JP2001229750A - Superconducting cable - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce AC loss caused by a loop between superconducting wires while maintaining the stability of a superconducting state. SOLUTION: A plurality of superconducting wires 1 are concentrically twisted at a pitch length lp1 to form a primary sub-cable 2, and the primary sub-cables 2 are concentrically twisted at a pitch length lp2. To form a secondary sub-cable 3, a plurality of the secondary sub-cables 3 are twisted concentrically and twisted at a pitch length lp 3 to form a tertiary sub-cable 4, and the least common multiple of the twist pitches lp 1 to lp 3 is Lp. Then, the ratio between each twist pitch lp1 to lp3 and the least common multiple Lp is set to be substantially an odd number.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting cable, and more particularly to a superconducting cable which is suitably applied to a case where a plurality of superconducting wires are twisted in a high order to form a superconducting cable.

[0002]

2. Description of the Related Art A conventional superconducting cable is formed by concentrically twisting a plurality of superconducting wires in order to increase the current carrying capacity while suppressing heat generation.

FIG. 5 is a sectional view showing the structure of a conventional superconducting cable 106. As shown in FIG. In FIG. 5, a plurality of superconducting wires 101a to 101c are twisted concentrically and have a pitch length lp.
1 to form a primary sub-cable 102a, and the plurality of primary sub-cables 102a to 102
c are twisted concentrically at a pitch length of lp2, and 2
The next sub-cable 103a is constructed,
Next sub-cables 103a to 103f are concentrically twisted with a twist pitch length lp3 to form a desired higher-order stranded wire. These higher-order stranded wires are housed in conduit 104.

In such a superconducting cable 106, a DC current can be passed without loss in a DC magnetic field, but heat is generated due to an AC loss in a fluctuating magnetic field, and heat loss occurs. This AC loss is roughly divided into three: hysteresis loss, coupling loss, and eddy current loss.

Hereinafter, the hysteresis loss and the coupling loss will be described as AC losses. Since the eddy current loss is usually smaller than the coupling loss, the description will be omitted.

First, the hysteresis loss is determined by the superconducting element 1
It has a characteristic that it is generated in proportion to the diameter in the superconducting filaments constituting 01a to 101c. So, in particular,
AC superconducting wires 101a to 10 operated at commercial frequency
1c, in order to reduce the hysteresis loss, several hundred superconducting filaments having a diameter as small as several microns are used.
An ultra-fine multi-core structure in which several thousands are embedded is used.

On the other hand, an induced current flows in the superconducting filament in a fluctuating magnetic field. For this reason, in the superconducting wires 101a to 101c having the ultrafine multi-core structure, the induced current flows between the superconducting filaments via the base material around the superconducting filaments.
Coupling loss occurs in the inside. The coupling loss is proportional to the square of the twist pitch length lp of the superconducting filament and inversely proportional to the resistivity of the base material through which the coupling current flows. Therefore, in the ultra-fine multi-core structure, the coupling current is reduced by twisting the superconducting filament. However, the twist pitch length lp is restricted by the manufacturing, and the diameter of the superconducting wires 101a to 101c is substantially reduced. Proportional. For this reason, in order to shorten the twist pitch length lp, it is necessary to reduce the diameter of the superconducting wires 101a to 101c,
When the diameter of the superconducting wires 101a to 101c is reduced, the critical current per superconducting wire decreases. Therefore, in order to increase the current capacity of the superconducting cable 106, it is necessary to use a large number of superconducting wires 101a to 101c.

[0008] When the superconducting cable 106 is formed by using a large number of superconducting wires 101a to 101c, similar to the above-described generation mechanism in the superconducting wires 101a to 101c,
Coupling loss also occurs between superconducting wires 101a to 101c. In particular, since the stranded pitch length of the final stranded wire is the longest,
Between the superconducting wires 101a to 101c, the ratio is proportional to the square of the twist pitch length of the final stranded wire, and
Coupling loss occurs in inverse proportion to the equivalent resistance between 101c.

In order to reduce the coupling loss, in the conventional superconducting cable 106, superconducting wires 101a to 101
A method has been adopted in which the equivalent resistance between c and c is increased. Also,
In order to increase the equivalent resistivity between the superconducting wires 101a to 101c, a method of changing the ratio of the superconducting wires 101a to 101c and the surrounding space to reduce the contact between the superconducting wires 101a to 101c has been adopted. Was.

On the other hand, when the superconducting cable 106 is formed by twisting a plurality of sub-cables, if each sub-cable is ideally twisted concentrically, the length of the least common multiple Lp of the twist pitch length lpn of each sub-cable will be described. In contrast, when a uniform fluctuating magnetic field is applied, the magnetic flux due to the fluctuating magnetic field received by the area surrounded by the center line 105 of the superconducting cable and each of the superconducting wires 101a to 101c extends over the length of the least common multiple Lp. Integrating the fluctuating magnetic field results in zero.

For this reason, such a superconducting cable 10
6, the coupling loss does not occur, and the AC loss is only the hysteresis loss. However, if a plurality of sub-cables are ideally concentrically twisted to form the superconducting cable 106,
Superconducting cable 1 that wastes a lot of space and is full of gaps
06. Superconducting cable 1 with such a large gap
06, the superconducting wire 101 is generated even if a slight electromagnetic force is generated.
Since a to 101c move and the superconducting cable transitions from the superconducting state to the normal conducting state, there is a concern that the quench may eventually occur.

For this reason, in the actual superconducting cable 106, when storing the high-order stranded wire in the conduit 104,
By compressing from outside the superconducting cable 106,
By reducing the proportion of the space where refrigerant such as helium flows,
The superconducting wires 101a to 101c were configured so as not to come into contact with each other and move.

[0013]

However, in the above-described method of increasing the equivalent resistance between the superconducting wires 101a to 101c, commutation between the superconducting wires 101a to 101c is prevented, and the superconducting wires 101a to 101c are disturbed. Quench occurs in the superconducting wires 101a to 101c through which a large amount of current flows, and there is a problem that the entire superconducting cable 106 eventually quench.

In the method of ideally concentrically twisting the sub-cables, it is necessary to compress the superconducting cable 106 from above, below, left and right in order to reduce the gap between the superconducting cables 106.

However, when the superconducting cable 106 is compressed from the top, bottom, left and right, the area surrounded by the center line 105 of the superconducting cable 106 and each of the superconducting wires 101a to 101c is linked to the externally fluctuating magnetic field by the magnetic flux. There is a problem that the integration over the least common multiple Lp of the pitch is not zero, and the coupling loss cannot be reduced.

FIG. 6 is a diagram in which the locus of the center of superconducting wires 101a to 101c constituting conventional superconducting cable 106 is projected onto a plane perpendicular to the longitudinal direction of the conductor. Here, the superconducting cable 106 has a primary twist pitch length of 2 cm, 2
It is assumed that each of the sub-cables is formed of a tertiary stranded wire having a next twist pitch length of 3 cm and a third twist pitch length of 6 cm, and each sub-cable is ideally twisted concentrically.

In FIG. 6, superconducting wires 101a to 101a to 10c
Although the center of 1c is vertically symmetric,
Locus 11 of large asymmetry to the right from the center 111 of 06
When the superconducting cable 106 is compressed from up, down, left, and right, the right portion of the center 111 is greatly deformed. Therefore, the superconducting cable 1
06 from the top, bottom, left and right
The locus 110 at the center of 101c is deformed unevenly. As a result, the magnetic flux in which the area surrounded by the center line 105 of the superconducting cable 106 and each of the superconducting wires 101a to 101c interlinks with the external fluctuating magnetic field is not zero by integration over the least common multiple Lp of the twist pitch of each sub-cable. Therefore, coupling loss occurs.

That is, the three superconducting wires 10 in contact with each other
The loops composed of these three superconducting wires 101a to 101c are not generally zero because 1a to 101c come into contact again at a distance of the least common multiple Lp of the twist pitch of each sub-cable. For this reason, an induced voltage proportional to the interlinking magnetic flux is generated in each loop, and a coupling current flows accordingly, resulting in a coupling loss. This coupling loss is
Since the loop has a long distance of the least common multiple Lp, the loss time constant becomes long. As a result, when a fast fluctuating magnetic field is interlinked in a loop having the loss time constant, almost all of the loss due to the interlinkage magnetic flux generates heat, resulting in an extremely large AC loss, and the superconducting cable 106 may be quenched. There is also.

An object of the present invention is to provide a superconducting cable capable of reducing the AC loss caused by a loop between superconducting wires while maintaining the stability of the superconducting state.

[0020]

According to the first aspect of the present invention, the locus of the center of the superconducting element wire is point-symmetrical in a plane perpendicular to the longitudinal direction of the superconducting cable. There is a feature.

Thus, even if the superconducting cable formed by twisting the sub-cables is uniformly compressed from the surroundings, it is possible to uniformly deform the locus of the center of the superconducting element wire. For this reason, by enabling the current to be commutated between the superconducting wires, even when a loop is formed between the superconducting wires, it is possible to cancel the magnetic flux linked to the loop formed by the superconducting wires. Therefore, it is possible to reduce the AC loss generated in the loop between the superconducting wires while maintaining the stability of the superconducting state.

According to the second aspect of the present invention, the primary sub-cable is formed by twisting superconducting wires, and (n +
1) In a superconducting cable in which (n ≧ 1) order sub-cables are formed by twisting n-order sub-cables, the twist pitch lpn of each order n and the least common multiple Lp of the twist pitch lpn of each order n The ratio (Lp / lpn)
It is characterized by being substantially odd.

Thus, when a superconducting cable is formed by twisting the sub-cables, the twisting can be performed while shifting the twisting phase of each sub-cable between the sub-cables. For this reason, it is possible to make the locus of the center of the superconducting wire point-symmetric in a plane perpendicular to the longitudinal direction of the superconducting cable, and when the superconducting cable is uniformly compressed from its surroundings, the Since it is possible to uniformly deform the loop, the strength of the superconducting cable can be improved while reducing the AC loss of the superconducting cable.

According to the third aspect of the present invention, the superconducting element wire is formed by twisting a superconducting filament, and the twist pitch lpn of each order n, the twist pitch lp of the superconducting filament, and the order n Twist pitch lp
The ratio (Lp / lpn) between n and the least common multiple Lp of the twist pitch lp is substantially odd.

This makes it possible to configure the superconducting cable in consideration of not only the twist pitch of each sub-cable but also the twist pitch of the superconducting filament, and it is possible to further reduce the AC loss generated in the superconducting cable. Becomes

Here, the superconducting cable is preferably inserted into a conduit made of stainless steel, Incoloy, or a titanium alloy.

Thus, the strength of the superconducting cable can be improved, and a superconducting cable for a high magnetic field and a large current capacity can be produced.

Further, in order to improve the strength of the superconducting cable, the superconducting cable is twisted with stainless steel, Incoloy, titanium alloy or copper alloy.
Alternatively, it may be carried out while being wound around a plate having a rectangular cross section having their surfaces insulated or a line having a circular cross section or an elliptical cross section.

Further, the surface of the superconducting element wire is formal,
Insulation material such as Teflon or polyethylene, or Cu
It is preferably coated with a high-resistance material such as Ni, chromium, stainless steel, and titanium.

Thus, the current flowing between the superconducting wires can be reduced, and the AC loss can be further reduced together with the effect of canceling out the magnetic flux linked to the loop constituted by the superconducting wires. It becomes possible to plan.

The superconducting wires are made of NbTi, Nb ₃ S
n or Nb ₃ Al metallic superconducting wire, or Y
It is preferable to use an oxide high temperature superconducting wire of a system, Bi system, Tl system, or Hg system.

Here, NbTi, Nb ₃ Sn, or NbTi
By using a metal superconducting wire of b ₃ Al, it becomes possible to easily perform winding processing, etc.
By using a high-temperature superconducting wire such as a system, Tl system, or Hg system, it is possible to increase the critical temperature and improve the superconducting stability.

It is preferable that the ratio (Lp / lpn) between the twist pitch lpn and the least common multiple Lp is smaller as the order n is higher.

This makes it possible to increase the twist pitch lpn of each sub-cable in accordance with the diameter of the sub-cable of each order n, and it is possible to easily twist each sub-cable.

It is preferable that the length of the least common multiple Lp is shorter than one turn of the coil formed by the superconducting element wire.

Accordingly, when the superconducting coil is formed by winding the superconducting cable in a coil shape, the distance from the center of the superconducting coil can be kept constant over the length of the least common multiple Lp of the superconducting wire. Become. For this reason, the magnetic flux linked to the loop constituted by the superconducting wires is reduced by the least common multiple Lp.
It is possible to keep the uniformity within the range of the length, and to make the effect of canceling out the magnetic flux linked to the loop constituted by the superconducting wires more complete, thereby further reducing the AC loss. Can be reduced.

Preferably, the superconducting wires are short-circuited at the position of the least common multiple Lp.

This makes it possible to equalize the current flowing in each superconducting wire while canceling out the magnetic flux linked to the loop formed by the short circuit between the superconducting wires, and to further improve the superconducting stability. Can be achieved.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A superconducting cable according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the configuration of a superconducting cable according to the first embodiment of the present invention. In the embodiment of FIG. 1, a case will be described as an example where the superconducting element wire 1 having a tertiary stranded structure is concentrically formed in an ideal state. FIG.
In the superconducting cable 6, a plurality of superconducting wires 1 are concentrically twisted at a pitch lp1 to form a primary sub-cable 2, and a plurality of these primary subcables 2 are concentrically twisted at a pitch lp2. Together, the secondary sub-cables 3 are configured.
Are concentrically twisted at a twist pitch of lp3 to form the tertiary sub-cable 4.

Here, assuming that the least common multiple of the twist pitches lp1 to lp3 is Lp, the twisting is performed such that the ratio between each of the twist pitches lp1 to lp3 and the least common multiple Lp is substantially odd. By performing the stranded wire in this manner, the superconducting wire 1
Is projected on a plane perpendicular to the longitudinal direction of the superconducting cable 6, it can be point-symmetric with respect to the center line 5 of the superconducting cable 6. Therefore, the superconducting cable 6
Can be uniformly deformed from its surroundings, and the trajectory of the superconducting wire 1 can be deformed evenly, and the loop surrounded by the superconducting wire 1 can be deformed evenly. As a result, it is possible to cancel the magnetic flux linked to the loop formed by the superconducting element wires 1 and to reduce the AC loss generated in such a loop, so that the heat generated in the superconducting cable 6 can be reduced. It is possible to reduce the amount and improve the superconducting stability.

FIG. 2 is a diagram in which the locus of the center of superconducting element wire 1 constituting superconducting cable 6 of FIG. 1 is projected on a plane (xy plane) perpendicular to the conductor longitudinal direction (z axis). here,
As the superconducting cable 6, the primary twist pitch lp1 is 3c.
m, secondary twist pitch lp2 is 5 cm, tertiary twist pitch l
Those having a p3 of 15 cm were used. In this case, the least common multiple Lp of the twist pitches lp1 to lp3 is 15 cm. Therefore, the ratio (Lp / lpn) between the least common multiple Lp and each of the twist pitches lp1 to lp3 is “5” for the primary stranded wire,
"3" for secondary stranded wire, "1" for tertiary stranded wire
Which is odd for all orders 1-3.

In FIG. 2, when the ratio (Lp / lpn) between the least common multiple Lp of the twist pitch lpn of each order n of the superconducting cable 6 and the twist pitch length lpn of each order n is an odd number, the superconducting wire 1 It can be seen that the center locus 10 is point-symmetric with respect to the center 11 of the superconducting cable 6.

That is, the locus 1 of the center of each superconducting element wire 1
0, when the longitudinal direction of the superconducting cable 6 is taken on the z-axis, on an xy plane perpendicular to the z-axis, x (z = 0) = − x (z = Lp / 2) y (z = 0) = −y (z = Lp / 2), and when the light beam advances half the distance of the least common multiple Lp in the z-axis direction, it comes to a point-symmetric position with respect to the z-axis. For this reason, even if deformation is applied to the upper, lower, left and right of the superconducting cable 6, the locus 10 of the superconducting wire 1 is deformed by the same amount in the upper, lower, left and right directions.
For this reason, the magnetic flux linked to the area surrounded by the two superconducting wires 1 that are in contact with each other at a certain position to form a loop becomes substantially zero when integrated over a distance of the least common multiple Lp. For this reason, even when loops are formed by contact of the superconducting wires 1, it is possible to reduce the AC loss due to these loops. As a result, it is possible to reduce the equivalent resistance between the superconducting wires 1 while suppressing the AC loss, thereby enabling a configuration in which a current can be commutated between the superconducting wires 1. Even when the cable 6 is composed of a plurality of superconducting wires 1, each superconducting wire 1
It is possible to improve the superconducting stability by eliminating the non-uniformity of the current flowing through the superconductor.

FIG. 3 is a diagram illustrating the effect of canceling out magnetic flux due to a fluctuating magnetic field in the superconducting cable 6 according to one embodiment of the present invention. In FIG. 3A, when the superconducting wires 21a and 21b are twisted, these superconducting wires 21a and 21b are twisted.
a and 21b contact at specific positions to form loops R1 and R2. When a fluctuating magnetic field is applied to the superconducting cable 6, an electromotive force E is generated in these loops R1 and R2, and an induced current flows. Here, the superconducting wires 21a,
When the wire 21b is twisted, the induced currents flowing through the loops R1 and R2 become opposite to each other. Therefore, each loop R1,
Assuming that the magnetic flux density linked to R2 is B1, B2, and the area of each loop R1, R2 is S1, S2, respectively, the electromotive force E generated in these loops R1, R2 is: E = d (S1B1) / dt -D (S2B2) / dt, and the magnetic flux density B linked to each loop R1, R2
When 1, B2 are equal to each other and the areas S1, S2 of the loops R1, R2 are equal to each other, the magnetic fluxes of the loops R1, R2 cancel each other, and no electromotive force E is generated.

Here, as shown in FIG.
When the center locus 110 of each of the superconducting wires 101a to 101c is asymmetric with respect to the center 111 of the superconducting cable 106, the center locus 110 of the superconducting wires 101a to 101c becomes uneven when the superconducting cable 106 is compressed from above, below, left and right. Deform to. For this reason, the areas S1 and S2 of the loops R1 and R2 formed by the superconducting wires 21a and 21b are not equal to each other, and the magnetic fluxes of the loops R1 and R2 do not cancel each other, and an AC loss due to the fluctuating magnetic field occurs. .

On the other hand, as shown in FIG. 2, the locus 10 of the center of the superconducting wire 1 is
, The superconducting cable 6 can be compressed from up, down, left, and right while maintaining the areas S1, S2 of the loops R1, R2 formed by the superconducting wires 1 equal to each other. , R2 can cancel each other, so that the AC loss due to the fluctuating magnetic field can be reduced.

In the case of a high-order stranded wire, the trajectory of the superconducting wire 1 becomes complicated, but as shown in FIG. 3B, the area surrounded by the center line 22 of the superconducting cable 6 and each superconducting wire 1 Pay attention to. These areas are defined as S11, S12, S1
3, if the locus 10 of the center of the superconducting element wire 1 is point-symmetric with respect to the center 11 of the superconducting cable 6, even if the superconducting cable 6 is compressed from up, down, left and right, these areas S11 , S12, S13,... Can be made zero by integration over the least common multiple Lp of the twist pitch of each sub-cable. For this reason, it is possible to cancel the magnetic flux linked to the loop formed by the superconducting element wires 1, and it is possible to reduce the AC loss due to the fluctuating magnetic field.

Here, the superconducting element wire 1 is made of metallic Nb.
Ti, Nb ₃ Sn, and Nb ₃ Al wires may be used. In addition, when a Y-based, Bi-based, Tl-based, or Hg-based oxide high-temperature superconducting wire is used, the operating temperature can be increased and the specific heat can be increased, so that the superconducting stability can be improved.

Further, in order to eliminate an electric current passing between the superconducting wires 1 and reduce the AC loss, the surface of the superconducting wires 1 is coated with an insulating material such as formal, polyimide or polyamide, Surface of wire 1 is C
It may be coated with uNi, chromium, stainless steel, titanium or the like.

Further, since the diameter of the sub-cable of each order n sequentially increases with the order n, the least common multiple Lp of the twist pitch lpn of the sub-cable of each order n and the twist pitch lpn of the sub-cable of each order n Ratio (Lp / l
pn) preferably decreases as the order n increases. Thereby, in response to the increase in the diameter of the sub-cable, it becomes possible to sequentially increase the twist pitch lpn of the sub-cable of each order n together with the order n, and it is possible to arrange high-order stranded wires well. Become.

Further, the magnetic flux that the area surrounded by the center line 22 of the superconducting cable 6 and each superconducting element wire 1 interlinks with the external fluctuating magnetic field is made zero by integration over the least common multiple Lp of the twist pitch of each sub-cable. For this purpose, it is necessary to make the magnetic flux density interlinking the region surrounded by the center line 22 of the superconducting cable 6 and each superconducting element wire 1 constant within the range of the least common multiple Lp. Here, when the superconducting cable 6 is wound in a coil shape to form a superconducting coil, the magnetic field generated in the superconducting coil becomes axially symmetric and changes in the radial direction of the superconducting coil, but is substantially constant within the same radius of the superconducting coil. Become. For this reason, it is preferable that the length of the least common multiple Lp of the twist pitch lpn of the sub-cable of each order n be shorter than one turn of the coil. This makes it possible to apply a substantially uniform magnetic field to the superconducting cable 6 over a distance of the least common multiple Lp of the twist pitch lpn of each order n, and to effectively cancel the magnetic flux linked to the loop. As a result, the AC loss can be effectively reduced.

The superconducting element wire 1 may be positively short-circuited at a distance of the least common multiple Lp of the twist pitch lpn of each order n. Thereby, the short circuit is useful for transferring the transport current between the superconducting wires 1 irrespective of the AC loss, so that the superconducting stability can be improved.

It is preferable to use, as the superconducting element wire 1, an ultrafine multicore structure in which several hundred to several thousand superconducting filaments having a short diameter of about several microns are embedded. In this case, the ratio (Lp) between the twist pitch lpn of each order n and the least common multiple Lp of the twist pitch lpn of each order n
/ Lpn) is an odd number, and each order n is considered in consideration of the twist pitch lp of the superconducting filament.
May be determined.

FIG. 4 is a perspective view showing a configuration of a superconducting cable 35 according to a second embodiment of the present invention. FIG.
In the embodiment, the case where the superconducting element wire 31 has a secondary stranded wire structure will be described as an example. In FIG. 4, a superconducting cable 35 is configured such that a plurality of superconducting wires 31 are concentrically twisted to form a primary sub cable 32. The primary sub cable 32 is twisted while being wound around a plurality of reinforcing members 34 having a rectangular cross section. The secondary sub-cable 33 is configured by the combination.

As described above, by forming the superconducting cable 35 into a compression-molded stranded wire and satisfying the above-mentioned pitch condition, the flux linkage over the distance of the least common multiple is reduced to almost zero, and the AC loss is reduced. In addition to being able to withstand a larger electromagnetic force.

The material of the reinforcing member 34 is stainless steel,
Preferably, it is incoloy, a titanium alloy, or a copper alloy. Further, the surface of the reinforcing member 34 may be insulated. Further, the reinforcing member 34 is a plate having a rectangular cross section,
A line having a circular cross section or an elliptical cross section may be used.

Further, the high-order stranded cable is made of stainless steel,
It may be inserted into a conduit made of Incoloy or a titanium alloy. Thus, in combination with the reinforcement by the reinforcing member 34, a configuration capable of withstanding a larger electromagnetic force can be provided, and a superconducting cable for a high magnetic field and a large current capacity can be manufactured.

[0059]

As described above, according to the present invention,
The superconducting cable is formed by twisting the sub-cables, and even if the superconducting cable is compressed evenly from the surroundings, the locus of the center of the superconducting wire can be deformed evenly, so the superconducting element It is possible to cancel the magnetic flux linked to the loop composed of lines,
It is possible to reduce the AC loss occurring in the loop between the superconducting wires while maintaining the stability of the superconducting state.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a superconducting cable according to a first embodiment of the present invention.

FIG. 2 is a diagram in which a locus of a center of a superconducting element wire constituting a superconducting cable according to one embodiment of the present invention is projected on a plane perpendicular to a longitudinal direction of a conductor.

FIG. 3 is a diagram illustrating the effect of canceling out magnetic flux due to a fluctuating magnetic field in the superconducting cable according to one embodiment of the present invention.

FIG. 4 is a perspective view showing a configuration of a superconducting cable according to a second embodiment of the present invention.

FIG. 5 is a sectional view showing a configuration of a conventional superconducting cable.

FIG. 6 is a diagram in which a locus of the center of a superconducting wire constituting a conventional superconducting cable is projected on a plane perpendicular to the conductor longitudinal direction.

[Explanation of symbols]

 1, 21a, 21b, 31 Superconducting wire 2, 32 Primary sub-cable 3, 33 Secondary sub-cable 4 Tertiary sub-cable 5 Center line of superconducting cable 6, 35 Superconducting cable 10 Cross-sectional locus of superconducting wire 34 Reinforcement Lumber

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hitoshi Shimada 2-4-4 Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture F-term in Toshiba Keihin Works (reference) 5G321 AA01 AA11 AA12 BA01 BA14 CA09 CA16 CA48 CA52

Claims (10)

[Claims] 1. A superconducting cable characterized in that the locus of the center of the superconducting element wire is point-symmetric in a plane perpendicular to the longitudinal direction of the superconducting cable. 2. A superconducting cable in which a primary sub-cable is formed by twisting superconducting wires and an (n + 1) (n ≧ 1) -order sub-cable is formed by twisting n-th sub-cables. ratio between the twist pitch lpn of n and the least common multiple Lp of the twist pitch lpn of each order n (Lp / lpn)
Wherein the number is substantially odd. 3. The superconducting element wire is formed by twisting a superconducting filament, the twist pitch lpn of each order n and the twist pitch lp of the superconducting filament, the twist pitch lpn of each order n and the twist pitch lp. 3. The superconducting cable according to claim 2, wherein a ratio (Lp / lpn) of the superconducting cable to the least common multiple Lp is substantially an odd number. 4. The superconducting cable according to claim 1, wherein the superconducting cable is inserted into a conduit made of stainless steel, Incoloy, or a titanium alloy. 5. The twisting in the superconducting cable is made of stainless steel, Incoloy, a titanium alloy, or a copper alloy, or a plate having a rectangular cross section or a wire having a circular cross section or an elliptical cross section, the surface of which is insulated. The superconducting cable according to any one of claims 1 to 4, wherein the superconducting cable is wound while being wound. 6. A surface of the superconducting wire is formal,
2. An insulating material such as Teflon or polyethylene, or a high resistance material such as CuNi, chromium, stainless steel or titanium.
The superconducting cable according to any one of claims 5 to 5. 7. The superconducting element wire is composed of NbTi, Nb ₃ S
n or Nb ₃ Al metallic superconducting wire, or Y
The superconducting cable according to any one of claims 1 to 6, wherein the superconducting cable is a high-temperature superconducting wire of a system, Bi system, Tl system, or Hg system. 8. The method according to claim 3, wherein a ratio (Lp / lpn) between the twist pitch lpn and the least common multiple Lp is smaller as the order n is higher. Superconducting cable. 9. The superconducting cable according to claim 3, wherein the length of the least common multiple Lp is shorter than one turn of the coil formed by the superconducting element wire. 10. The superconducting element wire is short-circuited at the position of the least common multiple Lp.
The superconducting cable according to any one of claims 9 to 9.