JP2004063225A - Dislocation superconductivity tape unit and superconductive cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a dislocation superconductive tape unit in which the dislocation crossover part is not floated by being easily bent edgewise even if a base material having a high rigidity is used and, therefore, has a strength capable of enduring a great electromagnetic force impressed on the superconductive coil at generation of magnetic field, and a superconductive cable. <P>SOLUTION: The dislocation superconductive tape unit is formed by taping a plurality of superconductive element wires in which oxide superconductors are vapor deposited on a tape surface of stainless steel or Hastelloy alloy having a width (W) and a thickness (t) with a crossover length (L) and stranded in dislocation. In this case, the relationship of the crossover length (L) and the width (W) and the thickness (t) of the tape material is to be ( W<SP>2</SP>/ Lt )≤ 0.313. <P>COPYRIGHT: (C)2004,JPO

Description

【００１９】
ここで、断面のアスペクト比Ｗ／ｔが大きいほど同じ断面積でもエッジワイズ方向の断面二次モーメントが大きく、エッジワイズに曲がりにくい。また、同じテープ幅でもＷ／Ｌが大きい、つまりＬがＷに対して小さい方が同じ力でも小さいモーメントとなり、結局エッジワイズに曲がりにくい。つまり、これら２つのパラメーターＷ／ＬとＷ／ｔとの積　Ｗ^２　／Ｌｔ　はエッジワイズに曲がりにくさを表す指標となり、このＷ^２　／Ｌｔの値が有る値よりも小さいと、エッジワイズ曲げ可能であることを示している。
表１から（Ｗ^２　／Ｌｔ）の値が０．３１３よりも小さいと、エッジワイズ曲げ可能であるといえる。すなわち、
（Ｗ^２　／Ｌｔ）≦０．３１３・・・・・・（１）
が導かれる。
【００２０】
超電導ケーブルは、このようにして得られた転位超電導テープユニットの複数組（例えば、２４組）を、パイプ状のフォーマ（管体）の周囲に所定の螺旋ピッチでＺ巻あるいはＳ巻で螺旋状に巻回して形成する。ここでの螺旋ピッチとしては、１００〜２０００ｍｍ程度の範囲内とするのが好ましい。
【００２１】
【発明の効果】
本発明の超電導ケーブルは、捻られていない超電導素線からなるテープ状の超電導導体を用いる場合と比べて、交流通電時の交流損失を低減できる。また、超電導素線を平坦化したテープ状の超電導導体を複数本転位撚り合わせた転位渡り間で浮きの生じない転位超電導テープユニットを用いたことにより、この転位超電導テープユニットを構成する各テープ状の超電導導体がその長尺方向において順次その位置を代えて変位しており、すなわち各テープ状の超電導導体が転位超電導テープユニットの最内側（フォーマ側）位置から最外側位置まで繰り返して経由しながら超電導ケーブルの長さ方向に延在しているので、各テープ状の超電導導体を流れる電流の値と自己磁場から受ける影響との均等化を図ることができる。各テープ状の超電導導体１８において流れる電流と自己磁場から受ける影響とが等しいため、交流通電時の偏流を防止でき、内側に位置するテープ状の超電導導体にも外側に位置するテープ状の超電導導体と略同量の電流を流すことができ、よって臨界電流密度を増大でき、超電導ケーブルの大容量化を図ることができる。
【図面の簡単な説明】
【図１】本発明の超電導ケーブルの一実施形態を示す斜視図である。
【図２】本発明の転位超電導テープユニットの一実施形態を示す斜視図である。
【図３】図２の線Ａ−Ａ’に沿った断面図である。
【図４】転位超電導テープユニットの浮き上がりの状態を説明する図である。
【符号の説明】
１０・・・超電導ケーブル、１１・・・基材、１２・・・超電導層、１５・・・転位超電導テープユニット、１７・・・フォーマ（管体）、１８・・・テープ状の超電導導体（超電導テープ）、１９・・・テープ状の超電導素線、２０・・・絶縁層、３０・・・テープ止め部、３１・・・転位渡り部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a dislocation superconducting tape unit in which a plurality of tape-shaped superconducting conductors are twisted together and an improvement of a superconducting cable using the same, and more particularly, dislocation superconducting conductor having sufficient superconducting characteristics and improved strength. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape unit and a superconducting cable using the same, which suppresses drift when an alternating current is supplied.
[0002]
[Prior art]
A superconducting cable using a tape-shaped superconducting conductor is used in superconducting applied devices such as a superconducting transformer, a superconducting magnet, and a superconducting current limiter.
As an example of a conventional superconducting cable, a superconducting conductor is spirally wound around a pipe-shaped former (tube body) made of stainless steel or the like, and a plurality of superconducting conductor layers are laminated. There is known a superconducting cable in which an interlayer insulating layer is interposed. The superconducting conductor is formed by covering a plurality of core portions made of a superconductor with a sheath material made of silver or the like. The winding directions of the superconducting conductors of the respective superconducting conductor layers are alternately opposite directions. For example, the winding direction of the first superconductor conductor layer from the former side is S winding (right-handed winding), The winding direction of the third superconducting conductor layer is Z winding (left winding), the winding direction of the third superconducting conductor layer is S winding (right winding), and the winding direction of the fourth superconducting conductor layer is It is Z-winding (left winding).
[0003]
The material used as the core _{portion, Bi 2 Sr 2 Ca 1 Cu} 2 O x (Bi -based 2212 _{phase), Bi 2 Sr 2 Ca 2} Cu 3 Oy (Bi -based 2223 _phase), Bi 1.6 _{Pb 0.4} An oxide superconducting material having a composition such as Sr ₂ Ca ₂ Cu ₃ O _x , Tl ₂ Ba ₂ Ca ₂ Cu ₃ O _y is used. Among them, Bi-based, in particular, Bi-based 2223 phase oxide superconducting material is used for the core part as a stable material having a high critical temperature. The interlayer insulating layer is formed by winding an insulating tape such as a polyimide tape. Usually, a protective layer is formed and used on the outer periphery of the superconducting cable having such a configuration (see, for example, JP-A-11-203959).
[0004]
In a conventional superconducting cable, when an alternating current is supplied, an eddy current F is generated in each superconducting conductor due to the effect of a self-magnetic field due to the alternating current flowing through the superconducting conductors. At this time, since the sheath material is made of Ag having a low electric resistivity (1.63 μΩcm at 20 ° C. for Ag), the eddy current is conducted to the sheath material of the adjacent superconducting conductor. As a result, since the eddy current is conducted across the superconducting conductor layer laminate, the eddy current becomes dominant in the entire superconducting cable, and there is a problem that the AC loss increases. Further, in the conventional superconducting cable having the above-described structure, due to the difference in inductance between the superconducting conductor layers, the current flows more in the outer superconducting conductor layer, and the current hardly flows in the inner superconducting conductor layer. There was a problem that happened.
[0005]
For this reason, in order to provide a superconducting cable that can reduce AC loss when AC is applied and can prevent drift, a plurality of tape-shaped superconducting conductors in which elementary insulation is applied to the outer periphery of the tape-shaped superconducting elementary wire are provided. A superconducting cable in which a dislocation superconducting tape unit in which dislocations are twisted is wound around a tubular body has been proposed (see, for example, JP-A-11-203959). The tape-shaped superconducting element wire is a twisted superconducting element obtained by twisting a superconducting element wire provided with a core portion made of a superconductor or a core portion having a material that becomes a superconductor by heat treatment provided inside a base made of a sheath material. This is a flattened line.
[0006]
However, since the conventional dislocation superconducting tape unit mainly uses a silver sheath material, the dislocation twisting process is easy, but the tensile strength is weak, and it breaks at about 300 MPa.
In a superconducting magnet used in a strong magnetic field, a strong electromagnetic force is applied to the superconducting winding when a magnetic field is generated. For this reason, various developments have been made for the purpose of improving the strength of the superconducting wire. One of them is to increase the strength of the silver sheath. The strength of the silver sheath is increased by adding a specific element to silver as a sheath material. In this case, how to secure the superconducting characteristics becomes an issue, and a satisfactory result has not yet been obtained.
[0007]
In addition, if a superconducting tape is made of a material such as Hastelloy to increase strength and rigidity, dislocation twisting becomes difficult. Therefore, select a material having appropriate flexibility for the base material, reduce the thickness, partially wind a fixing tape made of polyimide resin, etc., and displace the dislocation twisted even number of tape-shaped superconducting conductors. It has been proposed to adopt a structure for fixing the twist so as not to break.
[0008]
[Problems to be solved by the invention]
By the way, when a dislocation twisting process is performed on a material having high strength and high rigidity and a tape stop portion 30 is provided at both ends with a dislocation transition length L and constrained, the dislocation transition portion 31 is not edgewise bent as shown in FIG. In some cases, only the gap g rises. When the dislocation crossover portion is raised, when the dislocation superconducting tape unit is wound around the drum while the conductor or the like is being formed, the raised portion is forcibly pressed against the drum surface, so that the tape may be bent or damaged.
The object of the present invention is that even when a rigid base material is used, the dislocation transition portion is not easily edgewise bent and lifted up, and therefore, the strong electromagnetic force applied to the superconducting winding when a magnetic field is generated is reduced. The purpose is to obtain a superconducting wire having a strength that can withstand the above.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, there is provided a tape unit in which a plurality of tape-shaped superconducting conductors having a thickness t (mm) and a width W (mm) are twisted together, and the thickness of the tape-shaped superconducting conductor is A dislocation superconducting tape unit having t (mm), width W (mm) and transition length L (mm) satisfying the following condition (1) was obtained.
(W ² /Lt)≦0.313 (1)
As a result of various studies of the structure of the dislocation transition portion, it has been found that if the dimensional relationship of each portion is set as in the expression (1), the dislocation transition portion is not easily edgewise bent and does not float.
[0010]
In the present invention, a superconducting conductor having a superconducting layer on the surface of stainless steel or a Hastelloy alloy can be used.
Further, as the superconducting layer, a layer made of an oxide superconductor can be used.
If stainless steel or Hastelloy alloy is used, the tensile strength and rigidity are remarkably enhanced, and it is easy to form a high-performance oxide superconductor layer on the surface by using a vapor deposition technique.
[0011]
Further, a superconducting cable of the present invention is formed by winding the above-described dislocation superconducting tape unit of the present invention around a tubular body.
With a superconducting cable having such a structure, the strength is improved because a strand made of a highly rigid material is used as a base material, and the superconducting winding withstands the strong electromagnetic force applied to the superconducting winding when a magnetic field is generated A superconducting cable having strength can be obtained.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a dislocation superconducting tape unit and a superconducting cable according to the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing one embodiment of the superconducting cable of the present invention. The superconducting cable 10 is configured such that a dislocation superconducting tape unit 15 in which a plurality of tape-shaped superconducting conductors 18 are displaced and twisted is spirally wound around a pipe-shaped former (tube body) 17.
[0013]
As shown in FIG. 2, the dislocation superconducting tape unit 15 is a long belt-shaped superconducting tape (superconducting tape) 18 formed by twisting a plurality (12 in the drawing) of superconducting conductors. In the dislocation superconducting tape unit 15, when a plurality of tape-shaped superconducting conductors 18 are assembled and twisted, each tape-shaped superconducting conductor 18 is displaced in its longitudinal direction by sequentially changing its position. It is twisted.
In the dislocation superconducting tape unit 15 described above, the tape stoppers 30 each formed by winding a fixing tape made of a polyimide resin or the like are formed at both ends of the dislocation transition portion 31, and an even number of tape-shaped dislocation twists are formed. The superconducting conductor 18 is fixed so that the dislocation twist does not collapse.
The winding direction of such a dislocation superconducting tape unit 15 is a direction of S winding (right winding) or a direction of Z winding (left winding). The former 17 is made of stainless steel or the like. The surface of such a former 17 is subjected to an insulation treatment in order to suppress a current flow between the former 17 and the dislocation superconducting tape unit 15. The inside of the former 17 is used as a flow path of a cooling medium such as liquid nitrogen, and the tape-shaped superconducting conductor 18 is cooled.
[0014]
As shown in FIG. 3, the tape-shaped superconducting conductor 18 is formed by forming an insulating layer 20 on the outer periphery of a tape-shaped superconducting wire 19 as wire insulation. The cross-sectional shape of superconducting conductor 18 is preferably rectangular. The superconducting conductor 18 preferably has a width (W) in the range of about 1.0 mm to 5.0 mm and a thickness (T) in the range of about 0.1 mm to 1.0 mm.
The superconducting element wire 19 has a superconducting layer 12 formed on the surface of a base material 11 made of tape-shaped stainless steel or a Hastelloy alloy.
As an insulating material forming the insulating layer 20, polyester, polyesterimide, polyesterimide hydantoin, enamel, or the like is used. The thickness of the insulating layer 20 is in a range of about 0.1 to 100 μm.
[0015]
As the material becomes superconducting layer 12, for example, (oxide-based material such as Y123, Bi-2223-based, Bi2212) oxide superconductor material, a metal-based superconducting conductor material _(Nb 3 Sn, A15-type material such as _Nb 3 Al) MgB One or more superconducting materials selected from superconducting materials represented by ₂ or the like are used. In particular, a Y-based oxide superconducting material based on Hastelloy or the like is preferably used.
In order to form these superconducting materials on the surface of a tape-shaped stainless steel or a Hastelloy alloy, a vacuum evaporation method, a sputtering method, a laser evaporation method, an MBE (molecular beam epitaxy) method, a CVD (chemical vapor deposition) method, an IVD ( (Vapor Ion Vapor Deposition) method can be used. In these various formation methods, a vacuum process is used to form a uniform oxide superconducting layer having good superconductivity from a target. A physical vapor deposition method such as a sputtering method or a laser vapor deposition method for depositing the deposited particles on a counter substrate is preferably used.
[0016]
The tape-shaped superconducting element wire 19 is obtained by forming an intermediate layer and a YBCO layer on a Hastelloy substrate. The cross-sectional shape of such a superconducting element wire 19 is preferably rectangular. The dislocation superconducting tape unit 15 as shown in FIG. 2 is formed by twisting at a predetermined dislocation transition length.
[0017]
Here, the dislocation transition length is in the range of about 10 mm to 1000 mm, and is determined by the width and thickness of the tape-shaped base material of the superconducting wire used.
For example, Table 1 shows that the SUS304 having high rigidity is used as the tape-shaped base material, a dislocation superconducting tape unit having six strands is formed, and the width (W: mm) and thickness (t: mm) of the tape-shaped base material and This is to examine whether or not floating of the dislocation transition portion occurs when the dislocation transition length (L: mm) is variously changed.
[0018]
[Table 1]

[0019]
Here, as the aspect ratio W / t of the cross section increases, the second moment of area in the edgewise direction increases even with the same cross-sectional area, and it is difficult to bend edgewise. In addition, even when the tape width is the same, W / L is large, that is, when L is smaller than W, the moment becomes small even with the same force, and it is difficult to bend edgewise in the end. That is, the product W ² / Lt of these two parameters W / L and W / t is an index indicating the difficulty of bending edgewise, and if the value of W ² / Lt is smaller than a certain value, the edgewise bending is performed. Indicates that it is possible.
From Table 1, when the value of (W ² / Lt) is smaller than 0.313, it can be said that edgewise bending is possible. That is,
(W ² /Lt)≦0.313 (1)
Is led.
[0020]
In the superconducting cable, a plurality of sets (for example, 24 sets) of the dislocation superconducting tape units obtained in this manner are spirally wound around a pipe-shaped former (tube) at a predetermined spiral pitch in a Z or S winding. And formed. The helical pitch here is preferably in the range of about 100 to 2000 mm.
[0021]
【The invention's effect】
ADVANTAGE OF THE INVENTION The superconducting cable of this invention can reduce the AC loss at the time of alternating current energization compared with the case where the tape-shaped superconducting conductor which consists of an untwisted superconducting wire is used. In addition, by using a dislocation superconducting tape unit that does not float between dislocation transitions in which a plurality of tape-shaped superconducting conductors with flattened superconducting wires are dislocation twisted, each tape forming this dislocation superconducting tape unit is used. Of the superconducting conductors are sequentially displaced in the longitudinal direction while changing their positions, that is, while each tape-shaped superconducting conductor repeatedly passes from the innermost (former side) position of the dislocation superconducting tape unit to the outermost position. Since the cable extends in the length direction of the superconducting cable, it is possible to equalize the value of the current flowing through each tape-shaped superconducting conductor and the effect of the self-magnetic field. Since the current flowing through each tape-shaped superconducting conductor 18 and the influence of the self-magnetic field are equal, it is possible to prevent drift when AC current is applied, and the tape-shaped superconducting conductor located on the inside and the tape-shaped superconducting conductor located on the outside And the critical current density can be increased, and the capacity of the superconducting cable can be increased.
[Brief description of the drawings]
FIG. 1 is a perspective view showing one embodiment of a superconducting cable of the present invention.
FIG. 2 is a perspective view showing one embodiment of a dislocation superconducting tape unit of the present invention.
FIG. 3 is a sectional view taken along line AA ′ of FIG. 2;
FIG. 4 is a diagram illustrating a state in which a dislocation superconducting tape unit is lifted.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... superconducting cable, 11 ... base material, 12 ... superconducting layer, 15 ... dislocation superconducting tape unit, 17 ... former (tubular body), 18 ... tape-shaped superconducting conductor ( Superconducting tape), 19: tape-shaped superconducting element wire, 20: insulating layer, 30: tape fixing part, 31: transposition transition part

Claims (4)

A tape unit in which a plurality of tape-shaped superconducting conductors having a thickness of t (mm) and a width of W (mm) are twisted together, and the tape-shaped superconducting conductor has a thickness of t (mm) and a width of W (mm) And a transition length L (mm) satisfying the following condition (1):
(W ² /Lt)≦0.313 (1) The dislocation superconducting tape unit according to claim 1, wherein the superconducting conductor has a superconducting layer on a surface of stainless steel or a Hastelloy alloy. The dislocation superconducting tape unit according to claim 2, wherein the superconducting layer is made of an oxide superconductor. 4. A superconducting cable, wherein the transposed superconducting tape unit according to claim 1 is wound around a tubular body.

Images