Patent Description:
For example, a superconducting coil is used in a nuclear magnetic resonance apparatus (NMR) or in a magnetic resonance imaging apparatus (MRI) to generate a powerful magnetic field. A superconducting coil is formed by a superconducting wire wound on a winding frame.

When quenching occurs in which a superconducting state of a portion of the superconducting wire is broken and transitions to a normal conducting state, for example, current flowing through the superconducting coil fluctuates and a magnetic field generated by the superconducting coil becomes unstable.

Further, for example, Joule heat generated at the portion where the quenching has occurred may cause thermal runaway in which a large amount of heat is generated instantaneously. If thermal runaway occurs, the superconducting coil may be burned out.

One of causes of quenching is heat generation due to release of strain energy of impregnated resin surrounding a superconducting wire. Due to the heat generation, temperature of the superconducting wire rises to equal to or more than superconducting transition temperature, and quenching occurs.

When the superconducting coil is cooled, strain energy is accumulated in the impregnated resin due to difference in thermal shrinkage between metal included in the superconducting wire and the impregnated resin. When the superconducting coil is energized, strain energy is accumulated in the impregnated resin so as to inhibit action of the superconducting wire caused by electromagnetic force. The accumulated strain energy is released by, for example, cracking occurred in the impregnated resin, and heat is generated.

In order to reduce difference in thermal shrinkage between the metal included in the superconducting wire and the impregnated resin, inorganic filler is added to the impregnated resin. By adding the inorganic filler, difference in coefficient of thermal expansion between the metal included in the superconducting wire and the impregnated resin is reduced, and the difference in thermal shrinkage is reduced. Reduction of the difference in thermal shrinkage between the metal included in the superconducting wire and the impregnated resin reduces strain energy accumulated during cooling of the superconducting coil. Therefore, cracking is less likely to occur, and occurrence of quenching is suppressed.

Further, inclusion of filler in the impregnated resin increases fracture toughness of the impregnated resin. Even if strain energy accumulates and an initial cracking occurs, the increased fracture toughness of the impregnated resin hinders crack propagation, and occurrence of quenching is suppressed.

D1: <CIT> discloses a superconducting coil for a magnetic resonance apparatus formed by one or more wound superconducting conductors that are embedded in a cured sealing compound, with nanoparticles added to the sealing compound.

D2: <CIT> discloses a superconducting magnet coil <NUM> using curable resin composition having <NUM>-<NUM>% of thermal shrinkage amount when cooled to liquid helium temperature, i.e., <NUM> from a glass transition temperature, <NUM>-<NUM>% of a bending rupture distortion at <NUM> and <NUM>-<NUM>/mm<NUM> of an elastic modulus as impregnating resin, its resin composition and a method for manufacturing the same coil <NUM>.

D3: <CIT> discloses a superconducting magnet constituted by winding a superconducting wire <NUM> around a bobbin <NUM>, and fixing the wire <NUM> to the bobbin <NUM> and each wound part of the wire <NUM> to another with a thermoplastic resin layer <NUM>. The resin layer <NUM> is composed of a thermoplastic resin having a melting point of ≤<NUM> selected from among ionomer, ethylene methacrylic acid copolymer, phenoxy, polyamide <NUM>, polyamide <NUM>, polyethylene, and polyolefin. The resin layer <NUM>, in addition, contains a filler selected from among silica, silicon nitride, aluminum nitride, and alumina and having an average grain size of ≤<NUM>. The filler is shaped to a spheric or subspheric shape. Document <CIT> discloses superconducter coils wound on a frame and embedded in an insulator resin layer.

A superconducting coil according to the present invention is alternatively defined by claim <NUM> or claim <NUM>. Dependent claims relate to preferred embodiments.

A superconducting coil of the present arrangements includes a substrate having a curved surface; a superconducting wire wound on the curved surface, the superconducting wire having a first region and a second region facing the first region; a first resin layer surrounding the superconducting wire and including a plurality of first particles and first resin surrounding the first particles; and a second resin layer positioned between the first region and the second region, the second resin layer covering the first resin layer and including a plurality of second particles and second resin surrounding the second particles and the second resin being made of material different from material of the first resin.

Hereinafter, arrangements of the present disclosure will be described with reference to the drawings. In the following description, the same or similar members will be denoted by the same reference signs, and description of a member described once will be appropriately omitted.

In the present specification, "superconducting wire" is used as a term indicating a part excluding a coating layer such as resin, and "superconducting wire rod" is used as a term indicating a part including the superconducting wire and the coating layer such as resin.

A superconducting coil of a first arrangement includes a substrate having a curved surface, a superconducting wire wound on the curved surface, the superconducting wire having a first region and a second region facing the first region, a first resin layer surrounding the superconducting wire and including a plurality of first particles and first resin surrounding the first particles, and a second resin layer positioned between the first region and the second region, the second resin layer covering the first resin layer and including a plurality of second particles and second resin surrounding the second particles and being made of material different from material of the first resin.

<FIG> are schematic diagrams illustrating a superconducting coil of the first arrangement. <FIG> is a top view and <FIG> is a cross-sectional view. <FIG> illustrates a cross section taken along the line A-A' of <FIG>. <FIG> is an enlarged schematic cross-sectional view illustrating the superconducting coil of the first arrangement.

A superconducting coil <NUM> of the first arrangement is used as, for example, a coil for magnetic field generation of a superconducting device, such as an NMR, an MRI, heavy particle therapy equipment, a superconducting magnetic levitation railway vehicle, or a single-crystal pulling magnet. The superconducting coil <NUM> of the first arrangement is a so-called saddle type coil.

The superconducting coil <NUM> includes an insulating substrate <NUM>, a superconducting wire <NUM>, a first fixing resin layer <NUM>, an inter-wire resin layer <NUM>, a second fixing resin layer <NUM>, and a coating resin layer <NUM>.

The insulating substrate <NUM> is an example of a substrate. The first fixing resin layer <NUM> is an example of the first resin layer. The inter-wire resin layer <NUM> is an example of the second resin layer. The second fixing resin layer <NUM> is an example of a third resin layer. The coating resin layer <NUM> is an example of a fourth resin layer.

The insulating substrate <NUM> has a curved surface. The insulating substrate <NUM> is an insulator. The insulating substrate <NUM> is formed of, for example, fiber-reinforced plastic.

The superconducting wire <NUM> is line shaped, for example. The superconducting wire <NUM> is wound in a three-dimensional shape on the curved surface of the insulating substrate <NUM>, as illustrated in <FIG>. In <FIG>, a resin layer covering the superconducting wire <NUM> is not illustrated.

<FIG> is a schematic cross-sectional view illustrating a superconducting wire of the first arrangement.

A cross section of the superconducting wire <NUM> is, for example, circular. A diameter of the superconducting wire <NUM> is, for example, <NUM> or more and <NUM> or less.

The superconducting wire <NUM> includes superconducting materials 12x and a metal matrix 12y. The superconducting wire <NUM> has a structure in which a plurality of superconducting materials 12x are disposed in the metal matrix 12y.

The superconducting material 12x is, for example, a low-temperature superconducting material having a critical temperature Tc of <NUM> or higher and <NUM> or lower. The superconducting material 12x is, for example, a niobium-titanium alloy-based, niobium-tin compound-based, niobium-aluminum compound-based, or magnesium diboride-based low-temperature superconducting material.

The metal matrix 12y is metal. The metal matrix 12y is, for example, copper.

As illustrated in <FIG>, the superconducting wire <NUM> has a first region 12a and a second region 12b. The second region 12b faces the first region 12a. The first region 12a and the second region 12b are regions disposed adjacent to each other in parallel on the insulating substrate <NUM>.

The first fixing resin layer <NUM> is disposed on the insulating substrate <NUM>. The first fixing resin layer <NUM> surrounds the superconducting wire <NUM>. The first fixing resin layer <NUM> has a function of bonding and fixing the superconducting wire <NUM> to the insulating substrate <NUM>. Thickness of the first fixing resin layer <NUM> is, for example, <NUM> or more and <NUM> or less.

The inter-wire resin layer <NUM> is disposed on the insulating substrate <NUM>. The inter-wire resin layer <NUM> is disposed between the first region 12a and second region 12b of the superconducting wire <NUM>. The inter-wire resin layer <NUM> covers the first fixing resin layer <NUM>. The inter-wire resin layer <NUM> is in contact with the first fixing resin layer <NUM>.

The inter-wire resin layer <NUM> has a function of inhibiting the superconducting wire <NUM> from moving by vibration generated during use of the superconducting coil <NUM> or by electromagnetic force on the superconducting wire, and from being quenched by voltage generation or frictional heat caused by coil deformation. Further, the inter-wire resin layer <NUM> has a function of providing insulation between portions of the superconducting wire <NUM>.

The second fixing resin layer <NUM> is disposed on the insulating substrate <NUM>. The second fixing resin layer <NUM> is continuously disposed in layers on a surface of the insulating substrate <NUM>.

The second fixing resin layer <NUM> is disposed between the insulating substrate <NUM> and the first fixing resin layer <NUM>. The second fixing resin layer <NUM> is disposed between the insulating substrate <NUM> and the inter-wire resin layer <NUM>. The second fixing resin layer <NUM> is in contact with the first fixing resin layer <NUM>. The second fixing resin layer <NUM> is in contact with the inter-wire resin layer <NUM>.

The second fixing resin layer <NUM> has a function of, along with the first fixing resin layer <NUM>, bonding and fixing the superconducting wire <NUM> to the insulating substrate <NUM>. Thickness of the second fixing resin layer <NUM> is, for example, <NUM> or more and <NUM> or less.

The coating resin layer <NUM> is disposed on the insulating substrate <NUM>. The coating resin layer <NUM> is disposed between the superconducting wire <NUM> and the first fixing resin layer <NUM>. The coating resin layer <NUM> surrounds the superconducting wire <NUM>. The coating resin layer <NUM> is in contact with the first fixing resin layer <NUM>.

The coating resin layer <NUM> has a function of coating and protecting the superconducting wire <NUM>. Thickness of the coating resin layer <NUM> is, for example, <NUM> or more and <NUM> or less.

<FIG> are explanatory diagrams of the first to fourth resin layers of the first arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first resin layer, that is, the first fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second resin layer, that is, the inter-wire resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the third resin layer, that is, the second fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the fourth resin layer, that is, the coating resin layer <NUM>.

As illustrated in <FIG>, the first fixing resin layer <NUM> includes a plurality of first particles 14a and first resin 14x. The first resin 14x surrounds the first particles 14a. The first particles 14a are so-called filler.

The first resin 14x is, for example, thermoplastic resin. The first resin 14x is, for example, phenoxy resin.

Material of the first resin 14x can be identified by, for example, a Fourier transform infrared spectrometer (FT-IR).

The first particles 14a are inorganic. The first particles 14a include, for example, at least one inorganic substance selected from a group including silica, alumina, silicon nitride, and alumina nitride. For example, the at least one inorganic substance occupies <NUM>% or more of volume of the first particles 14a.

A chemical composition of the first particles 14a can be determined by, for example, identifying crystal by an X-ray diffraction method. In a case where the first particles 14a have poor crystallinity, the chemical composition of the first particles 14a can be measured by observing a cross section of the first fixing resin layer <NUM> with a scanning electron microscope (SEM), and performing an elemental analysis with an energy dispersive X-ray spectroscopy (EDS).

A median particle diameter of the first particles 14a is, for example, <NUM> or more and <NUM> or less. The median particle diameter of the first particles 14a can be obtained from, for example, major axes of the plurality of first particles 14a which are measured with an image acquired by the SEM (an SEM image).

A shape of the first particles 14a is, for example, but not particularly limited to, a plate shape, a spherical shape, a bale shape, a spheroidal shape, a columnar shape, a fibrous shape, or an irregular shape. <FIG> exemplifies a case where the first particles 14a have a spherical shape.

Occupancy ratio of the first particles 14a in the first fixing resin layer <NUM> is, for example, <NUM>% or more and <NUM>% or less.

The occupancy ratio of the first particles 14a in the first fixing resin layer <NUM> is represented by, for example, a proportion of the first particles 14a occupying an area observed in the SEM image. The occupancy ratio of the first particles 14a can be obtained by, for example, an image analysis of the SEM image.

As illustrated in <FIG>, the inter-wire resin layer <NUM> includes a plurality of second particles 16a and second resin 16x. The second resin 16x surrounds the second particles 16a. The second particles 16a are so-called filler.

Material of the second resin 16x is different from material of the first resin 14x. A chemical composition of the second resin 16x may be different from a chemical composition of the first resin 14x. The second resin 16x is, for example, thermo-setting resin. The second resin 16x is, for example, epoxy resin, phenol resin, unsaturated polyester resin, silicone resin, urethane resin, urea resin, polyimide resin, or a melamine resin.

The second particles 16a are inorganic. The second particles 16a include, for example, at least one inorganic substance selected from a group including silica, alumina, silicon nitride, and alumina nitride. For example, the at least one inorganic substance occupies <NUM>% or more of volume of the second particles 16a.

A median particle diameter of the second particles 16a is, for example, <NUM> or more and <NUM> or less.

A shape of the second particles 16a is, for example, but not particularly limited to, a plate shape, a spherical shape, a bale shape, a spheroidal shape, a columnar shape, a fibrous shape, or an irregular shape. <FIG> exemplifies a case where the second particles 16a have a spherical shape.

Occupancy ratio of the second particles 16a in the inter-wire resin layer <NUM> is, for example, <NUM>% or more and <NUM>% or less.

As illustrated in <FIG>, the second fixing resin layer <NUM> includes a plurality of third particles 18a and third resin 18x. The third resin 18x surrounds the third particles 18a. The third particles 18a are so-called filler.

Material of the third resin 18x is different from material of the second resin 16x. The third resin 18x is, for example, thermoplastic resin. Material of the third resin 18x is identical to material of the first resin 14x, for example. Glass transition temperature (Tg) of the third resin 18x is, for example, <NUM>° C or lower. The third resin 18x is, for example, phenoxy resin.

The third particles 18a are inorganic. The third particles 18a include, for example, at least one inorganic substance selected from a group including silica, alumina, silicon nitride, and alumina nitride. For example, the at least one inorganic substance occupies <NUM>% or more of volume of the third particles 18a. Material of the third particles 18a is identical to material of the first particles 14a, for example.

A median particle diameter of the third particles 18a is, for example, <NUM> or more and <NUM> or less.

A shape of the third particles 18a is, for example, but not particularly limited to, a plate shape, a spherical shape, a bale shape, a spheroidal shape, a columnar shape, a fibrous shape, or an irregular shape. <FIG> exemplifies a case where the third particles 18a have a spherical shape.

Occupancy ratio of the third particles 18a in the second fixing resin layer <NUM> is, for example, <NUM>% or more and <NUM>% or less.

As illustrated in <FIG>, the coating resin layer <NUM> includes a plurality of fourth particles 20a and fourth resin 20x. The fourth resin 20x surrounds the fourth particles 20a. The fourth particles 20a are so-called filler.

Material of the fourth resin 20x is different from material of the first resin 14x. The fourth resin 20x is, for example, thermoplastic resin.

The fourth resin 20x is, for example, polyvinyl formal resin, polyvinyl fluoride resin, saturated polyester resin, or polyurethane resin.

The fourth particles 20a are inorganic. The fourth particles 20a include, for example, at least one inorganic substance selected from a group including silica, alumina, silicon nitride, and alumina nitride. For example, the at least one inorganic substance occupies <NUM>% or more of volume of the fourth particles 20a.

A median particle diameter of the fourth particles 20a is, for example, <NUM> or more and <NUM> or less.

A shape of the fourth particles 20a is, for example, but not particularly limited to, a plate shape, a spherical shape, a bale shape, a spheroidal shape, a columnar shape, a fibrous shape, or an irregular shape. <FIG> exemplifies a case where the fourth particles 20a have a spherical shape.

Next, a method for manufacturing the superconducting coil <NUM> of the first arrangement will be described.

<FIG>, <FIG>, and <FIG> are schematic diagrams illustrating a method for manufacturing the superconducting coil of the first arrangement. <FIG>, <FIG>, and <FIG> illustrate a cross section corresponding to <FIG>.

First, the insulating substrate <NUM> is prepared (<FIG>).

Next, the second fixing resin layer <NUM> is applied to the insulating substrate <NUM> (<FIG>).

Next, the superconducting wire <NUM> is disposed on a surface of the second fixing resin layer <NUM> of the insulating substrate <NUM> (<FIG>). The superconducting wire <NUM> is wound such that a second region 12b of the superconducting wire <NUM> is disposed on the surface of the second fixing resin layer <NUM> so as to be substantially parallel to an adjacent first region 12a of the superconducting wire <NUM> previously disposed (<FIG>). The coating resin layer <NUM> is formed on the superconducting wire <NUM> in advance.

The superconducting wire <NUM> on which the coating resin layer <NUM> is formed is passed through a tank filled with the first particles 14a and the first resin 14x to form the first fixing resin layer <NUM> of the coating resin layer <NUM>. Then, the superconducting wire <NUM> is fixed to the surface of the second fixing resin layer <NUM> while, for example, the first fixing resin layer <NUM> is partially being softened by heat generated by ultrasonic irradiation.

After winding the superconducting wire <NUM> on the insulating substrate <NUM>, the inter-wire resin layer <NUM> is applied to the superconducting wire <NUM>. Because the superconducting wire <NUM> is fixed to the insulating substrate <NUM> with the first fixing resin layer <NUM> and the second fixing resin layer <NUM>, a position of the superconducting wire <NUM> is less likely to shift when the inter-wire resin layer <NUM> is applied.

Then, the superconducting wire <NUM> is fixed to the insulating substrate <NUM> by the inter-wire resin layer <NUM> being thermally set. By using the above manufacturing method, the superconducting coil <NUM> illustrated in <FIG> is formed.

Next, functions and effects of the superconducting coil <NUM> of the first arrangement will be described.

Further, inclusion of filler in the impregnated resin increases fracture toughness of the impregnated resin. Even if strain energy accumulates, the increased fracture toughness of the impregnated resin reduces occurrence of cracking, and occurrence of quenching is suppressed.

<FIG> is an enlarged schematic cross-sectional view illustrating a superconducting coil of a comparative example of the first arrangement.

As similar to the superconducting coil <NUM> of the first arrangement, a superconducting coil <NUM> of the comparative example is a so-called saddle type coil.

The superconducting coil <NUM> of the comparative example includes, as similar to the superconducting coil of the first arrangement, an insulating substrate <NUM>, a superconducting wire <NUM>, a first fixing resin layer <NUM>, an inter-wire resin layer <NUM>, a second fixing resin layer <NUM>, and a coating resin layer <NUM>.

<FIG> are explanatory diagrams of a first to fourth resin layers of the comparative example of the first arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the inter-wire resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the coating resin layer <NUM>.

As illustrated in <FIG>, the superconducting coil <NUM> of the comparative example is different from the superconducting coil <NUM> of the first arrangement in that the first fixing resin layer <NUM>, the second fixing resin layer <NUM>, and the coating resin layer <NUM> do not include filler.

In the superconducting coil <NUM> of the comparative example, the first fixing resin layer <NUM>, the second fixing resin layer <NUM> and the coating resin layer <NUM> do not include filler. Therefore, when the superconducting coil <NUM> is cooled, the first fixing resin layer <NUM>, the second fixing resin layer <NUM>, and the coating resin layer <NUM> are likely to be subjected to cracking due to difference in coefficient of thermal expansion between the first fixing resin layer <NUM>, the second fixing resin layer <NUM>, or the coating resin layer <NUM>, and the metal matrix 12y included in the superconducting wire <NUM>.

Further, non-inclusion of filler causes insufficient fracture toughness of the first fixing resin layer <NUM>, the second fixing resin layer <NUM>, and the coating resin layer <NUM>, cracking is likely to occur.

Therefore, in the superconducting coil <NUM> of the comparative example, quenching is likely to occur due to occurrence of cracking in the first fixing resin layer <NUM>, the second fixing resin layer <NUM>, or the coating resin layer <NUM>. In particular, the first fixing resin layer <NUM> and the coating resin layer <NUM> are closer to the superconducting wire <NUM> than the inter-wire resin layer <NUM> is. Therefore, if cracking occurs in the first fixing resin layer <NUM> or the coating resin layer <NUM>, quenching is more likely to occur.

In the superconducting coil <NUM> of the first arrangement, the first fixing resin layer <NUM>, the second fixing resin layer <NUM> and the coating resin layer <NUM> include filler. Therefore, the difference in coefficient of thermal expansion between the first fixing resin layer <NUM>, the second fixing resin layer <NUM>, or the coating resin layer <NUM>, and the metal matrix 12y included in the superconducting wire <NUM> is small, as compared to a case of the superconducting coil <NUM> of the comparative example. Further, fracture toughness of the first fixing resin layer <NUM>, the second fixing resin layer <NUM>, and the coating resin layer <NUM> is high, as compared to a case of the superconducting coil <NUM> of the comparative example. Therefore, as compared to a case of the superconducting coil <NUM> of the comparative example, occurrence of cracking is suppressed in the first fixing resin layer <NUM>, the second fixing resin layer <NUM>, and the coating resin layer <NUM>, and occurrence of quenching is suppressed.

As described above, according to the first arrangement, a superconducting coil in which occurrence of quenching is suppressed can be implemented.

A superconducting coil of a second arrangement is different from the superconducting coil of the first arrangement in that a fourth resin layer does not include fourth particles. Hereinafter, a part of description of content overlapping content of the first arrangement will be omitted.

<FIG> are explanatory diagrams of first to fourth resin layers of the second arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first resin layer, that is, a first fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second resin layer, that is, an inter-wire resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the third resin layer, that is, a second fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the fourth resin layer, that is, a coating resin layer <NUM>.

As illustrated in <FIG>, the coating resin layer <NUM> does not include filler.

In the superconducting coil of the second arrangement, the first fixing resin layer <NUM> and the second fixing resin layer <NUM> include filler. Therefore, as compared to a case of the superconducting coil <NUM> of the comparative example, occurrence of cracking is suppressed in the first fixing resin layer <NUM> and the second fixing resin layer <NUM>, and occurrence of quenching is suppressed.

As described above, according to the second arrangement, a superconducting coil in which occurrence of quenching is suppressed can be implemented.

A superconducting coil of a third arrangement is different from the superconducting coil of the first arrangement in that particle diameter distribution of first particles is bimodal. Hereinafter, a part of description of content overlapping content of the first arrangement will be omitted.

<FIG> are explanatory diagrams of first to fourth resin layers of the third arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first resin layer, that is, a first fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second resin layer, that is, an inter-wire resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the third resin layer, that is, a second fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the fourth resin layer, that is, a coating resin layer <NUM>.

As illustrated in <FIG>, a plurality of first particles 14a included in the first fixing resin layer <NUM> include a large-sized particle and a small-sized particle. Particle diameter distribution of the first particles 14a is bimodal.

Whether or not the particle diameter distribution of the first particles 14a is bimodal can be determined by measuring major axes of the first particles 14a with an SEM image, and obtaining frequency distribution of the major axes of the first particles 14a.

In the particle diameter distribution of the first particles 14a, a particle diameter indicating a first peak is, for example, <NUM> or more and <NUM> or less, and a particle diameter indicating a second peak is, for example, <NUM> or more and <NUM> or less.

Because the particle diameter distribution of the first particles 14a is bimodal, fracture toughness of the first fixing resin layer <NUM> is high.

As illustrated in <FIG>, a plurality of third particles 18a included in the second fixing resin layer <NUM> include a large-sized particle and a small-sized particle. Particle diameter distribution of the third particles 18a is bimodal.

Because the particle diameter distribution of the third particles 18a is bimodal, fracture toughness of the second fixing resin layer <NUM> is high.

In a case of the superconducting coil of the third arrangement, as compared to a case of the superconducting coil <NUM> of the first arrangement, occurrence of cracking is further suppressed in the first fixing resin layer <NUM> and the second fixing resin layer <NUM>. Therefore, occurrence of quenching is further suppressed.

As described above, according to the third arrangement, a superconducting coil in which occurrence of quenching is further suppressed can be implemented.

A superconducting coil of a fourth arrangement is different from the superconducting coil of the first arrangement in that a median particle diameter of first particles is smaller than a median particle diameter of second particles. Hereinafter, a part of description of content overlapping content of the first arrangement will be omitted.

<FIG> are explanatory diagrams of first to fourth resin layers of the fourth arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first resin layer, that is, a first fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second resin layer, that is, an inter-wire resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the third resin layer, that is, a second fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the fourth resin layer, that is, a coating resin layer <NUM>.

As illustrated in <FIG>, a particle diameter of a plurality of first particles 14a included in the first fixing resin layer <NUM> is smaller than a particle diameter of a plurality of second particles 16a included in the inter-wire resin layer <NUM>. Therefore, a median particle diameter of the first particles 14a is smaller than a median particle diameter of the second particles 16a.

Because the median particle diameter of the first particles 14a is smaller than the median particle diameter of the second particles 16a, fracture toughness of the inter-wire resin layer <NUM> is lower than the fracture toughness of the inter-wire resin layer <NUM> of the first arrangement.

Because the fracture toughness of the inter-wire resin layer <NUM> is low, cracking is more likely to occur in the inter-wire resin layer <NUM>, which is farther from a superconducting wire <NUM> than the first fixing resin layer <NUM> is. In other words, cracking is less likely to occur in the first fixing resin layer <NUM>, which is closer to the superconducting wire <NUM>.

Therefore, cracking is further less likely to occur in the first fixing resin layer <NUM>, which is closer to the superconducting wire <NUM>, as compared to a case of the superconducting coil <NUM> of the first arrangement. Therefore, occurrence of quenching is further suppressed.

As described above, according to the fourth arrangement, a superconducting coil in which occurrence of quenching is further suppressed can be implemented.

A superconducting coil of a fifth arrangement is different from the superconducting coil of the first arrangement in that occupancy ratio of first particles in a first resin layer is higher than occupancy ratio of second particles in a second resin layer. Hereinafter, a part of description of content overlapping content of the first arrangement will be omitted.

<FIG> are explanatory diagrams of first to fourth resin layers of the fifth arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first resin layer, that is, a first fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second resin layer, that is, an inter-wire resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the third resin layer, that is, a second fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the fourth resin layer, that is, a coating resin layer <NUM>.

As illustrated in <FIG>, occupancy ratio of a plurality of first particles 14a included in the first fixing resin layer <NUM> is higher than occupancy ratio of a plurality of second particles 16a included in the inter-wire resin layer <NUM>.

Because the occupancy ratio of the first particles 14a is higher than the occupancy ratio of the second particles 16a, fracture toughness of the inter-wire resin layer <NUM> is lower than the fracture toughness of the inter-wire resin layer <NUM> of the first arrangement.

As described above, according to the fifth arrangement, a superconducting coil in which occurrence of quenching is further suppressed can be implemented.

A superconducting coil of a sixth arrangement is different from the superconducting coil of the first arrangement in that second particles include crystal having cleavage. Hereinafter, a part of description of content overlapping content of the first arrangement will be omitted.

<FIG> are explanatory diagrams of first to fourth resin layers of the sixth arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first resin layer, that is, a first fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second resin layer, that is, an inter-wire resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the third resin layer, that is, a second fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the fourth resin layer, that is, a coating resin layer <NUM>.

A plurality of second particles 16a included in the inter-wire resin layer <NUM> include crystal having cleavage.

The second particles 16a have volume resistivity of <NUM>-<NUM> Ω· m or more and include crystal having cleavage. The crystal is a main component of the second particles 16a. The crystal occupies <NUM>% or more of volume of the second particles 16a. The second particles 16a are, for example, the crystal itself.

Cleavage is a property of crystal tending to break parallel to a specific crystal plane. Cleavage is classified as perfect, good, distinct, or indistinct, depending on a degree. The second particles 16a have, for example, perfect or distinct cleavage.

Volume resistivity and cleavage are physical properties unique to crystal. If the crystal included in the second particles 16a is identified, volume resistivity and cleavage of the crystal can be determined. The crystal included in the second particles 16a can be identified by, for example, a powder X-ray diffraction method.

The crystal included in the second particles 16a is, for example, at least either of phyllosilicate mineral or hexagonal boron nitride. Volume resistivity of the phyllosilicate mineral or the hexagonal boron nitride is, for example, <NUM>-<NUM> Ω· m or more and <NUM><NUM> Ω· m or less. Further, the phyllosilicate mineral or the hexagonal boron nitride has cleavage.

The phyllosilicate mineral has a sheet structure formed by a two-dimensionally spread SiO<NUM> tetrahedra. The phyllosilicate mineral is plate-shaped or flake-shaped and has perfect or distinct cleavage parallel to a bottom surface.

The phyllosilicate mineral included in the second particles 16a is, for example, at least one of mineral belonging to the mica group, clay mineral, pyrophyllite, or talc. The mineral belonging to the mica group is, for example, muscovite, phlogopite or biotite. The clay mineral is, for example, kaolinite or montmorillonite.

A shape of the second particles 16a is, for example, but not particularly limited to, a plate shape, a spherical shape, a bale shape, a spheroidal shape, a columnar shape, a fibrous shape, or an irregular shape. <FIG> exemplifies a case where the second particles 16a have a plate shape.

Crystal having cleavage breaks by relatively little stress. Therefore, because the second particles 16a include crystal having cleavage, fracture toughness of the inter-wire resin layer <NUM> is lower than the fracture toughness of the inter-wire resin layer <NUM> of the first arrangement.

The second particles 16a have volume resistivity of <NUM>-<NUM> Ω· m or more, and therefore insulation between portions of the superconducting wire <NUM> is secured.

As described above, according to the sixth arrangement, a superconducting coil in which occurrence of quenching is further suppressed can be implemented.

A superconducting coil of a seventh arrangement is different from the superconducting coil of the sixth arrangement in that second particles include a spherical particle. Hereinafter, a part of description of content overlapping content of the sixth arrangement will be omitted.

<FIG> are explanatory diagrams of first to fourth resin layers of the seventh arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first resin layer, that is, a first fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second resin layer, that is, an inter-wire resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the third resin layer, that is, a second fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the fourth resin layer, that is, a coating resin layer <NUM>.

A plurality of second particles 16a included in the inter-wire resin layer <NUM> include crystal having cleavage and a spherical particle.

Because the second particles 16a include a spherical particle, fracture toughness is higher, as compared to a case where crystal having cleavage alone is included. Therefore, as compared to a case of the superconducting coil of the sixth arrangement, occurrence of quenching is further suppressed.

As described above, according to the seventh arrangement, a superconducting coil in which occurrence of quenching is further suppressed can be implemented.

A superconducting coil of an eighth arrangement is different from the superconducting coil of the first arrangement in having an irregular shape. Hereinafter, a part of description of content overlapping content of the first arrangement will be omitted.

<FIG> are explanatory diagrams of first to fourth resin layers of the eighth arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first resin layer, that is, a first fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second resin layer, that is, an inter-wire resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the third resin layer, that is, a second fixing resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the fourth resin layer, that is, a coating resin layer <NUM>.

A plurality of second particles 16a included in the inter-wire resin layer <NUM> have an irregular shape. The second particles 16a are, for example, crushed silica.

A particle having an irregular shape breaks by relatively little stress, as compared to a spherical particle, for example. Therefore, because the second particles 16a have an irregular shape, fracture toughness of the inter-wire resin layer <NUM> is lower than the fracture toughness of the inter-wire resin layer <NUM> of the first arrangement.

Therefore, cracking is further less likely to occur in the first fixing resin layer <NUM>, which is closer to the superconducting wire <NUM>, as compared to a case of the superconducting coil <NUM> of the first arrangement.

Therefore, occurrence of quenching is further suppressed.

As described above, according to the eighth arrangement, a superconducting coil in which occurrence of quenching is further suppressed can be implemented.

A superconducting coil of a ninth arrangement includes a winding frame, a superconducting wire wound on the winding frame, the superconducting wire having a first region and a second region facing the first region, a first resin layer surrounding the superconducting wire and including a plurality of first particles and first resin surrounding the first particles, and a second resin layer positioned between the first region and the second region, the second resin layer covering the first resin layer and including a plurality of second particles and second resin surrounding the second particles and being made of material different from material of the first resin.

<FIG> is a schematic perspective view illustrating the superconducting coil of the ninth arrangement. <FIG> is a schematic cross-sectional view illustrating the superconducting coil of the ninth arrangement.

A superconducting coil <NUM> of the ninth arrangement is used as a coil for, for example, magnetic field generation of a superconducting device, such as an NMR, an MRI, heavy particle therapy equipment, or a superconducting magnetic levitation railway vehicle. The superconducting coil <NUM> of the ninth arrangement is a so-called solenoid coil.

The superconducting coil <NUM> includes a winding frame <NUM>, an inner peripheral insulation layer 31a, an upper insulation layer 31b, a lower insulation layer 31c, and a winding unit <NUM>. The winding unit <NUM> includes a superconducting wire <NUM>, a coating resin layer <NUM>, and an inter-wire resin layer <NUM>.

The coating resin layer <NUM> is an example of the first resin layer. The inter-wire resin layer <NUM> is an example of the second resin layer.

The inner peripheral insulation layer 31a, the upper insulation layer 31b, and the lower insulation layer 31c are formed of, for example, fiber-reinforced plastic. The inner peripheral insulation layer 31a, the upper insulation layer 31b, and the lower insulation layer 31c have a function of insulating the winding unit <NUM> from the winding frame <NUM> or an outside.

The superconducting wire <NUM> is linear shape, for example. The superconducting wire <NUM> is wound on the winding frame <NUM> in a solenoid shape around a winding center C.

<FIG> is a schematic cross-sectional view illustrating a superconducting wire of the ninth arrangement.

A cross section of the superconducting wire <NUM> is, for example, rectangular.

The superconducting wire <NUM> includes superconducting materials 40x and a metal matrix 40y. The superconducting wire <NUM> has a structure in which a plurality of superconducting materials 40x are disposed in the metal matrix 40y.

The superconducting material 40x is, for example, a low-temperature superconducting material having a critical temperature Tc of <NUM> or higher and <NUM> or lower. The superconducting material 12x is, for example, a niobium-titanium alloy-based, niobium-tin compound-based, niobium-aluminum compound-based, or magnesium diboride-based low-temperature superconducting material.

The metal matrix 40y is metal. The metal matrix 40y is, for example, copper.

<FIG> is an enlarged schematic cross-sectional view illustrating a part of a winding unit of the superconducting coil of the ninth arrangement.

As illustrated in <FIG>, the superconducting wire <NUM> has a first region 40a and a second region 40b. The first region 40a and the second region 40b are regions disposed adjacent to each other in parallel.

The coating resin layer <NUM> surrounds the superconducting wire <NUM>. The coating resin layer <NUM> has a function of coating and protecting the superconducting wire <NUM>. Thickness of the coating resin layer <NUM> is, for example, <NUM> or more and <NUM> or less.

The inter-wire resin layer <NUM> is disposed between the first region 40a and second region 40b of the superconducting wire <NUM>. The inter-wire resin layer <NUM> covers the coating resin layer <NUM>. The inter-wire resin layer <NUM> is in contact with the coating resin layer <NUM>. The inter-wire resin layer <NUM> surrounds the coating resin layer <NUM>, for example.

<FIG> are explanatory diagrams of the first resin layer and the second resin layer of the ninth arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first resin layer, that is, the coating resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second resin layer, that is, the inter-wire resin layer <NUM>.

As illustrated in <FIG>, the coating resin layer <NUM> includes a plurality of first particles 42a and first resin 42x. The first resin 42x surrounds the first particles 42a. The first particles 42a are so-called filler.

The first resin 42x is, for example, thermoplastic resin. The first resin 42x is, for example, polyvinyl formal resin.

Material of the first resin 42x can be identified by, for example, an FT-IR.

The first particles 42a are inorganic. The first particles 42a include, for example, at least one inorganic substance selected from a group including silica, alumina, silicon nitride, and alumina nitride. For example, the at least one inorganic substance occupies <NUM>% or more of volume of the first particles 42a.

A chemical composition of the first particles 42a can be determined by, for example, identifying crystal by an X-ray diffraction method. In a case where the first particles 42a have poor crystallinity, the chemical composition of the first particles 42a can be measured by observing a cross section of the coating resin layer <NUM> with an SEM, and performing an elemental analysis with an EDS.

A median particle diameter of the first particles 42a is, for example, <NUM> or more and <NUM> or less. The median particle diameter of the first particles 42a can be obtained from, for example, major axes of the plurality of first particles 42a which are measured with an image acquired by the SEM (an SEM image).

A shape of the first particles 42a is, for example, but not particularly limited to, a plate shape, a spherical shape, a bale shape, a spheroidal shape, a columnar shape, a fibrous shape, or an irregular shape. <FIG> exemplifies a case where the first particles 42a have a spherical shape.

Occupancy ratio of the first particles 42a in the coating resin layer <NUM> is, for example, <NUM>% or more and <NUM>% or less.

The occupancy ratio of the first particles 42a in the coating resin layer <NUM> is represented by, for example, a proportion of the first particles 42a occupying an area observed in the SEM image. The occupancy ratio of the first particles 42a can be obtained by, for example, an image analysis of the SEM image.

As illustrated in <FIG>, the inter-wire resin layer <NUM> includes a plurality of second particles 44a and second resin 44x. The second resin 44x surrounds the second particles 44a. The second particles 44a are so-called filler.

Material of the second resin 44x is different from material of the first resin 42x. The second resin 44x is, for example, thermo-setting resin. The second resin 44x is, for example, epoxy resin.

The second particles 44a are inorganic. The second particles 44a include, for example, at least one inorganic substance selected from a group including silica, alumina, silicon nitride, and alumina nitride. For example, the at least one inorganic substance occupies <NUM>% or more of volume of the second particles 44a.

A median particle diameter of the second particles 44a is, for example, <NUM> or more and <NUM> or less.

A shape of the second particles 44a is, for example, but not particularly limited to, a plate shape, a spherical shape, a bale shape, a spheroidal shape, a columnar shape, a fibrous shape, or an irregular shape. <FIG> exemplifies a case where the second particles 44a have a spherical shape.

Occupancy ratio of the second particles 44a in the inter-wire resin layer <NUM> is, for example, <NUM>% or more and <NUM>% or less.

When the superconducting coil <NUM> of the ninth arrangement is manufactured, the superconducting wire <NUM> coated by the coating resin layer <NUM> is wound on the winding frame <NUM> while the second resin 44x including the second particles 44a is being applied. Then, the inter-wire resin layer <NUM> is formed and a superconducting wire <NUM> is fixed by the second resin 44x being thermally set.

Next, functions and effects of the superconducting coil <NUM> of the ninth arrangement will be described.

<FIG> is an enlarged schematic cross-sectional view illustrating a superconducting coil of a comparative example of the ninth arrangement.

As similar to the superconducting coil <NUM> of the ninth arrangement, a superconducting coil <NUM> of the comparative example is a so-called solenoid coil.

As similar to the superconducting coil <NUM> of the ninth arrangement, the superconducting coil <NUM> of the comparative example includes a winding frame <NUM>, an inner peripheral insulation layer 31a, an upper insulation layer 31b, a lower insulation layer 31c, and a winding unit <NUM>. The winding unit <NUM> includes a superconducting wire <NUM>, a coating resin layer <NUM>, and an inter-wire resin layer <NUM>.

<FIG> are explanatory diagrams of first resin layer and second resin layer of the comparative example of the ninth arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first resin layer, that is, the coating resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second resin layer, that is, the inter-wire resin layer <NUM>.

As illustrated in <FIG>, the superconducting coil <NUM> of the comparative example is different from the superconducting coil <NUM> of the ninth arrangement in that the coating resin layer <NUM> does not include filler.

In the superconducting coil <NUM> of the comparative example, the coating resin layer <NUM> does not include filler. Therefore, when the superconducting coil <NUM> is cooled, the coating resin layer <NUM> is likely to be subjected to cracking due to difference in coefficient of thermal expansion between the coating resin layer <NUM> and the metal matrix 40y included in the superconducting wire <NUM>. Further, fracture toughness of the coating resin layer <NUM> is insufficient, and cracking is likely to occur.

Therefore, the superconducting coil <NUM> of the comparative example is likely to be subjected to quenching caused by occurrence of cracking in the coating resin layer <NUM>. In particular, the coating resin layer <NUM> is closer to the superconducting wire <NUM> than the inter-wire resin layer <NUM> is. Therefore, if cracking occurs in the coating resin layer <NUM>, quenching is more likely to occur.

In the superconducting coil <NUM> of the ninth arrangement, the coating resin layer <NUM> includes filler. Therefore, the difference in coefficient of thermal expansion between the coating resin layer <NUM> and the metal matrix 40y included in the superconducting wire <NUM> is small, as compared to a case of the superconducting coil <NUM> of the comparative example. Further, the fracture toughness of the coating resin layer <NUM> is high, as compared to a case of the superconducting coil <NUM> of the comparative example. Therefore, as compared to a case of the superconducting coil <NUM> of the comparative example, occurrence of cracking is suppressed in the coating resin layer <NUM>, and occurrence of quenching is suppressed.

As described above, according to the ninth arrangement, a superconducting coil in which occurrence of quenching is suppressed can be implemented.

A superconducting coil of a tenth arrangement is different from the superconducting coil of the ninth arrangement in that particle diameter distribution of first particles is bimodal. Hereinafter, a part of description of content overlapping content of the ninth arrangement will be omitted.

<FIG> are explanatory diagrams of a first resin layer and second resin layer of the tenth arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first resin layer, that is, a coating resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second resin layer, that is, an inter-wire resin layer <NUM>.

As illustrated in <FIG>, a plurality of first particles 42a included in the coating resin layer <NUM> include a large-sized particle and a small-sized particle. Particle diameter distribution of the first particles 42a is bimodal.

Whether or not the particle diameter distribution of the first particles 42a is bimodal can be determined by measuring major axes of the first particles 42a with an SEM image, and obtaining frequency distribution of the major axes of the first particles 42a.

In the particle diameter distribution of the first particles 42a, a particle diameter indicating a first peak is, for example, <NUM> or more and <NUM> or less, and a particle diameter indicating a second peak is, for example, <NUM> or more and <NUM> or less.

Because the particle diameter distribution of the first particles 42a is bimodal, fracture toughness of the coating resin layer <NUM> is high.

In a case of the superconducting coil of the tenth arrangement, as compared to a case of the superconducting coil <NUM> of the ninth arrangement, occurrence of cracking is further suppressed in the coating resin layer <NUM>. Therefore, occurrence of quenching is further suppressed.

As described above, according to the tenth arrangement, a superconducting coil in which occurrence of quenching is further suppressed can be implemented.

A superconducting coil of an eleventh arrangement is different from the superconducting coil of the ninth arrangement in that a median particle diameter of first particles is smaller than a median particle diameter of second particles. Hereinafter, a part of description of content overlapping content of the ninth arrangement will be omitted.

<FIG> are explanatory diagrams of a first resin layer and second resin layer of the eleventh arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first resin layer, that is, a coating resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second resin layer, that is, an inter-wire resin layer <NUM>.

As illustrated in <FIG>, a particle diameter of a plurality of first particles 42a included in the coating resin layer <NUM> is smaller than a particle diameter of a plurality of second particles 44a included in the inter-wire resin layer <NUM>. Therefore, a median particle diameter of the first particles 42a is smaller than a median particle diameter of the second particles 44a.

Because the median particle diameter of the first particles 42a is smaller than the median particle diameter of the second particles 44a, fracture toughness of the inter-wire resin layer <NUM> is lower than the fracture toughness of the inter-wire resin layer <NUM> of the ninth arrangement.

Because the fracture toughness of the inter-wire resin layer <NUM> is low, cracking is more likely to occur in the inter-wire resin layer <NUM>, which is farther from a superconducting wire <NUM> than the coating resin layer <NUM> is. In other words, cracking is less likely to occur in the coating resin layer <NUM>, which is closer to the superconducting wire <NUM>.

Therefore, cracking is further less likely to occur in the coating resin layer <NUM>, which is closer to the superconducting wire <NUM>, as compared to a case of the superconducting coil <NUM> of the ninth arrangement. Therefore, occurrence of quenching is further suppressed.

As described above, according to the eleventh arrangement, a superconducting coil in which occurrence of quenching is further suppressed can be implemented.

A superconducting coil of a twelfth arrangement is different from the superconducting coil of the ninth arrangement in that occupancy ratio of first particles in a first resin layer is higher than occupancy ratio of the second particles in a second resin layer. Hereinafter, a part of description of content overlapping content of the ninth arrangement will be omitted.

<FIG> are explanatory diagrams of first resin layer and the second resin layer of the twelfth arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first resin layer, that is, a coating resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second resin layer, that is, an inter-wire resin layer <NUM>.

As illustrated in <FIG>, occupancy ratio of a plurality of first particles 42a included in the coating resin layer <NUM> is higher than occupancy ratio of a plurality of second particles 44a included in the inter-wire resin layer <NUM>.

Because the occupancy ratio of the first particles 42a is higher than the occupancy ratio of the second particles 44a, fracture toughness of the inter-wire resin layer <NUM> is lower than the fracture toughness of the inter-wire resin layer <NUM> of the ninth arrangement.

As described above, according to the twelfth arrangement, a superconducting coil in which occurrence of quenching is further suppressed can be implemented.

A superconducting coil of a thirteenth arrangement is different from the superconducting coil of the ninth arrangement in that second particles include crystal having cleavage. Hereinafter, a part of description of content overlapping content of the ninth arrangement will be omitted.

<FIG> are explanatory diagrams of a first resin layer and second resin layer of the thirteenth arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first resin layer, that is, a coating resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second resin layer, that is, an inter-wire resin layer <NUM>.

A plurality of second particles 44a included in the inter-wire resin layer <NUM> include crystal having cleavage.

The second particles 44a have volume resistivity of <NUM>-<NUM> Ω·m or more and include crystal having cleavage. The crystal is a main component of the second particles 44a. The crystal occupies <NUM>% or more of volume of the second particles 44a. The second particles 44a are, for example, the crystal itself.

Cleavage is a property of crystal tending to break parallel to a specific crystal plane. Cleavage is classified as perfect, good, distinct, or indistinct, depending on a degree. The second particles 44a have, for example, perfect or distinct cleavage.

Volume resistivity and cleavage are physical properties unique to crystal. If the crystal included in the second particles 44a is identified, volume resistivity and cleavage of the crystal can be determined. The crystal included in the second particles 44a can be identified by, for example, a powder X-ray diffraction method.

The crystal included in the second particles 44a is, for example, at least either of phyllosilicate mineral or hexagonal boron nitride. Volume resistivity of the phyllosilicate mineral or the hexagonal boron nitride is, for example, <NUM>-<NUM> Ω·m or more and <NUM><NUM> Ω· m or less. Further, the phyllosilicate mineral or the hexagonal boron nitride has cleavage.

The phyllosilicate mineral included in the second particles 44a is, for example, at least one of mineral belonging to the mica group, clay mineral, pyrophyllite, or talc. The mineral belonging to the mica group is, for example, muscovite, phlogopite or biotite. The clay mineral is, for example, kaolinite or montmorillonite.

A shape of the second particles 44a is, for example, but not particularly limited to, a plate shape, a spherical shape, a bale shape, a spheroidal shape, a columnar shape, a fibrous shape, or an irregular shape. <FIG> exemplifies a case where the second particles 44a have a plate shape.

Crystal having cleavage breaks by relatively little stress. Therefore, because the second particles 44a include crystal having cleavage, fracture toughness of the inter-wire resin layer <NUM> is lower than the fracture toughness of the inter-wire resin layer <NUM> of the ninth arrangement.

The second particles 44a have volume resistivity of <NUM>-<NUM> Ω· m or more, and therefore insulation between portions of the superconducting wire <NUM> is secured.

As described above, according to the thirteenth arrangement, a superconducting coil in which occurrence of quenching is further suppressed can be implemented.

A superconducting coil of a fourteenth arrangement is different from the superconducting coil of the ninth arrangement in having an irregular shape. Hereinafter, a part of description of content overlapping content of the ninth arrangement will be omitted.

<FIG> are explanatory diagrams of a first resin layer and second resin layer of the fourteenth arrangement. <FIG> is an enlarged schematic cross-sectional view of a part of the first resin layer, that is, a coating resin layer <NUM>. <FIG> is an enlarged schematic cross-sectional view of a part of the second resin layer, that is, an inter-wire resin layer <NUM>.

A plurality of second particles 44a included in the inter-wire resin layer <NUM> have an irregular shape. The second particles 44a are, for example, crushed silica.

A particle having an irregular shape breaks by relatively little stress, as compared to a spherical particle, for example. Therefore, because the second particles 44a have an irregular shape, fracture toughness of the inter-wire resin layer <NUM> is lower than the fracture toughness of the inter-wire resin layer <NUM> of the ninth arrangement.

As described above, according to the fourteenth arrangement, a superconducting coil in which occurrence of quenching is further suppressed can be implemented.

A superconducting device of a fifteenth arrangement includes a superconducting coil of the first to fourteenth arrangements. Hereinafter, a part of description of content overlapping content of the first to fourteenth arrangements will be omitted.

<FIG> is a block diagram illustrating the superconducting device of the fifteenth arrangement. The superconducting device of the fifteenth arrangement is heavy particle therapy equipment <NUM>. The heavy particle therapy equipment <NUM> is an example of a superconducting device.

The heavy particle therapy equipment <NUM> includes an injection system <NUM>, a synchrotron accelerator <NUM>, a beam transportation system <NUM>, an irradiation system <NUM>, and a control system <NUM>.

For example, the injection system <NUM> has a function of generating a carbon ion used for treatment and performing pre-acceleration to inject the carbon ion into the synchrotron accelerator <NUM>. The injection system <NUM> has, for example, an ion generation source and a linear accelerator.

The synchrotron accelerator <NUM> has a function of accelerating a carbon ion beam injected from the injection system <NUM> to energy suitable for treatment. The synchrotron accelerator <NUM> uses a superconducting coil of the first to fourteenth arrangements.

The beam transportation system <NUM> has a function of transporting the carbon ion beam injected from the synchrotron accelerator <NUM> to the irradiation system <NUM>. The beam transportation system <NUM> has, for example, a bending electromagnet.

The irradiation system <NUM> includes a function of irradiating the carbon ion beam injected from the beam transportation system <NUM> to a patient as an irradiation object. The irradiation system <NUM> has, for example, a rotary gantry that allows irradiation of a carbon ion beam from any direction. The rotary gantry uses a superconducting coil of the first to fourteenth arrangements.

The control system <NUM> controls the injection system <NUM>, the synchrotron accelerator <NUM>, the beam transportation system <NUM>, and the irradiation system <NUM>. The control system <NUM> is, for example, a computer.

In the heavy particle therapy equipment <NUM> of the fifteenth arrangement, the synchrotron accelerator <NUM> and the rotary gantry use a superconducting coil of the first to fourteenth arrangements. Therefore, occurrence of quenching is suppressed, and high reliability is achieved.

In the fifteenth arrangement, a case of the heavy particle therapy equipment <NUM> is described as an example of the superconducting device. The superconducting device, however, may be an NMR, an MRI, or a superconducting magnetic levitation railway vehicle.

A superconducting wire rod for superconducting coil of a sixteenth arrangement includes a superconducting wire and a resin layer that coats the superconducting wire and includes particles and resin surrounding the particles.

A superconducting wire rod <NUM> of the sixteenth arrangement is linear shape, for example. By being wound on a surface of an insulating substrate in a three-dimensional shape, for example, the superconducting wire rod <NUM> forms a saddle-type superconducting coil. By being wound on a winding frame, for example, the superconducting wire rod <NUM> forms a solenoid superconducting coil.

<FIG> is a schematic cross-sectional view illustrating a superconducting wire rod of the sixteenth arrangement.

A cross section of the superconducting wire rod <NUM> is, for example, circular. A diameter of the superconducting wire rod <NUM> is, for example, <NUM> or more and <NUM> or less.

The superconducting wire rod <NUM> includes a superconducting wire <NUM> and a coating resin layer <NUM>. The coating resin layer <NUM> is an example of a resin layer.

The superconducting wire <NUM> includes superconducting materials 60x and a metal matrix 60y. The superconducting wire <NUM> has a structure in which a plurality of superconducting materials 60x are disposed in the metal matrix 60y.

The superconducting material 60x is, for example, a low-temperature superconducting material having a critical temperature Tc of <NUM> or higher and <NUM> or lower. The superconducting material 60x is, for example, a niobium-titanium alloy-based, niobium-tin compound-based, niobium-aluminum compound-based, or magnesium diboride-based low-temperature superconducting material.

The metal matrix 60y is metal. The metal matrix 60y is, for example, copper.

The coating resin layer <NUM> coats the superconducting wire <NUM>. The coating resin layer <NUM> is in contact with the superconducting wire <NUM>.

The coating resin layer <NUM> includes particles 62a and resin 62x. The resin 62x surrounds the particles 62a. The particles 62a are so-called filler.

The resin 62x is, for example, thermoplastic resin. The resin 62x is, for example, polyvinyl formal resin.

Material of the resin 62x can be identified by, for example, an FT-IR.

The particles 62a are inorganic. The particles 62a include, for example, at least one inorganic substance selected from a group including silica, alumina, silicon nitride, and alumina nitride. For example, the at least one inorganic substance occupies <NUM>% or more of volume of the first particles 42a.

A chemical composition of the particles 62a can be determined by, for example, identifying crystal by an X-ray diffraction method. In a case where the particles 62a have poor crystallinity, the chemical composition of first particles 14a can be measured by observing a cross section of the coating resin layer <NUM> with an SEM, and performing an elemental analysis with an EDS.

A median particle diameter of the particles 62a is, for example, <NUM> or more and <NUM> or less. The median particle diameter of the particles 62a can be obtained from, for example, major axes of a plurality of particles 62a which are measured with an image acquired by the SEM (an SEM image).

A shape of the particles 62a is, for example, but not particularly limited to, a plate shape, a spherical shape, a bale shape, a spheroidal shape, a columnar shape, a fibrous shape, or an irregular shape. <FIG> exemplifies a case where the particles 62a have a spherical shape.

Occupancy ratio of the particles 62a in the coating resin layer <NUM> is, for example, <NUM>% or more and <NUM>% or less.

The occupancy ratio of the particles 62a in the coating resin layer <NUM> is represented by, for example, a proportion of the particles 62a occupying an area observed in the SEM image. The occupancy ratio of the particles 62a can be obtained by, for example, an image analysis of the SEM image.

In the superconducting wire rod <NUM> of the sixteenth arrangement, the coating resin layer <NUM> includes filler. Therefore, difference in coefficient of thermal expansion between the coating resin layer <NUM> and the metal matrix 60y included in the superconducting wire <NUM> is small, as compared to a case where the coating resin layer <NUM> does not include filler. Further, fracture toughness of the coating resin layer <NUM> is high, as compared to a case where the coating resin layer <NUM> does not include filler. Therefore, in a case where the superconducting wire rod <NUM> is applied to a superconducting coil, occurrence of cracking is suppressed in the coating resin layer <NUM>, and occurrence of quenching is suppressed in the superconducting coil.

As described above, according to the sixteenth arrangement, a superconducting wire rod for superconducting coil in which occurrence of quenching is suppressed can be implemented.

Claim 1:
A superconducting coil (<NUM>) comprising:
a substrate (<NUM>) having a curved surface;
a superconducting wire (<NUM>) wound on the curved surface, the superconducting wire (<NUM>) having a first region (12a) and a second region (12b) facing the first region (12a);
a first resin layer (<NUM>) surrounding the superconducting wire (<NUM>) and including a plurality of first particles (14a) and first resin (14x) surrounding the first particles (14a); and
a second resin (<NUM>) layer positioned between the first region (12a) and the second region (12b), the second resin layer (<NUM>) covering the first resin layer (<NUM>) and including a plurality of second particles (16a) and second resin (16x) surrounding the second particles (16a) and the second resin (16x) being made of material different from material of the first resin (14x).