JP2013012645A - Oxide superconducting coil and superconducting apparatus - Google Patents

Abstract

An object of the present invention is to provide an oxide superconducting coil with good cooling efficiency of an oxide superconducting wire.
The present invention provides a plurality of element coils formed by winding a tape-shaped oxide superconducting wire provided with a metal base material and an oxide superconducting layer around at least one of an insulating member and a resin layer. An oxide superconducting coil comprising a coil laminate formed by stacking each element coil in the direction of the central axis thereof via a metal cooling plate, wherein at least the element coil side surface of each cooling plate has high heat At least one of the edge of the insulating member, the edge of the resin layer, and the edge of the oxide superconducting wire, which are formed of a conductive insulating member and constitute the end surface of the element coil, are in direct contact with the high thermal conductive insulating member. It is characterized by that.
[Selection] Figure 1

Description

  The present invention relates to an oxide superconducting coil having good cooling efficiency.

Superconducting coils are used for various applications such as magnetic resonance imaging apparatus (MRI) and superconducting magnetic energy storage apparatus (SMES). Until now, metallic superconductors such as NbTi have been widely used for these applications as superconducting wires, but in recent years, bismuth-based superconducting wires (Bi ₂ Sr ₂ CaCu ₂ O _{8 + δ} : Bi2212, Bi ₂ Sr ₂ Ca ₂ Cu ₃ O _{10 + δ} : Bi2223) and yttrium-based superconducting wire REBa ₂ Cu ₃ O _7-δ (RE123, RE: rare earth element) are being developed.
Oxide high-temperature superconducting wires can be used at higher temperatures than metal-based superconducting wires, and application development to coils and the like is also underway. Most oxide superconducting wires currently provided are in the form of tapes, and as a superconducting coil using such a tape-like superconducting wire, there are a plurality of pancake coils, double pancake coils, or double pancake coils. An oxide superconducting coil formed by stacking is known.

Conventional superconducting coils using metal-based superconducting wires have a low superconducting transition temperature, so they are often cooled with expensive liquid helium, etc., but oxide superconducting wires are relatively inexpensive because they have a relatively high superconducting transition temperature. It is possible to operate by cooling with liquid nitrogen.
However, the oxide superconducting wire is said to have relatively poor critical current density and magnetic field characteristics at liquid nitrogen temperature. For this reason, it is considered that the oxide superconducting coil is cooled to a temperature lower than the liquid nitrogen temperature by conduction cooling with a refrigerator and operated so that a high critical current density can be obtained even in a magnetic field.

As an example of a superconducting coil by this conduction cooling, a configuration described in Patent Document 1 below is known. The superconducting coil described in Patent Document 1 is made of metal in which a plurality of pancake coils are stacked and a cooling plate is provided between each pancake coil, and these cooling plates are connected to a refrigerator. The superconducting coil can be efficiently cooled by cooling through the heat conduction bar.
As another example of the conduction cooling superconducting coil, a configuration described in Patent Document 2 below is known. The superconducting coil described in Patent Document 2 has a configuration in which a coil wound in a pancake shape is cooled in contact with a cooling plate. In this example, the side surface of the tape-shaped superconducting wire is specifically a resin. It is configured to be conductively cooled by being brought into contact with a cooling plate via a layer and an insulating layer.

JP-A-11-186025 JP 2010-267887 A

  The conductive cooling by the cooling plate as described above uses a metal cooling plate having high thermal conductivity such as copper as described in Patent Documents 1 and 2, and for insulation, a superconducting coil and a cooling plate are used. It is made by interposing an insulating material such as FRP (fiber reinforced plastic) between them. However, resin insulation materials such as FRP have a thermal conductivity that is at least three orders of magnitude lower than that of metals such as copper in the low temperature range where oxide superconducting wires are used. In this case, there is a problem that the cooling efficiency is lowered.

  The present invention has been made in view of the above-described conventional situation, and an object of the present invention is to provide a technique capable of providing a superconducting coil with good cooling efficiency.

The oxide superconducting coil of the present invention has a plurality of element coils formed by winding a tape-shaped oxide superconducting wire around at least one of an insulating member and a resin layer, and each element coil is made of a metal cooling in the central axis direction. An oxide superconducting coil provided with a coil laminate configured to overlap with a plate, wherein at least the element coil side surface of each cooling plate is formed of a high heat conductive insulating member having a thermal conductivity of 50 W / m / K or more. And at least one of the edge of the insulating member constituting the end face of the element coil, the edge of the resin layer, and the edge of the oxide superconducting wire are in direct contact with the high thermal conductive insulating member. .
Since the edge of the oxide superconducting wire is in contact with the cooling plate via the high thermal conductive insulating member, the oxide superconducting coil can efficiently cool the edge of the oxide superconducting wire from the cooling plate via the high thermal conductive insulating member. Can provide.
In other words, the end face of the element coil is configured by gathering the edge of the insulating member or the edge of the resin layer in addition to the edge of the base material constituting the oxide superconducting wire and the edge of the oxide superconducting layer. Since the metal substrate edge and the oxide superconducting layer edge are exposed on the end face side of the coil, the metal substrate and the oxide superconducting layer can be brought into direct contact with the high thermal conductive insulating member. These can be efficiently cooled by conductive cooling of the cooling plate.

The oxide superconducting coil according to the present invention includes a winding drum provided so as to penetrate the center of the coil laminate, and metal flanges provided at both ends in the length direction of the winding drum to form a bobbin. In addition, a high heat conductive insulating member is provided on the inner end face side of both flanges, a coil laminate is provided between the two flanges, and a high heat conductive insulating member is provided on the outer end face of the element coil located at one end of the winding drum. The other flange is brought into contact with the outer end face of the element coil located at the other end of the winding drum via a high heat conductive insulating member.
Since the edge of the oxide superconducting wire is in contact with the metal flange via the high thermal conductivity insulating member, the edge of the oxide superconducting wire can be efficiently cooled via the flange and the high thermal conductivity insulating member. A good oxide superconducting coil can be provided.
In other words, the end face of the element coil is configured by gathering the edge of the insulating member or the edge of the resin layer in addition to the edge of the base material constituting the oxide superconducting wire and the edge of the oxide superconducting layer. Since the metal substrate edge and the oxide superconducting layer edge are exposed on the end face side of the coil, the metal substrate and the oxide superconducting layer can be brought into direct contact with the high thermal conductive insulating member. These can be efficiently conducted and cooled through the metal flange and the high thermal conductive insulating member.

In the oxide superconducting coil of the present invention, it is preferable that the high thermal conductivity insulating member is an insulator having a thermal conductivity of 50 W / m / K or more.
If the thermal conductivity is 50 W / m / K or more, the thermal conductivity is clearly higher than that of the resin material, and the thermal conductivity is comparable to that of the metal, so that efficient conductive cooling can be performed.
The oxide superconducting coil according to the present invention has a laminated structure in which the oxide superconducting wire includes an orientation intermediate layer, an oxide superconducting layer, and a metal stabilization layer above a tape-like base material, and the outer side of the element coil. The edge of the base material and the edge of the stabilization layer are exposed on the end face, and these are in contact with the high thermal conductive insulating member.
Since the edge of the metal base, the edge of the oxide superconducting layer, and the edge of the metal stabilization layer are exposed on the outer end face of the element coil, and these are in direct contact with the high thermal conductivity insulating member The oxide superconducting layer can be efficiently conducted and cooled from the cooling plate through the high thermal conductive insulating member.

In the oxide superconducting coil of the present invention, the high thermal conductive insulating member is made of at least one of aluminum nitride and silicon carbide.
If it is aluminum nitride and silicon carbide, it has excellent insulation and thermal conductivity, so that the oxide superconducting wire constituting the element coil has excellent insulation and can efficiently cool the oxide superconducting wire. An oxide superconducting coil having an element coil can be provided.

An oxide superconducting coil according to the present invention includes a vacuum vessel, the oxide superconducting coil according to any one of the above provided inside the vacuum vessel, and a cooling plate of the superconducting coil provided in the vacuum vessel. Superconducting equipment equipped with a refrigerator for cooling.
According to the present invention, a superconducting device provided with an oxide superconducting coil with good cooling efficiency can be provided.

  According to the present invention, in the structure of an oxide superconducting coil having an element coil formed by winding an oxide superconducting wire together with a resin layer and an insulating material together with a cooling plate, direct oxidation is performed from the cooling plate through a high thermal conductive insulating member. An oxide superconducting coil with good cooling efficiency that can cool the superconducting layer can be provided. In addition, since the metal base can be directly cooled from the cooling plate via the high thermal conductive insulating member, the oxide superconducting layer formed above the metal base that is efficiently cooled can be efficiently used. A structure that can be cooled can be provided.

The oxide superconducting coil which concerns on 1st Embodiment of this invention is shown, FIG. 1 (A) is a side view, FIG.1 (B) is an expanded sectional view of the B section of FIG. 1 (A). The disassembled perspective view of the coil laminated body provided in the oxide superconducting coil shown in FIG. The expansion perspective view of the oxide superconducting wire applied to the superconducting coil shown in FIG. The block diagram which shows an example of the superconducting apparatus provided with the superconducting coil shown in FIG. The oxide superconducting coil which concerns on 2nd Embodiment of this invention is shown, FIG. 5 (A) is a side view, FIG.5 (B) is a partial expanded sectional view. Sectional drawing which shows an example structure of a bismuth-type oxide superconducting wire.

Hereinafter, although a first embodiment of an oxide superconducting coil according to the present invention will be described with reference to the drawings, the present invention is not limited to the following embodiment.
As shown in FIG. 1 (A), the oxide superconducting coil A of this embodiment includes a plurality of thin ring-shaped element coils 1 (seven in the case of the form shown in FIG. 1 (A)), and their central axes. Are stacked, and stacked in a thickness direction via a donut plate-like cooling plate 2.
Further, a bobbin 7 is configured by including a cylindrical winding drum 5 and donut plate-like flanges 6 and 6 attached to both ends in the length direction, and wound so as to be inserted through the central portion of the coil laminate 3. The body 5 is installed, and the flanges 6 and 6 are installed so as to sandwich both sides of the coil stack 3 in the stacking direction (up and down of the coil stack 3 in FIG. 1A) to form the oxide superconducting coil A. .

  The element coil 1 is configured by winding a tape-like oxide superconducting wire 10 together with a resin layer 8 and an insulating material 9 in a pancake shape as shown in FIGS. In this embodiment, the oxide superconducting wire 10 has a laminated structure in which a plurality of layers are laminated on a tape-like substrate 11 as shown in FIG. That is, the oxide superconducting wire 10 includes, as an example, an underlayer 12, an orientation intermediate layer 15, a cap layer 16, an oxide superconducting layer 17, a first stabilizing layer 18, and a second stabilizing layer on a substrate 11. In this structure, the chemical layer 19 is laminated. A bismuth-based oxide superconducting wire having a structure described later may be used as the oxide superconducting wire 10. Further, as the base material 11, an oriented Ni—W alloy tape base material in which a texture is introduced into a Ni alloy can also be applied.

The base material 11 applicable to the oxide superconducting wire 10 of this embodiment is preferably made of a nickel alloy. If it is a commercial product, Hastelloy (trade name, manufactured by Haynes, USA) is suitable, and its thickness is, for example, 10 to 500 μm.
The underlayer 12 has high heat resistance and reduces interfacial reaction, and has a film thickness of 10 to 200 nm, for example. A diffusion preventing layer may be interposed between the base material 11 and the base layer 12, and the thickness thereof is, for example, 10 to 400 nm. Al ₂ O ₃ can be exemplified as the diffusion preventing layer, and Y ₂ O ₃ can be exemplified as the underlayer 12.

The orientation intermediate layer 15 is selected from materials that are biaxially oriented. Specifically, the orientation intermediate layer 15 can be exemplified by a metal oxide such as Gd ₂ Zr ₂ O ₇ or MgO. If the orientation intermediate layer 15 is formed with a good crystal orientation (for example, a crystal orientation degree of 15 ° or less) by ion beam assisted deposition (IBAD method), the crystal orientation of the cap layer 16 formed thereon. Can be set to a good value (for example, the degree of crystal orientation is about 5 °), and the superconducting characteristics can be exhibited with good crystal orientation of the oxide superconducting layer 17 formed on the cap layer 16. Can be able to.

The thickness of the orientation intermediate layer 15 can usually be in the range of 0.005 to 2 μm. In particular, a metal oxide layer formed by the IBAD method is preferable, and the IBAD method is a method of orienting crystal axes by irradiating an ion beam at a predetermined angle with respect to the underlying vapor deposition surface during vapor deposition. .
The cap layer 16 is preferably one in which crystal grains are selectively grown in the in-plane direction. As an example of the cap layer 16, CeO ₂ can be selected. The film thickness of the cap layer 16 can be 50 to 1000 nm.

The oxide superconducting layer 17 may be a known material, and examples thereof include REBa ₂ Cu ₃ O _7-x (RE represents a rare earth element such as Y, La, Nd, Sm, Er, Gd). Examples of the oxide superconducting layer 17 include Y123 (YBa ₂ Cu ₃ O _7-X ) or Gd123 (GdBa ₂ Cu ₃ O _7-X ). The thickness of the oxide superconducting layer 17 is preferably about 0.5 to 5 μm.

The first stabilizing layer 18 laminated on the oxide superconducting layer 17 is formed as a layer made of Ag or a noble metal, and the thickness of the stabilizing layer 18 can be formed to about 1 to 30 μm.
The second stabilization layer 19 is preferably made of a highly conductive metal material. When the oxide superconducting layer 17 transitions from the superconducting state to the normal conducting state, the first stabilizing layer 18 together with the oxide superconducting layer It functions as a bypass where the current of the layer 17 commutates. As the second stabilization layer 19, it is preferable to use a relatively inexpensive material such as a copper alloy such as copper or brass (Cu—Zn alloy). The thickness of the second stabilization layer 19 can be 10 to 300 μm.

The tape-shaped oxide superconducting wire 10 having the above configuration is wound in a pancake shape on a winding frame (not shown) together with the resin layer 8 and the insulating material 9 to form a thin ring-shaped element coil 1. A center hole 1 b is formed at the center of the element coil 1.
The resin layer 8 provided in the element coil 1 is composed of an epoxy resin layer as an example, but is composed of a layer obtained by firing a prepreg in which carbon fibers or fiber fibers are mixed inside a thermosetting resin. Also good.
The insulating material 9 is made of polyimide tape, FRP (fiber reinforced plastic) tape, or the like.
In the above structure, the resin layer 8 is provided mainly for integration between the wound oxide superconducting wire 10 and is provided for fixing the cooling plate 2 and the oxide superconducting wire 10 together. The insulating material 9 is provided for insulation between the oxide superconducting wires 10.
When a liquid epoxy resin is used as the resin layer 8, the insulating material 9 is indispensable because the oxide superconducting wire 10 may come into contact with each other and short-circuit if there is no insulating material 9 during winding. When a prepreg is used as the resin layer 8, it can have both a function as a resin layer and a function as an insulating material, but it does not want to bond the resin to the second stabilization layer 19 located on the surface of the oxide superconducting wire 10. In this case, it is preferable to provide the insulating material 9 in addition to the resin layer 8.

In the present embodiment, as shown in FIG. 1B, the base material 11 of the oxide superconducting wire 10 is on the outside (outside the bobbin 3), and the second stabilization layer 19 is on the inside (on the bobbin 3). The element coil 1 is formed by winding so as to be disposed inside. In addition, the element coil 1 is configured by being wound in a pancake shape so that the resin layer 8 is disposed outside the oxide superconducting wire 10 and the insulating material 9 is disposed inside. The element coil 1 has a shape in which the edge of the oxide superconducting wire 10, the edge of the resin layer 8, and the edge of the insulating material 9 are spirally exposed on both end faces 1a.
If the resin layer 8 is positively brought into contact with the stabilization layer 19, the superconducting characteristics may be deteriorated due to thermal contraction during cooling. Therefore, it is preferable to provide the insulating material 19 immediately above the stabilization layer 19. In addition, the method of winding the oxide superconducting wire 10 around the bobbin 3 may be basically either the outer side or the inner side of the base material 11.

  The cooling plate 2 is made of a metal material having good heat conductivity and is formed in a donut plate shape having a thickness of about 1 to several mm. The central hole 2a of the cooling plate 2 is formed to have the same diameter as the central hole 1b of the element coil 1 and is formed so that the center holes 1b and 2a can be aligned when the element coil 1 and the cooling plate 2 are overlapped. Has been. The outer diameter of the cooling plate 2 is formed to be slightly larger than the outer diameter of the element coil 1, and the peripheral portion of the cooling plate 2 protrudes slightly outward from the element coil 1 in a state where the element coil 1 and the cooling plate 2 are overlapped. ing.

Although omitted in the drawings, the stacked element coils 1 are interconnected with the oxide superconducting wires 10 drawn from the inner peripheral portions thereof, and the oxides of the stacked element coils 1 are connected to each other. The superconducting wires 10 are electrically connected to each other so that the oxide superconducting wires 10 of all the element coils 1 can be energized.
The metal material constituting the cooling plate 12 is not particularly limited and can be changed as appropriate. However, a metal material excellent in thermal conductivity is desirable, for example, copper or copper such as oxygen-free copper, tough pitch copper, brass, phosphor bronze, etc. An alloy, aluminum, an aluminum alloy, etc. are mentioned.

  The front and back surfaces of the cooling plate 12 of this embodiment are covered with a high thermal conductive insulating member 2a made of at least one of aluminum nitride (AlN) and silicon carbide (SiC). The high thermal conductivity insulating member 2a is configured by sticking aluminum nitride or silicon carbide sheets to the front and back surfaces of the cooling plate 12, or the aluminum nitride or silicon carbide coating layer is formed by a thermal spraying method or a vapor deposition method. It forms by forming into a film on the front and back. Further, the high thermal conductive insulating member 2 a is also formed on the surface on the element coil 1 side in the flange 6 installed at the top and bottom of the coil laminate 3.

  The thermal conductivity of aluminum nitride at normal temperature is 100 to 350 W / m / K, the dielectric breakdown voltage is 11.7 MV / cm, and the thermal conductivity of silicon carbide at normal temperature is 50 to 350 W / m / K, the dielectric breakdown voltage. Is 2.0 MV / cm. In this type of superconducting coil, if the insulation withstand voltage is about 1 kV, it is considered that the insulation voltage is good. Therefore, a thickness of about 10 μm in a material of 1 MV / cm is sufficient. Therefore, in the case of the above-described material, a structure having a sufficient withstand voltage can be obtained and high thermal conductivity can be obtained if the high thermal conductive insulating member 2a having a thickness of about 10 μm is used. Moreover, in this embodiment, high thermal conductivity shows the material whose thermal conductivity in normal temperature is 50-350 W / m / K as an example.

The oxide superconducting coil A shown in FIG. 1 is used after being incorporated into the superconducting device 20 shown in FIG. 4 and cooled, for example.
The superconducting device 20 shown in FIG. 4 is for cooling the storage container 21 such as a vacuum container, the oxide superconducting coil A installed therein, and the oxide superconducting coil A inside the storage container 21 to a critical temperature or lower. The refrigerator 22 is provided. The container 21 is connected to a vacuum pump (not shown) and is configured so that the inside can be depressurized to a desired degree of vacuum. The oxide superconducting coil A is connected to a power source 25 outside the container 21 via current lead wires 25a and 25b, and the oxide superconducting coil A can be energized from the power source 25.

In FIG. 4, the element coil 1 provided in the oxide superconducting coil A is abbreviated in a four-stage configuration for simplification of the drawing. In the configuration of FIG. 4, the current lead wire 25 a is connected to the oxide superconducting wire 10 of the uppermost element coil 1, the connection wire 25 b is connected to the oxide superconducting wire 10 of the lowermost element coil 1, and the power supply 25 The oxide superconducting coil A can be energized.
In the superconducting device 20, a plurality of cooling rods 23 are provided so as to vertically penetrate the cooling plate 2 and the flange 6 of the oxide superconducting coil A. These cooling rods 23 extend upward through the flange 6 on the upper side of the oxide superconducting coil A and are connected to a metal frame member 25 installed above the oxide superconducting coil A. A frame member 25 is connected to the lower end of the refrigerator 22.

In the superconducting device 20 shown in FIG. 4, when the refrigerator 22 is operated, the refrigerator 22 cools the flanges 6 and 6 and the plurality of cooling plates 2 via the frame member 25 and the cooling rod 23, so The oxide superconducting wire 10 in contact with the side through the high thermal conductive insulating member 2a can be directly cooled.
During this cooling operation, the edge of the base material 11 of the oxide superconducting wire 10 and the oxide superconducting layer 17 with respect to the high thermal conductivity insulating member 2a excellent in thermal conductivity with respect to the metal cooling plate 2 Since the edge, the edge of the first stabilization layer 18, and the edge of the second stabilization layer 19 are in direct contact as shown in FIG. 1B, with good thermal conductivity. As a result of conducting and cooling the oxide superconducting layer 17, the oxide superconducting layer 17 can be efficiently cooled.
In the above-described configuration, since the high thermal conductive insulating member 2a made of at least one of aluminum nitride (AlN) and silicon carbide (SiC) having a thermal conductivity of 50 to 350 W / m / K is provided, good cooling efficiency can be obtained. .

The base material 11, the first stabilizing layer 18 and the second stabilizing layer 19 are all made of metal and have good thermal conductivity. These are efficient through the cooling plate 2 and the high thermal conductive insulating member 2a. As a result of being able to cool well, the oxide superconducting layer 17 can be efficiently cooled via the metal base 11, the first stabilizing layer 18 and the second stabilizing layer 19 located on both sides thereof.
Further, when the oxide superconducting wire 10 is energized, a superconducting current flows through the oxide superconducting layer 17. Even if the edge of the oxide superconducting layer 17 is close to the metal cooling plate 2, the cooling plate 2 Since the high thermal conductivity insulating member 2a is interposed between the two, a problem does not occur in terms of insulation even when energized. Since the high thermal conductive insulating member 2a has excellent insulation resistance as described above, there is no shortage in terms of insulation resistance.

  In the case where the element coil 1 is configured, even if the base 11, the oxide superconducting layer 17, the first stabilizing layer 18, and the second stabilizing layer 19 are formed with the same width, they are oxidized. The superconducting wire 10 is not necessarily completely uniform over the entire length. Therefore, when the element coil 1 is formed by winding the oxide superconducting wire 10, the end faces 1 a on both sides of the element coil 1 are not ideal smooth surfaces, but have some unevenness. That is, the both end faces 1a of the element coil 1 are formed from the edge of the substrate 11, the edge of the oxide superconducting layer 17, the edge of the first stabilizing layer 18, the edge of the second stabilizing layer 19, and the resin. Unevenness formed by the edge of the layer 8 and the edge of the insulating material 9 is generated.

  In this case, as shown in FIG. 1 (B), a state where the edges are ideally aligned is changed to a state having some unevenness, and the end surface 1a of the element coil 1 is pressed against the high thermal conductive insulating member 2a while having the unevenness. It is done. Of the oxide superconducting wire 10 having a laminated structure, the edge of the base material 11 and the edge of the second stabilization layer 19 occupying most of the thickness are both made of metal and have excellent thermal conductivity and rigidity. Also excellent. In the structure in which the element coil 1 and the high thermal conductive insulating member 2a are brought into contact with each other, the edge of the highly rigid metal base 11 and the edge of the second stabilizing layer 19 are connected to the resin layer 8 or the insulating material 9. Since the high thermal conductivity insulating member 2a side can be strongly contacted with respect to the edge, the high thermal conductivity insulating member 2a can be surely brought into contact with the base material 11 or the second stabilization layer 19 having excellent thermal conductivity. The oxide superconducting layer 17 can be cooled with good thermal efficiency.

FIG. 5 shows an oxide superconducting coil C according to a second embodiment of the present invention. The oxide superconducting coil C according to this embodiment has a structure substantially equivalent to that of the oxide superconducting coil A according to the first embodiment. The difference is that the entire cooling plate 2A interposed between the element coils 1 and 1 is made of a highly heat-conductive insulating member. In the present embodiment, the cooling plate 2 </ b> A is also interposed between the flange 6 of the bobbin 7 and the element coil 1.
Since other structures are the same as those of the oxide superconducting coil A of the first embodiment, the description of the structure of the equivalent parts is omitted.

  In the oxide superconducting coil C of the second embodiment, since the entire cooling plate 2A is made of a highly heat conductive insulating member, the same effects as the oxide superconducting coil A of the first embodiment can be obtained.

However, so far in the embodiment described, the oxide superconducting wire structure provided with REBa 2 Cu ₃ O _7-x having a composition based oxide superconducting layer 17 via the orientation of intermediate layer 15 above the substrate 11 10 has been described an example of forming the element coils 1 with the present invention bismuth based superconducting wires _{(Bi 2 Sr 2 CaCu 2 O} 8 + δ: Bi2212, Bi 2 Sr 2 Ca 2 Cu 3 O 10 + δ: Bi2223) applied to Of course you can.
Since the structure of the bismuth-based superconducting wire is mainly composed of an oxide superconducting wire 32 including an oxide superconducting layer 31 inside a sheath 30 made of a tape-like stabilizing material such as Ag, as illustrated in FIG. An oxide superconducting coil using a bismuth-based oxide superconducting wire 32 by using a tape-like bismuth-based oxide superconducting wire 32 instead of the oxide superconducting wire 10 of the first and second embodiments. The present invention can be applied to.
Even in the case of forming a coil in a bismuth-based superconducting wire, if the width of the insulating tape or prepreg is made slightly narrower than that of the superconducting wire, irregularities are formed on both ends of the wire, so the sheath 30 of the Ag stabilizing material is cooled. Since it can be pressed strongly against the film on the plate and brought into contact, the heat transfer efficiency in that case can be improved, and the cooling efficiency as the oxide superconducting coil can be improved.

A tape-shaped base material having a width of 10 mm and a thickness of 0.1 mm made of Hastelloy C276 (trade name of Haynes, USA) is prepared, and a diffusion preventing layer having a thickness of 100 nm made of Al ₂ O ₃ is formed on the surface of the tape-shaped base material. Further, a 30 nm thick bed layer made of Y ₂ O ₃ was formed thereon by ion beam sputtering. In carrying out the ion beam sputtering method, the tape-shaped substrate was wound around a reel inside the sputtering apparatus, and formed into the entire length of the substrate so that film formation was possible while it was fed from one reel to the other reel. Next, an alignment layer of MgO having a thickness of 10 nm was formed on the bed layer by ion beam assisted vapor deposition. In this case, the incident angle of the assist ion beam was set to 45 ° with respect to the normal line of the tape-shaped substrate film forming surface.

Subsequently, a cap layer of CeO _{2 having} a thickness of 500 nm was formed on the MgO alignment layer using a pulsed laser deposition method (PLD method). Further, an oxide superconducting layer of GdBa ₂ Cu ₃ O _{7-x having} a thickness of about 2 μm was formed on the cap layer by a pulse laser deposition method.
Next, a first stabilizing layer of Ag having a thickness of 10 μm was formed on the oxide superconducting layer by sputtering, and oxygen annealing was performed at 500 ° C. Thereafter, a copper tape having a thickness of 300 μm was soldered on the first stabilizing layer to obtain an oxide superconducting wire.
Oxide having a structure comprising a diffusion prevention layer, a bed layer, an orientation layer, a cap layer, an oxide superconducting layer, a first stabilization layer, and a second stabilization layer on a tape-like substrate by the above process. A superconducting wire was formed.

Next, this oxide superconducting wire, polyimide tape 10 mm wide and 0.0125 mm (12.5 μm) thick, and epoxy resin tape 10 mm wide and 0.1 mm thick are wound together to form an inner diameter of 70 mm. A pancake coil was prepared by winding the film 35 times. Seven pancake coils were produced in the same procedure. An aluminum nitride film was coated on the front and back surfaces of a cooling plate having a thickness of 1 mm, an outer diameter of 87 mm, and a central opening of 70 mm by a thermal spraying method to a thickness of 10 μm. Six cooling plates were produced. A similar aluminum nitride film was also formed on the inner surface of the flange plate of the copper bobbin by a thermal spraying method.
Seven pancake coils are stacked on a copper bobbin winding drum through a cooling plate, and a flange with an aluminum nitride film is pressed and fixed to both ends of the winding drum to form a bobbin, as shown in FIG. An oxide superconducting coil having a structure was obtained.

“Comparative Example 1”
For comparison, a polyimide tape-covered oxide superconducting wire in which a polyimide tape having a thickness of about 0.0125 mm was spirally wound around the entire circumference of the same oxide superconducting wire as before was obtained. Based on the same process as described above, this oxide superconducting wire was co-wound with an epoxy resin tape and wound 35 times concentrically with an inner diameter of 70 mm to produce a pancake coil. Seven of these pancake coils were stacked using a cooling plate not provided with an aluminum nitride film and incorporated into a bobbin to produce an oxide superconducting coil. The oxide superconducting coil has a structure in which a polyimide layer is interposed between the cooling plate and the oxide superconducting wire because the entire circumference of the oxide superconducting wire is covered with a polyimide tape.

The above-described oxide superconducting coil having the structure shown in FIG. 1A and the oxide superconducting coil of Comparative Example 1 are incorporated in a vacuum container having the structure shown in FIG. 5 and incorporated in a superconducting device, and cooling is started by a refrigerator. Then, the time during which the oxide superconducting wire can be cooled to −253 ° C. (20 K) was measured.
It took 20 hours for the oxide superconducting coil of the example to reach −253 ° C., and 24 hours for the oxide superconducting coil of Comparative Example 1 to reach −253 ° C.

From the comparison of the oxide superconducting coil of the example and the oxide superconducting coil of the comparative example 1, it is clear that the oxide superconducting coil of the example can be cooled in a shorter time, so that the cooling efficiency is excellent. It was.
In addition, when creating a pancake coil using the oxide superconducting wire of the previous embodiment, the width of the polyimide tape and the epoxy resin tape is 9 mm, and the pancake coil is created in the same manner as the previous embodiment. Using this pancake coil, an oxide superconducting coil was prepared, and a cooling test using a similar refrigerator was performed. The width | variety of the base material and stabilization layer of a superconducting wire is 10 mm.
In the case of this structure, cooling to −253 ° C. under the same cooling operation condition was possible in 18 hours. This is because the substrate width of the superconducting wire and the width of the stabilization layer are slightly larger than those of polyimide tape and epoxy resin tape, so when a superconducting coil is constructed, oxide superconductivity is applied to the aluminum nitride film coated on the cooling plate. This is probably because the heat conduction efficiency is increased as a result of the close contact between the substrate of the wire and the stabilization layer.

  The present invention can be applied to an oxide superconducting coil used in various superconducting devices such as a superconducting motor and a superconducting power storage device.

  A, C ... Superconducting coil, 1 ... Element coil, 2 ... Cooling plate, 2a, 2A ... High thermal conductivity insulating member, 3 ... Coil laminate, 5 ... Winding drum, 6 ... Flange, 7 ... Bobbin, 8 ... Resin layer , 9 ... Insulating material, 10 ... Oxide superconducting wire, 11 ... Base material, 12 ... Underlayer, 15 ... Orientation intermediate layer, 16 ... Cap layer, 17 ... Oxide superconducting layer, 18 ... First stabilization layer , 19 ... second stabilizing layer, 20 ... superconducting equipment, 21 ... vacuum vessel, 22 ... refrigerator, 23 ... cooling rod, 25 ... power supply.

Claims (5)

A coil comprising a plurality of element coils formed by winding a tape-shaped oxide superconducting wire around at least one of an insulating member and a resin layer, each element coil being stacked with a metal cooling plate in the central axis direction thereof An oxide superconducting coil provided with a laminate,
At least the element coil side surface of each cooling plate is formed of a high thermal conductive insulating member having a thermal conductivity of 50 W / m / K or more, and an edge of the insulating member and an edge of the resin layer constituting the end surface of the element coil An oxide superconducting coil characterized in that at least one of the above and an edge of the oxide superconducting wire are in direct contact with the high thermal conductivity insulating member.   The bobbin includes a winding drum provided so as to pass through the center of the coil stack and metal flanges provided at both ends in the longitudinal direction of the winding drum, and high heat is generated on the inner end face side of both flanges. A conductive insulating member is provided, a coil laminate is provided between the flanges, and one flange is in contact with the outer end surface of the element coil located at one end of the winding drum via a high thermal conductive insulating member. 2. The oxide superconducting coil according to claim 1, wherein the other flange is brought into contact with the outer end face of the element coil located at the other end of the element coil via a high thermal conductive insulating member.   The oxide superconducting wire has a laminated structure including an orientation intermediate layer, an oxide superconducting layer, and a metal stabilization layer above a tape-shaped substrate, and an edge of the substrate is formed on an outer end face of an element coil. 3. The oxide superconducting coil according to claim 1, wherein an edge of the stabilization layer is exposed and is in contact with the high thermal conductivity insulating member.   The oxide superconducting coil according to any one of claims 1 to 3, wherein the high thermal conductive insulating member is made of at least one of aluminum nitride and silicon carbide.   A vacuum vessel, an oxide superconducting coil according to any one of claims 1 to 4 provided inside the vacuum vessel, and a refrigerator provided in the vacuum vessel for cooling a cooling plate of the superconducting coil. And superconducting equipment.

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