pipeline 19 and the lead base 20 depends on the material of the thin-walled tube.

Preferably, the lead base 20 and the 4K inner cable 10 are connected by soldering to ensure effective conduction of the circulation loop formed by the external power supply 9 , the excitation cable 8 , the current lead 6 , the 4K inner cable 10 and the superconducting coil 2 .

Preferably, vent holes 21 are provided on the walls of the upper pipeline 18 and the lower pipeline 19 , as shown in FIG. 5 . Wherein, vent holes 21 are provided on the walls of the upper pipeline 18 and the lower pipeline 19, because the vent holes 21 can enhance the effect of convective heat transfer, so as to ensure that the current lead 6 can be sufficiently cooled during excitation or demagnetization. The number, size and position of the ventilation holes 21 can be determined according to the actual situation and actual needs during actual operation.

Preferably, the insulator 13 includes a filling block sandwiched between the middle pipeline 17 and the metal flange 12, and the filling block is made of aluminum nitride. That is to say, aluminum nitride can be used to fill between the middle pipeline 17 and the metal flange 12 . Aluminum nitride has the function of insulating and conducting cold, so as to ensure that the metal flange 12 only conducts cooling and does not conduct electricity to the current lead 6 .

Preferably, a solid resin piece 22 is provided at the connection between the middle pipeline 17 and the metal flange 12 . The metal flange 12 can be made of pure copper, and the middle pipeline 17 of the current lead 6 can be fixed on the metal flange 12 by using the solid resin part 22, so that the current lead 6 does not need to be inserted and pulled out repeatedly.

The shape, structure, position, etc. of the filling block and the solid resin piece 22 can be determined according to the actual situation and actual needs during actual operation.

In addition, it should be noted that the orientation or positional relationship indicated by "up and down", "left and right" in this application is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of simplified description and understanding, rather than Nothing indicating or implying that a referenced device or element must have a particular orientation, be constructed, and operate in a particular orientation should therefore not be construed as limiting the invention.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other. Any combination of all the embodiments provided by the present invention is within the protection scope of the present invention, and will not be repeated here.

The air-cooled current leads and the superconducting magnet system provided by the present invention have been introduced in detail above. In this paper, specific examples are used to illustrate the principle and implementation of the present invention, and the descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

An air-cooled current lead and a superconducting magnet system, characterized in that it comprises: a 4K container (3) equipped with liquid helium (1) and a superconducting coil (2), a heating device for heating the liquid helium (1) The heater (4), the cold head device (5) with cooling function, the current lead (6) and the control device (7), the upper end of the current lead (6) can be respectively connected to the external power supply through the excitation cable (8) (9) is connected to the positive pole of the joint and the negative pole of the joint, and the lower end of the current lead (6) can be connected to the positive pole of the joint and the negative pole of the joint of the superconducting coil (2) respectively through a 4K inner cable (10). (4), the cold head device (5) and the external power supply (9) are both connected to the control device (7);

The current lead (6) is a tubular structure, and the top is provided with an exhaust pipe (11) for discharging helium (23), and the current lead (6) and the cold head device (5) pass the same metal method The flange (12) is fixed in the 4K container (3), an insulator (13) is sandwiched between the current lead (6) and the metal flange (12), and the current lead (6) A high temperature superconducting strip (14) is pasted in the tubular structure below the metal flange (12).
The air-cooled current lead wire and superconducting magnet system according to claim 1, wherein the current lead wire (6) comprises two symmetrically distributed lead tubes (15), and the two lead tubes (15) The top is connected, and the exhaust pipe (11) is provided on the top of the connection of the lead pipe (15), and the outer circumference of the connection is provided with a transition ring (16), and the transition ring (16) is an insulating Material pieces.
The air-cooled current lead wire and superconducting magnet system according to claim 2, characterized in that, the lead pipe (15) connected to the metal flange (12) is a middle pipeline (17), located in the The lead pipe (15) above the metal flange (12) is an upper pipeline (18), and the upper pipeline (18) is a stainless steel piece, a brass piece or a pure copper piece, and the middle pipeline (17 ) is a pure copper piece, and the upper pipeline (18) and the middle pipeline (17) are connected by vacuum brazing or soldering.
The air-cooled current lead wire and superconducting magnet system according to claim 3, characterized in that, the lead tube (15) located below the metal flange (12) is a lower section pipeline (19), and the lower section The pipeline (19) is made of epoxy material or stainless steel, and the lower pipeline (19) and the middle pipeline (17) are connected by resin curing or brazing.
The air-cooled current lead wire and superconducting magnet system according to claim 4, characterized in that, the inner wall of the lower pipeline (19) is axially provided with at least one for installing the high-temperature superconducting strip (14 ), the high temperature superconducting strip (14) and the groove are connected through resin curing.
The air-cooled current lead and superconducting magnet system according to claim 4, characterized in that, the bottom of the lower pipeline (19) is provided with a lead base (20), and the lead base (20) is made of pure copper pieces.
The air-cooled current lead and superconducting magnet system according to claim 6, characterized in that the lead base (20) and the 4K inner cable (10) are connected by soldering.
The air-cooled current lead wire and superconducting magnet system according to any one of claims 4 to 7, characterized in that the walls of the upper pipeline (18) and the lower pipeline (19) are provided with vent holes (twenty one).
The air-cooled current lead wire and superconducting magnet system according to any one of claims 3 to 7, characterized in that, the insulator (13) includes a metal frame sandwiched between the middle pipeline (17) and the metal method. Filling blocks between the flanges (12), the filling blocks are made of aluminum nitride.
The air-cooled current lead and superconducting magnet system according to any one of claims 3 to 7, characterized in that a solid resin is provided at the connection between the middle pipeline (17) and the metal flange (12) pieces (22).