JP2011238455A - Superconducting wire rod, superconducting coil, and superconductivity protective device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superconducting wire rod, superconducting coil, and superconductivity protective device which can easily detect temperature change of a superconductor.SOLUTION: A superconducting wire rod 1A of the present invention comprises a first superconducting wire rod 1a and a second superconducting wire rod 10 for temperature detection, and a critical temperature Tc of the first superconducting wire rod 1a and a critical temperature Tx of the second superconducting wire rod 10 satisfy the relation of Tx<Tc. In the superconducting wire rod 1A, it is preferable that an operation temperature Top which makes the first superconducting wire rod 1a in superconducting state, the critical temperature Tc, and the critical temperature Tx satisfy the relation of Top<Tx<Tc.

Description

  The present invention relates to a superconducting wire, a superconducting coil, and a superconducting protection device.

Low temperature superconducting coils using metal-based low temperature superconductors such as alloy superconductors such as NbTi and compound based superconductors such as Nb ₃ Sn have a low superconductor critical temperature of 10K or less, so the operating temperature is about 4K. The temperature is very low and the specific heat is small. Therefore, a quench occurs in the low temperature superconducting coil that transitions from the superconducting state to the normal conducting state for some reason. Therefore, it is important to reliably and promptly detect the occurrence of quenching in the superconducting coil to prevent the normal conducting region from expanding. As a method for detecting a normal conduction transition in a low temperature superconducting coil using a metallic low temperature superconductor, a method for detecting a voltage generated by the normal conduction transition and a method for detecting a balance voltage are known.

However, an oxide superconductor such as a Bi-based or Y-based one has a critical temperature as high as about 100K. Therefore, an operating temperature of 20K or higher is assumed, and power consumption such as a refrigerator can be reduced. Compared with a metal-based low-temperature superconductor, the specific heat at the operating temperature is large, and the propagation speed when the normal conducting transition is made becomes slow. For this reason, the detection method based on the conventional voltage measurement may not be able to successfully detect the occurrence of the normal conduction transition.
As a method of detecting a minute temperature rise, a method of detecting a voltage by providing a carbon film on a superconductor and converting the detected voltage into a temperature has been proposed (see Patent Document 1). In addition, a method using an optical fiber has been proposed as a quench detection method that is electromagnetically resistant to noise rather than a detection method based on voltage measurement (see Non-Patent Document 1).

Japanese Patent No. 2577682

Fujikura Technical Report No. 80 April 1991 Pages 1-6

The method described in Patent Document 1 is a method using the temperature dependence of the electric resistance R, and the detection accuracy of quench (normal conduction transition) is detected using the fact that the change rate of dR / dT is large when the temperature T is 10K or less. Is raised. However, in the method described in Patent Document 1, a carbon film is bonded by coating or sputtering on a superconductor in which a copper layer and an insulating film are provided on the outer periphery of the alloy-based superconductor NbTi. Providing a carbon film in the longitudinal direction of the superconducting wire is not practical because productivity is significantly reduced.
Non-Patent Document 1 proposes a method in which an interference system is assembled with laser light propagating through an optical fiber having two cores, and a temperature rise of about 10K is detected by a phase change of the laser light. However, with this detection method, the optical fiber heating length of the temperature rise is as long as 2 to 6 m and can be applied to a large superconducting coil, but it is difficult to detect the temperature rise in a minute section of about several centimeters. Conceivable.

  The present invention has been made in view of such a conventional situation, and an object thereof is to provide a superconducting wire, a superconducting coil, and a superconducting protection device capable of easily detecting a temperature change of a superconductor.

In order to solve the above problems, the present invention has the following configuration.
The superconducting wire of the present invention comprises a first superconducting wire and a second superconducting wire for temperature detection, wherein the critical temperature Tc of the first superconducting wire and the critical temperature Tx of the second superconducting wire are Tx <Tc. It is characterized by satisfying the relationship.
In the superconducting wire of the present invention, it is preferable that the operating temperature Top, the critical temperature Tc, and the critical temperature Tx that bring the first superconducting wire into a superconducting state satisfy the relationship of Top <Tx <Tc.
In the superconducting wire of the present invention, the first superconducting wire includes a superconducting layer and a metal stabilizing layer, and the second superconducting wire is disposed at a position in contact with the metal stabilizing layer of the first superconducting wire. Preferably it is.
In the superconducting wire of the present invention, it is also preferable that at least a part of the second superconducting wire is disposed inside the metal stabilizing layer of the first superconducting wire.
In the superconducting wire of the present invention, a metal stabilizing base layer is interposed between the superconducting layer and the metal stabilizing layer of the first superconducting wire, and the second superconducting wire is in contact with the metal stabilizing base layer. It can also be set as the structure arranged like this.
In the superconducting wire of the present invention, the metal stabilizing layer of the first superconducting wire is disposed on an upper portion and a side portion of the superconducting layer, and the second superconducting wire is disposed on a side of the superconducting layer. It can also be.
The superconducting wire of the present invention preferably includes at least two of the second superconducting wires.
Moreover, this invention provides the superconducting coil which uses the said superconducting wire.
Furthermore, the present invention provides a superconducting protection device using the superconducting coil.

The superconducting wire of the present invention is provided with the second superconducting wire for temperature detection, so that even if a normal conducting transition occurs, the superconducting wire at the time when the critical temperature Tx of the second superconducting wire for temperature detection is exceeded. The second superconducting wire becomes a normal conducting state, and the voltage of the second superconducting wire rapidly increases. Thereby, the temperature rise accompanying the normal conducting transition in the superconducting wire can be easily detected.
In addition, the superconducting wire of the present invention sets the critical temperature Tc of the first superconducting wire higher than the critical temperature Tx of the second superconducting wire for temperature detection. When the transition occurs, it is possible to take measures such as reducing the current value when the occurrence of the normal conduction transition is detected at the temperature Tx, thereby preventing the normal conduction transition region in the superconducting wire from expanding. Can do.
The superconducting wire of the present invention is arranged such that the second superconducting wire for temperature detection is in contact with the metal stabilizing layer close to the superconducting layer, or at least a part thereof is located inside the metal stabilizing layer. Thus, even if a normal conduction transition occurs, a temperature change (temperature increase) can be detected with good accuracy and responsiveness.

The superconducting coil of the present invention includes a coil body formed by winding the superconducting wire of the present invention, so that even if a normal conducting transition occurs, the criticality of the second superconducting wire for temperature detection is expected. When the temperature rises to the temperature Tx, the voltage value of the second superconducting wire greatly increases, so that a temperature change (normal conducting transition) in the superconducting coil can be easily detected.
The superconducting protection device of the present invention is provided with the superconducting coil of the present invention, so that the temperature rises to the critical temperature Tx of the second superconducting wire for temperature detection even if a normal conducting transition occurs. Thus, the voltage value of the second superconducting wire is greatly increased, and the voltage value immediately detected by the detector is greatly changed. Therefore, the temperature change (normal conduction transition) in the superconducting coil can be easily detected. Further, in the superconducting coil constituting the superconducting protection device of the present invention, the critical temperature Tc of the first superconducting wire is set higher than the critical temperature Tx of the second superconducting wire for temperature detection. Therefore, since the superconducting protection device of the present invention can take measures such as reducing the current value at the time when the occurrence of the normal conducting transition is detected at the temperature Tx, the normal conducting transition region in the superconducting coil is expanded. The superconducting coil can be protected in a good state.

It is a schematic sectional drawing which shows an example of the superconducting wire which concerns on 1st Embodiment of this invention. It is a schematic perspective view which shows the other example of the superconducting wire which concerns on 1st Embodiment of this invention. It is a schematic sectional drawing which shows an example of the superconducting wire which concerns on 2nd Embodiment of this invention. It is a schematic sectional drawing which shows an example of the superconducting wire which concerns on 3rd Embodiment of this invention. It is a schematic sectional drawing which shows the other example of the superconducting wire which concerns on 3rd Embodiment of this invention. It is a schematic sectional drawing which shows an example of the superconducting wire which concerns on 4th Embodiment of this invention. It is a schematic sectional drawing which shows an example of the superconducting wire which concerns on other embodiment of this invention. It is a schematic perspective view which shows an example of the superconducting coil which concerns on this invention. It is a schematic block diagram which shows an example of the superconducting protection apparatus which concerns on this invention. Resistance of MgB ₂ - is a graph plotting an example of the temperature characteristics. It is a schematic sectional drawing which shows the other example of the superconducting wire which concerns on 3rd Embodiment of this invention.

[Superconducting wire]
<First Embodiment>
FIG. 1 is a schematic cross-sectional view showing an example of a superconducting wire according to the first embodiment of the present invention.
The superconducting wire 1A of the present embodiment includes a first superconducting wire 1a and a second superconducting wire 10 for temperature detection.
In the superconducting wire 1A of the present embodiment, a bed layer 15, an intermediate layer 16, and a superconducting layer 17 are laminated on a tape-like base material 11, and a metal stabilizing base layer 18 and a metal stabilizing layer are formed on the superconducting layer 17. The first superconducting wire 1a formed by laminating the activating layer 19 and the temperature detecting first housed in the housing groove 9 provided in the upper part (upper layer part) of the metal stabilizing layer 19 of the first superconducting wire 1a. 2 is constituted roughly by the superconducting wire 10.

  The base material 11 applicable to the first superconducting wire 1a constituting the superconducting wire 1A of the present embodiment can be used as a base material for a normal superconducting wire, has only to be high strength, and is a tape for making a long cable. It is preferably in the form of a heat-resistant metal. Examples thereof include various metal materials such as silver, platinum, stainless steel, copper, nickel alloys such as Hastelloy, or ceramics disposed on these various metal materials. Among various heat resistant metals, nickel alloys are preferable. Among them, if it is a commercial product, Hastelloy (trade name, manufactured by Haynes, USA) is suitable, and Hastelloy B, C, G, N, W, etc. having different amounts of components such as molybdenum, chromium, iron, and cobalt are suitable. Any of these types can be used. What is necessary is just to adjust the thickness of the base material 11 suitably according to the objective, and it is 10-500 micrometers normally.

The bed layer 15 has high heat resistance and is used for reducing interfacial reactivity, and is used for obtaining the orientation of a film disposed thereon. Such a bed layer 15 is arranged as necessary, and is made of, for example, yttria (Y ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₃ , also referred to as “alumina”), or the like. Composed. The bed layer 15 is formed by a film forming method such as sputtering, and has a thickness of 10 to 200 nm, for example.
In the present invention, the first superconducting wire 1 a is not limited to the structure shown in FIG. 1, and may have a structure in which a diffusion preventing layer is interposed between the base material 11 and the bed layer 15. The diffusion preventing layer is formed for the purpose of preventing the diffusion of the constituent elements of the substrate 11, and is composed of silicon nitride (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₃ ), rare earth metal oxide, or the like. The thickness is, for example, 10 to 400 nm. Note that since the crystallinity of the diffusion preventing layer is not questioned, it may be formed by a film forming method such as a normal sputtering method.
By interposing the diffusion preventing layer between the base material 11 and the bed layer 15 in this way, when forming other layers such as an intermediate layer 16 and a superconducting layer 17 described later, inevitably heated, When receiving a thermal history as a result of the heat treatment, it is possible to effectively suppress a part of the constituent elements of the base material 11 from being diffused to the superconducting layer 17 side through the bed layer 15. As an example in the case of interposing a diffusion preventing layer between the base material 11 and the bed layer 15, a combination using Al ₂ O ₃ as the diffusion preventing layer and Y ₂ O ₃ as the bed layer 15 can be exemplified.

The intermediate layer 16 may have either a single layer structure or a multilayer structure, and is selected from materials biaxially oriented in order to control the crystal orientation of the superconducting layer 17 laminated thereon. Specifically, preferred materials for the intermediate layer 16 are Gd ₂ Zr ₂ O ₇ , MgO, ZrO ₂ —Y ₂ O ₃ (YSZ), SrTiO ₃ , CeO ₂ , Y ₂ O ₃ , Al ₂ O 3, Gd ₂ O. ₃ , metal oxides such as Zr ₂ O ₃ , Ho ₂ O ₃ and Nd ₂ O ₃ can be exemplified. Note that the superconducting wire 1A of the present embodiment is not limited to the structure shown in FIG. 1, and a cap layer is preferably interposed between the intermediate layer 16 and the superconducting layer 17.
If this intermediate layer 16 is formed with a good crystal orientation (for example, a crystal orientation of 15 ° or less) by ion beam assisted deposition (hereinafter abbreviated as IBAD), the crystal of the cap layer formed thereon The orientation can be set to a good value (for example, the degree of crystal orientation is around 5 °), and thus the superconducting layer 17 formed on the cap layer can have a good crystal orientation and can exhibit excellent superconducting characteristics. Can be.

The thickness of the intermediate layer 16 may be adjusted as appropriate according to the purpose, but is usually in the range of 0.005 to 2 μm.
The intermediate layer 16 is formed by physical vapor deposition such as sputtering, vacuum vapor deposition, laser vapor deposition, electron beam vapor deposition, ion beam assisted vapor deposition (IBAD), chemical vapor deposition (CVD); (MOD method): It can be laminated by a known method for forming an oxide thin film such as thermal spraying. In particular, the metal oxide layer formed by the IBAD method is preferable in that the crystal orientation is high and the effect of controlling the crystal orientation of the superconducting layer 17 and the cap layer is high. The IBAD method is a method of orienting crystal axes by irradiating an ion beam at a predetermined angle with respect to an underlying vapor deposition surface during vapor deposition. Usually, an argon (Ar) ion beam is used as the ion beam. For example, the intermediate layer 16 made of Gd ₂ Zr ₂ O ₇ , MgO, or ZrO ₂ —Y ₂ O ₃ (YSZ) reduces the value of ΔΦ (FWHM: full width at half maximum), which is an index representing the degree of crystal orientation in the IBAD method. This is particularly suitable because it is possible.

The cap layer was formed through a process of epitaxially growing on the surface of the intermediate layer 16 and then grain growth (overgrowth) in the lateral direction (plane direction), and crystal grains were selectively grown in the in-plane direction. Those are preferred. Such a cap layer has a higher in-plane orientation degree than the intermediate layer 16 made of the metal oxide layer.
The material of the cap layer is not particularly limited as long as it can exhibit the above functions, but specifically, preferred examples include CeO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , Gd ₂ O ₃ , and Zr ₂ O. ₃ , Ho ₂ O ₃ , Nd ₂ O _{3 and the} like. When the material of the cap layer is CeO ₂ , the cap layer may contain a Ce—M—O-based oxide in which part of Ce is substituted with another metal atom or metal ion.

The CeO ₂ layer can be formed by a PLD method (pulse laser deposition method), a sputtering method, or the like, but it is desirable to use the PLD method from the viewpoint of obtaining a high film formation rate. The film formation conditions for the CeO ₂ layer by the PLD method can be performed in an oxygen gas atmosphere at a substrate temperature of about 500 to 1000 ° C. and about 0.6 to 100 Pa.
The film thickness of the CeO ₂ layer may be 50 nm or more, but is preferably 100 nm or more, and more preferably 500 nm or more in order to obtain sufficient orientation. However, if it is too thick, the crystal orientation deteriorates.

The superconducting layer 17 is not particularly limited as long as the critical temperature Tc is higher than the critical temperature Tx of the superconductor constituting the second superconducting wire 10 to be described later, but an oxide superconductor having a high critical temperature is preferable, and REBa _{A material made of 2} Cu ₃ O _y (RE represents a rare earth element such as Y, La, Nd, Sm, Er, Gd) can be exemplified. Specifically, as this superconducting layer 17, Y123 (YBa ₂ Cu ₃ O _7-X : critical temperature Tc = 93K) or Gd123 (GdBa) which is an oxide superconductor whose critical temperature is higher than the liquid nitrogen temperature (77K). ₂ Cu ₃ O _7-X : critical temperature Tc = 95K). Further, other oxide superconductors, for _{example, Bi 2 Sr 2 Ca n-} 1 Cu n O 4 + 2n + δ (Bi2223 phase (n = 3: the critical temperature Tc = 110K), Bi2212-phase (n = 2: the critical temperature Tc = 80K ), Etc.), other oxide superconductors with high critical temperature typified by compositions such as BiSrCaCu ₂ O _z (critical temperature Tc = 105K), Tl ₂ Ba ₂ Ca ₂ Cu ₃ O _y (critical temperature Tc = 120K), etc. Of course, it is also possible to use one made of

The thickness of the superconducting layer 17 is about 0.5 to 5 μm and is preferably uniform.
The superconducting layer 17 is laminated by a physical vapor deposition method such as sputtering, vacuum vapor deposition, laser vapor deposition, electron beam vapor deposition, chemical vapor deposition (CVD), or thermal coating decomposition (MOD). Among these, from the viewpoint of productivity, it is preferable to use the TFA-MOD method (organic metal deposition method using trifluoroacetate, coating pyrolysis method), PLD method or CVD method.

  As described above, when the superconducting layer 17 is formed on the cap layer having a good orientation, the superconducting layer 17 laminated on the cap layer is also crystallized so as to match the orientation of the cap layer. Therefore, the superconducting layer 17 formed on the cap layer has almost no disorder in the crystal orientation, and electricity flows in the thickness direction of the substrate 11 in each of the crystal grains constituting the superconducting layer 17. The hard c-axis is oriented, and the a-axis or b-axis is oriented in the length direction of the substrate 11. Therefore, the obtained superconducting layer 17 is excellent in quantum connectivity at the crystal grain boundary, and hardly deteriorates in the superconducting characteristics at the crystal grain boundary, so that it becomes easy to flow electricity in the length direction of the base material 11 and is sufficiently high. A critical current density is obtained.

  The metal stabilizing base layer 18 laminated on the superconducting layer 17 is formed as a layer made of a metal material having good conductivity, such as Ag, and having a low contact resistance with the superconducting layer 17 and a familiarity. The thickness of the metal stabilizing base layer 18 is preferably 1 to 30 μm. The metal stabilizing base layer 18 can be formed by a known method, but among them, it is preferably formed by a sputtering method.

The metal stabilization layer 19 is made of a highly conductive metal material, and when the superconducting layer 17 attempts to transition from the superconducting state to the normal conducting state, the metal stabilizing base layer 18 and the bypass of the current flowing through the superconducting layer 17 are commutated. Function as.
The metal material constituting the metal stabilizing layer 19 is not particularly limited as long as it has good conductivity, but is relatively inexpensive such as copper, copper alloys such as brass (Cu—Zn alloy), stainless steel, and the like. It is preferable to use copper, and copper is more preferable because it has high conductivity and is inexpensive. As a result, it is possible to increase the thickness of the metal stabilization layer 19 while keeping the material cost low, and it is possible to obtain the superconducting wire 1A that can withstand an accident current at low cost. The thickness of the metal stabilizing layer 19 is preferably 10 to 300 μm. By making the lower limit value or less, a higher effect of stabilizing the superconducting layer 17 is obtained, and by making the upper limit value or less, the superconducting wire 1A can be thinned. The metal stabilization layer 19 can be formed by a known method, and can be formed by a sputtering method or a method of soldering a metal tape such as copper onto the metal stabilization base layer 18.

The second superconducting wire 10 for temperature detection is a long wire having a superconducting core portion 10a. A metal coating layer 10b is formed on the outer periphery of the superconducting core portion 10a, and an insulating layer is formed on the outer periphery of the metal coating layer 10b. (Not shown) is formed.
The superconducting core portion 10a of the second superconducting wire 10 is formed of a superconductor having a critical temperature Tx lower than the critical temperature Tc of the superconducting layer 17 of the first superconducting wire 1a. The critical temperature Tx of the second superconducting wire 10 is set to be higher than the operating temperature Top at which the superconducting wire 1A is in a superconducting state. That is, the critical temperature Tc of the first superconducting wire 1a, the critical temperature Tx of the second superconducting wire 10, and the operating temperature Top of the superconducting wire 1A are set to satisfy the relationship of Top <Tx <Tc. The critical temperature Tc of the first superconducting wire 1a, the critical temperature Tx of the second superconducting wire 10, and the operating temperature Top of the superconducting wire 1A are not particularly limited as long as the above relationship is satisfied, but Tc ≧ 77K. , Top ≦ Tx−5K is preferably set so as to satisfy the relationship.

The superconductor forming the superconducting core portion 10a of the second superconducting wire 10 is not particularly limited as long as it is a superconductor satisfying the above temperature relationship. Specifically, the operating temperature Top at which the superconducting wire 1A is in a superconducting state can be, for example, a liquid helium temperature (4.2K), a refrigerator cooling temperature (about 20K to 77K), etc. Since it is cheaper to use the machine, it is preferable to set the cooling temperature. Moreover, it is preferable that the superconducting layer 17 of the first superconducting wire 1a is formed of an oxide superconductor having a high critical temperature as described above. Therefore, since the critical temperature Tx of the second superconducting wire 10 is a temperature between them, the superconductor forming the superconducting core portion 10a is a temperature between the critical temperature Tc of the first superconducting wire 1a and the operating temperature Top. Those having a critical temperature in the region are preferred. Specifically, as the superconductor forming the superconducting core portion 10a, MgB ₂ (critical temperature Tx = 39K), LaFeAsO _1-x F _x (critical temperature Tx = 26K), NdFeAsO _1-x F _x (critical temperature) Tx = 51K), SmFeAsO _1-x F _x (critical temperature Tx = 55K), Gd _1-x Th _x FeAsO (critical temperature Tx = 56K), CeFeAsO _1-x F _x (critical temperature Tx = 41K), La _{2 -X} Sr _x CuO ₄ (critical temperature Tx = 40K), La _2-x Ba _x CuO ₄ (critical temperature Tx = 30K), Nb ₃ Ge (critical temperature Tx = 23K), etc. MgB ₂ is preferred.

  The cross-sectional shape of the superconducting core portion 10a is not limited to the circular shape shown in FIG. 1, and may be flat or polygonal, and may be multi-core. The diameter and thickness of the superconducting core portion 10a or the width of the region is preferably 0.01 to 0.3 mm. Further, the superconducting characteristics such as the current density of the second superconducting wire 10 for temperature detection are not particularly limited as long as the current for temperature detection can flow.

The metal coating layer 10b of the second superconducting wire 10 is not particularly limited as long as it does not react with the superconducting core portion 10a, but is preferably formed of copper, copper alloy, silver, silver alloy, etc. It is particularly preferable that it is made of copper because of good workability and low cost. The thickness of the metal coating layer 10b is preferably 0.01 to 0.3 mm.
The insulating layer of the second superconducting wire 10 is not particularly limited as long as it has insulating properties and can withstand a low temperature such as a superconducting critical temperature. For example, polyimide resin or ETFE (tetrafluoroethylene-ethylene co-polymer) can be used. Polymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) and the like are preferably used. The thickness of the insulating layer is preferably 5 to 20 μm.

The diameter or thickness of the long superconductor-like second superconducting wire 10 is 0.01 to 0.3 mm.
Although the manufacturing method of the 2nd superconducting wire 10 is not specifically limited, Since it is simple and can be reduced in diameter, manufacturing by the PIT method (Powder In Tube method) is preferable. In this PIT method, a superconductor powder forming the superconducting core portion 10a or a raw material powder capable of forming a superconductor is charged into a metal tube such as copper or silver which is a metal constituting the metal coating layer 10b. This is a technique of heating and sintering, drawing together with this tubular metal to form a wire.
As an example of the manufacturing method of the second superconducting wire 10, the superconducting core part 10a is MgB _2, illustrates the case where the metal coating layer 10b is formed of copper. In this case, the MgB ₂ powder is accommodated in a copper metal tube, and the wire is drawn, rolled, and fired repeatedly to increase the diameter (ex situ method), or the copper metal tube contains 1 Mg powder and B powder. : A method of forming MgB ₂ in the wire by heat treatment after enclosing the raw material powder mixed in a molar ratio of 2 and repeating wire drawing, rolling and firing to reduce the diameter and length (in situ method) The second superconducting wire 10 can be manufactured by forming a superconducting element wire by using a polyimide resin or the like and then forming an insulating layer on the outer periphery thereof.

  The second superconducting wire 10 for temperature detection was continuously formed in the longitudinal direction of the superconducting wire 1A (first superconducting wire 1a) on the upper part (upper layer part) of the metal stabilizing layer 19 of the first superconducting wire 1a. Inside the storage groove 9 is stored along the longitudinal direction of the superconducting wire 1A (first superconducting wire 1a). The storage groove 9 may be formed by processing with a laser or the like after the metal stabilizing layer 19 is laminated on the metal stabilizing base layer 18, or the metal stabilizing layer 19 may be soldered with a metal tape such as copper. If it is attached, the metal stabilization layer 19 may be laminated after the storage groove 9 is previously formed on the metal tape by a conventionally known method. The method of installing the second superconducting wire 10 in the housing groove 9 is such that the width of the housing groove 9 in the short direction of the first superconducting wire 1a is substantially equal to or slightly equal to the diameter (size) of the second superconducting wire 10. For example, a method of fitting the second superconducting wire 10 into the storage groove 9 or joining with an adhesive or solder may be used. In addition, when joining the 2nd superconducting wire 10 to the storage groove | channel 9 using an adhesive agent, the 2nd superconducting wire 10 and the storage groove 9 (namely, metal stabilization layer) are prevented so that the detection precision of a temperature change may not be caused. 19) is preferably as small as possible in the region where the adhesive is interposed. Among these, the method of fitting the second superconducting wire 10 into the housing groove 9 is simpler, and the contact area between the second superconducting wire 10 and the housing groove 9 (that is, the metal stabilization layer 19) is increased. This is preferable because the temperature change detection accuracy is improved.

The depth of the storage groove 9 can be appropriately adjusted according to the diameter (size) of the second superconducting wire 10, but the diameter of the second superconducting wire 10 is d, and the depth of the storage groove 9 is L. In this case, it is preferable that d ≦ L. A part of the second superconducting wire 10 may be structured to protrude from the upper surface of the metal stabilization layer 19. However, as described above, d ≦ L and the second inside the metal stabilization layer 19 is second. The structure in which the superconducting wire 10 is arranged not only increases the contact area between the second superconducting wire 10 and the metal stabilizing layer 19 and further improves the temperature change detection accuracy, but also makes the superconducting wire 1A thinner. Therefore, when the superconducting wire 1A is wound concentrically to form a superconducting coil, it is preferable because the superconducting wire 1A can be wound at a high density and a good current density can be obtained.
In addition, in FIG. 1, although the case where the cross-sectional shape of the storage groove 9 is a quadrangle is illustrated, this embodiment is not limited to this example. For example, as shown by a broken line in FIG. 1, the second superconducting wire 10 is formed by forming the bottom shape of the storage groove 9 in an arc shape or the like in accordance with the cross-sectional shape of the second superconducting wire 10 (circular in FIG. 1). It is possible to increase the contact area between the metal stabilizing layer 19 and the temperature change detection accuracy, or to further strengthen the joint structure by fitting the housing groove 9 and the second superconducting wire 10.

  Further, as shown in FIG. 2, the superconducting wire 1A may have a configuration in which the surrounding exposed surface is covered with an insulating insulating layer 20. The insulating layer 20 is made of a known material such as various resins and oxides that are usually used. Specific examples of the resin include polyimide resin, polyamide resin, epoxy resin, acrylic resin, phenol resin, melamine resin, polyester resin, silicon resin, silicon resin, alkyd resin, and vinyl resin. The thickness of the covering by the insulating layer 20 is not particularly limited, and may be adjusted as appropriate according to the portion to be covered. The insulating layer 20 may be formed by a known method depending on the material, for example, a raw material may be applied and cured. Moreover, when a sheet-like thing is available, you may coat | cover using this.

  In the present invention, the critical temperature Tc of the first superconducting wire 1a, the critical temperature Tx of the second superconducting wire 10, and the operating temperature Top at which the superconducting wire 1A is in the superconducting state are set so as to satisfy the relationship Top <Tx <Tc. Thus, when the superconducting wire 1A is operated at the operating temperature Top, the first superconducting wire 1a and the second superconducting wire 10 are cooled to temperatures lower than the critical temperatures Tc and Tx, respectively, and thus are in a superconducting state. However, if a normal conduction transition occurs in a part of the first superconducting wire 1a during the operation of the superconducting wire 1A, the metal stabilizing base layer 18 and the metal stabilizing layer are generated. 19, the current of the superconducting layer 17 is commutated. At that time, in the metal stabilizing base layer 18 or the metal stabilizing layer 19, a commutated current flows, so that Joule heat is generated and heat is generated. In the superconducting wire 1A of the present embodiment, when the temperature rises due to the heat generated by the normal conducting transition in this way, the second superconducting wire 10 is always at the time when the temperature exceeds the critical temperature Tx of the second superconducting wire 10 for temperature detection. As a result, the resistance of the second superconducting wire 10 is rapidly increased, and the voltage is rapidly increased. Thereby, the temperature rise accompanying the normal conducting transition in the superconducting wire 1A can be detected.

In general, the amount of change in resistance when a superconductor transitions to normal conduction is considerably large. As an example, FIG. 10 shows a graph plotting resistance-temperature characteristics of MgB ₂ . As shown in FIG. 10, in MgB ₂ (critical temperature 39K), the resistance value is 0 in the superconducting state, but the resistance value in the normal conducting state is about 100 μΩcm. Therefore, the configuration using the second superconducting wire 10 for temperature detection as in the present invention makes it possible to compare the conventional temperature detection medium (carbon resistance, semiconductor, etc.) whose voltage value changes with known temperature. Thus, since the resistance increase with respect to the temperature change is remarkably large, the temperature change (normal conduction transition) can be easily detected. In the present invention, since the critical temperature Tc of the first superconducting wire 1a is set higher than the critical temperature Tx of the second superconducting wire 10 for temperature detection, the normal conduction transition occurs at the temperature Tx. Since it is possible to take measures such as reducing the current value at the time of detection, the normal conduction transition region of the first superconducting wire 1a (superconducting wire 1A) can be prevented from expanding.

  In the present embodiment, the configuration in which one second superconducting wire 10 for temperature detection is arranged inside the metal stabilization layer 19 of the first superconducting wire 1a is exemplified. It is not limited, and in order to improve the reliability of the superconducting wire 1 </ b> A, it is also preferable that two or more second conductive wires 10 are arranged inside the metal stabilizing layer 19.

Second Embodiment
FIG. 3 is a schematic cross-sectional view showing an example of a superconducting wire according to the second embodiment of the present invention. In FIG. 3, the same components as those in the superconducting wire 1A shown in FIGS. 1 and 2 are denoted by the same reference numerals. In the following description, portions different from the first embodiment described above will be mainly described, and description of similar portions will be omitted.
The superconducting wire 2A of the present embodiment includes a laminated body S1 in which a bed layer 15, an intermediate layer 16, a superconducting layer 17, and a metal stabilizing base layer 18 are laminated in this order on a tape-like base material 11, and this laminated body. A first superconducting wire 2a constituted by metal stabilizing layers 19a, 19b, 19c, 19d (metal stabilizing layer 19) formed so as to cover the upper surface, one side surface, the other side surface and the lower surface of S1, A temperature detecting second superconducting wire 10 disposed in the metal stabilizing layer 19a on the laminated body S1 of the first superconducting wire 2a so as to be in contact with the upper surface of the metal stabilizing base layer 18 which is the upper surface of the laminated body S1; Is schematically configured.
In the superconducting wire 2A of the second embodiment, the metal stabilizing layer 19 is provided around the laminate S1, and the second superconducting wire 10 for temperature detection is in contact with the metal stabilizing base layer 18. This is different from the superconducting wire 1A of the first embodiment.

The metal stabilization layers 19a, 19b, 19c, 19d (metal stabilization layer 19) of the first superconducting wire 2a are made of a highly conductive metal material, and the superconducting layer 17 tries to transition from the superconducting state to the normal conducting state. Sometimes, it functions as a bypass through which the current of the superconducting layer 17 commutates together with the metal stabilizing base layer 18. The metal material constituting the metal stabilization layers 19a to 19d (metal stabilization layer 19) is not particularly limited as long as it has good conductivity, but a relatively inexpensive material such as copper is used. preferable. This makes it possible to increase the thickness of the metal stabilization layers 19a to 19d (metal stabilization layer 19) while keeping the material cost low, and the superconducting wire 2A that can withstand accidental current can be obtained at a low cost.
The thickness of the metal stabilizing layers 19a to 19b is preferably 10 to 300 μm. By making the lower limit value or less, a higher effect of stabilizing the superconducting layer 17 is obtained, and by making the upper limit value or less, the superconducting wire 2A can be made thinner. The metal stabilization layers 19a to 19d are formed by a plating method.

  In the present embodiment, the second superconducting wire 10 for temperature detection is such that the upper surface of the metal stabilizing base layer 18 and the lower surface of the second superconducting wire 10 are in contact with each other in the metal stabilizing layer 19 on the metal stabilizing base layer 18. It is arranged in. As a method of installing the second superconducting wire 10 in the metal stabilizing layer 19a in this way, the base 11, the bed layer 15, the intermediate layer 16, the superconducting layer 17, the metal stabilizing base layer 18 of the first superconducting wire 2a, After the laminate S1 is formed, a highly conductive metal such as copper is plated by placing the second superconducting wire 10 along the upper surface of the laminate S1 (the upper surface of the metal stabilizing base layer 18). There is a method in which the stabilization layers 19a to 19d are formed and the second superconducting wire 10 is buried and fixed in the metal stabilization layer 19a.

  In the first superconducting wire 1a of the superconducting wire 2A, if a normal conducting transition occurs in a part of the first superconducting wire 1a, the current of the superconducting layer 17 is commutated to the metal stabilizing base layer 18 and the metal stabilizing layer 19 and Joule heat. Occurs and heat is generated. The superconducting wire 2A of the present embodiment is disposed in the metal stabilizing layer 19a in such a state that the lower surface of the second superconducting wire 10 for temperature detection is in contact with the upper surface of the metal stabilizing base layer 18 laminated on the superconducting layer 17. Therefore, in addition to the effect of the superconducting wire 1A of the first embodiment described above, the detection accuracy and responsiveness of temperature change (temperature rise) can be further improved.

  Although FIG. 3 illustrates the case where the thickness of the metal stabilization layer 19a and the diameter of the second superconducting wire 10 are substantially the same, this embodiment is not limited to this. The thickness of the metal stabilization layer 19a may be set larger than the diameter of the second superconducting wire 10, and the temperature detection medium 10 may be completely buried in the metal stabilization layer 19a. The diameter (thickness) may be larger than the thickness of the metal stabilizing layer 19a, and a part of the second superconducting wire 10 may be exposed.

  In the present embodiment, the configuration in which one temperature detection second superconducting wire 10 is arranged inside the metal stabilization layer 19a is illustrated, but the present invention is not limited to this. In order to improve the reliability of the superconducting wire 2A, it is also preferable that two or more second superconducting wires 10 are arranged inside the metal stabilization layer 19a.

<Third Embodiment>
FIG. 4 is a schematic cross-sectional view showing an example of a superconducting wire according to the third embodiment of the present invention. 4, the same components as those of the superconducting wire 1A shown in FIGS. 1 and 2 and the superconducting wire 2A shown in FIG. 3 are denoted by the same reference numerals. In the following description, portions different from those of the first embodiment and the second embodiment described above will be mainly described, and description of similar portions will be omitted.
The superconducting wire 3A of the present embodiment includes a laminated body S1 in which a bed layer 15, an intermediate layer 16, a superconducting layer 17, and a metal stabilizing base layer 18 are laminated in this order on a tape-shaped substrate 11, and this laminated body. A first superconducting wire 3a composed of metal stabilizing layers 19a, 19b, 19c, 19d (metal stabilizing layer 19) formed so as to cover the upper surface, one side surface, the other side surface and the lower surface of S1, The second superconducting wire 10 for temperature detection disposed in the metal stabilization layer 19b on the side of the superconducting layer 17 of the first superconducting wire 3a is roughly constituted.
The superconducting wire 3A of the third embodiment is different from the superconducting wire 2A of the second embodiment described above in that the second superconducting wire 10 for temperature detection is disposed in the metal stabilization layer 19b.

  Examples of the metal stabilizing layers 19a to 19d are the same as those in the second embodiment, and are formed by a plating method. As a method of installing the second superconducting wire 10 in the metal stabilizing layer 19b, a good conductivity such as copper with the second superconducting wire 10 placed along one side surface of the laminate S1 of the first superconducting wire 3a. The metal stabilizing layers 19a to 19d are formed by plating the above metal, and at the same time, the second superconducting wire 10 is buried and fixed in the metal stabilizing layer 19b.

  In the superconducting wire 3A of the present embodiment, the second superconducting wire 10 for temperature detection is disposed in the metal stabilization layer 19b in contact with the side surface of the superconducting layer 17 of the first superconducting wire 3a. When the transition occurs, it is possible to detect heat generation due to current flowing from the superconducting layer 17 to the metal stabilizing layer 19b with good accuracy and responsiveness. Furthermore, by providing the second superconducting wire 10 in the vicinity of the superconducting layer 17 in the metal stabilizing layer 19b, the accuracy and responsiveness of temperature detection can be further improved.

  FIG. 4 illustrates the case where the thickness of the metal stabilization layer 19b and the diameter (thickness) of the second superconducting wire 10 are substantially the same, but this embodiment is not limited to this. . The thickness of the metal stabilization layer 19b may be set larger than the diameter of the second superconducting wire 10, and the second superconducting wire 10 may be completely buried in the metal stabilizing layer 19b, or the second superconducting wire 10 The diameter (thickness) may be made larger than the thickness of the metal stabilizing layer 19b, and a part of the second superconducting wire 10 may be exposed.

  Moreover, in this embodiment, although the structure which has arrange | positioned the 2nd superconducting wire 10 for temperature detection inside the metal stabilization layer 19b was illustrated, this invention is not limited to this. In order to improve the reliability of the superconducting wire 3 </ b> A, it is also preferable to include two or more second superconducting wires 10 for temperature detection. When the superconducting wire 3A includes two or more second superconducting wires 10, the arrangement of the plurality of second superconducting wires 10 is not particularly limited, and a plurality of the superconducting wires 10A may be arranged in the metal stabilization layer 19b or may be laminated. The metal stabilization layer 19b on one side surface of the body S1 and the metal stabilization layer 19c on the other side surface of the stacked body S1 may be disposed. Further, as a modification of the present embodiment, temperature detection is performed on the metal stabilization layer 19b on the side of the multilayer body S1 and the metal stabilization layer 19a on the multilayer body S1 as in the superconducting wire 3B shown in FIG. The second superconducting wire 10 for use may be arranged. Furthermore, it is of course possible to adopt a configuration in which the second superconducting wire 10 is disposed on the metal stabilization layer 19a on the multilayer body S1 and the metal stabilization layers 19b and 19c on both side surfaces of the multilayer body S1, respectively. In addition, the number of second superconducting wires 10 for temperature detection per first superconducting wire is not particularly limited.

  Furthermore, as another example of the modification of the present embodiment, as in the superconducting wire 3C shown in FIG. 11, a laminate S2 in which the base material 1, the bed layer 15, the intermediate layer 16, and the superconducting layer 17 are laminated in this order, The metal stabilizing base layers 18a, 18b, 18c and 18d (metal stabilizing base layer 18) formed so as to cover the upper surface, one side surface, the other side surface and the lower surface of the laminate S2, and the metal stabilizing base layer 18 The side of the superconducting layer 17 of the first superconducting wire 3c of the first superconducting wire 3c constituted by the metal stabilizing layers 19a, 19b, 19c, 19d (metal stabilizing layer 19) formed so as to cover the outer periphery. The second superconducting wire 10 for temperature detection may be disposed in the metal stabilizing layer 19b so as to be in contact with the metal stabilizing base layer 18b. In this case, the metal stabilizing base layers 18a, 18b, 18c, and 18d (metal stabilizing base layer 18) are formed by a plating method from the same material as that of the first embodiment. In the superconducting wire 3C shown in FIG. 11, the second superconducting wire 10 may of course be arranged so as to be in contact with the metal stabilizing base layer 18 in the metal stabilizing layers 19c, 19a and the like. However, the number of second superconducting wires 10 for temperature detection per one first superconducting wire 3c is not particularly limited.

<Fourth embodiment>
FIG. 6 is a schematic cross-sectional view showing an example of a superconducting wire according to the fourth embodiment of the present invention. In FIG. 6, the same components as those in the superconducting wire 1A shown in FIGS. 1 and 2 are denoted by the same reference numerals. In the following description, portions different from the first embodiment described above will be mainly described, and description of similar portions will be omitted.
In the superconducting wire 4A of the present embodiment, a bed layer 15, an intermediate layer 16 and a superconducting layer 17 are laminated on a tape-like base material 11, and a metal stabilizing base layer 18 and a metal stabilizing layer are formed on the superconducting layer 17. The first superconducting wire 4a formed by laminating the activating layer 19 and the second superconducting wire 10 for temperature detection provided so as to be in contact with the upper surface of the first superconducting wire 4a (the upper surface of the metal stabilizing layer 19). It is roughly structured.

As a method of installing the second superconducting wire 10 for temperature detection on the upper surface of the first superconducting wire 4a (upper surface of the metal stabilization layer 19), a method of fixing with an adhesive or the like, or an outer peripheral portion as shown in FIG. When the insulating layer 20 is provided, an insulating tape or the like is wound so as to be in contact with the upper surface of the first superconducting wire 4a, so that the space between the upper surface of the first superconducting wire 4a and the insulating layer 20 is wound. The method etc. to arrange | position to can be illustrated. The superconducting wire 4A of this embodiment is preferable because the method for installing the second superconducting wire 10 on the first superconducting wire 4a is simple and the productivity is good.
In the superconducting wire 4A of the present embodiment shown in FIG. 6, an example is shown in which the second superconducting wire 10 is installed so as to be in contact with the upper surface of the metal stabilizing layer 19 of the first superconducting wire 4a. It is not limited to this. As shown in FIG. 2, the second superconducting wire may be disposed on the upper surface of the insulating layer 20 formed so as to cover the outer periphery of the first superconducting wire, and the second superconducting wire is disposed inside the insulating layer 20. May be.

<Other embodiments>
In the first to fourth embodiments, the superconducting wire having a thin film laminated structure has been described, but the present invention is not limited to this.
FIG. 7 is a schematic cross-sectional view showing an example of a superconducting wire according to another embodiment of the present invention. The superconducting wire 5 </ b> A of this embodiment is a wire having a flat cross-sectional shape, and covers a superconducting layer 37 having a flat cross-sectional shape formed by a plurality of superconductor filaments extending in the longitudinal direction, and the periphery of the superconducting layer 37. A first superconducting wire 5a composed of a flat metal stabilizing layer 39, and a second superconducting wire 10 for temperature detection housed in a housing groove 9 formed in the metal stabilizing layer 39 of the first superconducting wire 5a. And is roughly composed.

Examples of the material for forming the superconducting layer 37 include Bi ₂ Sr ₂ Ca ₁ Cu ₂ O _x (Bi 2212 phase: critical temperature Tc = 80 K), Bi ₂ Sr ₂ Ca ₂ Cu ₃ O _y (Bi 2223 phase: critical temperature Tc = 110K), Bi _1.6 Pb _0.4 Sr ₂ Ca ₂ Cu ₃ O _x , Tl ₂ Ba ₂ Ca ₂ Cu ₃ O _y , oxide having a composition shown by Y ₁ Ba ₂ Cu ₃ O _7-x, etc. One or more materials selected from high-temperature superconducting materials such as superconducting materials are used, and Bi2223 phase or Bi2212 phase Bi-based oxide superconducting materials are particularly used.
The metal stabilization layer 39 is made of silver or a silver alloy. The storage groove 9 and the second superconducting wire 10 can have the same configuration and structure as in the first embodiment.

The superconducting wire 5A of this embodiment is a PIT method (Powder In Tube) in which a pipe made of silver or a silver alloy filled with the raw powder of the superconducting layer 37 is drawn to be multi-core, and then repeatedly drawn, rolled and fired. Method). The thickness of the superconducting wire 5A (first superconducting wire 5a) is about 0.2 to 0.3 mm in the case of a tape-shaped conductor structure, and the volume ratio between the superconducting layer 37 and the metal stabilizing layer 39 is, for example, 2: 3.
In the first superconducting wire 5a of the superconducting wire 5A of the present embodiment, the metal stabilizing layer 39 covers the entire circumference of the superconducting layer 37. On the both ends in the width direction of the superconducting layer 37, the outer side of the superconducting layer 37 is provided. A protrusion 39a is formed on the surface. The second superconducting wire 10 for temperature detection is formed in the upper portion of the protruding portion 39a on one end side in the width direction of the superconducting layer 37, inside the storage groove 9 formed continuously in the longitudinal direction of the first superconducting wire 5a. The first superconducting wire 5a is housed along the longitudinal direction. The storage groove 9 is formed by, for example, processing the metal stabilization layer 19 with a laser or the like after the superconducting layer 37 and the metal stabilization layer 39 are formed by wire drawing, rolling and firing, or roll rolling. Sometimes, it can be performed by forming a groove by roll rolling in the protruding portion 39a where there is no superconducting layer 37. The method of installing the second superconducting wire 10 in the storage groove 9 is the same as in the first embodiment described above.

The superconducting wire 5A of the present embodiment also includes the first superconducting wire 5a and the second superconducting wire 10 for temperature detection as in the above embodiment, so that a temperature rise occurs in a part of the superconducting wire 5A and the second superconducting wire 5A. When the critical temperature Tx of the wire 10 is reached, the voltage value of the second superconducting wire 10 is significantly increased, so that a temperature change (temperature increase) can be easily detected.
Further, in the superconducting wire 5A of the present embodiment, the second superconducting wire 10 for temperature detection is arranged on the metal stabilization layer 39 of the first superconducting wire 5a, similarly to the superconducting wires of the first to third embodiments. Therefore, even if a normal conduction transition occurs, a temperature change (temperature increase) can be detected with good accuracy and responsiveness. Furthermore, the superconducting wire 5A of the present embodiment can be made thinner as compared with the case where the temperature detection medium is installed on the outer peripheral surface of the superconducting wire, and the superconducting wire 5A is wound concentrically to form a superconducting coil. In this case, the superconducting wire 5A can be wound at a high density, and a good current density can be obtained.

  In the present embodiment, the configuration in which one temperature detection second superconducting wire 10 is arranged inside the metal stabilizing layer 39 is exemplified, but the present invention is not limited to this, and the superconducting wire 5A is provided. In order to improve the reliability, it is also preferable that two or more second superconducting wires 10 are arranged inside the metal stabilizing layer 39. Further, the arrangement of the second superconducting wire 10 in the metal stabilization layer 39 can be changed as appropriate. Further, in the present embodiment, an example in which the superconducting layer 37 is formed from a plurality of superconducting filaments has been shown, but the present embodiment is not limited to this, and the superconducting layer 37 is formed from one superconducting filament. It may be.

[Superconducting coil]
Next, an embodiment of a superconducting coil according to the present invention will be described.
FIG. 8 is a schematic perspective view showing an embodiment of the superconducting coil 50 of the present invention.
The superconducting coil 50 is configured by coaxially laminating a second coil body 52 on a first coil body 51.
The first coil body 51 is configured by winding the superconducting wire 2A of the second embodiment according to the present invention described above many times concentrically and counterclockwise with the metal stabilizing layer 19a side outside. It is a pancake type coil body. In the metal stabilization layer 19a of the superconducting wire 2A constituting the first coil body 51, the second superconducting wire 10 for temperature detection is disposed. The second superconducting wire 10 is wound with the winding of the superconducting wire 2A. Is also concentric and wound many times counterclockwise.
The second coil body 52 is a pan formed by winding the above-described superconducting wire 2A according to the second embodiment of the present invention a number of times concentrically and clockwise with the metal stabilizing layer 19a side outside. It is a cake-shaped coil body. In the metal stabilization layer 19a of the superconducting wire 2A constituting the second coil body 52, the second superconducting wire 10 for temperature detection is arranged, and the second superconducting wire 10 is wound with the winding of the superconducting wire 2A. Is also concentric and wound many times clockwise.
The outer peripheral end 51a, which is the winding end of the first coil body 51, and the outer peripheral end 52a, which is the winding end of the second coil body 52, are arranged so as to be adjacent to each other, and have good conductivity. It is electrically and mechanically connected by a connection plate (not shown).

  In the superconducting coil 50 of the present embodiment, the second superconducting wires 10 and 10 for temperature detection provided in the respective superconducting wires 2A and 2A constituting the first coil body 51 and the second coil body 52 are provided in the superconducting coil 50. As long as the temperature change (temperature rise) can be detected, each coil body may be arranged independently, or may be continuously arranged in two coil bodies. For example, the second superconducting wire 10 for temperature detection provided in the superconducting wire 2A of the first coil body 51 and the second superconducting wire 10 for temperature detection provided in the superconducting wire 2A of the second coil body 52 are individually connected to the outside. May be communicated with the detecting means (not shown). Further, the second superconducting wire 10 for temperature detection of the first coil body 51 and the second superconducting wire 10 for temperature detection of the second coil body 52 are outer peripheral ends that are winding ends of the first coil body 51. 51a and an outer peripheral end 52a that is a winding end of the second coil body 52 are continuously connected to each other, and the end of the second superconducting wire 10 is an external detection means (not shown). You may communicate with.

  The superconducting coil 50 of the present invention includes the first and second coil bodies 51 and 52 formed by winding the superconducting wire 2A of the present invention, so that even if a normal conducting transition occurs, When the temperature rises to the critical temperature Tx of the second superconducting wire 10 for detection, the voltage value of the second superconducting wire greatly increases, so that a temperature change (normal conduction transition) in the superconducting coil 50 can be easily detected. can do. In the superconducting wire 2A of the present invention, the critical temperature Tc of the first superconducting wire is set higher than the critical temperature Tx of the second superconducting wire 10 for temperature detection. Since it is possible to take measures such as lowering the current value at the time when the occurrence of this is detected, it is possible to prevent the normal conduction transition region of the first superconducting wire constituting the superconducting coil 50 from expanding.

  In addition, in this embodiment, although the superconducting coil 50 of the structure which laminated | stacked two coil bodies was illustrated, this invention is not limited to this, Even if formed from three or more coil bodies Of course it is good. Further, the first coil body 51 and the second coil body 52 constituting the superconducting coil 50 are the superconducting wires 1A, 2A, 3A, 3B of the first to fourth embodiments and other embodiments according to the present invention described above. Of course, it may be formed of any superconducting wire among 4A and 5A.

[Superconducting protection device]
Next, an embodiment of the superconducting protection device according to the present invention will be described.
FIG. 9 is a schematic configuration diagram showing an embodiment of the superconducting protection device 100 of the present invention.
In the superconducting protection device 100, one end 60a of the second superconducting wire means 60 for temperature detection provided in the superconducting coil 50 of the present invention communicates with the power supply 61, and the other end 60b of the second superconducting wire 60 communicates with the detector 62. It is roughly structured. The superconducting protection device 100 operates the power supply 61 to cause a current to flow from the one end 60a of the second superconducting wire 60 to the second superconducting wire 60, and at the other end 60b of the second superconducting wire 60, by the detector 62, A change in the voltage value of the wire 60 is observed, and a temperature change (normal conduction transition) in the superconducting coil 50 is detected. As a result, if a superconducting transition occurs in the superconducting coil 50, a change appears in the voltage value detected immediately when the temperature in the superconducting coil rises to the critical temperature Tx of the second superconducting wire 60. Conductive transitions can be detected.

  The superconducting protection device 100 of the present invention includes the superconducting coil 50 of the present invention, so that the temperature rises to the critical temperature Tx of the second superconducting wire 60 for temperature detection even if a normal conducting transition occurs. At that time, the voltage value of the second superconducting wire 60 is greatly increased, and the voltage value immediately detected by the detector 62 is greatly changed, so that the temperature change (normal conduction transition) in the superconducting coil 50 is easily detected. can do. In the superconducting coil 50 constituting the superconducting protection device 100 of the present invention, the critical temperature Tc of the first superconducting wire is set higher than the critical temperature Tx of the second superconducting wire for temperature detection. Therefore, since the superconducting protection device 100 of the present invention can take measures such as reducing the current value when the occurrence of the normal conducting transition is detected at the temperature Tx, the normal conducting transition region in the superconducting coil 50 can be applied. Can be prevented and the superconducting coil 50 can be protected in a good state.

  As described above, the superconducting wire, the superconducting coil, and the superconducting protection device of the present invention have been described.In the above embodiment, each part of the superconducting wire, each part that constitutes the superconducting coil, and each part that constitutes the superconducting protection device are examples. Modifications can be made as appropriate without departing from the scope of the present invention.

EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited to these Examples.
(Example)
"Production of the first superconducting wire"
A 1.2 μm thick Gd ₂ Zr ₂ O ₇ (IBAD method) is formed on a tape-like base material made of tape-like Hastelloy (trade name, manufactured by Haynes, USA) having a width of 5 mm and a thickness of 0.1 mm. After forming GZO (intermediate layer), a 1.0 μm-thick CeO ₂ (cap layer) was formed by a pulse laser deposition method (PLD method). Next, YBa ₂ Cu ₃ O ₇ (superconducting layer) having a thickness of 1.0 μm was formed on the CeO ₂ layer by the PLD method, and further a 10 μm silver layer (metal stabilizing base layer) was formed on the superconducting layer by the sputtering method. Thereafter, a first superconducting wire (critical temperature Tc = 93K) was produced by laminating a 0.1 mm thick copper layer (metal stabilization layer) on the silver layer with solder.

"Production of second superconducting wire"
An MgB ₂ superconducting wire (critical temperature Tx = 39K) with a diameter Φ = 0.8 mm manufactured by the PIT method (Powder In Tube method) is prepared, and a polyimide having a thickness of 12.5 μm is formed on the outer periphery of the MgB ₂ superconducting wire. A second superconducting wire was produced by winding the tape.

"Preparation of superconducting wire and superconducting coil"
A second superconducting wire is placed on the upper surface of the copper layer of the first superconducting wire produced above, and a polyimide tape having a thickness of 12.5 μm is wound around the wire, thereby having the structure shown in FIG. A superconducting wire was produced.
Next, the obtained superconducting wire with polyimide tape was wound 35 times concentrically with an inner diameter of 70 mm to produce a coil body. Next, a superconducting coil having a height of 10 mm and a total number of turns of 70 (35 turns × 2) was produced by coaxially laminating two coil bodies produced by the same procedure.

"Evaluation"
The produced superconducting coil was cooled to 20K by conduction cooling with a refrigerator, and a superconducting state was obtained. Next, when the temperature was raised by the temperature controller, it was confirmed that the voltage value of the second superconducting wire was generated immediately when the temperature exceeded 39K. From this result, according to the present invention, it is clear that the normal conduction transition (temperature rise) in the superconducting coil (and superconducting wire) can be easily detected.

  1A, 2A, 3A, 3B, 4A, 5A ... superconducting wire, 1a, 2a, 3a, 3b, 4a, 5a ... first superconducting wire, 9 ... storage groove, 10, 60 ... second superconducting wire, 11 ... substrate 15 ... bed layer, 16 ... intermediate layer, 17, 37 ... superconducting layer, 18 ... metal stabilizing base layer, 19, 19a, 19b, 19c, 19d, 39 ... metal stabilizing layer, 20 ... insulating layer, 50 ... superconducting Coil, 51 ... first coil body, 52 ... second coil body, 100 ... superconducting protection device.

Claims (9)

A first superconducting wire and a second superconducting wire for temperature detection;
The superconducting wire, wherein the critical temperature Tc of the first superconducting wire and the critical temperature Tx of the second superconducting wire satisfy a relationship of Tx <Tc.   2. The superconducting wire according to claim 1, wherein an operating temperature Top at which the first superconducting wire is in a superconducting state, the critical temperature Tc, and the critical temperature Tx satisfy a relationship of Top <Tx <Tc. The first superconducting wire comprises a superconducting layer and a metal stabilizing layer,
The superconducting wire according to claim 1, wherein the second superconducting wire is disposed at a position in contact with the metal stabilizing layer of the first superconducting wire.   4. The superconducting wire according to claim 3, wherein at least part of the second superconducting wire is disposed inside the metal stabilizing layer of the first superconducting wire. 5.   A metal stabilizing base layer is interposed between the superconducting layer of the first superconducting wire and the metal stabilizing layer, and the second superconducting wire is disposed so as to contact the metal stabilizing base layer. The superconducting wire according to claim 4.   The metal stabilization layer of the first superconducting wire is disposed on an upper portion and a side portion of the superconducting layer, and the second superconducting wire is disposed on a side of the superconducting layer. Or the superconducting wire of 4.   The superconducting wire according to claim 1, comprising at least two of the second superconducting wires.   A superconducting coil using the superconducting wire according to any one of claims 1 to 7.   A superconducting protection device using the superconducting coil according to claim 8.

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