JP2016039289A - High temperature superconducting coil and high temperature superconducting magnet device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-temperature superconducting coil and a high-temperature superconducting magnet device with electric resistance value between winding wires settable in a wide range and uniform in a tape lengthwise direction.SOLUTION: A superconducting coil 10 includes: a tape-like high-temperature superconducting wire 20 including at least an oxide superconductor; and a normal conductor 12 which is disposed between neighboring adjacent surfaces 11 of the wound wire 20 being in contact electrically with each of the adjacent surfaces 11 at plural points.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a superconducting coil using a high-temperature superconducting wire and a technique for preventing burning of a superconducting device using the superconducting coil.

Currently, BSCCO wires using Bi ₂ Sr ₂ Ca ₂ Cu ₃ O ₁₀ and high temperature superconducting wires typified by REBCO wires using (RE) Ba ₂ Cu ₃ O ₇ including rare earth (RE) are used. Research on high-temperature superconducting coils has been actively conducted.
Such a high-temperature superconducting coil is operated at 20K to 77K where the specific heat is increased, unlike a low-temperature superconducting coil which is normally operated near 4.2K.
For this reason, unexpected sudden normal conduction transition (quenching phenomenon) hardly occurs due to cracks in the impregnated resin or slight movement of the superconducting wire (wire movement).

However, in the high temperature superconducting coil, the superconducting current may exceed the critical current of the high temperature superconducting wire due to an increase in operating temperature, etc., which may cause thermal runaway.
In the case of a high-temperature superconducting coil, due to the magnitude of its specific heat, even if a thermal runaway occurs, the normal conducting transition remains local, making it difficult to detect thermal runaway and is likely to cause burnout.

One means for preventing burnout is to increase the thickness of the stabilization layer in REBCO wires in which a metal substrate, an intermediate layer, a superconducting layer, a protective layer, and a stabilization layer are laminated.
However, when the stabilization layer is thickened, the current density of the coil is lowered, and the advantage of using a high-temperature superconducting wire (hereinafter simply referred to as “wire”) is reduced.
As a method for preventing current burnout by maintaining the current density, a method for electrically connecting adjacent wire rods (hereinafter referred to as “between wire wires”) that have been wound has been studied in recent years.

Conventionally, gaps between winding wires (hereinafter referred to as “winding wire gaps”) have been filled and insulated with an impregnating material made of an insulator.
In order to ensure this insulation, a method of arranging ceramic fibers as spacers has also been proposed.
By the way, in order to effectively prevent contact between the wires and improve the superconducting characteristics after the heat treatment, a spacer may be disposed between the winding wires in the process of manufacturing the high-temperature superconducting coil.
This spacer is known to be carbon fiber, but generally burns during heat treatment. Even when a part of the winding wire remains, the gap between the winding wires is filled with the impregnating material, and the winding wires are electrically insulated.
This is because, when the winding wires are not insulated, the superconducting current is short-circuited without going around along the path formed by winding the wire, and the magnetic field is not generated at the predetermined strength.

However, if the winding wires are electrically connected, the superconducting current flowing in the portion where normal conduction is changed (hereinafter simply referred to as “normal conduction portion”) can be bypassed to the adjacent wire.
By bypassing the normal conducting portion, although the generation of the magnetic field is inhibited, the normal conducting portion can be enlarged while suppressing local heat generation, thereby avoiding burning.
A similar idea of conducting between winding wires has been proposed as a method for avoiding damage when a large superconducting coil is quenched before the discovery of a high-temperature superconducting material.

JP 2000-277322 A US Pat. No. 4,760,365 JP-A-10-289623

However, in the conventional technique described above, during excitation, the superconducting current is short-circuited and the generation of a magnetic field with a predetermined strength is hindered or greatly delayed.
Therefore, it is necessary to apply a suitable electrical resistance between the winding wires and to conduct them, to minimize the inhibition of the generation of the magnetic field and to bypass the superconducting current.

However, it is not easy to strictly adjust the electrical resistance between the winding wires without reducing the current density.
For example, if a method is adopted in which a normal conductor tape having the same width as the wire and a flat surface is disposed in the gap between the winding wires, the electrical resistivity of the tape is determined when the tape material is determined.
Therefore, in order to increase the electrical resistance of the tape, it is necessary to increase the thickness of the tape, thereby reducing the current density of the superconducting coil.

Further, from the viewpoint of detouring the normal conducting portion and stabilizing the generated magnetic field, an unstable change in electrical resistance in the longitudinal direction of the tape or unscheduled nonuniformity is not preferable.
However, in order to integrate the windings and increase the mechanical strength, when the winding wire gap is filled with an impregnation material that is an electrical insulator, the impregnation material penetrates unevenly into the gap between the tape and the wire, etc. It is not easy to make the electric resistance between the winding wires uniform and stable.

  The present invention has been made in consideration of such circumstances, and it is possible to set a wide range of electrical resistance values between the winding wires, and the electrical resistance value is uniform in the longitudinal direction of the tape. An object is to provide a high-temperature superconducting magnet device.

  The high-temperature superconducting coil according to the present embodiment is arranged between a tape-shaped high-temperature superconducting wire including at least an oxide superconductor and an adjacent surface between the wound high-temperature superconducting wire, and each of the adjacent surfaces. And a normal conductor that makes electrical contact at a plurality of locations.

  The present invention provides a high-temperature superconducting coil and a high-temperature superconducting magnet device that can be set in a wide range of electrical resistance values between winding wires and have a uniform electrical resistance value in the longitudinal direction of the tape.

1 is a schematic top cross-sectional view of a high temperature superconducting coil according to a first embodiment. The composition perspective view of a high temperature superconducting wire. The perspective view of the spacer of the high temperature superconducting coil concerning 1st Embodiment. (A) is a figure which shows an example of the arrangement method of the spacer with respect to the high temperature superconducting wire before winding, (B) is a figure which shows the modification of the arrangement method of the spacer with respect to the high temperature superconducting wire before winding, (C) is winding The figure which shows the modification of the arrangement | positioning method of the spacer with respect to the high temperature superconducting wire before rotation. (A) is a block diagram of the spacer of the high temperature superconducting coil concerning 2nd Embodiment, (B) is sectional drawing in the AA cross section of the spacer of FIG. 5 (A). The outline external view of the high temperature superconducting coil concerning a 3rd embodiment. The schematic perspective view of the high temperature superconducting coil concerning 3rd Embodiment. Sectional drawing of the high temperature superconducting wire and impregnation material of the high temperature superconducting coil concerning 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a schematic top sectional view of a high-temperature superconducting coil 10 (hereinafter simply referred to as “superconducting coil 10”) according to the first embodiment.

As shown in FIG. 1, the superconducting coil 10 according to the first embodiment includes a tape-like high-temperature superconducting wire 20 (hereinafter simply referred to as “wire 20”) and an adjacent surface at a position where the wound wire 20 is opposed to each other. And a normal conductor 12 disposed between the adjacent surfaces 11 and in electrical contact with each of the adjacent surfaces 11 at a plurality of locations.
In the first embodiment, the normal conductor 12 is a spacer 12a (12) as shown in FIG.

First, the configuration of the wire 20 of the superconducting coil 10 according to each embodiment will be described with reference to FIG. FIG. 2 is a configuration perspective view of the wire 20.
The wire 20 is a tape-shaped wire including an oxide superconducting layer 25 made of, for example, a second-generation RE-based high-temperature superconducting material.

  For example, the wire 20 is formed on the substrate 22 made of a high-strength metal material such as a nickel-base alloy, stainless steel, or copper, and is formed on the substrate 22 and is caused by the thermal contraction of the substrate 22 and the oxide superconducting layer 25. An intermediate layer 24 for preventing thermal distortion; an alignment layer 23 made of magnesium or the like for aligning the intermediate layer 24 on the surface of the substrate 22; an oxide superconducting layer 25 made of an oxide formed on the intermediate layer 24; , A protective layer 26 that is composed of silver, gold, platinum, or the like and that protects the oxide superconducting layer 25 by preventing oxygen contained in the oxide superconducting layer 25 from diffusing from the oxide superconducting layer 25, and copper or aluminum And a stabilizing layer 21 that is a highly conductive metal such as a detour path for excess current to the oxide superconducting layer 25 and prevents the quenching phenomenon.

However, the kind and number of each layer which comprise the wire 20 are not limited to this, You may increase or decrease as needed. Also, the present invention is not limited to the REBCO wire having such a layer structure, and may be a BSCCO wire made of an oxide superconductor filament or an MgB ₂ wire.
Although not shown in the figure, the uppermost and lowermost two stabilization layers 21 are electrically connected to each other.
The wire 20 configured as described above is overlapped on the spacer 12a (FIG. 4A), and is wound around, for example, the winding frame 13 (FIG. 6) while applying high tension together with the spacer 12a.

Here, FIG. 3 is a perspective view of the spacer 12a of the superconducting coil 10 according to the first embodiment.
As shown in FIG. 3, the spacer 12a is processed into a corrugated shape having an amplitude in the tape thickness direction.
The spacer 12a is made of a metal or carbon fiber having normal conductivity, such as copper or silver as a main component.

Such a spacer 12a is wound together with the wire rod 20 to be arranged in the winding wire rod gap.
And the path | route which makes the adjacent wire 20 conduct | conductive is formed by electrically contacting the adjacent surface 11 in multiple places.

For example, as shown in FIG. 1, when the normal conducting portion 17 is locally generated, an electrical resistance equivalent to that of the spacer 12a is generated in the normal conducting portion 17.
When the electric resistance is generated, a part of the current that has flowed into the normal conducting portion 17 flows to the adjacent wire 20 via the spacer 12a in accordance with Ohm's law.
As described above, part of the superconducting current I bypasses the normal conducting portion 17, so that the normal conducting portion 17 can be prevented from being burned out.

By the way, the superconducting current I does not easily circulate along the wire 20 during excitation due to the inductance based on the wound shape of the wire 20.
Therefore, if the electrical resistance between the winding wires is low, the superconducting current I crosses the wire 20 and does not contribute to the generation of the magnetic field as planned.
However, the electrical resistance between the winding wires is adjusted by bringing the spacers 12a into contact with only the corrugated antinodes and adjusting the number of contact points.

This adjustment can be determined at the time of molding the spacer 12a, and the electrical resistance can be easily changed by changing the wavelength.
Therefore, if the spacer 12a is used, it is possible to easily adjust the electric resistance, so that the electric resistance that suppresses the minute current i that is generated for a long time can be obtained.
The electrical resistance can also be adjusted by changing the thickness of the spacer 12a.
In this case, since the thickness of the spacer 12a can be changed without changing the amplitude of the spacer 12a, the current density is not reduced by enlarging the winding wire gap.

By the way, as the spacer 12a, one that generates an elastic deformation rate of 1 to 200% by an external force when wound is suitably used.
This is because the spacer 12a is surely brought into contact with both the adjacent surfaces 11 of the adjacent wire rods 20 at the corrugated antinodes by being distorted in this way.

By ensuring contact, even when the superconducting coil 10 is impregnated with the impregnating material 16, the impregnating material 16 is prevented from easily entering the contact portion and being electrically insulated.
That is, even when the spacer 12a and the wire 20 are fixed by the impregnating material 16 and the mechanical strength of the superconducting coil 10 is improved, the spacer 12a regularly contacts the adjacent surface 11, so that the electrical resistance between the winding wires is Maintained uniformly.

FIG. 4A is a diagram illustrating an example of a method of arranging the spacer 12a with respect to the wire 20 before winding.
For example, as illustrated in FIG. 4A, the spacer 12 a has the same tape width as that of the wire 20 and is laminated together with each layer of the wire 20.
For example, the wire 20 and the spacer 12a are wound around the winding frame 13 while being tensioned.

FIGS. 4B and 4C are diagrams showing a modification of the arrangement method of the spacer 12a with respect to the wire 20 before winding.
As shown in FIG. 4 (B), the spacer 12a may be spirally wound around the wire 20, and the wire 20 integrated with the spacer 12a in advance may be wound.
Further, as shown in FIG. 4C, the tape width spacer 12a of the wire 20 may be covered around the wire 20 in a cylindrical shape.

As described above, according to the superconducting coil 10 according to the first embodiment and the high-temperature superconducting magnet device using the superconducting coil 10, it is possible to set the electric resistance value between the winding wires in a wide range, This electric resistance value can be made uniform in the longitudinal direction of the tape.
In addition, in order to improve the mechanical strength of the superconducting coil 10, when the spacer 12a and the wire 20 are fixed with the impregnating material 16, the winding is secured even if an external force is applied at the contact site while ensuring electrical connection. The electrical resistance value between the wires does not change easily.
That is, even if an external force is applied to the superconducting coil 10, the electrical resistance value between the winding wires in the tape longitudinal direction can be maintained uniformly.

(Second Embodiment)
FIG. 5A is a configuration diagram of the spacer 12b of the superconducting coil 10 according to the second embodiment, and FIG. 5B is a cross-sectional view of the spacer 12b in FIG.

As shown in FIGS. 5 (A) and 5 (B), the superconducting coil 10 according to the second embodiment includes a spacer 12b in which a plurality of conductive thin wires 14 are knitted vertically.
By knitting the plurality of fine wires 14, the spacer 12b has a waveform in the thickness direction even if a straight wire is used for the fine wires 14. Naturally, the thin wire 14 may be subjected to waveform processing.
The spacer 12b formed by knitting in this manner is also slightly distorted with elasticity due to the external force by being wound, and reliably contacts the adjacent surfaces 11.

Since the second embodiment has the same structure and operation procedure as the first embodiment except that the spacer 12b is knitted with a plurality of thin wires 14, a duplicate description is omitted.
Also in the drawings, portions having a common configuration or function are denoted by the same reference numerals, and redundant description is omitted.

As described above, according to the second embodiment, the spacer 12b can be brought into contact with both of the adjacent wire rods 20 at a plurality of locations without processing the shape of the spacer 12b.
Further, when the same material is used, the mechanical strength against an external force applied perpendicularly to the thin wire surface is higher than that of the spacer 12a of the first embodiment.

(Third embodiment)
FIG. 6 is a schematic external view of a superconducting coil 10A according to the third embodiment.
FIG. 7 is a schematic perspective view of a superconducting coil 10A according to the third embodiment.

As shown in FIG. 6, the superconducting coil 10 </ b> A according to the third embodiment includes n layers (n = 1, 2, 3) in which a single wire 20 repeats layer winding and folding along the winding center axis. ,...).
Then, as shown in FIG. 7, the spacer 12 c is disposed in a gap between the k-th layer layer 19 _k and the k + 1-th layer layer 19 _{k + 1} (k = 1, 2,..., N−1).
Spacer 12c is, for example, a rectangular sheet having a width that covers the circumference and the vertical width and the winding portions of the same k-th layer layer 19 _k.
The spacer 12c has a corrugated shape in the thickness direction, like the spacer 12a of the first embodiment or the spacer 12b of the second embodiment.

The high temperature superconducting coil 10 is generally classified into several types according to the difference in winding method.
A well-known example is a pancake coil wound concentrically around a central axis or a layer-wound coil 10A (10) as shown in FIG.
The layer winding coil 10 </ b> A is usually formed by winding one wire 20 in a spiral shape, for example, along the winding frame 13, turning back at the end of the winding frame 13, and similarly winding in a spiral shape.

By the way, if the usage-amount of the spacer 12c increases, the current density of the whole superconducting coil 10 will fall correspondingly.
Therefore, as shown in FIG. 7, the k-th layer layer 19 _k is formed by winding the wire 20 not covered with the spacer 12 c in a spiral shape, and the spacer 12 c is formed on the outer surface of the k-th layer layer 19 _k. Cover once.

Then, the wire 20 folded back at the end portion of the winding frame 13 is wound so as to cover the spacer 12c, thereby forming the (k + 1) th layer layer _{19k + 1} .
By disposing the spacer 12c in the gap between the kth layer layer _19k and the (k + 1) th layer layer _{19k + 1} , when the normal conducting portion 17 is generated in a part of the layer layers 19, a small current is generated in the other layer layers 19 i can be traversed.

Since the third embodiment has the same structure and operation procedure as those of the first embodiment except that the spacer 12c is disposed every time the layer layer 19 is formed, a duplicate description is omitted.
Also in the drawings, portions having a common configuration or function are denoted by the same reference numerals, and redundant description is omitted.

Thus, according to the third embodiment, in addition to the effects of the first embodiment, the current density of the superconducting coil 10 as a whole can be further improved.
Moreover, even when the wire 20 is not previously covered with the spacer 12c, the spacer 12c can be disposed in the winding wire gap.

(Fourth embodiment)
FIG. 8 is a cross-sectional view of the wire 20 and the impregnating material 16 of the superconducting coil 10 according to the fourth embodiment.

In the superconducting coil 10 according to the fourth embodiment, as shown in FIG. 8, the spacer 12 a is a particle mixed in the impregnating material 16 (hereinafter referred to as “normal conducting particle 12 d”).
The normal conducting particles 12d have a particle size of about 1 to several tens to several tenths with respect to the gap width of the adjacent wire 20.
The normal conductive particles 12d and the normal conductive particles 12d and the wire 20 are stochastically in contact with each other to make the wire 20 conductive.

By increasing the mixing ratio of the normal conductive particles 12d, the probability of such contact increases, and more crossing minute currents i can be generated.
Therefore, the ease of generation of the minute current i can be changed at the stage of impregnation of the wound superconducting coil 10 into the impregnation material 16.

Further, the adjustment of the ease of generation is very easy because the amount of the normal conductive particles 12d is adjusted.
Therefore, after arranging the spacers 12 (12a to 12c) of the first to third embodiments and further impregnation, the ease of generation of the final minute current i is adjusted by the normal conductive particles 12d. Also good.

In addition, since 4th Embodiment becomes the same structure and operation | movement procedure as 1st Embodiment except the normal conductor 12 being the normal conductive particle 12d, the overlapping description is abbreviate | omitted.
Also in the drawings, portions having a common configuration or function are denoted by the same reference numerals, and redundant description is omitted.

  Thus, according to the superconducting coil 10 according to the fourth embodiment, in addition to the effects of the first embodiment, it is possible to adjust the ease of generating the minute current i that traverses more easily.

  According to the superconducting coil 10 and the high-temperature superconducting magnet device using the superconducting coil 10 according to at least one embodiment described above, the winding conductor is formed by arranging the normal conductor 12 having the above-described shape in the gap between the winding wires. The electric resistance value can be set in a wide range, and the electric resistance value can be made uniform in the longitudinal direction of the tape.

Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention.
These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations can be made without departing from the scope of the invention.
These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... High temperature superconducting coil (superconducting coil), 10A (10) ... Layer winding coil, 11 ... Adjacent surface, 12 ... Normal conductor, 12a-12c (12) ... Spacer, 12d (12) ... Normal conducting particle, 13 ... Winding frame, 14 ... fine wire, 16 ... impregnating material, 17 ... normal conducting portion, 19 ... layer layer, _{19k + 1} (19) ... kth layer layer, 20 ... high temperature superconducting wire (wire), 21 (20) ... Stabilization layer, 22 (20) ... substrate, 23 (20) ... orientation layer, 24 (20) ... intermediate layer, 25 (20) ... oxide superconducting layer, 26 (20) ... protective layer, I ... superconducting current, i: Micro current.

Claims (10)

A tape-like high-temperature superconducting wire containing at least an oxide superconductor;
A high-temperature superconducting coil, comprising: a normal conductor disposed between adjacent surfaces between the wound high-temperature superconducting wires and electrically contacting each of the adjacent surfaces at a plurality of locations. The high-temperature superconducting coil according to claim 1, wherein the normal conductor is processed into a corrugated shape having an amplitude in a tape thickness direction. 3. The high-temperature superconducting coil according to claim 1, wherein the normal conductor is formed by braiding conductive thin wires vertically and horizontally. 4. The high-temperature superconducting coil according to any one of claims 1 to 3, wherein the normal conductor and the high-temperature superconducting wire are impregnated with an impregnating material and fixed to each other. The high-temperature superconducting coil according to any one of claims 1 to 4, wherein the material of the normal conductor is carbon fiber. The high-temperature superconducting coil according to claim 4 or 5, wherein the normal conductor is a particle mixed in the impregnating material. The high-temperature superconducting wire is composed of layer layers of n layers (n = 1, 2, 3,...) By repeating layer winding and folding along the winding central axis in one,
The said normal conductor is arrange | positioned in the gap | interval of a kth layer layer and a k + 1th layer layer (k = 1, 2, ..., n-1), Any one of Claim 1-6 characterized by the above-mentioned. The high-temperature superconducting coil according to claim 1. The said normal conductor produces | generates the deformation rate of 1 to 200% which has elasticity with the external force at the time of being wound, The any one of Claims 1-7 characterized by the above-mentioned. High temperature superconducting coil. A tape-like high-temperature superconducting wire containing at least an oxide superconductor;
An impregnating material disposed between adjacent adjacent surfaces between the wound high-temperature superconducting wires;
A high-temperature superconducting coil comprising: a normal conductor particle mixed in the impregnating material. A high-temperature superconducting magnet device using the high-temperature superconducting coil according to any one of claims 1 to 9.

Images