JPH1022117A - Superconducting current supplying wire and method of its cooling, and method of its connection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact superconducting current supplying wire without requiring control of cooling medium in the long heat insulation pipe, a cooling method of the superconducting current supplying wire to lower than a superconductive transition temperature, and a connection method provided by quench measures. SOLUTION: Superconducting conductors 3a and 3b are put together on the circumference of a bobbin 3c made from pure metal with large heat conductivity with a plurality of superconducting wires wound, and at least an inside pipe 2b of a heat insulation pipe is made from pure metal with large heat conductivity and no path for cooling medium is formed in section of inner side of the inside pipe (low temperature). With regard to a cooling method, the inside pipe of the heat insulation pipe and a part of a long directional superconductive conductor and the bobbin 3c are directly cooled by liquid cooling medium, and the other part is indirectly cooled in long direction by heat conduction of the compound pure metal itself, then whole length of the superconducting conductor is cooled lower than the critical temperature of superconductivity. With regard to a connection method, the superconducting conductor is electrically connected to both or one of the inside pipe 3g and the outside pipe 3h of the heat insulation pipe at both ends.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a superconducting line technology, and more particularly to a superconducting current supply line using a superconducting wire, a method for cooling the same, and a method for connecting the same.

[0002]

2. Description of the Related Art FIG. 10 shows a conventional superconducting current supply line system using a superconducting material, and FIG. 11 shows a cross-sectional structure of the superconducting current supply line. In this system, as shown in FIG.
And the terminal portion 1b, and the terminal portion 1b circulates the refrigerant passing through the refrigerator 1i and the heat exchanger 1c into the main body 1a through the refrigerant passage 1d, so that the entire length of the superconducting conductor in the main body is immersed and cooled. .

As shown in FIG. 11, a superconducting current supply line itself used for such a cooling system is composed of a superconducting wire 1e having a coolant passage 1g as a center, an electric insulator 1f and a superconducting wire 1e arranged in this order. A heat insulating layer 1h is provided while securing a coolant passage 1g on the outside, and a coating material is applied to each layer. As the refrigerant, a liquid refrigerant; liquid helium or liquid nitrogen is used.

[0004]

According to the above-mentioned prior art, a refrigerant passage is required in the superconducting current supply line main body in order to circulate the refrigerant. Pressure control of the refrigerant is difficult when used in places where the temperature is not stable, the refrigerant pressure drops when cooling as a long line, the refrigerant vaporizes when thermal runaway occurs in the adiabatic pipeline, and the superconducting current supply line itself explodes And the cross-sectional area of the refrigerant passage limits the size reduction of the superconducting current supply line.

Therefore, the problems to be solved by the present invention (objects)
A first object of the present invention is to provide a superconducting current supply line that does not require refrigerant pressure control in a long heat-insulating conduit and can be reduced in size. A second object is to provide a method for cooling the superconducting current supply line to a superconducting transition temperature or lower.
Third, it is an object of the present invention to provide a connection method having a quench countermeasure for the superconducting current supply line.

[0006]

Means for Solving the Problems First means provided to achieve the first object (object) of the present invention; the superconducting current supply line is a superconducting current supply line with an adiabatic conduit,
The superconducting conductor is assembled by winding a plurality of superconducting wires around the outer periphery of a core material made of pure metal having high thermal conductivity,
At least the inner pipe of the heat-insulating pipe has a structure made of pure metal having high thermal conductivity.

As described above, by using a pure metal (eg, silver, copper, aluminum) material having a high thermal conductivity for the composite base material and the core material of the superconducting wire, the heat conduction in the longitudinal direction is increased. The superconducting wire and the core material themselves serve as a cooling medium by heat transfer. In addition, since the same pure metal (for example, copper, silver or aluminum) material is used for the inner pipe of the heat-insulating conduit, only cooling with a refrigerant or a refrigerator at an end portion,
In the longitudinal direction of the main body, the pipe is cooled by the solid heat transfer of the pipe itself. Further, the inner pipe of the heat insulating pipe absorbs radiant heat from the high temperature side of the heat insulating layer, and shields the superconducting wire from the radiant heat. Therefore, a system and control for circulating the refrigerant along the superconducting conductor for a long time become unnecessary, and the main body size of the superconducting current supply line can be reduced.

Further, a second means provided to achieve the second object (object); a method for cooling a superconducting current supply line, comprising: The superconducting conductor and part of the core material in the longitudinal direction are directly cooled using a liquid refrigerant, and the other parts are indirectly cooled in the longitudinal direction by the heat transfer of the composite pure metal itself, so that the total length of the superconducting conductor is reduced. It comprises a method of cooling below the critical temperature of superconductivity.

Further, a third means provided to achieve a third object (object); a method for connecting a superconducting current supply line, comprising the steps of: A method of electrically connecting a superconducting conductor to both or one of the outer tube and both ends thereof. By doing so, the metal tube of the heat-insulating conduit functions as an electrical stabilizing material that bypasses the current of the superconducting conductor, so that quench countermeasures can be achieved.

The heat insulation of the heat insulation pipe is preferably carried out in a vacuum or a laminated vacuum. The superconducting conductor is made of a superconducting material that can be cooled to a superconducting critical temperature or lower by using a refrigerator or a liquid refrigerant. In addition, the minimum necessary configuration of the main body of the superconducting current supply line is a superconducting conductor, a heat-insulating conduit, and a mechanical reinforcement. Electrical insulators are used as needed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1] FIG. 1 shows a first means of the present invention. It is a specific example of a superconducting current supply line. The superconducting current supply line in this specific example includes a forward superconducting conductor 3a and a return superconducting conductor 3b.
The superconducting conductor 3a for the outward path is formed by winding a plurality of oxide-based Bi-2223 superconducting silver sheathed wires around a core material 3c made of a copper round bar and assembling them. Consists of structured conductors. A polyethylene tape is wound around the outside of the outward superconducting conductor 3a to form an electric insulating layer 3d.
And a plurality of oxide-based Bi-2223 superconducting silver sheath wires are wound around the outside of the layer to form the return superconducting conductor 3b. Reference numeral 3f denotes a reinforcing layer formed by winding an aromatic polyimide film (film is used including a tape) known under the name of Kapton (trade name of DuPont, U.S.A.) on the return conductor 3b.

The superconducting conductor constructed as described above is inserted into a pure copper corrugated pipe 3g constituting the inner pipe of the heat insulating pipeline. Reference numeral 3h denotes a pure copper corrugated pipe constituting the outer pipe of the heat insulating pipeline, and a space 3k between the corrugated pipe and the inner corrugated pipe 3g via a spacer 3i.
And the space is vacuum-insulated. 3j is an exterior reinforcement layer made of vinyl chloride resin.

FIG. 2 shows a third means of the present invention. A specific example of a method of connecting a superconducting current supply line is described below, which is a method of electrically connecting the superconducting current supply line having the above configuration. 2a is an outer tube of the heat-insulated conduit, 2b is an inner tube of the heat-insulated conduit, 2c is a connection resistance, and 2d and 2e are superconducting conductors, respectively. Further, a superconducting current supply line connected by the above method is cooled by the second means of the present invention. FIG. 6 shows the concept of the cooling system. In this embodiment, as shown in FIG. 6, the present invention is applied to a current supply line between a superconducting coil 4b cooled by liquid helium 4a as a cryogen and a power supply 4c placed at room temperature. The superconducting current supply line is composed of a superconducting conductor 4d for the forward path, a superconducting conductor 4e for the return path, an inner pipe 4f of the heat-insulating pipe, and an outer pipe 4g of the heat-insulating pipe. The outer tube 4g of the heat insulating conduit is connected in parallel with the conductor 4e, and is connected in parallel with the outward superconducting conductor 4d.

With respect to the superconducting current supply line, the electric connection portions 4h, 4i, 4j, and 4k at one end are connected to liquid nitrogen 4v.
Immersed and cooled in the other end, and the electrical connection portions 41, 4 at the other terminal portion
m, 4n, 4p are immersed and cooled in liquid helium 4a, and the electrical connections 4q, 4s, associated with the outer tube 4g of the adiabatic conduit.
4t is kept at room temperature. Further, the superconducting coil 4b is connected so as to excite the superconducting coil 4b on the outward path and the return path of the copper lead 4u.

FIG. 7 shows a specific example of an end structure on the liquid helium 4a cooling side of the above-described cooling system, and FIG. 8 shows a specific example of an end structure on the liquid nitrogen 4v cooling side of the same cooling system.
Shown in To explain the detailed structure of FIG. 7, the electrical forward side (or high voltage side) includes the forward superconducting conductor 5a of the superconducting current supply line, the core material 5b, the lead 5d of the superconducting coil 5c, and the lead 5d and the forward path. 5e for connecting the superconducting conductor 5a to the outward connection conductor 5h, an outer pipe 5f of the heat insulating conduit, a connection flange 5g, and a connection portion 5i between the outward connection conductor 5h and the connection flange 5g. The outer tube 5f and the connection flange 5g of the heat-insulating pipeline are connected to each other by soldering, brazing, bolting, or welding. As the outward connection conductor 5h, a method of electrically connecting a support material such as stainless steel or brass mechanically constituting the inside of the cryostat 5j and using it together as a conductor or separately providing the conductor is adopted. The forward connection conductor 5h is not a conductor that always flows the rated current, but a conductor that does not burn out due to Joule heat by the short-time conduction of about 1 to 30 minutes.

The electrical return path (or low voltage side) includes a return path superconductor 5k, an inner pipe 51 of an adiabatic conduit, a lead 5m of a superconducting coil, a return path superconductor 5k and a lead 5m of a superconducting coil 5c, and an insulating pipe. It comprises a connecting portion 5n for electrically connecting the inner tube 51 of the road.

The forward path and the return path are electrically insulated by an electric insulating layer 5p in the superconducting current supply line, an electric field stress cone 5q at the end, and an insulating flange 5r.

In FIG. 7, the end of the outward superconducting conductor 5a, the core 5b, and the end of the inner tube 5l of the adiabatic conduit are immersed in liquid helium 5t and directly cooled, and the superconducting current supply line at the portion not immersed and cooled is Cooling by heat transfer.
The adiabatic conduit is vacuum-enclosed by welding and joining the inner tube 5l and the stainless steel flange 5v by welding 5u and the outer tube 5f and the connecting flange 5g by welding 5x. Not to enter.

Next, a specific example of FIG. 8 showing the other end structure will be described. Cryostat 6 of liquid nitrogen 6a
Within b, the end of the superconducting current supply line 6c and the forward copper lead 6d and the return copper lead 6e connected to the power supply source at room temperature are electrically connected. Inner pipe 6 of heat insulation pipe
The end of f is electrically connected by welding at the connection portion 6g, and is connected in parallel with the return path superconducting conductor 6P.
The inner pipe 6f of the heat-insulating pipe has a part immersed in the liquid nitrogen 6a, thereby performing the heat transfer cooling of the heat that has entered the heat-insulating pipe from the outside and cooling the pipe itself.

The outer pipe 6i of the heat-insulating pipe is provided with a metal flange 6
j and welding connection 6x, the metal flange 6j is electrically connected to the outward copper lead 6d by brazing 6y, and is connected in parallel with the outward superconductor 6h. The electrical insulation between the forward path and the return path includes an insulating flange 6l, an insulating layer 6m in the superconducting current supply line, and an electric field stress cone 6.
n. The cooling of the superconducting current supply line is performed by the principle of the surface heat flux immersed in the liquid nitrogen 6a at the end of the inner tube 6f of the heat insulating conduit, the outward superconducting conductor 6h, and the core material 6q and the solid heat transfer in the longitudinal direction. Done. Further, the inner pipe 6f of the heat insulating pipe and the stainless steel flange 6z are provided so that the vaporized liquid nitrogen 6a does not enter the vacuum layer of the heat insulating pipe.
Are welded at the joint 6w to be vacuum-sealed.

[Embodiment 2] As a modified example of the system of Embodiment 1 described above, the superconducting conductor 3a for the forward path and the superconducting conductor 3b for the backward path of FIG. 1 are made of an oxide Bi-2212 superconducting silver sheath wire or oxide Tl. -2223 Made of superconducting silver sheath wire.

[Embodiment 3] As a modification of the system of Embodiment 1 or 2, liquid helium 5t shown in FIG.
Was replaced with liquid nitrogen.

[Embodiment 4] Embodiment 1, 2 or 3
As a modification of the above system, the protective layer 3f in FIG. 1 is made of a metal tape. This is because the protective layer is also used as an electrical stabilizing material, and the heat shrinkage is set to a value close to that of the superconducting wire, thereby preventing the thermal distortion of the superconducting wire from deteriorating and through the direct cooling surface at the end. This is because the purpose is to increase the heat transfer in the longitudinal direction.

[Embodiment 5] As a modified example of the electrical connection between the inner pipe and the outer pipe of the heat-insulating pipe in the system of the first, second, third or fourth embodiment, they were connected as shown in FIG. This is a method in which the outer tube 2a is not electrically connected to the superconducting current supply line. When the superconducting conductor 2d is used under a high voltage, the outer tube 2a is used as a ground line, and no voltage surge is applied to the outer tube 2a. Is considered. In this case, in the terminal configuration portion of FIG. 7, the forward connection conductor 5h and the conductor connection portion 5i
8 is not required, so that consideration of electrical insulation for the connection flange 5g is not required. Further, in the terminal configuration portion in FIG. 8, the electrical connection portion of the outward copper lead 6d and the metal flange 6j is not required, and the superconducting current supply line is not required. The connection is simple. However, in the case of this method, the superconducting conductor 2d is
Although the number of parallel conductors with respect to the quench is reduced by one item and the reliability is inferior, if the superconducting conductor 2d itself has a sufficient quench countermeasure, the system is low in cost because it is simple to manufacture.

[Embodiment 6] As a modified example of the electrical connection between the inner pipe and the outer pipe of the heat insulating pipe in the system of the fifth embodiment,
The electrical connection method of FIG. 4 was adopted. This is a method applied when both the outer tube 2a and the inner tube 2b of the heat insulating conduit are used under the high voltage of the superconducting conductor 2e, or when the simplicity of the connection of the superconducting current supply line is considered. Further, in this method, by designing the connection resistance 2f to be larger than the connection resistance 2g, it is possible to reduce the heat load due to the Joule heat of the inner tube 2b on the low-temperature side of the heat-insulating pipeline, and to reduce the thermal stability of the superconducting conductor. It becomes a big system.

The terminal part in this case is basically the same as the structure of the fifth embodiment.
b and the outer tube 2d are connected by welding to vacuum seal them,
Another point is that the inner tube and the outer tube are electrically connected.

[Embodiment 7] As a modified example of the electrical connection between the inner pipe and the outer pipe of the heat-insulated conduit in the system of the fifth embodiment,
The electrical connection method of FIG. 5 was adopted. This is a system in which both the outer tube 2a and the inner tube 2b of the heat insulating conduit are electrically insulated from the superconducting conductor. Outer pipe 2a of heat insulating pipeline
And the inner tube 2b may be electrically connected.

Embodiment 8 This is a modification of the cooling method of Embodiment 4, 5, 6, or 7. FIG. 9 shows the terminal portion of FIG.
Terminal structure, ie, a cooling cryogen 7a for a superconducting coil
And a cryogen 7b for cooling the superconducting current supply line were arranged in another space.

[Regarding Applied System] In the above-mentioned embodiment, the current receiving side is limited to the superconducting coil. However, the present invention is not limited to this. It is also useful to use a superconducting current supply line for the device.

[0030]

According to the present invention as described above, firstly, there is provided a superconducting current supply line which does not require refrigerant pressure control in a long heat-insulating conduit and can be downsized. It is possible to achieve the intended object of providing a method of cooling the superconducting current supply line to a temperature lower than the superconducting transition temperature, and thirdly providing a connection method of the superconducting current supply line with quench measures. In addition, when a large current is supplied to the superconducting current supply line at a place where the height difference is large or where the height difference is not stable, it is advantageous in that the pressure control of the refrigerant becomes unnecessary. There is no problem of refrigerant pressure drop when performing long cooling. The risk of insulated pipeline explosion can be completely avoided. Maintenance is easy because a pump for circulating the refrigerant is not required. And the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a specific example of a superconducting current supply line as first means in Embodiment 1 of the present invention.

FIG. 2 is an explanatory view showing a specific example of a method of connecting a superconducting current supply line as a third means in the first embodiment of the present invention.

FIG. 3 is an explanatory view showing a specific example of a method of connecting a superconducting current supply line as a third means in a fifth embodiment of the present invention.

FIG. 4 is an explanatory view showing a specific example of a method of connecting a superconducting current supply line as a third means in a sixth embodiment of the present invention.

FIG. 5 is an explanatory view showing a specific example of a method of connecting a superconducting current supply line as a third means in a seventh embodiment of the present invention.

FIG. 6 is a conceptual diagram of a superconducting current supply line cooling system as a second means in the first embodiment of the present invention.

FIG. 7 is a detailed view of a terminal structure (liquid helium side) according to the first embodiment of the present invention.

FIG. 8 is a detailed diagram of a terminal structure (liquid nitrogen side) according to the first embodiment of the present invention.

FIG. 9 is a detailed view of a terminal structure of a superconducting current supply line according to an eighth embodiment of the present invention.

FIG. 10 is an explanatory view of a conventional example of a cooling system in a superconducting current supply line.

FIG. 11 is a cross-sectional view showing an example of a conventional superconducting current supply line.

[Explanation of symbols]

2a Outer pipe of heat insulating pipe 2b Inner pipe of heat insulating pipe 2c Connection resistance 2d Superconducting conductor 2e Superconducting conductor 2f Connection resistance (FIG. 4) 2g Connection resistance (FIG. 4) 3a Outgoing superconducting conductor 3b Returning superconducting conductor 3c Core Material: Copper round bar 3d Electrical insulating layer 3f Reinforcement layer (wrapping layer of aromatic polyimide film) 3g Inner pipe of heat insulating pipe; corrugated pipe 3h Outside heat insulating pipe; corrugated pipe 3i spacer 3k space; vacuum insulation 3j Exterior reinforcement layer 4a Refrigerant; liquid helium 4b Superconducting coil 4c Power supply source 4d Outgoing superconducting conductor 4e Incoming superconducting conductor 4f Inner pipe of heat insulating pipe 4g Outer pipe of heat insulating pipe 4h Electrical connection 4i Electrical connection 4j Electrical connection Part 4k electric connection part 4l electric connection part 4m electric connection part 4n electric connection part 4q electric connection part 4s electric connection part t Electrical connection part 4v Refrigerant; liquid nitrogen 4u Copper lead 5a Outgoing superconducting conductor 5b Core material 5c Superconducting coil 5d Lead 5e Connection part 5f Outer tube of heat insulating conduit 5g Connection flange 5h Outbound connection conductor 5i Conductor connection part 5j Cryostat 5k Return path superconducting conductor 5l Inner tube of heat insulating pipe 5m Lead 5n Connection 5p Electric insulating layer 5q Electric field stress cone 5r Insulating flange 5t Liquid helium 5v Stainless flange 5u Welding joint 5x Welding joint 5y Vacuum insulation 6a Liquid nitrogen 6b Cryostat flow 6c Superconductivity Supply line 6d Copper lead for forward path 6e Copper lead for return path 6f Inner tube of heat-insulated conduit 6g Connection part 6h Superconducting conductor for return path 6i Outer tube of heat-insulated conduit 6j Metal flange 6l Insulation flange 6m Insulation layer 6n Electric field stress cone 6p For return path Superconductivity Conductor 6q Core material 7a Coolant for cooling superconducting coil 7b Coolant for cooling superconducting current supply line

Claims (3)

[Claims] 1. A superconducting current supply line with an adiabatic conduit, wherein a superconducting conductor is assembled by winding a plurality of superconducting wires around an outer periphery of a core material made of pure metal having a high thermal conductivity, and is insulated. A superconducting current supply line, characterized in that at least the inner pipe of the pipe is made of pure metal having a high thermal conductivity. 2. A superconducting current supply line with an adiabatic conduit, wherein superconducting conductors are gathered by winding a plurality of superconducting wires around an outer periphery of a core material made of pure metal having a high thermal conductivity. A method for cooling a superconducting current supply line having a structure in which at least an inner tube of a conduit is made of a pure metal having a large thermal conductivity, comprising: Part of the direction is directly cooled using liquid refrigerant, and the other part is indirectly cooled in the longitudinal direction by the heat transfer of the pure metal itself, so that the entire length of the superconducting conductor is cooled below the critical temperature of superconductivity. A method for cooling a superconducting current supply line, comprising: 3. A superconducting current supply line with an adiabatic conduit, wherein the superconducting conductors are assembled by winding a plurality of superconducting wires around an outer periphery of a core material made of pure metal having high thermal conductivity. In a method of connecting a superconducting current supply line having a configuration in which at least an inner tube of a conduit is made of pure metal having a high thermal conductivity, the superconducting current supply line may be connected to at least one of the inner tube and the outer tube of the heat insulating conduit. On the other hand, a method for connecting a superconducting current supply line, wherein a superconducting conductor is electrically connected at both ends.