JP2510373B2 - Magnetic shield type bushing using composite superconductor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting application device such as a superconducting magnet, which is attached to an equipment storage container configured to cool the superconducting application device with a cooling body such as liquid helium. The present invention relates to a bushing for electrically connecting a device and a superconducting application device, and more specifically, a current lead portion electrically connected to the superconducting application device and the current lead portion shielded from an external magnetic field. The present invention relates to a magnetic shield type bushing using a composite superconductor in the magnetic shield part.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 8, a superconducting applied device MG such as a superconducting magnet is housed and a superconducting applied device MG is stored in a device storage container 53 for cooling the superconducting applied device MG with liquid helium He. To the superconducting application device MG in the liquid helium He and the power supply lines 54 and 55 from the power supply device that supplies the required power from the outside.
A bushing 58 for electrically connecting the lead wires 56 and 57 is attached. The bushing 58 is configured to cool two rod-shaped electrodes 59 and 60 formed of a bulk material of high temperature superconducting material by convection cold heat from the liquid helium He to obtain superconducting characteristics. At the upper ends of the electrodes 59 and 60, power supply lines 54 and 55 are provided.
Is connected and lead wires 56 and 57 are provided at the lower end.
Is connected.

[0003]

The conventional bushing 58 uses two electrodes 59 and 60 formed of a bulk material of a high temperature superconducting material having weak mechanical strength.
As a result of receiving a strong magnetic field due to a large current when the energizing circuit is short-circuited, an electromagnetic force is applied to the two electrodes 59 and 60, and the electrodes 59 and 60 may be broken. In addition, when the quenching phenomenon occurs in the electrodes 59, 60, the temperature rises due to heat generation at the quenching point due to the energization current, and the temperature rise region rapidly expands.
There is a problem that the superconducting properties of the entire 60 are lost and the electric resistance increases, and as a result, heat generation is instantaneously destroyed. Further, there is a problem that the electrodes 59 and 60 are in a magnetically unstable state and generate heat when being affected by an external magnetic field, and the superconducting characteristics are lost. Further, when connecting the lead wires to the electrodes 59 and 60 formed of the bulk material of the high temperature superconducting material, there is a problem that electrical connection is not easy because soldering or the like is difficult.

Therefore, in the present invention, a current lead portion for passing a current from the power supply device to the superconducting application equipment and a current lead portion are arranged so as to surround the current lead portion and shield the magnetism from the outside. By using a composite superconductor composed of a metal and a superconducting material for the magnetic shield part, (1) the mechanical strength of the current lead part is increased, and a large current is generated when the circuit is short-circuited. Do not destroy even if electromagnetic force is applied. (2) Even if a quench phenomenon occurs in the superconducting material in the current lead portion, the device is prevented from being damaged by heat generation by bypassing the passage of the electric current to the superconducting applied device through the metal cylindrical container having high conductivity. (3) The electrical connection of the external connection lead wire to the current lead portion is facilitated. (4) The shape of the current lead portion can be arbitrarily formed. (5) The shape of the magnetic shield part can be arbitrarily formed in accordance with the shape of the current shield part to improve the transport current of the current shield part and to superconduct the magnetic shield part. The magnetic shield effect is enhanced by passing the magnetic flux repelled by the Meissner effect of the substance through a metal having a high relative permeability. That is the technical problem to be solved.

[0005]

[Means for Solving the Problems] The technical means for solving the above-mentioned problems is to store a superconducting applied device manufactured by using a superconducting material, and attach the superconducting applied device to a device container for cooling the superconducting applied device with liquid helium. And a magnetic shield for electrically connecting an external power supply device and the superconducting application device, and a magnetic shield for surrounding the current lead portion to shield external magnetism. -In a bushing provided with a sleeve portion, the current lead portion is a tubular container formed of a metal having high conductivity, and the tubular container after being poured into the tubular container in a heating and melting state and cooled and solidified, The magnetic shield is composed of a composite superconductor having a ceramic melt solidified product which is heat-treated with the shaped container and converted into a superconducting substance.
The outer cylinder and the inner cylinder, at least the outer cylinder is a double-cylinder metal container in which at least the outer cylinder is formed of a ferromagnetic material, and the space between the outer cylinder and the inner cylinder of the double-cylinder metal container. It is composed of a composite superconductor having a ceramic melt solidified product which is poured into a heating and melting state, cooled and solidified, and then heat treated together with a double cylindrical metal container and converted into a superconducting substance.

[0006]

In the magnetic shield type bushing using the above-mentioned composite superconductor, the current lead portion is formed by inserting the ceramic melt solidified substance converted into the superconducting substance into the metal cylindrical container having high conductivity. Because of the structure, if the current lead portion is in the required cooling state, it conducts current with almost zero electric resistance, and the superconducting material is relatively fragile. Since they are mechanically reinforced, for example, two current lead parts are arranged in close proximity, and a large current such as a short circuit current flows through the two current lead parts, causing a large electromagnetic force. Even if it occurs, the problem that the current lead part is mechanically destroyed is solved. Further, even if the superconducting substance is in a quenching state during the passing of electric current, the metal cylindrical container functions as a bypass passage for the electric current, so that the superconducting substance is prevented from being damaged by the jule heat. On the other hand, in the magnetic shield part, at least the outer cylinder is made of a ferromagnetic material having a high relative magnetic permeability, so that the magnetic flux repelled by the Meissner effect of the superconducting material passes through the metal having a high relative magnetic permeability. , The magnetic shield effect is enhanced.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view showing the overall structure of the first embodiment of the present invention. As shown in FIG. 1, a device storage container 2 filled with liquid helium 1 contains a superconducting magnet 3 as a superconducting applied device. Further, in the equipment container 2, lead wires 4 and 5 connected to the coil of the superconducting magnet 3 and a power supply line from a power supply device (not shown) for supplying required power to the superconducting magnet 3 from the outside. Two bushings 6 and 6 of the same structure for electrically connecting the two are attached.

The current lead portion 6A arranged in the central portion of each bushing 6 is one in which the lead wires 4 and 5 connected to the coil of the superconducting magnet 3 are connected to the lower end portion. 3 forms a current path to be passed through.
The current lead portion 6A is a container 12 formed of a metal having a high conductivity, for example, copper, into which a ceramic melt solidified material 13 to be described later, which is a superconducting substance, is inserted. In No. 13, a ceramic composition that can be converted into a superconductor by a heat treatment described later is injected in a molten state by heating, cooled and solidified, and then reheated to be converted into a superconducting substance.

A cylindrical magnetic shield portion 6B arranged so as to surround the current lead portion 6A is provided in the space between the outer cylinder 14 and the inner cylinder 15 formed integrally with each other, and the ceramic melt is formed. A ceramic melt solidified material 16 converted into a superconducting substance in the same manner as the liquid solidified material 13 is inserted. The outer cylinder 14 is made of iron having a high relative magnetic permeability, and the inner cylinder 15 is made of a metal having a high electric conductivity such as copper. Or outer cylinder 1
Both 4 and the inner cylinder 15 may be formed of iron having a high relative magnetic permeability. An insulator 17 is interposed between the current lead portion 6A and the magnetic shield portion 6B configured as described above so that a constant gap is provided therebetween. An upper end of the magnetic shield portion 6B is covered with a disk-shaped lid 18 made of iron, and a rod-shaped terminal 19 made of copper is provided at the center of the lid 18 for insulation. It is attached through the body. A power supply line from a power supply device (not shown) that supplies the superconducting magnet 3 with required power from the outside is connected to the terminal 19.

Liquid nitrogen 20 is filled between the current lead portion 6A and the magnetic shield portion 6B, and the ceramic melt solidified material 13, 1 converted into a superconducting substance.
The current lead portion 6A and the magnetic shield portion 6B are cooled so that 6 functions as a superconductor. As a result, the magnetic shield section 6B shields the magnetic field from the outside by the Meissner effect.
At the same time, the current is supplied to the current lead portion 6A with the electric resistance being substantially zero.

Next, an example of a method of manufacturing the current lead portion 6A and the magnetic shield portion 6B will be described. 1. Current lead portion 6A (1) The container 12 is made of a metal having a high conductivity, such as copper. (2) Bi ₂ O ₃ , SrCO ₃ , CaCO ₃ , CuO,
The powder of Ag ₂ O was Bi / Sr / Ca / Cu / Ag = 2 /
The ceramic composition, which was weighed and mixed so as to have a molar ratio of 2/1/2 / 0.3, was placed in an alumina crucible, and 1
It is heated in an electric furnace maintained at 150 ° C. for 15 minutes and poured into the container 12 in a melted state, and cooled to room temperature to integrate the container 12 and the ceramic melt solidified product 13, and then the integration. 50 at 810 ° C
By heating for a long time, a copper / ceramic composite superconductor having superconducting properties is formed, and this is connected to the current lead portion 6A.
And As a result of the superconducting characteristic measurement, the critical temperature at which the electric resistance of the current lead portion 6A obtained as described above is zero is about 79 K (Kelvin), and the critical current density at zero external magnetic field is about 20 A / cm ^2. Met. 2. Magnetic shield part 6B (1) The outer cylinder 14 and the inner cylinder 15 are produced, and both are integrated. (2) Bi ₂ O ₃ , SrCO ₃ , CaCO ₃ , CuO,
The powder of Ag ₂ O was Bi / Sr / Ca / Cu / Ag = 2 /
The ceramic composition, which was weighed and mixed so as to have a molar ratio of 2/1/2 / 0.3, was placed in an alumina crucible, and 1
It is heated in an electric furnace maintained at 150 ° C. for 15 minutes to be melted and poured into the void formed by the outer cylinder 14 and the inner cylinder 15 and cooled to room temperature to cool the outer cylinder 14 and the inner cylinder 1.
5 and the ceramic melt solidified product 16 are integrated, and then the integrated composite is heated at 810 ° C. for 50 hours to form a metal / ceramic composite superconductor having superconducting properties. The shield portion 6B is used. As a result of superconducting property measurement, the critical temperature showing zero electric resistance and the critical current density at zero external magnetic field showed almost the same values as those of the current lead portion 6A. The above current
The ceramic composition for forming the magnetic shield portion 6A and the magnetic shield portion 6B is bismuth (Bi) -strontium (S
r) -calcium (Ca) -copper (Cu) -oxygen (O) -based ceramics as well as rare earth-barium (Ba) -copper (Cu) -oxygen (O) -based ceramics, or heat treatment to form a superconductor. There is no particular limitation as long as it is a convertible ceramic composition. The current lead portion 6A has a single structure in which the hollow portion of the container 12 is filled with the ceramic melt solidified material 13. However, as shown in FIG. 7, the hollow portion of the container 12 has a linear composite superconductor. A plurality of 13A may be arranged in parallel. Furthermore, each linear composite superconductor 1
You may twist 3A.

In the bushing 6 constructed as described above, (1) the mechanical strength of the current lead portion 6A is strengthened so as not to be destroyed even by an electromagnetic force due to a large current when the circuit is short-circuited. it can. (2) Even if the superconducting substance (ceramic melt solidified material 13) of the current lead portion 6A is quenched, the current passing through the superconducting magnet 3 is bypassed through the metal container 12 having a high conductivity such as copper. By letting
Prevents destruction due to heat generation. (3) Electrical connection of the lead wires 4 and 5 to the current lead portion 6A can be facilitated. (4) The shape of the current lead portion 6A can be arbitrarily formed. (5) The shape of the magnetic shield portion 6B can be arbitrarily formed according to the shape of the current lead portion 6A, the transport current of the current lead portion 6A can be improved, and the magnetic shield portion can be formed. -The superconducting material of the field portion 6B (ceramic melt solidified material 1
The magnetic shield effect can be enhanced by passing the magnetic flux repelled by the Meissner effect of 6) through the metal (outer cylinder 14) having a high relative magnetic permeability.

FIG. 2 is a perspective view showing the structure of the bushing 21 of the second embodiment of the present invention, and FIG. 3 stores the superconducting magnet 3 as in the first embodiment, and the superconducting magnet 3 is a liquid. It is sectional drawing of the state which attached the bushing 21 of 2nd Example to the equipment storage container 2 comprised so that it may cool with helium 1.

As shown in FIGS. 2 and 3, the bushing 21
The current lead portion 21A disposed in the central portion of the is formed coaxially with an outer conductor 22 and an inner conductor 23.
The lead wire 4 connected to the coil of the superconducting magnet 3 is connected to the outer conductor 22, while the lead wire 5 is connected to the inner conductor 23. The outer conductor 22 and the inner conductor 23 constituting the current lead portion 21A are formed in the hollow portions of the double pipe 24 and the single pipe 25, respectively, which are made of a metal having a high conductivity, such as copper, in the first embodiment. Ceramic melt solidified products 26 and 27 produced in the same manner are inserted, and have the same superconducting characteristics as those of the first embodiment. Further, an insulator 28 that electrically insulates the outer conductor 22 and the inner conductor 23 is interposed between the outer conductor 22 and the inner conductor 23.

The cylindrical magnetic shield portion 21B arranged so as to surround the current lead portion 21A is provided in the space between the outer cylinder 29 and the inner cylinder 30 formed integrally with each other, and the ceramic melt is formed. A ceramic melt solidified material 31 converted into a superconducting material is inserted in the same manner as the liquid solidified materials 26 and 27.
As in the first embodiment, the outer cylinder 29 is made of iron having a high relative magnetic permeability, and the inner cylinder 30 is made of copper.
0 may be iron. An insulator 32 is interposed between the current lead portion 21A and the magnetic shield portion 21B configured as described above so that a constant gap is provided therebetween. Further, a disk-shaped lid 33 made of iron is put on the upper end of the magnetic shield portion 21B, and the lid 33 is made of copper and has rod-shaped terminals 34 and 35 which are not shown in the figure. Is attached through. The upper ends of the terminals 34 and 35 are connected to a power supply line from a power supply device (not shown) for supplying required power to the superconducting magnet 3 from the outside, while the lower ends thereof are connected to the outer conductor 22 and the inner conductor 23. Lead wires 36 and 37 connected to the upper end of the are connected.

The bushing 21 having the above-described structure is filled with liquid nitrogen 38, the magnetic shield portion 21B shields a magnetic field from the outside due to the Meissner effect, and the current lead portion 21A has a magnetic field. current Ru is energized by electrical resistance substantially zero state.

In the bushing 21 configured as described above, (1) the mechanical strength of the current lead portion 21A is increased so as not to be destroyed even by an electromagnetic force due to a large current when the circuit is short-circuited. it can. (2) Even when the superconducting material (ceramic melt solidified material 26, 27) of the current lead portion 21A is quenched, the superconducting magnet 3 is formed of a metal having a high conductivity such as copper. By bypassing the double pipe 24 and the single pipe 25, destruction due to heat generation is prevented. (3) The electrical connection of the lead wires 4, 5 and the like to the current lead portion 21A can be facilitated. (4) The shape of the current lead portion 21A can be arbitrarily formed. (5) The magnetic shield is generated by passing the magnetic flux repelled by the Meissner effect of the superconducting substance (ceramic melt solidified material 31) of the magnetic shield portion 21B through the metal (outer cylinder 29) having a high relative permeability. The effect can be enhanced.

Next, a third embodiment will be described. FIG.
In the same manner as in the first and second embodiments, the superconducting magnet 3 is housed, and the superconducting magnet 3 is replaced with liquid helium 1.
It is sectional drawing in the state which attached the bushing 41 of 3rd Example to the apparatus storage container 2 comprised so that it might cool. The bushing 41 according to the third embodiment has a magnetic shield portion 41B formed in the same manner as the magnetic shield portion 21B of the bushing 21 according to the second embodiment.
A current lead portion 41A including an outer coil-shaped conductor 42 as shown in FIG. 6 and an inner coil-shaped conductor 43 as shown in FIG.
Is arranged. The lead wire 4 connected to the coil of the superconducting magnet 3 is connected to the outer coil-shaped conductor 42, while the lead wire 5 is connected to the inner coil-shaped conductor 43.
Is connected.

The outer coil-shaped conductor 42 and the inner coil-shaped conductor 43, which constitute the current lead portion 41A, are formed into a coil shape with a metal having a high conductivity, for example, a copper tube, and then the composite superconducting is carried out as follows. Converted to body. Bi ₂ O ₃ , SrC
The powder of O ₃ , CaCO ₃ , CuO, Ag ₂ O is Bi / S.
The ceramic composition was weighed and mixed so that the molar ratio of r / Ca / Cu / Ag = 2/2/1/2 / 0.3 was put in an alumina crucible and the temperature was maintained at 1150 ° C. in an electric furnace. After heating for 15 minutes to melt, insert one end of each copper tube into the melt, depressurize from the opposite end and suck the melt into the copper tube, then cool to room temperature The solidified materials 51 and 52 are formed. Then, the composite body in which each copper tube and the ceramic melt solidified material 51, 52 are integrated is heated at 810 ° C. for 50 hours in argon gas or in air, as shown in FIGS. 5 and 6. A coil-shaped copper / ceramic composite superconductor was obtained. The outer coil-shaped conductor 42 and the inner coil-shaped conductor 43 obtained in this manner are the same as the current leads of the first and second embodiments.
It showed superconducting properties similar to those of the ridge.

The current lead section 41 constructed as described above
An insulator 44 is interposed between A and the magnetic shield portion 41B so as to have a constant distance therebetween. Further, a disk-shaped lid 45 made of iron is provided on the upper end of the magnetic shield portion 41B.
The lid 45 is covered with rod-shaped terminals 46 and 47 made of copper. This terminal 4
A power supply line from a power supply device (not shown) for supplying required power to the superconducting magnet 3 from the outside is connected to the upper ends of the coils 6, 47, while the outer coil-shaped conductor 42 and the inner coil-shaped conductor 42 are connected to the lower ends. Lead wires 48, 49 connected to the upper end of the conductor 43 are connected.

The bushing 41 having the above construction is filled with liquid nitrogen 50, the magnetic shield portion 41B shields a magnetic field from the outside by the Meissner effect, and the current lead portion 41A is electrically connected. resistance current Ru is energized at almost zero state.

[0022]

As described above, according to the present invention, the current leakage is
The cylindrical part is made of a metal with high conductivity, and the ceramic is poured into the cylindrical container in a heating and melting state, cooled and solidified, and then heat-treated together with the cylindrical container to be converted into a superconducting substance. On the other hand, the magnetic shield part is composed of an outer cylinder and an inner cylinder, and a double cylinder metal container in which at least the outer cylinder is made of a ferromagnetic material, A composite superconductor consisting of a ceramic melt solidified product, which is poured into the space between the outer cylinder and the inner cylinder in a heated and molten state, cooled and solidified, and then heat-treated with the double cylindrical metal container and converted into a superconducting substance. Because it consisted of the body,
It has the following effects. (1) The mechanical strength of the current lead portion can be increased so as not to be destroyed even by an electromagnetic force due to a large current when the circuit is short-circuited. (2) Even if a quench phenomenon occurs in the superconducting material of the current lead portion, by passing the electric current to the superconducting applied device through the metal cylindrical container having high conductivity, the current lead portion due to heat generation The destruction of can be prevented. (3) The electrical connection of the external connection lead wire to the current lead portion is facilitated. (4) The shape of the current lead portion can be arbitrarily formed. (5) Since the shape of the magnetic shield portion can be arbitrarily formed according to the shape of the current lead portion, the shield of external magnetism can be sufficiently achieved, and the transport current of the current lead portion can be improved. In addition, the magnetic shield effect can be enhanced by passing the magnetic flux repelled by the Meissner effect of the superconducting material of the magnetic shield part through the metal having high relative permeability.

[Brief description of drawings]

FIG. 1 is a sectional view showing an overall configuration of a first embodiment of the present invention.

FIG. 2 is a perspective sectional view of a second embodiment of the present invention.

FIG. 3 is a sectional view showing the overall configuration of a second embodiment of the present invention.

FIG. 4 is a sectional view showing the overall structure of a third embodiment of the present invention.

5 is a partial detailed perspective view of FIG. 4. FIG.

6 is a partial detailed perspective view of FIG. 4. FIG.

FIG. 7 is a perspective view showing a partially modified example of FIG.

FIG. 8 is a cross-sectional view showing the overall configuration of a conventional bushing.

[Explanation of symbols]

 1 Liquid Helium 2 Equipment Storage Container 3 Superconducting Magnet 4 Lead Wire 5 Lead Wire 6 Bushing 21 Bushing 41 Bushing 6A Current Lead Part 21A Current Lead Part 41A Current Lead Part 6B Magnetic Shield Part 21B magnetic shield part 41B magnetic shield part 13 ceramic melt solidified material 16 ceramic melt solidified material 26 ceramic melt solidified material 27 ceramic melt solidified material 31 ceramic melt solidified material 51 ceramic melt solidified material 52 ceramic Melt solidified

Claims (3)

(57) [Claims] 1. A superconducting application device manufactured by using a superconducting material is housed, and the superconducting application device is attached to a device storage container that is cooled by liquid helium so that an external power supply device and the superconducting application device are electrically connected to each other. In a bushing that includes a current lead portion that is electrically connected and a magnetic shield portion that is arranged so as to surround the current lead portion and shields the magnetism from the outside. Is a cylindrical container made of metal with high conductivity, and is poured into the cylindrical container in a molten state in a molten state, cooled and solidified, and then heat-treated together with the cylindrical container to solidify the ceramic melt. And the magnetic shield.
The outer cylinder and the inner cylinder, at least the outer cylinder is a double-cylinder metal container in which at least the outer cylinder is formed of a ferromagnetic material, and the space between the outer cylinder and the inner cylinder of the double-cylinder metal container. A composite superconductor characterized by being composed of a ceramic melt solidified product which is poured into a heating and melting state, cooled and solidified, and then heat-treated together with a double cylindrical metal container and converted into a superconducting substance. Magnetic shield type bushing using. 2. The composite superconductor according to claim 1, wherein the magnetic lead portion has an outer cylinder made of iron having a high relative magnetic permeability and an inner cylinder made of a metal having a high electrical conductivity. Magnetic shield type bushing using. 3. A magnetic shield type bushing using a composite superconductor according to claim 1, wherein the magnetic lead portion has an outer cylinder and an inner cylinder made of iron.