JP2010040962A - Superconducting coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a low-cost superconducting coil which prevents lowering of a critical current. <P>SOLUTION: In a superconducting coil, three or more pancake type superconducting coils in which tape shape superconducting wires are wound are laminated in an axis direction. Superconducting coils of at least both ends of the axis direction are formed by an RE123 superconducting wire material. An interlayer superconducting coil put between the superconducting coils made of the RE123 superconducting wire material is formed by a (Bi, Pb) 2223 superconducting material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a superconducting coil, and prevents a decrease in a current value (critical current value) that can be passed through the superconducting coil, so that the characteristics of the superconducting coil can be exhibited efficiently.

  Currently, (BI, Pb) 2223 superconducting materials such as first-generation bismuth-based oxide superconducting wires and RE123 superconducting wires such as second-generation yttrium-based oxide superconducting wires are being developed as high-temperature superconducting materials. . Japanese Patent Laid-Open No. 2002-110416 and the like propose a pancake coil in which these tape-shaped superconducting wires are wound in a flatwise manner and the wide surface of the superconducting wire is parallel to the coil axis direction. In some cases, a solenoid coil is formed by spirally winding a superconducting wire around an iron core.

The critical current of the superconducting coil is affected by the strength of the magnetic field applied to the superconducting wire, and is also affected by the direction of the magnetic field. That is, when a magnetic field perpendicular to the wide surface of the tape-shaped superconducting wire is applied, the loss increases and the critical current decreases.
Specifically, as shown in FIG. 6, when the laminate 101 of the pancake coil 100 is energized, a magnetic field 102 is generated from the inner peripheral surface of the laminate 101 to the outer peripheral surface through both ends of the laminate, and the laminate Near the center of the axial direction X of 101, the magnetic field 102 is parallel to the wide surface 100a of the coil 100, but at both end positions in the axial direction, it has a component in the radial direction of the coil 100, that is, a component orthogonal to the wide surface 100a. A magnetic field 102 is generated.

FIG. 7A shows the critical current when a magnetic field in the orthogonal direction is applied to the wide surface of the superconducting wire, and FIG. 7B shows the critical current when the wide surface and the magnetic field direction are parallel. . As can be seen from this graph, the superconducting wire subjected to the orthogonal magnetic field has a smaller critical current than the case where the parallel magnetic field is applied, regardless of the magnitude of the magnetic field and the cooling temperature conditions. Become. The numerical value on the vertical axis of the graph in FIG. 7 indicates the magnitude of the critical current when the critical current is 1 when the superconducting wire is energized in a state where the magnetic flux density is 0 stella (T) and the temperature is 77 Kelvin (K). Indicates.
In this way, when the laminate 101 of the superconducting coil 100 is energized, the magnetic field 102 having a component perpendicular to the wide surface of the superconducting wire is applied at both end positions of the laminate, and the critical current is lowered to quench. It tends to occur. As a result, there is a problem that the performance of the superconducting coil deteriorates.

  On the other hand, when the first generation (Bi, Pb) 2223 superconductor and the second generation RE123 superconductor are compared, the resistance of the (Bi, Pb) 2223 oxide superconductor to the magnetic field is weaker than that of the RE123 superconductor. Therefore, when a magnetic field having a component perpendicular to the wide surface of the tape-shaped superconducting wire is applied, the critical current value of the (Bi, Pb) 2223 oxide superconducting material is likely to be lower than that of the RE123 superconducting material.

  Thus, the RE123 superconductor is stronger than the (Bi, Pb) 2223 oxide superconductor, and has an advantage that the critical current value does not decrease. However, a tape-shaped superconducting wire made of RE123 superconducting material has a complicated manufacturing process and is delicate, so that it is difficult to obtain a long and uniform wire material capable of forming a coil, resulting in poor production yield. As a result, if the coil is formed only from the RE123 superconducting material, there is a problem that the cost increases.

JP 2002-110416 A

  The present invention has been made in view of the above problems, and it is an object of the present invention to provide a superconducting coil capable of suppressing a decrease in critical current even when a magnetic field perpendicular to the wide surface of the tape-shaped superconducting wire is applied. Yes.

In order to solve the above problems, as a first invention,
It consists of a superconducting coil in which three or more pancake superconducting coils wound with a tape-shaped superconducting wire are laminated in the axial direction.
The superconducting coils at least at both ends in the axial direction are made of RE123 superconducting wire, while the superconducting coil in the intermediate layer sandwiched between the superconducting coils made of the RE123 superconducting wire is made of (BI, Pb) 2223 superconducting wire. A superconducting coil is provided.

As a second invention,
It consists of a superconducting coil in which pancake-type superconducting coils with tape-shaped superconducting wires wound around both sides of a C-type iron core are laminated.
The superconducting coil disposed at least on the opening end side of the superconducting coil laminated portion disposed on both sides sandwiching the opening end is formed of the RE123 superconducting wire, while the superconducting coils other than the superconducting coil are (BI, Pb) 2223 superconducting. A superconducting coil characterized by being formed of a wire is provided.

In the first and second inventions, in a single pancake coil having a single pancake coil, three or more layers are laminated in the axial direction, and single pancake coils at both ends in the axial direction are formed of RE123 superconducting wires. An intermediate single-pancake type coil is formed of (BI, Pb) 2223 superconducting wire.
The same applies to the case where three or more double pancake coils with two upper and lower layers wound on the inner peripheral surface are laminated. The double pancake coils at both ends in the axial direction are formed of RE123 superconducting wire, A double pancake type coil is formed of (BI, Pb) 2223 superconducting wire.
When three or more double pancake-type coils are laminated, it is preferable that all the coils of the intermediate layer are formed of (BI, Pb) 2223 superconducting wire.
All pancake-type coils are preferably formed from double pancake-type coils.

  As described above, when superconducting coils formed of the RE123 superconducting wire that is strong against a magnetic field and is difficult to reduce the critical current are disposed at both ends in the axial direction where a magnetic field perpendicular to the wide surface is likely to be applied, the critical current is unlikely to decrease. It can be set as the superconducting coil which consists of a laminated body. In addition, a magnetic field in a direction parallel to the wide surface of the superconducting wire is applied at an intermediate position of the laminated body, and the magnetic field in the orthogonal direction is small, and therefore, it is weaker than the RE123 superconducting wire (BI, Pb) 2223 superconducting wire. Even if a superconducting coil is arranged, it is possible to prevent a decrease in critical current. In addition, since the (BI, Pb) 2223 superconducting wire can be obtained at a lower cost than the RE123 superconducting wire, the cost can be reduced.

Specifically, it is preferable to use a superconducting coil formed of the RE123 superconducting wire for a portion to which a magnetic field of 0.1 T or more is applied to the wide tape surface.
FIG. 8 shows the relationship between the magnetic field and the critical current when a magnetic field perpendicular to the superconducting wire is applied. As shown in FIG. 8, the critical current of (Bi, Pb) 2223 superconducting wire 6 is 77K, 0.1T or more, and at 20K, it drops at 2T or more, and becomes smaller than that of RE123 superconducting wire 5. By winding a portion where the magnetic field perpendicular to the tape surface is 0.1 T or more with the RE123 superconducting material 5, a superconducting coil capable of suppressing a decrease in the critical current value can be obtained at low cost.

It is preferable not to attach an iron core or an iron inner frame to the inner periphery of the laminated superconducting coil.
In some cases, a superconducting coil has an axial iron core disposed on the inner circumference of the coil in order to converge the dispersed magnetic flux generated on the inner circumference in the axial direction. In this case, a leakage magnetic flux is generated in the orthogonal direction from the outer peripheral surface of the iron core, and a magnetic field having a component in the orthogonal direction is also applied from the iron core to the wide surface of the superconducting wire. For this reason, when there is an iron core, the magnetic field of the component of the orthogonal direction added to the wide surface of a superconducting wire increases, and a critical current tends to fall compared with the case without an iron core.
Therefore, a magnetic field perpendicular to the iron core is likely to be applied to the wide surface of the (BI, Pb) 2223 superconducting wire disposed at the intermediate position of the laminate, and the critical current value is lowered. Is preferably not arranged.

As a third invention,
It consists of a solenoid-type superconducting coil spirally wound with a tape-shaped superconducting wire,
A superconducting coil is provided in which a RE123 superconducting wire is wound around both ends of the coil, and a (BI, Pb) 2223 superconducting wire is connected to the RE123 superconducting wire and wound around the center of the coil.

As a fourth invention, it comprises a solenoid type superconducting coil in which a tape-like superconducting wire is spirally wound on both sides of a C-type iron core,
The superconducting wire wound on both sides sandwiching the opening end is wound using the RE123 superconducting wire on the opening end side, and the (BI, Pb) 2223 superconducting wire is connected to the RE123 superconducting wire from the center of the both sides. A superconducting coil is provided that is wound to the end of the connecting portion.

In the third and fourth inventions, a solenoid-type superconducting coil in which a tape-like superconducting wire is spirally wound is used in place of the pancake-type coil. In the third invention, a cylindrical superconducting coil is provided. The C type superconducting coil is used.
In the superconducting coil, the superconducting wire wound around both sides sandwiching the opening end is wound using the RE123 superconducting wire on the opening end side, while the (BI, Pb) 2223 superconducting material is connected to the RE123 superconducting wire. It winds from the center part of a part to the connection part end side.

In a solenoid-type superconducting coil in which tape-like superconducting wires are spirally wound on both sides of a C-type iron core according to the fourth aspect of the invention, the magnetic field travels from the outer periphery of both sides to the continuous part of the iron core across the tip surface of both sides. Occurs in the route. Therefore, the superconducting wire wound on the opening end side of both sides is subjected to a magnetic field perpendicular to the wide surface, while the superconducting wire wound from the intermediate portion excluding the opening end side of both sides to the connecting portion side of the iron core The magnetic field is parallel to the wide surface, and the magnetic field in the orthogonal direction is less likely to be applied.
Therefore, as described above, the RE123 superconducting wire is arranged on the opening end side where the magnetic field perpendicular to the wide surface is likely to be applied, and the (BI, Pb) 2223 superconducting material is arranged from the intermediate part to the continuous side of the iron core. ing.
As a result, the third and fourth inventions, like the first and second inventions, can produce a superconducting coil in which the critical current value is unlikely to decrease at low cost.

  The tape-shaped (BI, Pb) 2223 superconducting material and the RE123 superconducting wire are preferably connected by soldering.

  As described above, in the superconducting coil of the present invention, the critical current value is decreased by using the RE123 superconducting wire that is strong against a magnetic field in a portion where a magnetic field perpendicular to the wide surface of the tape-shaped superconducting wire is easily applied. Is preventing. On the other hand, in the portion where the magnetic field is parallel to the wide surface and the magnetic field in the orthogonal direction is difficult to be applied, a tape-shaped superconducting wire having a uniform physical property but weaker than the RE123 superconducting wire can be obtained at low cost. BI, Pb) 2223 superconducting material is used. Thereby, an inexpensive superconducting coil capable of generating a strong magnetic field in which the critical current is difficult to decrease can be obtained.

Hereinafter, embodiments of the superconducting coil of the present invention will be described with reference to the drawings.
1 and 2 show a pancake-type superconducting coil 1 according to the first embodiment.

  The superconducting coil 1 is a laminated body in which a double pancake type coil 2 is laminated in the axial direction X in four layers. The coil 2 is externally fitted and held in an inner frame 3 formed of a nonmagnetic material such as FRP, stainless steel, or aluminum without an iron core in the inner periphery of the laminate.

  The lowermost coil 2A and the uppermost coil 2D are formed of the RE123 superconducting wire 5 shown in FIG. The intermediate layer coils 2B and 2C are formed of (BI, Pb) 2223 superconducting material 6 shown in FIG.

The RE123 superconducting wire 5 has a configuration in which a metal alignment substrate 21, an intermediate layer 22, a superconducting thin film layer 23, and a protective stable layer 24 are sequentially laminated, and both surfaces are sandwiched between protective layers 25 and 26. The metal alignment substrate 21 is made of, for example, Ni or Ni alloy. The intermediate layer 2 is made of yttrium-based stabilized zirconia. The protective layers 25 and 26 are made of silver or copper.
The (Bi, Pb) 2223 superconducting wire 6 has a plurality of (Bi, Pb) 2223 superconductor filaments 28 extending in the longitudinal direction and a sheath portion 29 made of silver or a silver alloy covering them.

The tape-like RE123 superconducting material 5 and the tape-like (Bi, Pb) 2223 oxide superconducting wire 6 are both flatwise with the wide surfaces 5a and 6a in the vertical direction parallel to the coil axis direction. The rolled double pancake type coil 2 is used. The double pancake-type coil 2 is continuous and wired on the inner peripheral surfaces of the upper and lower layers.
In the laminated coils 2A to 2D, the tips of the outer peripheral surfaces of the coils are electrically connected in series so that the same current flows.

In the superconducting coil 1 in which the double pancake type coils 2A to 2D configured as described above are laminated, the upper and lower ends in the axial direction are formed of RE123 superconducting wires that are strong against magnetic fields.
The superconducting coil 1 having such a configuration is energized while being maintained at a temperature of 30K. At that time, a magnetic field of 3T is applied to the coils 2B and 2C arranged in the central portion in the axial direction, and a magnetic field of 1T or less is applied to the outside of the coils 2A and 2B. That is, a strong magnetic field is applied to the coils 2B and 2C formed of the (Bi, Pb) 2223 superconducting material 6, while a magnetic field applied to the coils 2A and 2D formed of the RE123 superconducting wire 5 is small.

The magnetic field applied to the lower end surface of the lower coil 2A and the upper end surface of the upper coil 2D is small, and a radial magnetic field, that is, a magnetic field orthogonal to the wide surface 5a is applied. Since the coils 2A and 2D are formed of the RE123 superconducting wire 5 which is strong against a magnetic field, it is possible to prevent a decrease in critical current.
On the other hand, the coils 2B and 2C in the intermediate layer have a parallel magnetic field on the wide surface 6a located on the inner peripheral surface, and hardly apply a magnetic field in the direction orthogonal to the wide surface 6a. Even if (Bi, Pb) 2223 superconducting wire 5 is used, the critical current does not decrease.

  As described above, the superconducting coil 1 has the coils 2A and 2D formed by the RE123 superconducting wire 5 at the upper and lower ends where a magnetic field perpendicular to the wide surface of the tape-shaped superconducting wire is applied, and (Bi, By arranging the coils 2B and 2C formed of the Pb) 2223 superconducting wire 6, it is possible to obtain a superconducting coil that can suppress a decrease in the critical current value.

FIG. 3 shows a C-type superconducting coil 10 using the pancake-type coil of the second embodiment.
In the superconducting coil 10, double pancake coils 2A, 2B, 2C are laminated and fitted on both side portions 11b and 11c continuous to both ends of the connecting portion 11a of the C-type iron core 11, respectively. The double pancake-type coil 2 </ b> A disposed on the opening end 100 side of both side portions 11 b and 11 c is formed of the RE123 superconducting wire 5. On the other hand, the double pancake-type coils 2 </ b> B and 2 </ b> C are formed of (BI, Pb) 2223 superconducting wire 6.

4A, 4B, and 4C show a superconducting coil 20 according to the third embodiment.
As shown in FIG. 4A, the superconducting coil 20 is a cylindrical solenoid type superconducting coil in which a tape-shaped superconducting wire 12 is spirally wound around a round bar-shaped iron core 110.
The superconducting wire 12 has RE123 superconducting wire 5 on both sides in the length direction and (Bi, Pb) 2223 superconducting wire 6 in the middle, and these three superconducting wires 5, 6 and 5 are shown in FIG. As shown, it is soldered into a single continuous superconducting wire.
The superconducting wire 12 is spirally wound from one end to the other end of the round iron core 110 so that the RE123 superconducting wire is located on both ends of the cylindrical coil and the (Bi, Pb) 2223 superconducting wire is located in the center. The superconducting coil 10 is used.

  In addition, the superconducting wire 12 is spirally wound around the round bar-shaped iron core 110 to form a cylindrical solenoid type superconducting coil. After the superconducting coil 10 is cured, the round bar-shaped iron core 110 is pulled out and shown in FIG. A coil without an iron core may be used.

FIG. 5 shows a superconducting coil 30 according to the fourth embodiment.
In the superconducting coil 30, tape-like superconducting wires 120 are spirally wound around both side portions 11b and 11c protruding from both ends of the continuous portion 11a of the C-type iron core 11, respectively.
In the superconducting wire 120, the RE123 superconducting wire 5 is connected in series by soldering to one end side of the (Bi, Pb) 2223 superconducting wire 6 to form one continuous superconducting wire.

  In the superconducting wire 120, a portion made of the RE123 superconducting wire 5 is wound around the opening end on both sides 11 b and 11 c of the iron core 11, and the (Bi, Pb) 2223 superconducting material 6 is formed on the connecting portion 11 a side from the center. The part is wrapped.

  In the superconducting coil 30 composed of the C-type solenoid, the magnetic field is formed so as to cross the tips of the side portions 11b and 11c along the outer periphery of the C-type iron core 11, as shown in FIG. Therefore, a magnetic field in a direction orthogonal to the wide surface 120a of the superconducting wire 120 is applied to the distal ends of the side portions 11b and 11c. Since the superconducting wire 120 to which the magnetic field in the orthogonal direction is applied is formed of the RE123 superconducting material 5, it is possible to suppress a decrease in the critical current value.

  Thus, also in the solenoid type superconducting coils 20 and 30 of the third and fourth embodiments, a superconducting coil capable of suppressing a decrease in the critical current value can be obtained at low cost.

It is a mimetic diagram showing the pancake coil lamination type superconducting coil of a 1st embodiment of the present invention. (A) is a partial cross-sectional perspective view of RE123 superconducting wire, and (B) is a partial cross-sectional perspective view of (Bi, Pb) 2223 superconducting wire. It is a schematic diagram which shows the solenoid type superconducting coil of 2nd Embodiment. 3A and 3B are schematic views showing a superconducting coil, FIG. 3B is a drawing showing a connection part of a superconducting wire, and FIG. 3C is a schematic view showing a superconducting coil with an iron core removed. It is a schematic diagram which shows the solenoid type superconducting coil of 4th Embodiment. It is a schematic diagram which shows the conventional pancake type coil. (A) (B) is a graph which shows the relationship between the direction of the magnetic field added to a superconducting wire, and a critical current. It is a graph which shows the relationship between a magnetic field and critical current when a perpendicular magnetic field is added with respect to a superconducting wire.

Explanation of symbols

1, 10, 20, 30 Superconducting coil 2 (2A to 2D) Double pancake type coil 5 RE123 superconducting wire 6 (Bi, Pb) 2223 superconducting wire

Claims (8)

It consists of a superconducting coil in which three or more pancake superconducting coils wound with a tape-shaped superconducting wire are laminated in the axial direction.
The superconducting coils at least at both ends in the axial direction are made of RE123 superconducting wire, while the superconducting coil in the intermediate layer sandwiched between the superconducting coils made of the RE123 superconducting wire is made of (BI, Pb) 2223 superconducting wire. A superconducting coil characterized by It consists of a superconducting coil in which pancake-type superconducting coils with tape-shaped superconducting wires wound around both sides of a C-type iron core are laminated.
The superconducting coil disposed at least on the opening end side of the superconducting coil laminated portion disposed on both sides sandwiching the opening end is formed of the RE123 superconducting wire, while the superconducting coils other than the superconducting coil are (BI, Pb) 2223 superconducting. A superconducting coil characterized by being formed of a wire.   The superconducting coil formed of the RE123 superconducting wire is used for a portion to which a magnetic field of 0.1 T or more is applied to the wide tape surface, according to claim 1 or 2. Superconducting coil.   The superconducting coil according to any one of claims 1 to 3, wherein an iron core or an iron inner frame is not attached to an inner periphery of the laminated superconducting coils.   The superconducting coil according to any one of claims 1 to 4, wherein each of the superconducting coils is a double pancake type coil. It consists of a solenoid-type superconducting coil spirally wound with a tape-shaped superconducting wire,
A superconducting coil, wherein a RE123 superconducting wire is wound around both ends of the coil, and a (BI, Pb) 2223 superconducting wire is connected to the RE123 superconducting wire and wound around the center of the coil. It consists of a solenoid-type superconducting coil in which tape-shaped superconducting wires are spirally wound on both sides of a C-type iron core.
The superconducting wire wound on both sides sandwiching the opening end is wound using the RE123 superconducting wire on the opening end side, and the (BI, Pb) 2223 superconducting wire is connected to the RE123 superconducting wire from the center of the both sides. A superconducting coil, wherein the coil is wound to the end of the connecting portion.   The superconducting coil according to claim 6 or 7, wherein a portion to which a magnetic field of 0.1 T or more is applied to the wide tape surface is wound using an RE123 superconducting wire.

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