JP6356048B2 - Superconducting wire connection structure, superconducting cable, superconducting coil, and superconducting wire connection processing method - Google Patents

Description

  The present invention relates to a superconducting wire connection structure, a superconducting cable, a superconducting coil, and a superconducting wire connection processing method.

RE-based superconducting wire (2nd generation high-temperature superconducting wire) is a tape-like wire. A ceramic layer is formed on a metal substrate as an intermediate layer and a superconducting conductor layer, and a metal protective layer and a metal stabilization layer are formed. It is manufactured by.
That is, the high-temperature superconducting wire is a laminated structure of different materials, and the characteristics of the superconducting wire greatly depend on the orientation of the superconducting conductor layer. Since these are ceramics, deterioration is likely to occur due to bending of the wire. Even when it deteriorates, in many cases, it cannot be visually confirmed, and it is often found only after energization.
Further, in the case of local degradation, Joule heat is generated from the energized current at the degradation location, and the surrounding wires and structures are involved and burnt out. In application to applications such as coils and cables, the presence or absence of degraded parts greatly affects the reliability of the application.
One of the deterioration modes is peeling of the wire. This is a problem that a peeling force is applied to the surface of the superconducting wire, and the surface of the wire is peeled off by a ceramic layer such as an intermediate layer or a superconducting conductor layer. Peeling force is generated when the wire is cooled to the operating temperature, which is caused by the difference in the linear expansion coefficient between the superconducting wire and the impregnated material, insulation, or other structures, or when the coil is energized. Some of them are caused by electromagnetic force. If there is a connection between superconducting wires or between a superconducting wire and a current terminal in the application, the rigidity of the relevant part changes discontinuously, so stress generated by cooling or electromagnetic force is likely to concentrate, and deterioration is likely to occur. There was a possibility.

The connection between the superconducting wires is a connection structure (hereinafter referred to as “lap connection”) in which the ends of the superconducting wires to be connected are overlapped and joined, and the superconducting wires for other connections between the ends of the superconducting wires to be connected. A superconducting wire such as a connection structure (hereinafter referred to as “bridge connection”) in which the two wires are connected and overlapped with each other is opposed and connected with solder. In such a structure in which wires are overlapped and joined such as lap connection or bridge connection, the facing direction is the direction in which the superconducting conductor layers of the wires are joined by solder (both base materials are outside). In this structure, a resistor such as solder is passed through the current path as short as possible.
When such a connection structure is adopted, the connection part between the superconducting wires is the main element, each layer is laminated in the order of metal substrate, superconducting conductor layer, solder, superconducting conductor layer, metal substrate, rigidity The superconducting conductor layer, which is small and fragile, has a laminated structure sandwiched between layers of high rigidity such as a metal substrate and solder.
When a superconducting wire having such a laminated connection portion is bent or twisted, a peeling force is applied to the superconducting conductor layer, and peeling or deterioration may occur at the connection portion.
As a joining method for connecting the superconducting wires, a soldering method is mainly used, but a joining method using silver paste or ultrasonic connection has also been proposed. Even in these joining methods, the structure of the connection part between the superconducting wires is often a lap connection / bridge connection, and the problem of peeling or deterioration due to bending or twisting occurs as in the case of solder.
In recent years, a technique for joining superconducting conductor layers has been proposed. Even in this technique, the connection between superconducting wires has a structure in which a weak ceramic layer is sandwiched between metal substrates. The problem of peeling or deterioration due to twisting or twisting occurs.

Patent document 1 is mentioned as a literature relevant to the peeling problem in the connection part of superconducting wires.
That is, in the invention described in Patent Document 1, in the superconducting coil having the connecting portion between the superconducting conductors, the terminal portion of the second superconducting conductor arranged in the connecting portion becomes narrower as the width approaches the terminal. By being formed in this way, the proportion of the base material of the second superconducting conductor in the connecting portion in the winding portion decreases as it approaches the terminal, and the mechanical strength (bending strength) is also reduced. Therefore, the force (force toward the outer peripheral side) of returning to the base of the base material that has been heated in the joining process such as solder joining at the tip portion of the terminal portion of the second superconducting conductor is reduced, The superconducting conductor of No. 2 tries to prevent peeling between the base material side and the superconducting conductor layer side.

  Patent Document 2 is cited as a document disclosing a superconducting cable in which the superconducting wire having the above-described laminated structure is actively twisted.

JP 2012-195469 A U.S. Pat. No. 8437819

However, Patent Document 1 describes a delamination prevention measure against bending in the flatwise direction, and the delamination prevention effect against torsion is unknown, and the end of one superconducting wire to be connected becomes narrower as the width approaches the terminal. Thus, since it is cut out in a triangular shape, the bonding area with the other superconducting wire is reduced within a certain length of the bonding length in the longitudinal direction.
Bending moments and torsional moments can be applied during handling and installation of superconducting cables, and a torsional cable as described in Patent Document 2 can be constructed, or a superconducting coil can be constructed by winding this torsional cable. If you want to join.
When there is a connection part where the ends of superconducting wires are overlapped and joined by lap connection or bridge connection, the rigidity of the connection part is naturally higher than the other parts before and after the connection part, and it is difficult to twist. In addition to installation, it is difficult to produce the above-described twisted cable and the coil wound with this cable in an even state, and when it is forcibly twisted, the problem of peeling occurs as described above.
As described in Patent Document 1, even if the end portion of one superconducting wire disposed at the connection portion between the end portions of the superconducting wire is cut out in a triangular shape, this triangular end portion becomes the other triangular shape. Since it is piled up on the end portion of the superconducting wire that has not been made, the rigidity of the connecting portion is naturally higher than other portions before and after the connecting portion (non-overlapped portions), and the same problem arises.

  The present invention has been made in view of the above-described problems in the prior art, and it is an object of the present invention to make it difficult for peeling and deterioration to occur even when twisting is applied to a connecting portion between superconducting wires.

The invention according to claim 1 for solving the above problems is a connection structure of superconducting wires in which superconducting wires having a laminated structure including a base material and a superconducting conductor layer are connected in the longitudinal direction,
The connection end of one superconducting wire and the connection end of the other superconducting wire are overlapped in the stacking direction with their respective substrates facing outside, and a connection is formed that is joined to each other on the overlapped surface,
In the longitudinal direction, the connection end portion of the one superconducting wire and the connection end portion of the other superconducting wire are overlapped, and in the stacking direction, the base material of the one superconducting wire extends to the other superconducting wire. A superconducting wire connecting structure in which one or a plurality of slits for dividing the laminated structure of the connecting portion in the width direction is provided over the base material.

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The invention according to claim 2 is the superconducting wire connecting structure according to claim 1, wherein the slit is provided in a range corresponding to a central portion when the connecting portion is equally divided into three in the width direction.

  Invention of Claim 3 is the superconducting cable which hold | maintained the 2 or more superconducting wire connected by the connection structure of the superconducting wire of Claim 1 or Claim 2 in the twisted state.

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The invention according to claim 4 is a superconducting coil formed by winding the superconducting cable according to claim 3.

The invention according to claim 5 is a superconducting wire connection processing method in which superconducting wires having a laminated structure including a base material and a superconducting conductor layer are connected in the longitudinal direction.
After configuring the connection part where the connection end part of one superconducting wire and the connection end part of the other superconducting wire are overlapped in the stacking direction with their respective base materials facing outside, and joined to each other on the overlapped surface,
In the longitudinal direction, the connection end portion of the one superconducting wire and the connection end portion of the other superconducting wire are overlapped, and in the stacking direction, the base material of the one superconducting wire extends to the other superconducting wire. A process for connecting a superconducting wire, characterized by processing a slit that divides the laminated structure of the connecting portion in the width direction over the base material.

  According to the present invention, since the laminated structure from the base material to the base material formed in the connection part between the superconducting wires is divided in the width direction by one or a plurality of slits as necessary, the torsional rigidity is reduced and the torsional rigidity is reduced. Even if is added, the stress is kept low, and there is an effect that peeling and deterioration hardly occur.

It is a perspective view of the connection structure of the superconducting wire which concerns on one Embodiment of this invention. FIG. 2 is a schematic cross-sectional view (a) and a plan view (b) of a superconducting wire connecting structure according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view (a) and a plan view (b) when a superconducting wire connecting structure according to an embodiment of the present invention is bridge-connected. It is a sketch which shows a part of superconducting cable which concerns on one Embodiment of this invention. It is a sketch of the superconducting coil which concerns on one Embodiment of this invention. It is typical sectional drawing (a) and top view (b) of the connection structure of the superconducting wire which concerns on Example 1 of this invention. It is typical sectional drawing (a) and the top view (b) of the connection structure of the superconducting wire which concerns on Example 2 of this invention. It is typical sectional drawing (a) and the top view (b) of the connection structure of the superconducting wire which concerns on Example 3 of this invention. It is typical sectional drawing (a) and the top view (b) of the connection structure of the superconducting wire which concerns on Example 4 of this invention. It is typical sectional drawing (a) and top view (b) of the connection structure of the superconducting wire which concerns on Example 5 of this invention. It is typical sectional drawing (a) and top view (b) of the connection structure of the superconducting wire which concerns on Example 6 of this invention. It is typical sectional drawing (a) and top view (b) of the connection structure of the superconducting wire which concerns on Example 7 of this invention. It is typical sectional drawing (a) and top view (b) of the connection structure of the superconducting wire which concerns on Example 8 of this invention. It is typical sectional drawing (a) and top view (b) of the connection structure of the superconducting wire which concerns on Example 9 of this invention. It is typical sectional drawing (a) and top view (b) of the connection structure of the superconducting wire which concerns on Example 10 of this invention. It is typical sectional drawing (a) and top view (b) of the connection structure of the superconducting wire which concerns on Example 11 of this invention. It is typical sectional drawing (a) and top view (b) of the connection structure of the superconducting wire which concerns on Example 12 of this invention. FIG. 6 is a schematic cross-sectional view (a) and a plan view (b) of a superconducting wire connecting structure according to Comparative Example 1; FIG. 6 is a schematic cross-sectional view (a) and a plan view (b) of a superconducting wire connecting structure according to Comparative Example 2.

  An embodiment of the present invention will be described below with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention.

FIG. 1 is a perspective view of a superconducting wire connecting structure according to an embodiment of the present invention.
As shown in FIG. 1, the connection structure of the superconducting wire of this embodiment is a connection structure in which a superconducting wire 1 and a superconducting wire 2 are connected in the longitudinal direction. In the figure, a width direction X, a longitudinal direction Y, and a stacking direction (thickness direction) Z are shown.
The superconducting wires 1 and 2 are RE-based oxide superconducting wires, which have the same configuration. The intermediate layer 12 (22), the superconducting conductor layers 13 and (23), and the stabilization layer 14 are formed on the base material 11 (21). (24) is laminated in this order to form a tape-like structure.

The base material 11 (21) is a tape-like low magnetic metal substrate or ceramic substrate. As the material of the metal substrate, for example, a metal such as Co, Cu, Cr, Ni, Ti, Mo, Nb, Ta, W, Mn, Fe, and Ag, which is excellent in strength and heat resistance, or an alloy thereof is used. . In particular, from the viewpoint of excellent corrosion resistance and heat resistance, it is preferable to use Ni-based alloys such as Hastelloy (registered trademark) and Inconel (registered trademark), or Fe-based alloys such as stainless steel.
Various ceramics may be arranged on these various metal materials. Moreover, as a material of the ceramic substrate, for example, MgO, SrTiO ₃ , yttrium stabilized zirconia, or the like is used. In addition, sapphire may be used as a base material.

The intermediate layer 12 (22) is a layer for realizing, for example, high biaxial orientation in the superconducting conductor layer 13 (23). Such an intermediate layer 12 (22) has, for example, physical characteristics such as a coefficient of thermal expansion and a lattice constant that are intermediate between the base material 11 (21) and the superconductor constituting the superconducting conductor layer 13 (23). The value is shown.
The intermediate layer 12 (22) may have a single layer structure or a multilayer structure. In the case of a multilayer structure, the number and types of layers are not limited, but a bed layer containing amorphous Gd ₂ Zr ₂ O _7-δ (δ is an oxygen non-stoichiometric amount), Al ₂ O _3, Y ₂ O _3, or the like. And a forced alignment layer formed by IBAD (Ion Beam Assisted Deposition) method including crystalline MgO and the like, and an LMO layer including LaMnO _{3 + δ} (δ is an oxygen non-stoichiometric amount) are sequentially stacked. May be. Further, a cap layer containing CeO ₂ or the like may be further provided on the LMO layer.
The thickness of each of the above layers is 30 nm for the LMO layer, 40 nm for the MgO layer for forced alignment layer, 7 nm for the Y ₂ O ₃ layer for bed, and 80 nm for the Al ₂ O ₃ layer. These numerical values are only examples.

A superconducting conductor layer 13 (23) is laminated on the surface of the intermediate layer 12 (22). Superconducting conductor layer 13 (23) preferably contains an oxide superconductor, particularly a copper oxide superconductor. As the copper oxide superconductor, REBa ₂ Cu ₃ O _7-δ (hereinafter referred to as RE superconductor) as a high-temperature superconductor is preferable. The RE in the RE-based superconductor is a single rare earth element or a plurality of rare earth elements such as Y, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Lu. Y is preferable because it is difficult to cause substitution with the Ba site. Further, δ is an oxygen non-stoichiometric amount and is, for example, 0 or more and 1 or less, and is preferably closer to 0 from the viewpoint that the superconducting transition temperature is high. The oxygen non-stoichiometric amount may be less than 0, that is, take a negative value when high-pressure oxygen annealing or the like is performed using an apparatus such as an autoclave.

The stabilization layer 14 (24) covers the surface of the superconducting conductor layer 13 (23), but covers the entire periphery of the substrate 11 (21), the intermediate layer 12 (22), and the superconducting conductor layer 13 (23). More preferably.
The stabilization layer 14 (24) may have a single layer structure or a multilayer structure. In the case of a multilayer structure, the number and types of the layers are not limited, but a silver stabilization layer made of silver and a copper stabilization layer made of copper may be laminated in order.

  Now, as shown in FIG. 1, the connection structure 1a of the superconducting wire 1 and the connection end 2a of the superconducting wire 2 are laminated so that the base materials 11 and 21 are outside as shown in FIG. The connecting portion 4 is configured to be overlapped in the direction Z and joined to each other on the overlapped surface. The bonding material layer 3 for realizing this bonding is composed of solder, silver paste, or the like, but between the connection end 1a and the connection end 2a, such as a structure in which the superconducting conductor layers 13 and 23 are bonded together. A structure without the interposed bonding material layer 3 may be used.

2A is a cross-sectional view drawn with the superconducting wires 1 and 2 omitted, and the bonding material layer 3 omitted, and a corresponding plan view is shown in FIG. 2B.
As shown in FIGS. 1 and 2, the connection structure is provided with a slit S.
The slit S is formed substantially parallel to the longitudinal direction Y.
From the terminal end 1b of the superconducting wire 1 arranged at one end of the connecting part 4 to the terminal end 2b of the superconducting wire 2 arranged at the other end of the connecting part 4, the connecting end part 1a of the superconducting wire 1 in the longitudinal direction Y This corresponds to the range in which the connection end 2a of the superconducting wire 2 is overlapped. The slit S is formed in the longitudinal direction Y over a range from the terminal end 1b to the terminal end 2b. 1 and 2 illustrate a slit S formed to extend from the end 1b to the end 2b. Thus, the slit S may be formed beyond the range from the terminal end 1b to the terminal end 2b.
The slit S is preferably parallel to the longitudinal direction Y. However, if the slit S is within a range of about ± 10 degrees with respect to the longitudinal direction Y, it is practical.

The slit S is formed through the front and back.
That is, it is formed in the stacking direction Z from the base material 11 of the superconducting wire 1 to the base material 21 of the superconducting wire 2.
The slit S is formed over the above range, and the slit S divides the laminated structure of the connecting portion 4 in the width direction X.
Since the slit S divides the laminated structure of the connection portion 4 in the width direction X, the torsional rigidity of the connection portion 4 is reliably reduced as compared with the case where there is no slit S. The term “twist” here is a twist that causes a relative angle change in two XZ plane elements that are separated from each other in the longitudinal direction Y. Since the torsional rigidity is lowered, the stress is kept low even when torsion is applied, and there is an effect that the connection part 4 is hardly peeled off or deteriorated.
As shown in FIG. 1, the connecting portion 4 has a sandwich structure with highly rigid base materials 11 and 21, and when a torsional force such as F1 and F2 is applied, the high rigidity of the base materials 11 and 21 generally indicated by FG in FIG. The resulting cleavage force is generated, which causes peeling at the weak superconducting conductor layers 13 and 23 and the intermediate layers 12 and 22. According to this connection structure, by inserting the slit S in the connection portion 4, stress is prevented from concentrating on the connection portion 4 when torsion occurs, and the cleavage force FG is dispersed and reduced in each divided portion. Therefore, it is possible to obtain a connection structure in which delamination of superconducting wires and deterioration of conductive characteristics hardly occur.

  The connection structure shown in FIGS. 1 and 2 is a lap connection, but as shown in FIG. 3, a superconducting wire 5 for connection is bridged between the superconducting wires 1 and 2 placed flat and joined to each other. In this case, the present invention can be implemented. Also in the case of the bridge connection, as shown in FIG. 3, the laminated structure of the connection portions 41 and 42 is divided in the width direction X by the slit S. In FIG. 3, the connecting portions 41 and 42 of the wires 1 and 2 are provided apart from each other, but may be arranged so as to contact each other.

Using the above effects, the superconducting cable 30 in which two or more superconducting wires connected by this connection structure are held in a twisted state as shown in FIG. 4 can be easily configured with high quality. It is to be noted that a plurality of two or more superconducting wire connected bodies connected by this connection structure are further stacked to increase the thickness and increase the number of superconducting conductor layers to improve characteristics such as reduction of self-inductance.
Since the superconducting cable 30 held in a twisted state is easily bent at an arbitrary angle of 360 °, the superconducting coil 31 formed by winding the superconducting cable 30 as shown in FIG. High quality can be configured.

  In order to obtain the above effects, the slit S is preferably provided at the center in the width direction X. That is, the slit S should not be so close to the end in the width direction X. As a reference, the slit S corresponds to one third of the center when the connection portion 4 is equally divided into three in the width direction X. It is preferable that at least one is provided in the central portion 4c (see FIG. 2B).

1 and 2 show the case where one slit S is provided, a plurality of slits S may be provided. That is, a plurality of slits S arranged at a distance in the width direction X can be provided. As the number of the slits S increases, the number of divisions of the connection portion 4 increases, and thus the torsional rigidity of the connection portion 4 decreases.
However, if a large number of slits S are inserted, the superconducting conductor layers 13 and 23 are scraped when the slits S are processed, so that the conductive characteristics are deteriorated. The number of slits S should be selected by taking into consideration the point and the gain of the effect due to the reduction in torsional rigidity.
Further, as the method of processing the slit S, machining or laser processing can be applied, but a method with as little loss as possible in the area of the superconducting wires 1 and 2 is desirable. Therefore, laser processing is preferable.
The slit S is processed by superimposing the connecting end portion 1a of the superconducting wire 1 and the connecting end portion 2a of the superconducting wire 2 in the stacking direction Z with the respective base materials 11 and 21 being outside, and mutually overlapping surfaces. After the joining, that is, after the connection portion 4 is formed. For example, when soldering is applied as a joining method, the slit S is processed after the soldering. When soldering is applied, there is a possibility that the solder may be melted by heat at the time of processing of the slit S, so that the processing of the slit S is performed while holding the superconducting wires 1 and 2 so as not to move relatively. Is desirable.

〔Example〕
Various examples were produced and superconducting properties were examined and disclosed.

(A) As the slit enters, the surface area of the superconducting wire is lost and the critical current value decreases, so the number of slits is in a trade-off relationship with the characteristics of the superconducting wire.
(B) The wire width options of RE-based high-temperature superconducting wires that are commonly used at present are 4 mm width, 6 mm width, 10 mm width, and mm units. A YAG laser or the like is used as a laser type used for slit processing, and the loss width due to the laser used for slit processing is about 100 μm. Therefore, when a 4 mm width wire is used, if one laser slit is inserted, the tape width loss is about 3%. This loss is reflected in the characteristic deterioration of the superconducting wire, and means that the critical current value of the wire is reduced by 3%. Accordingly, the critical current value of the wire decreases as more slits are inserted.
(C) In the actual operation, the critical current is not passed up to the critical current value. In particular, the solder used for joining is the current commutation destination in the connection portion, so the slit in the connection portion 4 There is less risk of burning than slits at other locations.

The connection structure shown in FIGS. 1 and 2 of the above-described embodiment, in which solder is used for the bonding material layer 3, the length of the slit, the arrangement, the number of the slits, etc. are variously changed. For Examples 1 to 12 and Comparative Examples 1 to 5 described below, (1) no twist, (2) 45 degrees twisted, (3) 60 degrees twist added The superconducting properties in each were examined.
All are 4 mm width wires with a copper stabilizing layer, the length of the connecting portion 4 in the longitudinal direction Y is 10 cm, and the thickness of the connecting portion 4 is 230 μm.

Example 1
In Example 1, as shown in FIG. 6, one slit S was formed in the center in the width direction X so that both ends were extended by 30 mm from the connection portion 4.
(Example 2)
In Example 2, as shown in FIG. 7, one slit S was formed so that both ends protruded from the connection portion 4 by about 1 mm in the center in the width direction X.
(Examples 3 and 4)
As shown in FIG. 8, the third embodiment is compared with the first embodiment, and the fourth embodiment is compared with the second embodiment as shown in FIG. It has been changed to the location as the position.
(Examples 5 and 6)
As shown in FIG. 10, the fifth embodiment is arranged in a position that divides the slit S into two equal parts in the width direction X with respect to the first embodiment as shown in FIG. It is a thing.
(Examples 7 and 8)
As shown in FIG. 12, the seventh embodiment is compared to the first embodiment, and the eighth embodiment is compared to the second embodiment as shown in FIG. It has been changed to the location as the position.
(Examples 9 and 10)
As shown in FIG. 14, the ninth embodiment is arranged for the first embodiment, and the tenth embodiment is arranged for the second embodiment as shown in FIG. It is a thing.
(Example 11)
As shown in FIG. 16, the eleventh embodiment has slits S, S on both sides longer than the central slit S, as compared with the ninth embodiment.
(Example 12)
As shown in FIG. 17, the twelfth embodiment differs from the ninth embodiment in that the positions of the ends of the three slits S, S, S are different.

(Comparative Example 1)
As shown in FIG. 18, the first comparative example is different from the first embodiment in that no slit is provided in the connecting portion 4 and slits S and S are provided on both sides in the longitudinal direction Y of the connecting portion 4.
(Comparative Example 2)
As shown in FIG. 19, the comparative example 2 is one in which the slits S do not reach the both ends of the connecting portion 4 compared to the first embodiment.
(Comparative Example 3)
Comparative Example 3 has no slit (not shown).
(Comparative Example 4)
Comparative Example 4 has no slit, and has a structure in which the connecting end 1a of the superconducting wire 1 is cut out in a triangular shape so that the width becomes narrower as it approaches the terminal end 1b according to the invention described in Patent Document 1 (not shown). .
(Comparative Example 5)
In Comparative Example 5, only the connection end 1a of one superconducting wire 1 is divided in the width direction X by a slit, and the superconducting wire 2 is not provided with a slit (not shown).

The evaluation discrimination code is defined as follows.
(1) State without torsion In this case, evaluation was performed by reflecting the reduction rate of the critical current accompanying the addition of the slit described in (b) above.
A: Deterioration of critical current value of less than 5% occurs.
B: Deterioration of critical current value of 5% or more occurs.
(2) 45 degree twisted state In order to investigate the effect on the twisting by the slit, fix the outside of the region where the 20 cm twist is applied in the longitudinal direction Y, apply a tension of about 1 Kgf, As a result, a 45 degree twist was added. As representatively shown in FIG. 6, the connection portion 4 is arranged in the center of the region G (span 20 cm) to be twisted.
A: Even if twist was added, the superconducting properties were not deteriorated.
B: The superconducting property was deteriorated by adding a twist.
(3) A state in which a twist of 60 degrees is applied Further, in order to investigate the effect on the twist by the slit, the outside of the region to which a twist of 20 cm is applied in the longitudinal direction Y is fixed, a tension of about 1 Kgf is applied, and the longitudinal center line of the wire A twist of 60 degrees was applied around the axis. As representatively shown in FIG. 6, the connection portion 4 is arranged in the center of the region G (span 20 cm) to be twisted.
A: Even if twist was added, the superconducting properties were not deteriorated.
B: The superconducting property was deteriorated by adding a twist.

  The main points of the conditions of the examples and comparative examples of the present invention and the evaluation results are summarized in a table as follows.

(General comments)
About Examples 1-4 of this invention, it was "A" about any evaluation item. Even if the slit is short as in Examples 2 and 4, even if the length is different as in Example 11 or the end position is different as in Example 12, the connecting portion 4 is divided. If so, the effect was recognized.
In addition, the effect was recognized even when the slit slightly deviated from the center line as in Examples 3 and 4, but when the slit deviated from the central portion 4c corresponding to 1/3 as in Examples 7 and 8, 60 degrees Degradation of superconducting properties was observed for torsion. The allowable twist angle is considered to be smaller in Examples 3 and 4 than in Examples 1 and 2, but no difference was caused by twisting up to 60 degrees.
By increasing the number of slits as in Examples 5 and 6 and Examples 9 to 12, deterioration in superconducting properties was observed due to an increase in the defect area of the superconducting conductor layer, but deterioration due to the addition of torsion is It was not recognized, and an effect on torsion was recognized. Considering the superconducting characteristics and the effect on the predetermined torsion, it is more preferable to provide only one slit at the center when the wire is divided into three equal parts in the width direction as in Examples 1 to 4.
On the other hand, in Comparative Examples 1 to 5, deterioration of superconducting characteristics was observed due to the addition of twist. In Comparative Examples 1, 3, and 4, since there is no slit in the connecting portion 4, in Comparative Example 2, the connecting portion 4 remains in the width direction X and is not divided. In Comparative Example 5, one superconducting wire Since 2 and the bonding material layer 3 had no slit, peeling and stress concentration occurred with torsion, and superconducting characteristics deteriorated. It was confirmed that the slit is effective by being provided over the entire connecting portion 4 from the terminal end 1b to the terminal end 2b through the superconducting wire 1, the bonding material layer 3, and the superconducting wire 2.

DESCRIPTION OF SYMBOLS 1 Superconducting wire 1a Connection end part 1b Termination 2 Superconducting wire 2a Connection end part 2b Termination 3 Joining material layer 4 Connection part 11,21 Base material 12,22 Intermediate layer 13,23 Superconducting conductor layer 14,24 Stabilization layer S Slit

Claims (5)

A superconducting wire connecting structure in which superconducting wires having a laminated structure including a base material and a superconducting conductor layer are connected in the longitudinal direction,
The connection end of one superconducting wire and the connection end of the other superconducting wire are overlapped in the stacking direction with their respective substrates facing outside, and a connection is formed that is joined to each other on the overlapped surface,
In the longitudinal direction, the connection end portion of the one superconducting wire and the connection end portion of the other superconducting wire are overlapped, and in the stacking direction, the base material of the one superconducting wire extends to the other superconducting wire. A superconducting wire connecting structure in which one or a plurality of slits for dividing the laminated structure of the connecting portion in the width direction are provided up to the base material.   2. The superconducting wire connection structure according to claim 1, wherein the slit is provided in a range corresponding to a central portion when the connection portion is equally divided into three in the width direction.   A superconducting cable that holds two or more superconducting wires connected by the superconducting wire connecting structure according to claim 1 or 2 in a twisted state.   A superconducting coil configured by winding the superconducting cable according to claim 3. A superconducting wire connection processing method in which superconducting wires having a laminated structure including a base material and a superconducting conductor layer are connected in the longitudinal direction,
After configuring the connection part where the connection end part of one superconducting wire and the connection end part of the other superconducting wire are overlapped in the stacking direction with their respective base materials facing outside, and joined to each other on the overlapped surface,
In the longitudinal direction, the connection end portion of the one superconducting wire and the connection end portion of the other superconducting wire are overlapped, and in the stacking direction, the base material of the one superconducting wire extends to the other superconducting wire. A process for connecting a superconducting wire, characterized by processing a slit that divides the laminated structure of the connecting portion in the width direction over the substrate.

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