KR20170029084A - Superconducting wire equipped with stabilization layer of heterogeneous materials - Google Patents

Abstract

According to an embodiment of the present invention, the present invention relates to a superconducting wire, comprising: superconducting core including superconducting material therein; and a stabilization layer attached to at least a part of the outer circumference of the superconducting core. The stabilization layer includes at least one first area composed of first material of a first resistance and at least one second area composed of second material of a second resistance greater than the first resistance.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting wire having a stabilizing layer of a heterogeneous material,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field of superconducting wires, and more particularly, to a stabilizing layer applied to superconducting wires.

Superconducting phenomenon refers to the phenomenon that the electrical resistance suddenly disappears and the current flows without any obstacles when the metal or alloy of any kind is cooled to the absolute zero (0K: -273 °).

The temperature at which the superconducting phenomenon occurs depends on the type of metal. For example, mercury causes a superconducting phenomenon at 4.2K, which causes superconductivity at 18K in some alloys of tin and niobium. At present, it is found that superconducting phenomenon occurs in 25 kinds of metal elements and thousands of alloys and compounds including lead and thallium. The superconductors causing such a superconducting phenomenon are a low temperature superconductor (LTS) such as Nb3Sn, NbTi and Nb3Al, a YBCO (Y-Ba-Cu-O) system, a BSCCO (Bi-Sr-Ca- (HTS) system such as Bi-2212 (Bi2Sr2CaCu2O8) and Bi-2223 (Bi2Sr2Ca2Cu3O10), TCBCO (Tl-Ca-Ba- Cu- : High Temperature Superconductor (threshold temperature above 25K).

Low-temperature superconductors have a critical temperature of 25 K or less, which is a superconductor in liquefied helium. The low-temperature superconductor has advantages in that it can be easily processed as a wire and has excellent current characteristics. However, the use of helium has the disadvantage of high cooling costs. On the other hand, the high temperature superconductor has a critical temperature of 25 K or more and has advantages of using cooling liquid as a refrigerant to reduce the cooling cost and to have a high possibility of application.

In the case of a high-temperature superconductor, a stabilizing layer is attached to the outer periphery of the high-temperature superconductor in order to prevent the occurrence of an overcurrent phenomenon. The stabilizing layer bypasses the overcurrent when the overcurrent flows to the high-temperature superconductor, thereby preventing the high-temperature superconductor from being destroyed by heat.

When the stabilizing layer is made of a material having a very low resistance, it is preferable that the stability layer is made of a low resistance material in view of the protection of the teeth. However, when the high temperature superconducting magnet is driven for the first time, There is a problem in that the degree of deterioration is reduced. Therefore, it is required to optimize the resistance of the stabilizing layer for the application field of the superconductor.

It is an object of the present invention to provide a stabilized layer suitable for applications in which a superconducting wire is used.

Also, a superconducting wire having a stabilizing layer of a heterogeneous material according to an embodiment of the present invention aims at reducing loss due to a time-varying magnetic field of the superconducting wire.

According to an aspect of the present invention, there is provided a superconducting wire comprising:

A superconducting core comprising a superconducting material therein; And a stabilization layer attached to at least a portion of the periphery of the superconducting core, wherein the stabilization layer comprises at least one first region of a first material of a first resistance and a second region of a second resistance greater than the first resistance, And at least one second region of two materials.

By adjusting the width of the first region and the width of the second region, the resistance value of the stabilization layer can be adjusted.

The at least one first region and the at least one second region may be alternately formed along the width direction of the superconducting wire.

The at least one first region and the at least one second region may be alternately formed along the longitudinal direction of the superconducting wire.

The second material may be an insulating material.

The second material may include an MIT having an insulating property at or below a critical temperature and a conductive property at a critical temperature.

The superconducting wire includes a first generation high-temperature superconducting wire, and the superconducting core may include a superconducting filament bundle.

The superconducting wire includes a second-generation high-temperature superconducting wire, and the superconducting core may have a layered structure including a superconducting layer.

Some effects that can be achieved by a superconducting wire having a stabilizing layer of a heterogeneous material according to an embodiment of the present invention are as follows.

i) The reliability of the operation of the superconducting wire can be improved by having a resistance value between turns required by the application field of the superconducting wire.

ii) The loss of superconducting wire due to the time-varying magnetic field can be reduced.

However, the effect that the superconducting wire having the stabilizing layer of the heterojunction material according to the embodiment of the present invention can achieve is not limited to those mentioned above, and other effects not mentioned can be obtained from the following description And will be apparent to one of ordinary skill in the art.

1 (a) and 1 (b) show general first-generation high-temperature superconducting wires and second-generation high-temperature superconducting wires.
2 is a graph showing the center magnetic field characteristics of the superconducting wire coil according to the resistance value between turns of the second generation high-temperature superconducting wire coil.
3 (a) and 3 (b) are views showing a superconducting core applicable to the superconducting wire according to an embodiment of the present invention.
4 is a cross-sectional view of a superconducting wire according to an embodiment of the present invention.
5 is a plan view showing a stabilizing layer of the superconducting wire of FIG.
6 is a cross-sectional view of a superconducting wire according to another embodiment of the present invention.
7 is a plan view showing the stabilizing layer of the superconducting wire shown in Fig.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It is to be understood, however, that the intention is not to limit the invention to the specific embodiments, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the present invention, detailed description of known related arts will be omitted when it is determined that the gist of the present invention may be unnecessarily obscured. In addition, numerals (e.g., first, second, etc.) used in the description of the present invention are merely an identifier for distinguishing one component from another.

Also, in this specification, when an element is referred to as being "connected" or "connected" with another element, the element may be directly connected or directly connected to the other element, It should be understood that, unless an opposite description is present, it may be connected or connected via another element in the middle.

In addition, components referred to in this specification as 'units', 'modules', and the like refer to hardware components such as software, FPGA, or ASIC, and these components perform certain roles. However, the components are not limited to software or hardware. The component may be configured to reside on an addressable storage medium. Further, two or more components may be merged into one component, or one component may be divided into two or more functions according to a more refined function. In addition, each of the components to be described below may additionally perform some or all of the functions of the other components in addition to the main functions that the user is responsible for, and some of the main functions And may be performed entirely by components.

Hereinafter, exemplary embodiments according to the technical idea of the present invention will be described with reference to the drawings.

1 (a) and 1 (b) are views showing general first-generation high-temperature superconducting wire 10 and second-generation high-temperature superconducting wire 20.

1 (a) shows a first-generation high-temperature superconducting wire 10, and a first-generation high-temperature superconducting wire 10 is wound around the phase conductor 11 and the phase conductor 11 along the longitudinal direction of the phase conductor 11 and the phase conductor 11 And a superconducting filament bundle 13 contained therein. The superconducting filament bundle 13 may be composed of BSCCO 2223 or BSCCO 2212. The superconducting filament bundle 13 may be made of Ag or Ag alloy. Although not shown in Fig. 1 (a), the stabilizing layer can be attached to the outer periphery of the first generation high temperature superconducting wire 10 of Fig. 1 (a).

1B shows a second-generation high-temperature superconducting wire 20 having a substrate 21, a buffer layer 23, a superconducting layer 25, and a stabilizing layer 27 .

As the substrate 21, a conventional substrate for producing a superconducting wire such as a metal substrate or a ceramic substrate can be used. For example, the substrate 21 may be a metal substrate comprising nickel or a nickel alloy. The material and thickness of the substrate 21 in the present invention may vary depending on the use of the superconducting article, and the surface of the substrate 21 may be suitably treated or biaxially oriented.

The buffer layer 23 is interposed between the substrate 21 and the superconducting layer 25 so that the subsequent superconducting layer 25 provides a crystallographic orientation for exhibiting superconductivity and at the same time, And serves as a layer for preventing the diffusion of the substance. The buffer layer 23 may be formed of at least one material selected from the group consisting of ZrO2, CeO2, YSZ, Y2O3, and HfO2. The buffer layer 23 may be formed as a single layer or a plurality of layers depending on the use and manufacturing method of the superconducting product.

The superconducting layer 25 may be composed of a superconducting material containing a rare earth element. RE123 superconducting material represented by YBa2Cu3O7 may be used. The superconducting layer 25 may be a Bi-based superconducting material.

The stabilizing layer 27 may be composed of a conductive metal. For example, the stabilization layer 27 may be made of copper. The stabilizing layer 27 may be attached to at least a portion of the periphery of the substrate 21, the buffer layer 23, and the superconducting layer 25. [ As described above, the stabilizing layer 27 can increase the mechanical strength of the superconducting wire 20 while improving the overcurrent characteristics of the superconducting wire 20.

Although not shown, a capping layer may be positioned between the superconducting layer 25 and the stabilization layer 27. The capping layer is provided for electrical stabilization of the superconducting wire 20. The capping layer may preferably consist of at least one material selected from the group consisting of gold, silver, platinum and palladium, or an alloy thereof. Of course, in the present invention, any metal having electric conductivity other than the noble metal may be used. The capping layer may be formed by conventional techniques such as conventional physical vapor deposition (CVD) or sputtering.

The capping layer may be present on the superconducting layer 25, but depending on the embodiment, the capping layer may be formed as a side wall of the structure comprising the substrate 21, the buffer layer 23 and the superconducting layer 25.

Further, depending on the embodiment, the second generation superconducting wire 20 may not include the substrate 21. [ For this, the substrate 21 may be removed at an appropriate stage while the superconducting wire 20 is being manufactured, and physical or chemical etching may be applied to the removal of the substrate 21.

2 is a graph showing the center magnetic field characteristics of the superconducting wire coil according to the resistance value between turns of the second generation high-temperature superconducting wire coil.

(a) is a graph showing a center magnetic field characteristic in a case where stainless steel (SUS) is placed between turns in a second generation high temperature superconducting wire coil including a stabilizing layer made of copper, and b is a second generation 1 is a graph showing the center magnetic field characteristics when Hastelloy is placed between turns in a high-temperature superconducting wire coil; and c is a graph showing the relationship between the number of turns of a polyamide in a second generation high-temperature superconducting wire coil including a stabilizing layer made of copper This graph is a graph showing the center magnetic field characteristic.

When the second-generation high-temperature superconducting wire including the stabilizing layer made of copper is wound without insulation, there is a problem that the size of the center magnetic field of the coil is smaller than that of the current magnitude due to the low resistance property of copper. To avoid this, stainless steel, Hastelloy and polyamide may be placed between turns.

In the case of stainless steel with the smallest resistance value among stainless steel, Hastelloy and polyamide, the central magnetic field increases constantly up to about 90 G as the current increases. However, when the current continues to increase continuously, In the case of FIG.

In the case of Hastelloy, which has a higher resistance than stainless steel, the center magnetic field increases constantly to about 90G with increasing current. However, when the current increases more, the center magnetic field sharply decreases.

Finally, for a polyamide with the highest resistance value, the central magnetic field increases constantly up to about 90 G as the current increases, but if the current increases further, it can be seen that the central magnetic field no longer appears.

The fact that the central magnetic field does not appear as the current increases indicates that the superconducting wire has been destroyed due to the overcurrent characteristic flowing through the superconducting wire.

That is, in summary, the variation of the intensity of the central magnetic field of the superconducting coil and the operational stability of the superconducting coil are determined according to the resistance value between turns of the superconducting coil. More specifically, Although the stability of operation is improved, the amount of change of the intensity of the central magnetic field decreases, and as the resistance between turns increases, the variation of the intensity of the central magnetic field increases or is constant at the maximum value, but the stability of operation is reduced.

According to an embodiment of the present invention, it is possible to design the resistance value of the stabilization layer suitable for a field in which a user wants to apply the superconducting wire, and at the same time, the current loss due to the time-varying magnetic field can be reduced.

3 (a) and 3 (b) are views showing superconducting cores 310 and 320 applicable to a superconducting wire according to an embodiment of the present invention.

3 (a), the superconducting core 310 applicable to the superconducting wire according to an embodiment of the present invention may be the first generation high-temperature superconducting wire 10 of FIG. 1 (a) And may include a phase conductor 311 and a superconducting filament bundle 313.

3 (b), the superconducting core 320 may include a structure in which the stabilization layer 27 does not exist in the second-generation high-temperature superconducting wire 20 shown in FIG. Depending on the implementation, the superconducting core 320 of FIG. 3B may further include a capping layer stacked on top of the superconducting layer 325, or the substrate 321 may be omitted in the superconducting core 320 .

FIG. 4 is a cross-sectional view of a superconducting wire 400 according to an embodiment of the present invention, and FIG. 5 is a plan view illustrating a stabilizing layer 430 of the superconducting wire 400 of FIG.

4, a superconducting wire 400 according to an embodiment of the present invention includes a superconducting core 410 and a stabilization layer 430 of a heterogeneous material attached to at least a part of the outer periphery of the superconducting core 410 .

The stabilization layer 430 of the heterogeneous material may comprise a first material having a first resistance and a second material having a second resistance greater than the first resistance.

For example, the first material may comprise copper, SUS or hastelloy, and the second material may comprise V203 or Al2O3.

According to an embodiment, the second material may be an insulating material. Alternatively, the second material may comprise a metal-insulator transition (MIT). MIT refers to a material that exhibits a low electrical conductivity at a certain temperature (transition temperature) and behaves as an insulator but exhibits a drastic increase in electrical conductivity above the transition temperature. When the second material is MIT, the second material may have insulation characteristics during the initial operation of the superconducting wire 400 according to an embodiment of the present invention. However, when an overcurrent flows in the superconducting wire 400, When heat is generated, the second material has a low resistance conductive property, and the overcurrent can be bypassed.

5, the stabilization layer 430 includes a first region 432 made of a first material having a first resistance along the width w of the superconducting wire 400, and a second region 432 made of a second material having a second resistance And a second area 434 made up of a plurality of pixels.

The resistance value of the stabilization layer 430 can be variously determined by adjusting the ratio between the first region 432 and the second region 434 in the stabilization layer 430. For example, in a field where a low resistance stabilization layer is required, the resistance value of the stabilization layer 430 can be reduced by increasing the width S1 (or volume) of the first region 432, The resistance value of the stabilization layer 430 can be increased by increasing the width S2 (or volume) of the second region 434 in the field where the stabilization layer 430 is required. The width S 1 of the first region 432 is greater than the width S 1 of the second region 434 because the stabilizing layer 430 prevents the destruction of the superconducting wire 400 due to the occurrence of the trench. May be greater than the width S2 of the first region.

FIG. 6 is a cross-sectional view of a superconducting wire 600 according to another embodiment of the present invention, and FIG. 7 is a plan view showing a stabilizing layer 630 of the superconducting wire 600 of FIG.

6 and 7, a plurality of first regions 632 and second regions 634 may be alternately arranged along the width direction w of the superconducting wire 600. The first region 632 and the second region 634 may be alternately disposed along the longitudinal direction (d) of the superconducting wire 600.

The current loss in the superconducting wire 600 by the time-varying magnetic field can be reduced in accordance with the arrangement structure shown in Figs. That is, when the voltage induced in the superconducting wire 600 under the time-varying magnetic field is Vemf, Vemf is proportional to the cross-sectional area of the interdigital transducer, and therefore, according to the present invention, Sectional area, that is, the width S1 of each first region 632 may be reduced to prevent or reduce loss due to induced electromotive force. The greater the number of the first regions 632 divided into the second regions 634 in a state where the total area S1 of the first region 632 is constant, The loss due to the induced electromotive force can be further reduced as the number of the first regions 632 increases. In the case of the superconducting wire 400 shown in Figs. 4 and 5, the current loss can be reduced compared to the conventional superconducting wire.

[Mathematical Expression]

(Vemf is the induced electromotive force, B is the magnetic flux density, and S is the area)

As described above, the superconducting wire having the stabilizing layer of the heterogeneous material according to an embodiment of the present invention can provide the stabilizing layer suitable for the application field where the superconducting wire is used, and reduce the loss due to the time varying magnetic field.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. You will understand. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

310, 320, 410, 610: superconducting core
311: Phase conductor
313: superconducting filament
321: substrate
323: buffer layer
325: superconducting layer
400, 600: superconducting wire
430, 630: stabilization layer
432, 632:
434, 634: second region

Claims (8)

A superconducting core comprising a superconducting material therein; And
And a stabilizing layer attached to at least a portion of an outer periphery of the superconducting core,
Wherein the stabilizing layer comprises:
And at least one second region comprising a second material of a second resistance greater than the first resistance, and at least one second region of a first material of a first resistance.
The method according to claim 1,
Wherein the resistance of the stabilization layer is adjusted by adjusting the width of the first region and the width of the second region.
The method according to claim 1,
Said at least one first region and said at least one second region,
Wherein the superconducting wire is formed alternately along the width direction of the superconducting wire.
The method according to claim 1,
Said at least one first region and said at least one second region,
Wherein the superconducting wire is formed alternately along the longitudinal direction of the superconducting wire.
The method according to claim 1,
Wherein the second material comprises,
Wherein the superconducting wire is an insulating material.
The method according to claim 1,
Wherein the second material comprises,
A superconducting wire comprising an MIT having an insulation property at or below a critical temperature and having a conductive property when a critical temperature is exceeded.
The method according to claim 1,
The superconducting wire has a superconducting wire,
First generation high-temperature superconducting wire,
The superconducting core includes:
A superconducting wire comprising a superconducting filament bundle.
The method according to claim 1,
The superconducting wire has a superconducting wire,
Second generation high temperature superconducting wire,
The superconducting core includes:
Wherein the superconducting wire comprises a layered structure including a superconducting layer.

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