JPH0799111A - Current lead using oxide superconductor - Google Patents

Abstract

PURPOSE:To prevent the mechanical and thermal damage of a bar-shaped oxide superconductor by improving the structure of a lead on low temperature side. CONSTITUTION:In a current lead, which consists of the series-connected body composed of the lead 2 on the high temperature side consisting of a well conductive metal and the lead 15 on the low temperature side consisting of an oxide superconductor and is cooled with refrigerant gas GHe at low temperature, the lead 15 on low temperature side consists of the series-connected body composed of the bar-shaped oxide superconductor 18 conductively coupled between a middle coupling metal fitting 6 and a lower coupling metal fitting 20 and the flexible conductor 21 conductively coupled between a low coupling metal fitting and a low-temperature terminal metal fitting 19, and it is accommodated in the tubular container 17 for coupling the middle coupling metal fitting and the low-temperature terminal metal fitting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current lead for supplying a DC exciting current from an external power source to a superconducting coil housed in a vacuum insulation container, and more particularly to a current lead using an oxide superconductor for a low temperature side lead. Regarding mechanical protection structure.

[0002]

2. Description of the Related Art A superconducting coil of a superconducting magnet device is kept in a superconducting state by being cooled by a cryogenic refrigerant such as liquid helium. It is stored as it is dipped in. Further, the current lead is cooled by the low temperature helium gas in which liquid helium is vaporized, and is configured so as to prevent the intrusion heat from the room temperature side and the Joule heat generated in the current lead from invading the cryogenic portion. In the conventional current lead, a good electric conductor such as copper was used as a conductor, but since copper is a good conductor and a good heat conductor at the same time, heat entering the cryogenic part increases, and expensive liquid helium Vaporization loss increases. Therefore, an oxide superconductor, which is a high-temperature superconductor, is used on the low temperature side of the current lead to reduce the Joule heat to zero, and at the same time, to utilize the low thermal conductivity of the current lead to significantly reduce the heat entering the cryogenic part. Are known.

FIG. 9 is a side view schematically showing a conventional structure of a current lead of a superconducting magnet device, and FIG. 10 is an enlarged sectional view showing an internal structure of a main part of FIG. In the figure, the superconducting coil 10 is a liquid helium H
It is housed in a state of being immersed in e and electrically connected to the low temperature terminal 9A of the current lead 1 by the lead wire 10A. The current lead 1 is configured as a series connection body of a high temperature side lead 2 having a room temperature terminal 2A on the upper side and a low temperature side lead 5 having a low temperature terminal 9A, and low temperature helium gas GHe passes through the lead and escapes to the room temperature terminal 2A side. To be cooled. As shown in a part of FIG. 10, the high temperature side lead 2 has a conductor 3 whose lower end is conductively coupled to the intermediate connection fitting 6 inside the cylindrical container 4.
As a result, Joule heat generated by the low-temperature helium gas GHe flowing through the cooling passage formed in the gap is accommodated.

The low temperature side lead 5 has a rod-shaped oxide superconductor 8 made of, for example, yttrium-based or bismuth-based in a cylindrical container 7 made of a low thermal conductive metal or an insulating material, and an upper end portion thereof. It is accommodated in a state in which it is conductively coupled to the intermediate connection fitting 6 and the lower end thereof is conductively coupled to the low-temperature terminal fitting 9, and a cooling passage for the low-temperature helium gas GHe is formed between the cylindrical container 7 and the oxide superconductor 8 By cooling the temperature of the liquid nitrogen to the liquid nitrogen temperature (about 77 K) or less, the oxide superconductor 8 becomes a superconducting state, the Joule heat becomes zero, and the heat entering into the low temperature terminal 9A is small and the consumption of liquid helium He is small. The current lead 1 of the superconducting magnet device having a small amount can be obtained.

Further, in the assembling work of the low temperature side lead 5, the rod-shaped oxide superconductor 8 is inserted into the recess of the intermediate connecting metal fitting 6 and the conductive coupling is performed by soldering, and then the oxide superconductor. 8 is fitted into the recess of the low temperature terminal metal fitting 9 for conductive coupling by soldering, and then the cylindrical container 7 is inserted from the low temperature terminal metal fitting 9 side and both ends thereof are connected to the intermediate connection metal fitting 6 and the low temperature terminal metal fitting. 9 is carried out in the procedure of fixing to the outer peripheral surface of the oxide superconductor 8, and by fixing both ends of the oxide superconductor 8 to the cylindrical container 7 through a pair of metal fittings, a current having a high rigidity low temperature side lead 5 that can withstand an external force. The lead 1 is formed.

FIG. 11 is a cross-sectional view of a main part of a current lead using a plurality of oxide superconductors. The same members as those in FIG.
The duplicated description will be omitted by adding a code obtained by adding 5 to the digit of 0. In this figure, the intermediate connecting fitting 56 and the low temperature terminal fitting 59 are provided with protrusions 61 and 91 on the opposite sides, respectively.
Is provided, and the rod-shaped oxide superconductor 58 is attached to this via connecting pieces 62 and 92 attached by bolts. By adopting such a configuration,
To attach the oxide superconductor 58 to the intermediate connecting fitting 56 and the low temperature terminal fitting 59, simply connect the connecting pieces 62 and 92 to the projecting portion 61,
It's a simple task, just attach it to 91 with bolts.

FIG. 12 is a sectional view taken along the line D--D in FIG. 11, in which the tubular container 7 is not shown, and the intermediate connecting fitting 56, the protruding portion 61 and the connecting piece 62 are viewed in the direction of the arrow. It is also a figure. In this figure, the projecting portion 61 has a square cross section, a connecting piece 62 is attached to each piece, and an oxide superconductor 58 is attached to each connecting piece 62. It consists of four rod-shaped oxide superconductors. Assuming that the current capacity of one oxide superconductor 58 is the same as that of the oxide superconductor 8 in FIG. 10, the low temperature side lead 55 has a current capacity four times that of the low temperature side lead 5 in FIG. become. Oxide superconductor 58
And the connecting piece 62 are conductively coupled by soldering. that time,
In order to reduce the resistance of the joint, the oxide superconductor 58
A structure is adopted in which silver is vapor-deposited or a silver foil is attached to a portion to be soldered.

[0008]

As described above, in the conventional low temperature side leads 5 and 55 in which both ends of the rod-shaped oxide superconductors 8 and 58 are firmly fixed to the cylindrical container, the oxide superconductor 8 is used. , 58 is often finished with the mechanical strain applied thereto. However, the oxide superconductor 8,
Since 58 is a fired material, it has the property of being mechanically brittle, and high dimensional accuracy cannot be expected. Therefore, 58 due to mechanical stress or strain applied to the oxide superconductors 8, 58 during assembly of the low temperature side leads 5, 55. Since minute cracks may occur, and thermal stress generated by the difference in thermal contraction of the constituent materials when the current lead 1 is cooled after completion of assembly concentrates on the minute cracks and forms mechanical weak points, Occasionally, there arises a problem that the oxide superconductors 8, 58 are damaged. If damage to the oxide superconductor is found after the current lead assembly work is completed, the low temperature side leads 5, 58 or the current lead 1 as a whole is disassembled and replaced with a new oxide superconductor. Needs repair,
Not only does this lead to a large economic loss, but the current lead cannot be used during this time.

On the other hand, when a pair of current leads connected to both terminals of the superconducting coil 10 are arranged in parallel with each other, a large electromechanical force is generated due to the change of the current magnetic field accompanying the turning on and off of the exciting current. It acts on the body 8,58. In such a case, excessive bending stress is applied to the oxide superconductors 8 and 58 whose both ends are fixed, which causes a problem that the mechanically fragile oxide superconductor is damaged.

An object of the present invention is to enhance the mechanical stability, thermal stability, or resistance to electromagnetic mechanical force of an oxide superconductor by improving the structure of the low temperature side lead.

[0011]

In order to solve the above-mentioned problems, according to the present invention, a current for passing an exciting current from an external power source to a superconducting coil housed in a vacuum heat insulation container and kept at a cryogenic temperature. In the case where the lead comprises a series connection body of a high temperature side lead made of a good conductive metal and a low temperature side lead made of an oxide superconductor and is cooled by a low temperature refrigerant gas, the low temperature side lead is an intermediate connection. The rod-shaped oxide superconductor conductively coupled between the metal fitting and the lower connection metal fitting, and the flexible conductor conductively coupled between the lower metal fitting and the low temperature terminal metal fitting in series, and the intermediate connection. It shall be housed in a cylindrical container that connects the metal fitting and the low temperature terminal metal fitting.

The flexible conductor may be a bundle of good conductive metal braids, a bundle of good conductive metal foils, a bundle of metallic superconducting wires, or a bundle of oxide superconducting wires or oxide superconducting ribbons. It shall consist of either. Furthermore,
The lower connecting fitting holds a gap between the lower connecting fitting and the inner wall surface of the tubular container, and a steady rest is arranged around the rod-shaped oxide superconductor.

On the other hand, the current leads for passing the exciting current from the external power source to the superconducting coil housed in the vacuum heat insulating container and kept at the cryogenic temperature are the high temperature side lead made of a good conductive metal and the oxide superconductor. Consisting of a series connection body with a low temperature side lead, which is cooled by a low temperature refrigerant gas, wherein the low temperature side lead and a plurality of oxide superconductors conductively coupled between the intermediate connection metal fitting and the low temperature terminal metal fitting. And an intermediate support having a groove on the outer peripheral side that engages with the plurality of oxide superconductors, and is housed in a cylindrical container that connects the intermediate connection fitting and the low temperature terminal fitting. .

The intermediate support is made of a low heat conductor,
It shall be connected and supported by the intermediate connection fitting so as to be positioned between the intermediate connection fitting and the lower connection fitting. Further, the intermediate support and the oxide superconductor are bonded to each other in the groove by the adhesive layer. Furthermore, the plurality of recessed grooves of the intermediate support and the oxide superconductor engaged therewith are integrated with each other by a binding wire that binds this portion from the outside.

Further, the current lead for passing the exciting current from the external power source to the superconducting coil housed in the vacuum heat insulation container and kept at the cryogenic temperature is composed of a high temperature side lead made of a good conductive metal and a plurality of rods. Low-temperature lead made of oxide superconductor, intermediate connecting fitting for conductively coupling the high-temperature lead and the low-temperature lead, and a low-temperature terminal connected to the superconducting coil. A metal fitting, in which each oxide superconductor is connected to an intermediate connecting fitting and a low temperature terminal fitting via a connecting piece, respectively, which is attached to the intermediate connecting fitting and the low temperature terminal fitting A connecting material bridging between the connecting piece and the connecting piece shall be provided.

Further, the connecting material is assumed to be a cylindrical connecting cylinder coaxial with the oxide superconductor, or a predetermined number of rod-like connecting rods arranged around the oxide superconductor.

[0017]

In the structure of the present invention, the low temperature side lead is conductively coupled between the lower connection metal fitting and the low temperature terminal metal fitting, and the rod-shaped oxide superconductor conductively bonded between the intermediate connection metal fitting and the lower connection metal fitting. As a series connection body with a flexible conductor, a lower connection metal fitting in which the lower end portion of a rod-shaped oxide superconductor is joined by being configured to be housed in a cylindrical container connecting the intermediate connection metal fitting and the low temperature terminal metal fitting. The function of releasing the restraint of (1) by the flexible conductor is obtained. Therefore, the mechanical stress acting on the rod-shaped oxide superconductor during the assembly work of the low temperature side lead, and the thermal stress applied to the rod-shaped oxide superconductor due to the difference in thermal contraction of the members can be relaxed and its damage can be prevented. This makes it possible to eliminate mechanical and thermal weak points and obtain a reliable current lead.

Further, if a flexible conductor made of a good conductive metal is provided in series on the low temperature side of the rod-shaped oxide superconductor, good flexibility can be obtained and at the same time from the room temperature side. The intruding heat is cut off by the rod-shaped oxide superconductor, and the function of suppressing the increased Joule heat by providing the flexible conductor is obtained. On the other hand, if the flexible conductor is composed of a bundle of metal-based superconducting wires, the flexible conductor becomes superconducting by directly cooling the low temperature terminal with liquid helium, so Joule heat in the flexible conductor is eliminated. , The function of further reducing the consumption of liquid helium is obtained. Also,
If the flexible conductor is composed of a bundle of oxide superconducting wire material or oxide superconducting ribbon material, the low temperature side lead shows the superconducting state at the liquid nitrogen temperature and the consumption of liquid helium is significantly reduced, and the low temperature side lead is The function of improving the mechanical and thermal stability of is obtained.

Further, if a gap is provided between the lower connecting fitting and the inner wall surface of the cylindrical container and a steady rest is arranged around the rod-shaped oxide superconductor, the rod-shaped oxide superconductor can be formed. The restraint at the lower end of the rod-shaped oxide superconductor can be released more effectively, and damage to the rod-shaped oxide superconductor can be prevented, and the mechanical stress applied to the rod-shaped oxide superconductor can be shaken by vibrating the current lead or laying it down during transportation. Since the stopper is relaxed, the function of further improving the reliability of the current lead can be obtained.

On the other hand, when it is expected that the oxide superconductor is subjected to an electromagnetic mechanical force due to the current magnetic field between the current leads parallel to each other, the low temperature side leads are electrically connected to each other between the intermediate connection fitting and the low temperature terminal fitting. Oxide superconductor of
If an intermediate support having a groove on the outer peripheral side that engages with the plurality of oxide superconductors and a tubular container that connects the intermediate connection fitting and the low-temperature terminal fitting are provided, the oxide superconductor can be provided. By dividing the conductor into multiple sections and reducing the conductor cross-sectional area, dimensional errors that occur during firing of the oxide superconductor are reduced. The function of reducing strain and preventing its damage is obtained.

If a low thermal conductor is used for the intermediate support and the intermediate support is connected and supported so as to be positioned between the intermediate connector and the low temperature terminal, the oxide superconductor can be used as the intermediate support. Since both ends of the oxide superconductor can be soldered to the metal fittings while being supported, a function of preventing a trouble of damaging the oxide superconductor during the work can be obtained.

Further, the intermediate support and the oxide superconductor are bonded to each other in the groove by an adhesive layer, or the intermediate support and the oxide superconductor are integrated with each other by a binding wire for binding from the outside. With this configuration, the electromagnetic attraction force acting between the oxide superconductors due to the current flowing in the same direction between the divided oxide superconductors is absorbed as the radial compressive force of the intermediate support, and the parallel current leads are The electromagnetic repulsive force that acts on the oxide superconductor is greatly reduced by being transmitted and absorbed by the cylindrical container through the intermediate support and the intermediate connecting metal and acting on the oxide superconductor. The function of preventing damage is obtained.

In addition, in a current lead having a structure in which rod-shaped oxide superconductors are respectively attached to the intermediate connecting fitting and the low temperature terminal fitting via connecting pieces attached to both ends thereof, a connection to be attached to the intermediate connecting fitting A function to reduce the stress applied to the oxide superconductor when the external force is applied to the current lead and the connecting material bears the force by providing the connecting material bridging between the connecting piece and the connection piece attached to the low temperature terminal fitting. Is obtained. Further, the connecting material may be either a tubular connecting tube coaxial with the oxide superconductor or a predetermined number of rod-like connecting rods arranged around the oxide superconductor.

[0024]

EXAMPLES The present invention will be described below based on examples. FIG. 1 is a cross-sectional view showing a main part of a current lead using an oxide superconductor according to an embodiment of the present invention. The same components as those of the prior art are designated by the same reference numerals, and the duplicated description will be omitted. To do. In the figure, the low temperature side lead 15 connected to the high temperature side lead 2 via the intermediate connection metal fitting 6 is
The upper end is the middle connecting fitting 6, and the lower end is the lower connecting fitting 20.
Rod-shaped oxide superconductor 18 conductively coupled to the
A flexible conductor 21 whose upper and lower ends are conductively connected to the lower connecting metal fitting 20 and the low temperature terminal metal fitting 19, and upper and lower ends are connected to the intermediate connecting metal fitting 6 and the low temperature terminal metal fitting 19 to form the oxide superconductor 18 and It is configured with a cylindrical container 17 that houses the flexible conductor 21.

Further, the flexible conductor 21 is either a bundle of good conductive metal braided material or a good conductive metal foil material, a bundle of metal-based superconducting wire material, or a bundle of oxide superconducting wire material or oxide superconducting ribbon material. It is composed of Further, a gap 20G is provided between the lower connecting fitting 20 and the inner wall surface of the cylindrical container 17, and a steady rest 22 made of, for example, a fiber reinforced plastic material is arranged around the oxide superconductor 18. The low temperature helium gas GHe flowing through the low temperature terminal fitting 19, the steady rest 22 and the intermediate connecting fitting 6 in the cylindrical container toward the high temperature side lead side cools the oxide superconductor 18 into a superconducting state. The Joule heat is eliminated and the heat entering from the high temperature side lead is reduced.

In the thus constructed current lead, the mechanical restraint of the lower connecting fitting 20 to which the lower end portion of the oxide superconductor 18 is coupled is such that the flexible flexible conductor 21 and the surroundings of the lower connecting fitting 20. 20 G of the oxide superconductor, the mechanical stress caused by fixing both ends of the oxide superconductor 18 and the thermal stress acting on the oxide superconductor 18 due to the difference in thermal contraction of each member of the low temperature side lead 15. Is eliminated, and the steady rest 22 gently supports the oxide superconductor 18 to alleviate the vibration of the current lead and the bending load that acts when placed horizontally, so that the low temperature side lead 1
It becomes possible to eliminate almost all the mechanical stress that is expected to act on the oxide superconductor 18 after the assembling process of No. 5 is completed. Therefore, in order to prevent excessive mechanical stress from being applied to the oxide superconductor 18 when assembling the low temperature side lead, for example, the oxide superconductor 18 and the flexible conductor 21.
Insert the assembly jig that connects the metal fittings with each other in the recess of each metal fitting, and solder the conductive connection parts in this condition. It is possible to easily obtain an excellent current lead.

Further, if the flexible conductor 21 is composed of a bundle of braided material of good conductive metal such as copper or copper alloy or a bundle of metal foil of good conductive property, good flexibility can be obtained and at room temperature. Insect heat from the side is cut off by a rod-shaped oxide superconductor,
By providing the flexible conductor, the function of suppressing the increased Joule heat can be obtained. Furthermore, if the flexible conductor is composed of a bundle of metal-based superconducting wires, the flexible conductor will be in a superconducting state by taking measures such as directly cooling the low temperature terminal with liquid helium. The function of eliminating and further reducing the consumption of liquid helium is obtained. Furthermore, if the flexible conductor is composed of a bundle of oxide superconducting wire material or oxide superconducting ribbon material, even when liquid nitrogen is used to cool the superconducting coil, the flexible conductor is kept in a superconducting state, and Since the function of reducing the loss of the leads can be obtained, it is possible to obtain the current leads with a lower running cost.

FIG. 2 is a sectional view showing the main part of a current lead using an oxide superconductor according to another embodiment of the present invention.
FIG. 3 is a sectional view taken along the line AA in FIG. In the drawing, the low temperature side lead 35 connected to the high temperature side lead 2 via the intermediate connecting metal fitting 36 has the upper end portion to the intermediate connecting metal fitting 36,
A plurality of divided thin rod-shaped oxide superconductors 38 each having a lower end electrically conductively coupled to the low temperature terminal fitting 39, and a U-shaped recess 33 formed along the oxide superconductors 38.
Intermediate support 32 having an outer peripheral side and an intermediate connection fitting 36
And a cylindrical container 37 whose both ends are connected to the low temperature terminal fitting 39.
The rod-shaped connecting portion 32A of the intermediate support 32, which is provided with a fiber reinforced plastic material, is screwed to the intermediate connection fitting 36, for example, and is located between the intermediate connection fitting 36 and the low temperature terminal fitting 39. Unlike the above-mentioned embodiment, the oxide superconductor 38 and the intermediate support 32 are firmly supported by each other and are fixed to each other in the groove 33 by an adhesive layer 34 such as an epoxy resin. There is.

In the assembly work of the low temperature side lead, first, the connecting portion 32A of the intermediate support 32 is screwed into the screw hole formed in the intermediate connecting fitting 36 and fixed at a predetermined position, and the oxide superconductor 38 is recessed. In the state of being inserted into and supported by 33, both ends thereof are soldered to the intermediate connection fitting 36 and the low temperature terminal fitting 39, and further the oxide superconductor 38 and the intermediate support 32 are bonded in the groove 33. After that, the procedure is performed by covering the tubular container 37 and connecting both ends thereof to the metal fittings 36 and 39.

In the current lead thus constructed, the recessed groove 33 is used as a passage for the low temperature helium gas GHe so that the oxide superconductor 38 is cooled to maintain the superconducting state and has low thermal conductivity. Since the intruding heat from the high temperature side lead 2 side is blocked by the object superconductor 38 and the intermediate support 32, a current lead with a small vaporization loss of liquid helium can be obtained as in the above-described embodiment. Further, the oxide superconductor 38 is divided into a plurality of pieces to reduce a dimensional error during manufacturing, and the strain generated in the oxide superconductor 38 by restraining both ends can be reduced, and the oxide superconductor 38 can be supported by the intermediate support 32. Since both ends of the oxide superconductor 38 can be soldered to the metal fittings 36, 39 while being supported, troubles that damage the oxide superconductor 38 during the work can be prevented, and the intermediate support 32 and the oxide superconductor can be prevented. Since the electromagnetic mechanical resistance of the oxide superconductor 38 can be enhanced by bonding the body 38 to the inside of the plurality of recessed grooves 33, the oxide superconductor 38 is not damaged during assembly processing.
In addition, the oxide superconductor 38 is not damaged by the electromagnetic mechanical force acting between another parallel current lead,
A current lead having excellent mechanical stability can be obtained.

FIG. 4 is a sectional view showing a main part of a current lead using an oxide superconductor according to another embodiment of the present invention, and FIG. 5 is a sectional view taken along line BB in FIG. The side lead 45 is formed such that the depth of the U-shaped concave groove 43 of the intermediate support body 42 is as shallow as the diameter of the oxide superconductor 38, and the oxide superconductor 38 is inserted into the concave groove 43. Then, the outside is tightly bound with a tight binding wire 44, and the intermediate support 42
Is different from each of the above-described embodiments in that the oxide superconductor 38 and the oxide superconductor 38 are integrated. In the same manner as in the above-described embodiments, the oxide superconductor is not damaged during the assembly process and is parallel to each other. It is possible to obtain a current lead excellent in mechanical stability in which the oxide superconductor is not damaged by the electromagnetic mechanical force acting between the current lead and another current lead.

It should be noted that the adhesive layer 34 and the binding wire 44 may be configured to be used together, so that a current lead having more excellent mechanical stability can be obtained. FIG. 6 is a cross-sectional view of an essential part showing another embodiment of the present invention, in which one oxide superconductor 58 of FIG. 11 is taken out and shown.
The same reference numerals are given to the same members as those described above and detailed description is omitted. In FIG. 6, connecting pieces 62C and 92C are attachment parts 621, 9 to the intermediate connecting fitting 56 and the low temperature terminal fitting 59.
The support parts 622 and 922 except 21 are oxide superconductors 5.
The oxide superconductor 58 has an axially symmetric structure with respect to the axis of 8, and the oxide superconductor 58 is inserted into the holes provided in the connection pieces 62C and 92C and soldered, and a ring is provided on the outer periphery of the connection pieces 62C and 92C. Portions 623 and 923 are provided, and the connecting rod 51 is supported and fixed by the ring portions 623 and 923.

Since the connecting pieces 62C and 92C have a similar structure, the connecting piece 62C will be mainly described in more detail. The connecting piece 62C includes a mounting portion 621 that is bolted to the intermediate connecting metal fitting 56, a support portion 622 provided with a hole into which the oxide superconductor 58 is inserted, and a ring portion provided so as to project to the outer periphery of the support portion 622. 623, and the connecting rod 51 is attached to the ring portion 623.

FIG. 7 is a sectional view taken along line CC of FIG.
Similarly, four oxide superconductors are shown. In this figure, the support portion 622 and the ring portion 6 of the connection piece 62C are shown.
23 is coaxially symmetric with respect to the oxide superconductor 58, and four connecting rods 51 are arranged at equal intervals along the circumferential direction of the ring portion 623. The ring portion 623 is provided with a hole into which the connecting rod 51 is inserted, and the connecting rod 51 is inserted into this hole and adhered and fixed.

The four connecting rods 51 are connecting pieces 62C and 92C.
Is mechanically integrated with one oxide superconductor 58 by means of and the connecting rod 51 is on the outer diameter side of the oxide superconductor 58, so that the connecting rod 51 does not move when an external force such as a bending force is applied. Oxide superconductor 5 should bear this external force more.
Since the bending stress applied to No. 8 is reduced, the mechanical strength of the current lead is improved. The structure for connecting the oxide superconductor 58 to the connecting pieces 62C and 92C is different from that shown in FIGS. 11 and 12 in that the oxide superconductor 58 is inserted into the holes provided in the connecting pieces 62C and 92C. However, it is also possible to adopt a configuration similar to that shown in FIGS. 11 and 12 regardless of the axially symmetric structure.

FIG. 8 is a sectional view of the same position as the portion 7 showing an embodiment different from FIG. The difference from FIG. 7 in this figure is that a connecting cylinder 52 is used instead of the connecting rod 51. In accordance with this, a concentric groove is provided in the ring portion 633 of the connecting piece 63, and the connecting cylinder 52 is inserted into this groove and fixed by adhering. This structure can be interpreted as the limit when the number of connecting rods 51 is increased in the case of FIG.

The connecting members such as the connecting rods 51 and the connecting cylinders 52 are required not only to have mechanical strength but also to have low thermal conductivity in order to reduce invasion heat. Suitable for such connecting materials are fiber reinforced composite materials, stainless steel and the like. In order to secure the strength required as the connecting member, in the case of the connecting rod 51, the thickness and the number of the connecting rods 51 are set to appropriate values. Further, in the case of the connecting cylinder 52, its thickness dimension and diameter are set to appropriate values. In the case of the connecting cylinder 52, the oxide superconductor 58 is shielded by the connecting cylinder 52 and the cooling effect is deteriorated. Therefore, a through hole is provided in the connecting cylinder 52 and the like. Allow helium gas, which is a refrigerant, to flow.

When stainless steel is used as a connecting material for the connecting rod 51, the connecting cylinder 52, etc., since the stainless steel is a conductive material, the connecting material should be in the normal conducting state by quenching the oxide superconductor 58. It can be expected that the current is commutated to prevent the oxide superconductor 58 from being damaged.

[0039]

As described above, according to the present invention, the low temperature side lead has a structure in which a flexible conductor is connected in series to the low temperature side of a rod-shaped oxide superconductor, and the rod-shaped oxide superconductor is swung. It was configured to have a stopper. As a result, the flexible conductor absorbs and relaxes the mechanical stress and thermal stress acting on the rod-shaped oxide superconductor, so that the rod-shaped oxide superconductor is fixed to the cylindrical container through the connection fitting. It is possible to avoid damage to the rod-shaped oxide superconductor, which is a problem with the current lead, and it is possible to provide a current lead with a low temperature lead that is mechanically and thermally stable and highly reliable. . In addition, the Joule heat that increases due to the provision of the flexible conductor can be stopped by using a bundle of metal-based superconducting material or a bundle of oxide superconducting material for the flexible conductor, which consumes expensive liquid helium. It is possible to provide a current lead using an oxide superconductor that has a small amount and low running cost, and the reliability improves so that the need for disassembly and repair is eliminated, so the cost and time required for disassembly and repair are eliminated. can get.

On the other hand, the oxide superconductor is divided into a plurality of pieces and bonded to the inside of the concave groove of the intermediate support body supported by the intermediate connection fitting, or bound by a binding wire to be integrated. As a result, the intermediate support absorbs the electromagnetic mechanical force acting on the oxide superconductor by the current magnetic field between the parallel current leads, reducing the bending stress applied to the oxide superconductor and assembling the low temperature side lead. Sometimes the mechanical stress on the oxide superconductor can be reduced,
By using a low heat conductor for the intermediate support, it is possible to provide a current lead having a low temperature side lead that is thermally and mechanically stable and has excellent electromagnetic mechanical resistance.

In addition, in a current lead having a structure in which connecting pieces are attached to both ends of a rod-shaped oxide superconductor and the intermediate connecting fitting and the low temperature terminal fitting are respectively attached via the connecting pieces, the connecting piece to be attached to the intermediate connecting fitting and the lower portion are attached. By providing the connecting material bridging between the connecting piece attached to the connecting fitting, the connecting material bears the force when the external force is applied to the current lead, and the stress generated in the oxide superconductor is reduced. The effect of improving the mechanical strength of is obtained. Further, as the connecting material, the same effect can be obtained with any of a cylindrical connecting cylinder coaxial with the oxide superconductor or a predetermined number of rod-like connecting rods arranged around the oxide superconductor.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of a current lead using an oxide superconductor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of a current lead using an oxide superconductor according to another embodiment of the present invention.

FIG. 3 is a sectional view taken along the line AA in FIG.

FIG. 4 is a sectional view showing a main part of a current lead using an oxide superconductor according to another embodiment of the present invention.

5 is a sectional view taken along line BB in FIG.

FIG. 6 is a sectional view showing a main part of a current lead using an oxide superconductor according to another embodiment of the present invention.

7 is a sectional view taken along line CC of FIG.

8 is a sectional view taken along line CC of FIG. 6 showing an embodiment different from that of FIG.

FIG. 9 is a side view showing a simplified conventional structure of a current lead of a superconducting magnet device.

10 is an enlarged cross-sectional view showing the internal structure of the main part of FIG.

FIG. 11 is a sectional view of a main part of a conventional current lead using a plurality of oxide superconductors.

12 is a cross-sectional view taken along the line DD of FIG.

[Explanation of symbols]

 1 Current lead 2 High temperature side lead 2A Room temperature terminal 3 Bundle of good conductive metal wire 4 Cylindrical container 5,15,35,45,55 Low temperature side lead 6,36,56 Intermediate connection metal fitting 7,17,37 Cylindrical container 8,18,38,58 Oxide superconductor, 9,19,39,59 Low temperature terminal fitting 9A Low temperature terminal 10 Superconducting coil 20 Lower connection fitting 20G Gap 21 Flexible conductor 22 Steady stop material 32,42 Intermediate support 32A Connecting part 33,43 Recessed groove 34 Adhesive layer 44 Bonding wire material 51 Connecting rod (connecting material) 52 Connecting cylinder (connecting material) 61,91 Projection part 62,92,62C, 92C Connecting piece He Liquid helium GHe Helium gas

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H01L 39/00 C 9276-4M H01F 5/08 ZAA E ZAA B

Claims (12)

[Claims] 1. A current lead for passing an exciting current from an external power source to a superconducting coil housed in a vacuum heat insulating container and kept at a cryogenic temperature, and a high temperature side lead made of a good conductive metal,
An oxide superconductor consisting of a series connection body with a low temperature side lead, which is cooled by a low temperature refrigerant gas, wherein the low temperature side lead is a rod-shaped oxidation conductively coupled between an intermediate connection fitting and a lower connection fitting. A superconductor and a series connection body of a flexible conductor conductively coupled between the lower connection fitting and the low temperature terminal fitting, and in a cylindrical container connecting the intermediate connection fitting and the low temperature terminal fitting. A current lead using an oxide superconductor characterized by being housed. 2. The current lead using an oxide superconductor according to claim 1, wherein the flexible conductor is composed of a bundle of a good conductive metal braid material or a bundle of a good conductive metal foil material. 3. The current lead using an oxide superconductor according to claim 1, wherein the flexible conductor comprises a bundle of metal-based superconducting wires. 4. The current lead using an oxide superconductor according to claim 1, wherein the flexible conductor comprises a bundle of oxide superconducting wire or oxide superconducting ribbon material. 5. The lower connecting fitting holds a gap between the lower connecting fitting and the inner wall surface of the cylindrical container, and a steady rest is arranged around the rod-shaped oxide superconductor. A current lead using the described oxide superconductor. 6. A current lead for passing an exciting current from an external power source to a superconducting coil housed in a vacuum heat insulation container and kept at an extremely low temperature, and a high temperature side lead made of a good conductive metal,
In the case where the low temperature side lead is made of a series connection body with a low temperature side lead made of an oxide superconductor and is cooled by a low temperature refrigerant gas, the low temperature side lead is a plurality of oxidation conductively coupled between the intermediate connection metal fitting and the low temperature terminal metal fitting. Object superconductor and an intermediate support having a groove on the outer peripheral side that engages with the plurality of oxide superconductors, and is housed in a cylindrical container that connects the intermediate connection fitting and the low temperature terminal fitting. A current lead using an oxide superconductor. 7. The superconducting device according to claim 6, wherein the intermediate supporting member is made of a low heat conductor and is connected to and supported by the intermediate connecting member so as to be positioned between the intermediate connecting member and the lower connecting member. Current lead. 8. The current lead using an oxide superconductor according to claim 6, wherein the intermediate support and the oxide superconductor are bonded to each other in the groove by an adhesive layer. 9. An oxide characterized in that a plurality of recessed grooves of an intermediate support and an oxide superconductor engaging with the recesses are integrated with each other by a binding wire that binds this portion from the outside. A current lead using a superconductor. 10. A current lead for passing an exciting current from an external power source to a superconducting coil housed in a vacuum heat insulation container and kept at a cryogenic temperature, a high temperature side lead made of a good conductive metal, and a plurality of rod-shaped leads. Low temperature lead made of oxide superconductor, intermediate connecting metal fitting conductively coupling high temperature lead and low temperature lead, and low temperature terminal conductively coupled to low temperature lead provided with low temperature terminal connected to superconducting coil A metal fitting, in which each oxide superconductor is connected to an intermediate connecting fitting and a low temperature terminal fitting via a connecting piece, respectively, which is attached to the intermediate connecting fitting and the low temperature terminal fitting A current lead using an oxide superconductor, characterized in that a connecting material bridging between the connecting piece and the connecting piece is provided. 11. The current lead using an oxide superconductor according to claim 10, wherein the connecting member is a connecting pipe having a tubular shape coaxial with the oxide superconductor. 12. The current lead using an oxide superconductor according to claim 10, wherein the connecting member is a connecting rod having a predetermined number of rods arranged around the oxide superconductor.