WO2013161475A1 - AIMANT SUPRACONDUCTEUR À BASE DE MgB2 - Google Patents

AIMANT SUPRACONDUCTEUR À BASE DE MgB2 Download PDF

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Publication number
WO2013161475A1
WO2013161475A1 PCT/JP2013/058485 JP2013058485W WO2013161475A1 WO 2013161475 A1 WO2013161475 A1 WO 2013161475A1 JP 2013058485 W JP2013058485 W JP 2013058485W WO 2013161475 A1 WO2013161475 A1 WO 2013161475A1
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WO
WIPO (PCT)
Prior art keywords
superconducting
core
filament
wire
mgb
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PCT/JP2013/058485
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English (en)
Japanese (ja)
Inventor
洋太 一木
和英 田中
一宗 児玉
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株式会社 日立製作所
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Application filed by 株式会社 日立製作所 filed Critical 株式会社 日立製作所
Publication of WO2013161475A1 publication Critical patent/WO2013161475A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F6/00—Superconducting magnets; Superconducting coils
    • H01F6/06—Coils, e.g. winding, insulating, terminating or casing arrangements therefor
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N60/00—Superconducting devices
    • H10N60/01—Manufacture or treatment
    • H10N60/0856—Manufacture or treatment of devices comprising metal borides, e.g. MgB2

Definitions

  • the present invention relates to a MgB 2 superconducting magnet.
  • the critical temperature (transition temperature) of magnesium diboride (MgB 2 ) is 39K, which is higher than the critical temperature of conventional metal superconductors (eg, niobium titanium (NbTi), niobium 3 tin (Nb 3 Sn), etc.).
  • a wire using MgB 2 has a feature of high magnetic field stability when operated in a permanent current mode in a closed circuit using the wire.
  • Persistent current mode is an operation method that keeps current flowing in a closed circuit formed using a superconductor. That is, since the resistance of the superconducting wire is zero, once the current flows through the closed circuit, the current continues to flow without being attenuated.
  • a technique for connecting the ends of the superconducting wires with a superconductor is important.
  • Superconducting wire is generally used as a multicore wire composed of multiple superconducting filaments from the viewpoint of current capacity, wire length, magnetic stability, and AC loss. Is done.
  • MgB 2 wire material or a MgB 2 wire material
  • the following techniques are known.
  • Patent Document 1 describes a method for connecting MgB 2 wires using superconducting solder.
  • Superconducting wire connecting methods using superconducting solder are also used for connecting other superconducting wires such as NbTi wires.
  • Patent Document 2 filled with MgB 2 powder after inserting the MgB 2 wire material to the pipe, the connection method of the MgB 2 wire member for crimping them are described.
  • a method of mixing a metal having a low melting point is described in order to improve the bonding between the particles of MgB 2 powder.
  • Non-Patent Document 1 a wire containing a mixed powder of magnesium and boron, or an MgB 2 wire is inserted into a cylindrical container, and the mixed powder is filled and pressed from the opposite side with respect to the wire, followed by heat treatment. It is described. A sintered body of MgB 2 is generated by the heat treatment, and the wires are connected to each other.
  • JP 2006-174546 A Japanese Patent Laid-Open No. 2003-22719
  • An object of the present invention is to improve the current-carrying characteristics of the superconducting connection.
  • the present invention provides a multi-core superconducting wire having a plurality of filaments each having an MgB 2 core covered with a metal sheath, a superconducting coil wound around the multi-core superconducting wire, and the multi-core superconducting wire.
  • a superconducting magnet having a superconducting connecting portion in which an end portion of another superconducting wire is integrated via a sintered body containing MgB 2 , the plurality of filaments in the superconducting connecting portion are separated from each other.
  • Each of the filaments exposes the MgB 2 core in a part of the end portion in the circumferential direction, and forms an exposed surface that is partially exposed in the length direction from the end portion.
  • the area is larger than the cross-sectional area of the MgB 2 core when cut at a right angle to the length direction at the end of the filament.
  • the energization characteristics of the superconducting connection can be enhanced.
  • Configuration example of a superconducting magnet The example of the edge part process of a multi-core strand wire.
  • containers front view, top view, side view
  • connection part sectional view.
  • positioning in a connection part The example which has arrange
  • a plurality of filaments containing Mg and B or a compound containing them are bundled to form a single superconducting wire (multi-core superconducting wire).
  • the connection structure of the superconducting wire is inserted into a container with each filament in the superconducting wire separated one by one, filled with powder of Mg and B, or a compound containing them, and then subjected to heat treatment.
  • MgB 2 is generated in the connection portion.
  • the superconducting magnet is used in an MRI (Magnetic Resonance Imaging) apparatus, an NMR (Nuclear Magnetic Resonance) apparatus, or the like. Since such a device requires high magnetic field stability, the superconducting magnet is constituted by a superconductor alone to form a closed circuit and is operated in a “permanent current mode” in which a current continues to flow. For that purpose, a technology for connecting the superconducting coil, the permanent current switch, and the wiring connecting them through the superconductor is essential.
  • NbTi or Nb 3 Sn superconducting wires are used, and many of them are cooled to 4.2 K with liquid helium and operated.
  • a connection technique using superconducting solder typified by a PbBi alloy has been established.
  • Magnesium diboride (MgB 2 ) has a higher critical temperature for transition to superconductivity than conventional metal materials, and is expected to be put to practical use as a superconducting magnet by cooling with a refrigerator that does not use liquid helium. In that case, since it is calculated
  • the connection structure of the present invention is a superconducting connection part in which a multi-core superconducting wire containing MgB 2 , another superconducting wire to be connected, and a sintered body containing MgB 2 are integrated.
  • a plurality of filaments constituting the multi-core superconducting wire are separated from each other, and are connected to another superconducting wire by a sintered body.
  • the filament is a single core wire in which a MgB 2 core is covered with a metal sheath.
  • each filament in the multifilamentary wire is separated and inserted into a pressurized container, and the container is filled with Mg and B, or a powder of a compound containing them, pressurized, and heat treated to form Mg and B.
  • MgB 2 is produced by reaction. Instead of filling the MgB 2, because it produces a MgB 2 inside the container is a connection part, a good bonding between MgB 2 particles.
  • Each filament widely exposes the MgB 2 core by polishing or the like.
  • the core is exposed by a predetermined length in the length direction from a part of the filament in the circumferential direction.
  • the exposed area of the MgB 2 core can be increased as compared with the case of a multi-core superconducting wire in which a plurality of filaments are integrated in the base material.
  • a plurality of filaments with the MgB 2 core exposed are arranged, filled with powder forming a sintered body, and pressed in the radial direction, not in the filament length direction. That is, since the filament does not protrude in the direction of pressurizing the filled powder, the filament is not bent, so that the raw material powder can be pressed with high density. If it is heat-treated to produce MgB 2 , it is possible to realize a connection structure having high current-carrying characteristics with good intergranular connectivity.
  • FIG. 1 shows a configuration example of a superconducting magnet.
  • the superconducting magnet 17 of FIG. 1 has a superconducting coil 12 and a permanent current switch 13 disposed inside a cooling vessel 16, and these are cooled by a refrigerator (not shown) via a support plate 15.
  • Two superconducting connections 11 are provided between the superconducting coil 12 and the permanent current switch 13.
  • At least one of the superconducting wires to be connected is a multi-core superconducting wire having a plurality of filaments in which a core containing a raw material powder of MgB 2 or MgB 2 is coated with a metal sheath.
  • Mg powder or Mg compound powder and B powder or B compound powder are placed around the end of the wire and sintered under pressure to produce MgB 2 To do.
  • This embodiment can also be used to connect different types of superconducting wires.
  • the other superconducting wire to be connected can be NbTi wire, Nb 3 Sn wire or the like in addition to the MgB 2 superconducting wire, or a single core wire having a single filament.
  • the most common method for producing multi-core superconducting wire is to fill a metal tube with raw material powder, incorporate the drawn single core wire into a metal tube (base material), and further draw it.
  • base material a metal tube
  • the base material and a plurality of single core wires (filaments) are integrated.
  • the core exposed area is small, so a large current carrying capacity Cannot be secured. Even if it is cut obliquely, it is difficult to sufficiently increase the core exposed area for all filaments.
  • each filament was separated and polished to expose the core for each.
  • a method of mechanically polishing the base material or a method of chemically dissolving the base material can be considered.
  • the manufacturing method of multi-core wires not the method of incorporating multiple single-core wires into the base material, but finally drawing the single-core wires to the required filament diameter and twisting them together to form a multi-core superconducting wire It was a method. If it is in the state of a stranded wire, it can be used as a multi-core superconducting wire, and each filament can be separated by simply unwinding the wire without any special treatment.
  • FIG. 2 shows an example in which the end of the multi-core superconducting wire is separated and the core is exposed.
  • the filaments 4 constituting the multi-core superconducting wire 18 are unwound and separated one by one, the sheath 9 at the end is removed, and the core 8 is exposed.
  • the core may be exposed in any way as long as the core is not damaged or deteriorated, but a mechanical polishing method is general.
  • the larger the exposed surface area of the core the larger the contact area with the sintered body, so that the current carrying capacity at the interface with the sintered body is increased.
  • the exposed area should be determined by the current-carrying characteristics of the filament.
  • the exposed surface of the present invention means a portion where the sheath is peeled off and the core is exposed in the length direction of the filament.
  • the filaments are arranged side by side on one plane, and the exposed surface Should be oriented in the same direction. Further, since the sheath 9 remains on the side opposite to the exposed surface of the filament, the core can be made difficult to collapse even when the sintered body is pressed.
  • Mg powder or Mg compound powder and B powder or B compound powder are used as the raw material powder of MgB 2 for constituting the connecting portion.
  • an Mg alloy can be used to improve the reactivity, or an MgB 2 powder can be mixed to increase the density.
  • a compound containing carbon such as SiC, for the purpose of improving the current-carrying characteristics in a high magnetic field.
  • FIG. 3 shows a front view, a top view, and a side view of a container used for connecting a superconducting wire.
  • the container 1 is provided with a hole 2 for inserting a filament and a hole 3 for filling and pressurizing powder.
  • the filament is bent when the powder is pressurized, and the powder density at the end of the wire cannot be increased. Therefore, by opening the hole 3 in the radial direction of the filament as shown in FIG. 3, when pressed, the filament is pressed against the bottom surface of the hole 3 while lying down, so that the powder density near the end of the wire is increased. Can do.
  • the angle between the hole 2 and the hole 3 does not need to be strictly a right angle, and the container 1 may not be a rectangular parallelepiped. However, in order to improve the bondability between the filament core and the sintered body, the container 1 may be close to a right angle. desirable.
  • FIG. 3 shows a case where two multi-core superconducting wires formed of seven filaments are connected.
  • the container 1 is provided with 14 holes 2 for inserting filaments. It is possible to leave a large hole 2 so that all the filaments are all inserted into one hole. However, when pressing the raw material powder of the sintered body, the gap between the hole 2 and the filament is made as small as possible. In consideration of preventing leakage and fixing the filaments, it is desirable to make one hole 2 for each filament. If the number of wires or the number of filaments changes, the number of holes 2 also needs to be changed. Further, when the connecting wire is inserted into the container from the same direction, the space is hardly wasted, workability is improved, and a process such as heat treatment is facilitated. Therefore, in FIG. 3, the hole 2 is opened from the same direction. However, the insertion direction of the wire can be changed according to workability and installation location.
  • the hole 3 for filling the powder is preferably tapered at the entrance in consideration of workability at the time of filling.
  • the manufacturing procedure of the connecting portion is as follows. As shown in the sectional view of FIG. 4, the filament 4 is first inserted into the container 1.
  • the core portion at this time may be either Mg or B in an unreacted state or MgB 2 already generated. After inserting the filament 4, the powder containing Mg and B is filled, and the powder is pressed by the pressing member 6.
  • the pressurizing member 6 may be made of a hard material such as stainless steel or iron. After pressurization, the pressurizing member 6 for pressurizing may be removed as shown in FIG. When removed, the pressure member 6 can be reused many times.
  • the pressurized powder is heated to produce MgB 2 .
  • the heat treatment for generating MgB 2 is usually set to 500 ° C. to 800 ° C. using an electric furnace in vacuum or in an inert gas such as argon or nitrogen.
  • MgB 2 is generated simultaneously with the connecting portion.
  • Fe, Ni, Nb, Ta or their alloys are used as the material of the container 1 so that the container 1 does not react with Mg or B during the heat treatment.
  • MgB 2 is brittle, it is better not to move as much as possible after heat treatment. Therefore, it is desirable to fix the container 1 and the filament 4 with a wire fixing member 7 such as resin or solder.
  • the filament 4 and the container 1 are fixed after the heat treatment. This is because the heat treatment temperature is high and the solder and resin are melted.
  • FIG. 6 is a cross-sectional view taken along the line AA ′ in the cross-sectional view of the connection portion shown in FIG.
  • a 7-core wire (filament) 4A and a 7-core wire (filament) 4B are arranged side by side, and the respective filaments 4A and 4B are inserted into the container 1.
  • the multi-core superconducting wire composed of the filament 4A and the multi-core superconducting wire composed of the filament 4B are connected.
  • the current flowing through the sintered body at the boundary portion is the sum of the current flowing through each filament, and a large current flows locally. Therefore, if the filaments 4A and 4B are arranged so as to be adjacent to each other, it becomes easier for the current to flow through the sintered body as a whole, and a large current can be prevented from flowing locally. In particular, if the filaments 4A and 4B are alternately arranged as shown in FIG. 7, the current flowing through the sintered body is equalized, and no large current flows locally.
  • a partition 10 made of a non-superconducting material it is possible to reliably control the path of the current flowing through the plurality of sintered bodies. As a result, a large current path can be prevented, leading to an improvement in magnetic stability.
  • one of the filaments 4A and one of the filaments 4B are taken as a set and are divided by the partition 10 one by one, the current will not be redistributed at the connecting portion. It is desirable to partition each filament.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)

Abstract

La présente invention concerne un aimant supraconducteur (17) équipé : d'un matériau filiforme supraconducteur multipolaire (18) comprenant une pluralité de filaments (4) dans lequel un noyau de MgB2 (8) est recouvert par une gaine métallique (9); d'une bobine supraconductrice (12) dans laquelle le matériau filiforme supraconducteur multipolaire est enroulé; et d'une partie de connexion supraconductrice (11) dans laquelle une partie d'extrémité du matériau filiforme supraconducteur multipolaire et une partie d'extrémité du matériau filiforme supraconducteur sont assemblées par un corps fritté (5) comportant du MgB2. Chacun de la pluralité de filaments dans la partie de connexion supraconductrice se trouve en un état séparé, et chacun des filaments comprend le noyau en MgB2 exposé au niveau d'une partie dans la direction circonférentielle de la partie d'extrémité. En outre, une surface exposée dans laquelle une partie qui est exposée dans la direction longitudinale depuis la partie d'extrémité est formée, et la superficie de la surface exposée est plus grande que la superficie de section transversale du noyau en MgB2 lorsque la section transversale est formée à angle droit par rapport à la direction longitudinale à la partie d'extrémité du filament.
PCT/JP2013/058485 2012-04-23 2013-03-25 AIMANT SUPRACONDUCTEUR À BASE DE MgB2 WO2013161475A1 (fr)

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JP2012-097254 2012-04-23
JP2012097254A JP2013225598A (ja) 2012-04-23 2012-04-23 ＭｇＢ２超電導マグネット

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016143416A1 (fr) * 2015-03-10 2016-09-15 株式会社日立製作所 Pièce de connexion de fil supraconducteur
EP3876295A1 (fr) * 2020-03-02 2021-09-08 Hitachi, Ltd. Connecteur de fils supraconducteurs et procédé de connexion de fils supraconducteurs

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017208156A (ja) * 2014-08-29 2017-11-24 株式会社日立製作所 超電導線材の接続部及び超電導線材の接続方法
JP2023086180A (ja) * 2021-12-10 2023-06-22 株式会社日立製作所 超電導コイル装置

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JPH031469A (ja) * 1989-05-29 1991-01-08 Mitsubishi Electric Corp 超電導線および化合物超電導線の接続方法
JPH0384903A (ja) * 1989-08-29 1991-04-10 Mitsubishi Electric Corp 超電導コイル装置
JPH06314584A (ja) * 1993-04-30 1994-11-08 Toshiba Corp 超電導導体の接続方法
JPH1167523A (ja) * 1997-08-21 1999-03-09 Toshiba Corp 酸化物超電導線材の接続方法、酸化物超電導コイル装置およびそれを用いた超電導装置
JP2003022719A (ja) * 2001-07-10 2003-01-24 Hitachi Ltd 超電導接続構造
JP2008258158A (ja) * 2007-03-30 2008-10-23 General Electric Co <Ge> ワイヤを連結するための低抵抗率ジョイント並びにその製作方法
JP2012094413A (ja) * 2010-10-28 2012-05-17 Hitachi Ltd 超電導線材の接続部及び超電導線材の接続方法

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JPH031469A (ja) * 1989-05-29 1991-01-08 Mitsubishi Electric Corp 超電導線および化合物超電導線の接続方法
JPH0384903A (ja) * 1989-08-29 1991-04-10 Mitsubishi Electric Corp 超電導コイル装置
JPH06314584A (ja) * 1993-04-30 1994-11-08 Toshiba Corp 超電導導体の接続方法
JPH1167523A (ja) * 1997-08-21 1999-03-09 Toshiba Corp 酸化物超電導線材の接続方法、酸化物超電導コイル装置およびそれを用いた超電導装置
JP2003022719A (ja) * 2001-07-10 2003-01-24 Hitachi Ltd 超電導接続構造
JP2008258158A (ja) * 2007-03-30 2008-10-23 General Electric Co <Ge> ワイヤを連結するための低抵抗率ジョイント並びにその製作方法
JP2012094413A (ja) * 2010-10-28 2012-05-17 Hitachi Ltd 超電導線材の接続部及び超電導線材の接続方法

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Title
WEIJUN YAO ET AL.: "A Superconducting Joint Technique for MgB2 Round Wires", IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, vol. 19, no. 3, June 2009 (2009-06-01), pages 2261 - 2264 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016143416A1 (fr) * 2015-03-10 2016-09-15 株式会社日立製作所 Pièce de connexion de fil supraconducteur
JPWO2016143416A1 (ja) * 2015-03-10 2017-10-19 株式会社日立製作所 超電導線材の接続部
US10714238B2 (en) 2015-03-10 2020-07-14 Hitachi, Ltd. Joint for superconducting wire
EP3876295A1 (fr) * 2020-03-02 2021-09-08 Hitachi, Ltd. Connecteur de fils supraconducteurs et procédé de connexion de fils supraconducteurs
US11972877B2 (en) 2020-03-02 2024-04-30 Hitachi, Ltd. Superconducting wire connector and method of connecting superconducting wires

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