JPH0696626A - Ac superconductive wire and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide an AC superconductive wire having a high current density and a low loss by forming a magnetic element containing coating layer of high concentration around superconductive filaments inside a metal base, and coating it with metal having a high electric resistance. CONSTITUTION:A Cu alloy layer 11 made of a Cu-Ni alloy foil including 10% or more of a magnetic element such as Mn, Fe, and Co is formed around a rod-like core material 10 made of an Nb-Ti alloy, and is covered with a high electric resistant alloy tube 12 made of a Cu-Ni alloy or the like, not including a magnetic element, followed by reducing a diameter as a whole, thus obtaining a composite wire 13. In this case, the total magnetic element content of the alloy layer 11 and the alloy tube 12 is set to 3% or less. A plurality of composite wires 13 are contained together in a Cu-Ni alloy tube 14 having a high electric resistance, followed by repeatedly reducing a diameter. Consequently, it is possible to manufacture an AC superconductive wire A provided with such structure that numerous fine superconductive filaments are dispersed and arranged in a metal base made of a Cu-Ni alloy.

Description

Detailed Description of the Invention

The present invention relates to an AC superconducting wire having a high current density and a low loss, and a method for manufacturing the same.

[Industrial applications]

[0002]

2. Description of the Related Art Conventionally, AC superconducting wires used for toroidal magnets for nuclear fusion reactors, magnets for particle accelerators, magnets for superconducting generators, etc. have been known. Further, as this type of AC superconducting wire, one having a structure in which a myriad of ultrafine superconducting filaments are dispersed and arranged inside a metal base made of a Cu alloy is known.

In order to manufacture an AC superconducting wire having this superconducting filament, Nb- as shown in FIG.
A plurality of composite bodies formed by covering a core material 1 made of a Ti rod with a tube body 2 made of Cu or a Cu alloy are inserted into a tube body 3 made of a Cu alloy to reduce the diameter. )
The primary strand 4 shown in is created. Next, a plurality of the primary strands 4 are assembled and inserted into a Cu alloy tube body 5 shown in FIG. 3C to reduce the diameter, and a secondary strand 6 shown in FIG. 3D is created. The secondary strands 6 can be subjected to heat treatment for strain relief or electrical insulation treatment, if necessary, to obtain the superconducting wire 7 for AC shown in FIG. 3 (e). The secondary wire 6 may be twisted if necessary. The alternating-current superconducting wire 7 manufactured as described above has a structure in which ultrafine filaments having a diameter of about 0.1 to 1 μm are dispersed and arranged inside a metal matrix of Cu alloy.

[0004]

In the superconductor 7 for alternating current manufactured as described above, the AC loss is related to the size of the superconducting filament, and in order to reduce the loss, the loss of the superconducting filament should be as small as possible. It is necessary to reduce the diameter.

However, when the diameter of the superconducting filaments is reduced, the interval between the superconducting filaments is also reduced. Therefore, when alternating current is applied, the superfine superconducting filaments are electromagnetically coupled to each other, and the superconducting proximity effect tends to occur. That is, the electron pair of the superconducting conductor seeps out to the surrounding metal base side, the hysteresis loss at the time of alternating current conduction increases due to the coupling between the adjacent superconducting filaments, and there is a problem that the effect of reducing the superconducting filament disappears. is there. Further, when the superconducting wire for alternating current is manufactured by sufficiently widening the interval between the superfine superconducting filaments so as not to cause the coupling loss, there is a problem that the electric current that can flow per section of one superconducting wire becomes small.

Therefore, conventionally, the metal matrix around the superconducting filaments is formed of a high electrical resistance alloy such as a Cu-Ni alloy, or a magnetic element such as Mn is added to the metal matrix so that the metal matrix tends to be generated between the superconducting filaments. Attempts have been made to suppress the proximity effect. However,
When a magnetic element such as Mn is contained in the metal matrix, the addition of the magnetic element itself increases the loss of the AC superconducting wire, so the addition amount of the magnetic element should be 5
There is a tendency to keep it below about%. However, if the amount of addition of the magnetic element is set to this value, there is a problem that it is difficult to obtain a large current density when the superconducting wire is used.

The present invention has been made in order to solve the above-mentioned problems. By adding a magnetic element, the coupling loss at the time of alternating current is reduced, and the loss due to the addition of the magnetic element is also reduced. It is an object of the present invention to provide a superconducting wire having excellent characteristics for alternating current and a manufacturing method thereof.

[0008]

In order to solve the above-mentioned problems, the present invention provides an AC superconducting wire in which a large number of superfine superconducting filaments are dispersed in a conductive metal base. A coating layer containing a high concentration of a magnetic element is formed around each of the superconducting filaments, and a metal base having high electrical resistance covers the coating layer.

In order to solve the above-mentioned problems, a second aspect of the present invention provides a method for producing an alternating-current superconducting wire according to the first aspect, in which a rod-shaped core material made of an Nb-Ti alloy is used.
High electrical resistance C containing high concentration of magnetic element of 0% or more
After forming a composite wire by covering the u alloy layer and assembling a plurality of the composite wires, Cu having a high electric resistance containing no magnetic element is formed.
It is inserted into an alloy pipe and reduced in diameter.

[0010]

[Function] Since the coating layer containing the magnetic element is contained in the metal matrix in which the superfine superconducting filaments are dispersed and arranged, when the Cooper electron pair exudes from the superconducting filament to the normal metal matrix side, The magnetic moment of the magnetic element breaks the pair, and the proximity effect that tends to flow to the metal matrix between the superconducting filaments when alternating current is applied is suppressed, and the alternating current loss is reduced. Further, since the coating layer of high-concentration magnetic element covers the periphery of each superconducting filament, the action of breaking the electron pair is strong. Furthermore, since the portion of the metal matrix excluding the coating layer does not contain a magnetic element, the content of the magnetic element is small when viewed from the whole of the superconducting wire, and the loss does not increase due to the addition of the magnetic element.

On the other hand, according to the method of the present invention, an AC superconducting wire having a structure in which a coating layer containing a high concentration of a magnetic element is provided around the superconducting filament, and the periphery thereof is covered with a metal base having a high electric resistance. It can be manufactured. Further, by adjusting the content of the magnetic element in the Cu alloy layer formed around the core material, the concentration of the magnetic element contained around the superconducting filament is adjusted.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 (a) to 1 (d) show an embodiment in which the method according to the present invention is applied to an Nb-Ti-based superconducting wire for alternating current. In order to manufacture the superconducting wire A for AC shown in FIG. 1), the outer periphery of the rod-shaped core material 10 made of the Nb-Ti alloy shown in FIG.
A Cu alloy layer 11 made of a Cu-Ni alloy is formed by covering a foil made of a Cu-Ni alloy to which a magnetic element such as Mn is added, and a high electric resistance of a Cu-Ni alloy or the like which does not contain a magnetic element outside the Cu alloy layer 11. A Cu alloy tube 12 made of an alloy is covered and the entire diameter is reduced to form a composite wire 13 shown in FIG.

Here, the Cu alloy layer 11 is formed of Mn, F
e, Co, Ni, Rh, Pd, Ce, Pr, Nd, Sm, Eu, G
One or more magnetic elements such as d, Tb, Dy, Ho, Er and Tm are added in a predetermined amount to a Cu-Ni alloy which is a high electric resistance alloy. Further, in order to form the Cu alloy layer 11, the foil may be wound as described above, the tubular body may be covered with the core material 10, or the core material 10 may be coated with a plating layer. The content of the magnetic element in the Cu alloy layer 11 is preferably 10% or more, and when the content is 10% or less, the proximity effect suppressing action becomes low. Further, in the case of Mn, the addition amount may be arbitrary depending on the solid solution limit with Cu, but other elements have different contents depending on the solid solution limit with Cu. However, when considering the Cu alloy layer 11 and the Cu alloy tube 12, it is preferable that the amount of magnetic elements contained in the whole is 3% or less. If the content of these magnetic elements exceeds 3%, the loss of the entire superconducting wire is increased and the superconducting characteristics are adversely affected.

Next, a plurality of the composite wires 13 shown in FIG.
As shown in FIG. 1D, after being assembled as shown in FIG. 1, the Cu alloy tube 14 made of a Cu-Ni alloy or the like having a high electrical resistance is housed in the Cu alloy tube 14 and the diameter is reduced once or plural times. In addition, it is possible to obtain an AC superconducting wire A having a structure in which a large number of ultrafine superconducting filaments are dispersed and arranged in a metal matrix made of a Cu-Ni alloy. The superconducting wire A is subjected to heat treatment as necessary for the purpose of strain removal and the like, and then an electric insulating layer is formed for use. If necessary, twisted wire processing may be performed before the electrical insulation treatment.

The internal structure of the AC superconducting wire A is as shown in FIG. That is, the diameter is 0.1 μm to 1 μm
Innumerable superconducting filaments 15 made of Nb-Ti alloy extremely finely divided, a coating layer 16 covering the periphery of each superconducting filament 15, and Cu-N covering the periphery of each coating layer 16.
The superconducting wire A is composed of a metal base 17 having a high electric resistance of an i alloy. The superconducting filament 15 is a core material 10.
The coating layer 16 is formed by processing the alloy layer 11, and the metal matrix 17 is formed by processing the Cu alloy tubes 12 and 14.

The superconducting wire A is cooled to a cryogenic temperature with a coolant such as liquid helium before use. When alternating current is applied, the superconducting filament 1 in the metal matrix 17
Coating layer 16 containing a high concentration of a magnetic element in a portion close to 5
Are disposed, it is possible to reduce the hysteresis loss generated between the superconducting filaments 15 ... Here, in the superconducting wire A, the superconducting multifilament 1 when alternating current is applied
The hysteresis loss occurs between 5 ... The superconducting wire A for AC
Then, the superconducting filament 15 has a diameter of 1 to 0.1.
The superconducting filament 15 having such an ultra-fine diameter is extremely thinned down to about μm, and the metal matrix 17 around it is formed.
This is because the electron pair of the superconducting conductor oozes out to the side, and an attempt is made to couple the electron pair between the adjacent superconducting filaments 15, 15.

In this respect, in the superconducting wire A having the above structure, the metal base 1 around the superconducting filaments 15 ...
If element 7 having magnetism is contained in 7, the Cooper electron pair is destroyed by the magnetic moment of the magnetic element, making it difficult for the coupling to occur and reducing the AC loss.

Further, since the layer to be coated 16 containing a high concentration of magnetic element directly covers the periphery of each superconducting filament 15, the action of breaking the electron pair becomes strong and the effect of suppressing the proximity effect is exerted. High enough. Further, since the portion of the metal matrix 17 does not contain a magnetic element, the amount of the magnetic element is small when viewed from the entire superconducting wire A, and the proximity effect due to the addition of the magnetic element does not occur. Therefore, the proximity effect can be efficiently suppressed while suppressing an increase in the loss of the superconducting wire A. It should be noted that the efficiency of suppressing the proximity effect depends on the core material 10.
It can be freely adjusted by adjusting the concentration of the magnetic element contained in the alloy layer 11 formed around the.

[0019]

[Production Example] Nb-Ti rod with a diameter of 15 mm and a thickness of 40
A manganin foil (Cu-12% Mn-2% Ni) of μm was wrapped around it, and then it was inserted into a tube containing 10% by weight of Ni and having an outer diameter of 18 mm and an inner diameter of 16 mm to reduce the diameter.
A 7 mm primary strand was obtained. Next, 283 of these primary strands were assembled and contained 10% by weight of Ni and had an outer diameter of 15 mm and an inner diameter of 1
Inserted into a 4 mm tube and reduced in diameter to a diameter of 0.1
A mm superconducting wire for alternating current was obtained.

The Nb-Ti system superconducting wire for alternating current manufactured as described above is subjected to alternating current and its critical temperature (T
When c) was measured, Tc was 8.5 K, and when the critical current density (Jc) was measured in a magnetic field of 0.5 T, Jc was 120,000 A / cm ^{2, which was} an excellent value.

On the other hand, the critical temperature of the superconducting wire for alternating current manufactured without winding the Mn foil is Tc = 8.5K and the critical current density (Jc).
Was measured in a magnetic field of 0.5T, Jc = 9600
The value was 0 A / cm ² . From this result, it became clear that the characteristics of the superconducting wire produced by winding the Mn foil were excellent.

[0022]

As described above, according to the present invention, since the magnetic element is contained in the peripheral portion of the superconducting filament, the exudation of the pair of superconducting conductors in the metal base around the superconducting filament during AC current application. Even if it occurs, since the pair of electrons can be broken by the magnetism of the magnetic element, it is possible to suppress the proximity effect during AC energization. Therefore, it is possible to obtain an AC superconducting wire having a high critical current density with a small loss during AC conduction.

Further, since the periphery of each superconducting filament is covered with the coating layer containing a high concentration of the magnetic element, the action of breaking the electron pair becomes strong, and the effect of suppressing the proximity effect becomes sufficiently high. In addition, since the portion of the metal matrix excluding the coating layer does not contain a magnetic element, the content of the magnetic element is small when viewed from the entire superconducting wire, so that the loss due to the addition of the magnetic element does not increase. Therefore, it is possible to efficiently suppress the proximity effect while suppressing an increase in loss of the superconducting wire, and to provide an AC superconducting wire having excellent characteristics.

On the other hand, according to the method of the present invention, an alternating-current superconducting wire having a structure in which a coating layer containing a high concentration of a magnetic element is provided around the superconducting filament, and the periphery of the coating layer is covered with a metal base having a high electric resistance is provided. It can be manufactured. Further, by adjusting the content of the magnetic element in the Cu alloy layer formed around the core material, the concentration of the magnetic element contained around the superconducting filament can be easily adjusted. And thereby, the effect of suppressing the proximity effect can be adjusted.

[Brief description of drawings]

1A is a cross-sectional view showing a state in which a core material is covered with an alloy layer and an alloy pipe, FIG. 1B is a cross-sectional view of a primary composite wire, and FIG. FIG. 1D is an enlarged cross-sectional view of the alternating-current superconducting wire according to the present invention, showing a cross-sectional view showing the assembled state of the primary composite wire.

FIG. 2 is an enlarged cross-sectional view of the AC superconducting wire shown in FIG.

FIG. 3 (a) is a cross-sectional view showing a state in which a conventional composite wire is assembled, and FIG. 3 (b) is a cross-sectional view of a primary composite wire.
(C) is a cross-sectional view showing a state of aggregation of conventional primary composite wires,
FIG. 1D is an enlarged cross-sectional view of a conventional superconducting wire.

[Explanation of symbols]

 A superconducting wire for AC 10 core material 11 Cu alloy layer 12 Cu alloy tube 14 Cu alloy tube 15 superconducting filament 16 coating layer 17 metal base

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[Procedure amendment]

[Submission date] October 12, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

1 (a) is a sectional view showing a state in which the core material covered with the alloy layer and the alloy tube, (b) is a sectional view of the primary composite wire, (c)
Is a cross-sectional view showing the assembled state of the primary composite wire, and ( d) is an enlarged cross-sectional view of the AC superconducting wire according to the present invention.

Figure 2 is an enlarged sectional view of the AC superconducting wire shown in FIG. 1 (d),

3 (a) is a sectional view showing the set state of the art composite wire, (b) show cross-sectional views of the primary composite wire, the (c) is a set state of the art primary composite wire Cross-sectional view, ( d) shows conventional
An enlarged cross-sectional view of the secondary wire , (e) is an enlarged cross-section of a conventional superconducting wire.
FIG.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Kono 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Electric Wire Co., Ltd.

Claims (2)

[Claims] 1. A superconducting wire for alternating current in which a large number of ultrafine superconducting filaments are dispersed inside a conductive metal matrix, wherein a coating layer containing a high concentration of a magnetic element is provided around each superconducting filament in the metal matrix. A superconducting wire for alternating current, which is formed and covers the periphery of the coating layer with a metal base having a high electric resistance. 2. The method for producing a superconducting wire for alternating current according to claim 1, wherein the rod-shaped core material made of an Nb-Ti alloy contains a high-concentration magnetic element of 10% or more and has a high electrical resistance. A superconducting wire for alternating current, which is characterized in that a composite wire is formed by coating layers, and a plurality of the composite wires are assembled and then inserted into a Cu alloy tube having high electrical resistance containing no magnetic element for diameter reduction processing. Method.