JP2005268189A - Superconductor apparatus and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superconductor apparatus possible to be joined under the condition of stable construction. <P>SOLUTION: This superconductor apparatus comprises a forced cooling type superconductors 1a and 1b having superconductor twisted wires 2a and 2b and conduits 3a and 3b enclosing the superconductor twisted wires 2a and 2b to form a cooling passage, wherein the the superconductors 1a and 1b connected have end portions facing to each other in the longitudinal direction and truncated in almost right angle to the longitudinal direction of the superconductors 1a and 1b, a copper plate 9 is inserted between the truncated superconductors 1a and 1b, and the superconductors 1a and 1b and the copper plate 9 are abutted and soldered. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a superconducting conductor device and a manufacturing method thereof, and particularly relates to a connection structure and a connection method thereof. For example, it is used for a forced cooling superconducting conductor having a conduit.

  The conventional superconducting conductor butt conductor connecting device has a structure in which a low-resistance metal is inserted and brazed between ends of the superconducting conductor (see Patent Document 1).

Japanese Patent No. 3104823 (Example 3, FIG. 3)

  In the conventional butt conductor connecting device for forced cooling type superconducting conductors having a conduit, brazing is applied to the connection of the superconducting conductors. When applying brazing, it is necessary to melt the brazing material by heating the connecting portion of the superconducting conductor end to a high temperature of, for example, 600 ° C. or more, and to metallurgically bond the superconducting conductor end portions or the interposition material. is there. Superconducting conductors are NbTi / copper composite superconducting wires that are currently in commercial use. When heated to 400 ° C or higher, the current capacity that can be conducted in the superconducting state, that is, the superconducting characteristics, is significantly deteriorated. However, there is a problem that the conventional technology cannot be applied to this type of superconducting conductor.

Further, in other practical Nb ₃ Sn / copper composite superconducting wires, the superconducting characteristics are not deteriorated even if heated to about 700 ° C. for a short time of about several minutes. Although applicable, it is difficult to control the temperature so that it is heated in a narrow temperature range in a short time, and there is also a problem that it is difficult to apply the conventional technique industrially.

  The present invention has been made to solve the above problems, and an object of the present invention is to obtain a superconducting conductor device that can be joined under stable construction conditions. Moreover, it aims at providing the manufacturing method suitable for this apparatus.

  A superconducting conductor device according to the present invention is a forced cooling superconducting conductor having a superconducting stranded wire and a conduit surrounding the superconducting stranded wire to form a refrigerant flow path, and the superconducting conductors to be connected are opposed to each other in the longitudinal direction. Ends are cut at substantially right angles to the longitudinal direction of the superconducting conductor, a copper plate is interposed between the cut ends of the superconducting conductor, and both the superconducting conductor ends and the copper plate are butt-joined with solder. It is a thing.

  Further, a method of manufacturing a superconducting conductor device according to the present invention is a forced cooling superconducting conductor having a superconducting stranded wire and a conduit surrounding the superconducting stranded wire to form a refrigerant flow path. Opposite ends in the longitudinal direction are cut at a substantially right angle to the longitudinal direction of the superconducting conductor, a copper plate is interposed between the cut superconducting conductor ends, and both the superconducting conductors in an inert gas atmosphere containing hydrogen The end and the copper plate are butt-joined with solder.

  Further, a forced cooling superconducting conductor having a superconducting stranded wire and a conduit surrounding the superconducting stranded wire to form a refrigerant flow path, the opposing ends of the superconducting conductors connected in the longitudinal direction of the superconducting conductor are A copper plate is interposed between the cut ends of the superconducting conductor and cut at a substantially right angle with respect to the longitudinal direction. The part and the copper plate are butt-joined with solder.

  Further, a forced cooling type superconducting conductor having a superconducting stranded wire and a conduit surrounding the superconducting stranded wire to form a refrigerant flow path, the opposing ends of the superconducting conductors connected in the longitudinal direction of the superconducting conductor are A copper plate is interposed between the cut ends of the superconducting conductor, cut at a substantially right angle with respect to the longitudinal direction, and thread-like solder is supplied from the outer periphery of the portion to be joined by soldering. The copper plates are butt-joined with solder.

  According to the superconducting conductor device of the present invention, it is possible to ensure the permeability of the solder to the joining surface, and the superconducting conductor can be joined without heating the superconducting conductor to an excessive temperature. A conductor device can be obtained.

  Further, according to the method of manufacturing a superconducting conductor device of the present invention, since the soldering was performed in an inert gas atmosphere containing hydrogen, the contact angle between the solder and the copper plate was greatly reduced, and as a result, the solder for joining It is possible to obtain a superconducting conductor device having good bonding performance and quality with good penetration into the interface, low electrical resistance and uniform bonding.

Embodiment 1 FIG.
1 is a longitudinal sectional view showing a superconducting conductor device according to Embodiment 1 of the present invention, FIG. 2 is a transverse sectional view taken along line AA in FIG. 1, and FIG. 3 is a transverse sectional view taken along line BB in FIG. . The superconducting conductor device has a superconducting conductor 1a of one unit of winding and another superconducting conductor 1b connected to the superconducting conductor 1a. In the figure, end portions of the superconducting conductors 1a and 1b are shown. ing. The superconducting conductor 1a is covered with a superconducting stranded wire 2a, a rectangular conduit 3a surrounding and confining the superconducting stranded wire 2a to form a refrigerant flow path such as liquid helium, and the end of the superconducting conductor 1a being welded to the end of the conduit 3a. It has a circular terminal tube 4a that is fixed and has a reduced diameter on the connecting part (joining part) side, a reduced diameter part 21a, and a refrigerant outlet pipe 7a.

  Similarly, the superconducting conductor 1b is covered with a superconducting stranded wire 2b, a rectangular conduit 3b surrounding and confining the superconducting stranded wire 2b to form a refrigerant flow path such as liquid helium, and a conduit 3b covering the end of the superconducting conductor 1b. It has a circular terminal tube 4b which is welded and fixed to the end and whose connecting portion (joining portion) side is reduced in diameter, a reduced diameter portion 21b, and a refrigerant outlet tube 7b. Reference numeral 10 denotes a joint where the end portions of the superconducting conductors 1a and 1b are connected.

  In superconducting conductors 1a and 1b, opposite ends in the longitudinal direction of the superconducting conductors to be connected are cut at substantially right angles to the longitudinal direction of the superconducting conductors, and the surfaces to be joined are processed flat. A copper plate 9 is interposed between these joint surfaces. The joint surface at the end of the superconducting conductor 1a and the copper plate 9 and the joint surface at the end of the superconducting conductor 1b and the copper plate 9 are joined by solder. In FIG. 2 showing an AA cross section, a superconducting stranded wire 2a is accommodated in a prismatic cross-section conduit 3a to constitute a square cross-sectional superconductor 1a as a whole. In the BB cross section of the superconducting conductor 1a shown in FIG. 3, the outer periphery of the conduit 3a is square, but the outer periphery of the terminal tube 4a is processed into a circle.

  FIG. 4 is a perspective view of the main part of the superconducting conductor device. In FIG. 1, the superconducting stranded wires 2a and 2b are formed by twisting many superconducting strands having a diameter of about 0.7 mm. The conduits 3a and 3b are made of metal and must have high strength, high toughness, high toughness, high weldability and high airtightness, such as stainless steel and titanium. used. The diameter reduction processing of the end portions of the superconducting conductors 1a and 1b is because it is necessary to reduce the porosity of the superconducting stranded wires 2a and 2b and increase the mechanical rigidity in order to accurately process the joining end faces. It is formed by caulking such as drawing.

  Next, the operation will be described. In the superconducting conductor device of the embodiment 1, the gap between the superconducting stranded wires 2a and 2b in the conduits 3a and 3b is 30 to 40% in terms of space factor, and the superconducting conductor device has supercritical helium (refrigerant) as a refrigerant in this gap. SHE) is cooled and held at a temperature of about 4K, which is the operating temperature of the coil, by flowing as indicated by arrow 8 in FIG. Current is applied to the terminal portions of the cooled superconducting conductors 1 a and 1 b, and current flows through the superconducting conductors 1 a and 1 b through the minute resistance of the junction 10. Due to this minute resistance, there is minute heat generation, but this heat generation is cooled by the refrigerant present in the superconducting conductor device, and the coil is maintained in the superconducting state.

  When soldering at the connecting portions at the ends of the superconducting conductors 1a and 1b, the vicinity of the connecting portions is heated to a temperature slightly higher than the solder melting temperature, for example, 250 ° C., and the solder is supplied from the outer periphery to the connecting portions. To do. Since the connection ends of the superconducting conductors 1a and 1b are reduced in diameter, there is a gap of about 20% which is smaller than the general part of the superconducting stranded wires 2a and 2b, and if the copper plate 9 is not present, the solder penetrates along the direction. Due to the scattered voids, good penetration of the solder is hindered, resulting in a solder joint with a low joint area ratio.

  If the solder joint rate is low, the electrical resistance of the joint surface is high, the heat generation is large, the current carrying capacity of the superconducting conductor is reduced, and in the worst case, there is a problem of superconducting breakdown before reaching the predetermined current. . However, in the present invention, since the smooth copper plate 9 exists between the end portions of the superconducting conductors 1a and 1b, the penetration of solder into the interface to be joined becomes extremely good, and an extremely high joining area ratio can be obtained. it can. It is very easy to interpose a copper plate at the joining interface, and a superconducting conductor device having high joining performance and quality and a superconducting coil device using this superconducting conductor device can be obtained.

Embodiment 2. FIG.
The thickness of the copper plate 9 interposed between the ends of the superconducting conductors 1a and 1b will be described. The thicker the copper plate 9 is, the more rigid the plate is and the easier it is to assemble the connecting portion. For example, when the copper plate 9 is extremely thin, the copper plate 9 is buckled during the work of inserting the copper plate due to a slight frictional force received from the ends of the superconducting conductors 1a and 1b. A certain amount of thickness is necessary because it becomes difficult. However, when the copper plate 9 becomes thicker, there is a disadvantage that the electrical resistance of the connecting portion of the superconducting conductors 1a and 1b increases due to the electrical resistance of copper, which is a normal conducting metal. It is necessary to set the thickness.

For example, in the case of a large conductor having a diameter of 40 mm at the ends of the superconducting conductors 1a and 1b, the buckling load of the copper plate 9 is expressed by Expression (1). As the dimensions of the copper plate 9 to be inserted, the diameter is 40 mm and the thickness is T (mm). In equation (1),
Wcr is the buckling load (N),
Ecu is the Young's modulus of the copper plate 9, about 100 (GPa),
I is the cross-sectional second moment of bending of the copper plate, T ³ /0.3 (mm ⁴ ),
D is the diameter of the copper plate 40 (mm).
Wcr = 兀² EcuI / (4D ² ) ---------------------------------

On the other hand, the electrical resistance of the copper plate 9 is expressed by Expression (2). In equation (2),
Rcu is the electrical resistance (Ω) of the copper plate 9 to be inserted into the connection part of the superconducting conductors 1a and 1b,
ρcu is the electrical resistivity of copper at the operating temperature, that is, around 4K, about 1.7 × 10 ⁻¹⁰ (Ωm),
T is the thickness of the copper plate (m),
S is an area of the copper plate ^{1.26 × 10 -3 (m 2)} lO -3 (m 2).
Rcu = ρcu T / S ---------------- Equation (2)

  In FIG. 5, the calculation result of Formula (1) and the calculation result of Formula (2) are shown. As shown in the figure, the buckling load of the copper plate 9 increases rapidly as the thickness of the copper plate 9 increases. As a result of experiments conducted by the inventors to manufacture the end connection portions of the superconducting conductors 1a and 1b, the lower limit of the thickness of the copper plate 9 is about 50 μm, and below this, the copper plate 9 is often buckled and bent. It turned out to be difficult. The electrical resistance of the conductor connecting portion of a large conductor having a diameter of 40 mm can be about 1 to 5 nΩ and can be allowed for heat generation. Although the electrical resistance of the superconducting conductors 1a and 1b is inevitably increased by installing the copper plate, the increase is required to be as small as possible. Specifically, it can be said that there is no problem if it is 1 to 2% of the electrical resistance value of the connection portion of the superconducting conductors 1a and 1b that can be realized without a copper plate.

  As can be seen from FIG. 5, if the upper limit of the thickness of the copper plate is 800 μm, the electrical resistance of the copper plate is approximately 10 nΩ or less, and this condition can be satisfied. If the thickness of the copper plate 9 inserted between the connecting portions of the superconducting conductors 1a and 1b is 50 μm or more and 800 μm or less, the superconducting conductor device having good assemblability and good performance and the superconducting coil device using this superconducting conductor device There is an effect that can be obtained.

Embodiment 3 FIG.
The magnitude | size of the copper plate 9 inserted in the connection part of the superconducting conductors 1a and 1b is demonstrated. When the size of the copper plate is made about 10 mm or more larger than the diameter of the end portions of the superconducting conductors 1a and 1b, the penetration of the supplied solder becomes good. FIG. 6 is a longitudinal sectional view showing the superconducting conductor device in the third embodiment. In the figure, the connecting portion of the superconducting conductors 1a and 1b is heated to a temperature higher than the solder melting temperature by the heater 14, and the solder is supplied to the interface between the copper plate 9 and the end portions of the superconducting conductors 1a and 1b. Here, the diameter of the copper plate 9 protrudes by about 5 mm or more from the outer peripheral ends of the end portions of the superconducting conductors 1a and 1b. Therefore, the molten solder penetrates well between the copper plate 9 which is an interface to be joined along the copper plate 9 and the end faces of the superconducting conductors 1a and 1b.

  If the copper plate has the same diameter as the ends of the superconducting conductors 1a and 1b, the molten solder will not penetrate into the interface, and the solder will flow down the outer peripheral edge of the ends of the superconducting conductors 1a and 1b. It does not penetrate and bonding becomes insufficient. For this reason, the electrical resistance of the connecting portion is high, heat generation is increased, and current carrying capacity is insufficient. As described above, in the third embodiment, since the diameter of the copper plate is larger than the diameter of the end portions of the superconducting conductors 1a and 1b, the penetration into the solder interface for bonding is good, the electric resistance is small, and the uniform There is an effect that it is possible to obtain a superconducting conductor device having high joining performance and quality as a joining and a superconducting coil device using this superconducting conductor device.

Embodiment 4 FIG.
The surface treatment of the copper plate 9 will be described. When the surface of the copper plate 9 is plated with gold, the penetration of the supplied solder becomes good and a solder joint surface with few voids can be obtained. As an index of solder permeability, there is a contact angle that is an angle formed by the outer periphery of the solder grain when the solder grain on the metal surface is heated and melted with the metal surface. The smaller the contact angle, that is, the flatter the molten particles, the better the solder permeability. The inventors placed PbSn solder on bare copper and a gold-plated copper plate, and measured the contact angle when heated to 300 ° C. in a hydrogenated nitrogen gas atmosphere. The results are shown in Table 1.

  According to Table 1, the contact angle when the copper plate remained as the material surface was 90 degrees or more, whereas the contact angle for the gold-plated copper plate was 1 degree or less, and the contact angle decreased dramatically. . As described above, in Embodiment 4, since the surface of the copper plate is gold-plated, the contact angle between the solder and the copper plate 9 is remarkably reduced, and as a result, the penetration into the solder interface for bonding is good. In addition, there is an effect that a superconducting conductor device having low electric resistance and uniform joining and high joining performance and quality and a superconducting coil device using the superconducting conductor device can be obtained.

Embodiment 5 FIG.
The material of the solder will be described. When the material of the solder is high-purity tin Sn, the electrical resistance at the cryogenic temperature at which the apparatus is used is reduced without impairing the permeability of the solder. FIG. 7 shows the results of measuring the electrical resistivity of the PbSn solder and the high-purity Sn (95% or more) solder in the absence of a magnetic field at a temperature of 4.2 K and in a magnetic field application state.

  Comparing the electrical resistivity of both, the PbSn solder is smaller in the absence of a magnetic field, but the Sn solder is smaller at a magnetic flux density of 1T or higher, and the magnetic field to which the conductor connection part is normally exposed, for example, the magnetic flux density of 1T, the Sn solder is smaller. The electrical resistivity is 1/5 that of PbSn solder. As described above, since the high purity Sn is used as the solder material in the fifth embodiment, the superconducting conductor device having high bonding performance and quality with good solder permeability and low electrical resistance, and superconductivity using this superconducting conductor device There is an effect that a coil device can be obtained.

Embodiment 6 FIG.
When phosphorus P is contained in the solder, the penetration of the supplied solder can be improved and a solder joint surface with few voids can be obtained. The contact angle shown above is compared as an index of solder permeability. The inventors measured the contact angle when PbSn solder and P-containing Pb-free solder were placed on a bare copper plate and heated to 350 ° C. in a nitrogen gas atmosphere. The results are shown in Table 2.

  According to Table 2, the contact angle was 90 or more when the solder material was PbSn solder, whereas the contact angle was 45 degrees when the solder containing P was 45 °, and the contact angle was greatly reduced. As described above, in the sixth embodiment, since P is contained in the solder, the contact angle between the solder and the copper plate is greatly reduced, and as a result, the penetration into the solder interface for bonding is good. There is an effect that it is possible to obtain a superconducting conductor device having a low electric resistance and uniform joining and having a high joining performance and quality, and a superconducting coil device using the superconducting conductor device.

Embodiment 7 FIG.
The atmosphere for soldering will be described. When the soldering is performed in a hydrogenated nitrogen atmosphere, the penetration of the supplied solder can be improved and a solder joint surface with few voids can be obtained. The contact angle shown above is compared as an index of solder permeability. The inventors placed PbSn solder on a bare copper plate and measured the contact angle when heated to 300 ° C. in a nitrogen gas and hydrogenated nitrogen atmosphere. The results are shown in Table 3.

  According to Table 3, the contact angle when the soldering atmosphere was nitrogen was 90 degrees or more, whereas the contact angle when hydrogenated nitrogen was 30 degrees, the contact angle was greatly reduced. As described above, in the seventh embodiment, since the soldering atmosphere is hydrogenated nitrogen, the contact angle between the solder and the copper plate is greatly reduced, and as a result, the penetration into the solder interface for bonding is good. In addition, there is an effect that a superconducting conductor device having low electric resistance and uniform joining and high joining performance and quality and a superconducting coil device using the superconducting conductor device can be obtained. The soldering atmosphere may use hydrogenated inert gas instead of hydrogenated nitrogen.

Embodiment 8 FIG.
In each of the above-described embodiments, the case where no gas is allowed to flow inside the ends of the superconducting conductors 1a and 1b has been described. However, an inert gas containing hydrogen is applied to the ends of the superconducting conductors 1a and 1b during soldering. When it flows inside the part, the solder wets well. FIG. 8 is a longitudinal sectional view showing a method of manufacturing the superconducting conductor device in the eighth embodiment. The ends to be connected to the superconducting conductors 1a and 1b and the opposite ends are connected to the hydrogenated nitrogen gas container 20, and hydrogenated nitrogen gas is introduced into the atmosphere from the gap between the copper plate 9 inserted between the soldered ends. To be released.

  As a result, the inside of the superconducting conductors 1a and 1b and the inside of the end portions are in a hydrogenated nitrogen gas atmosphere. When the end connected by the heater 14 is heated to a temperature equal to or higher than the solder melting temperature in this state, an oxide film on the surface of the copper plate inserted between the end surfaces to which the superconducting stranded wires 2a and 2b are connected is reduced by the reduction action of hydrogen. Removed. The gas is stopped for solder penetration, and immediately after that, the solder is supplied to the joint interface, so that the solder material penetrates into the joint interface and good soldering is obtained. As described above, in the eighth embodiment, in the soldering of the end connecting portions of the superconducting conductors 1a and 1b, the inert gas containing hydrogen is caused to flow in the superconducting conductors 1a and 1b and in the end portions. Therefore, it is possible to obtain a superconducting conductor device with high joining performance and quality having a uniform joining, and a superconducting coil device using this superconducting conductor device.

Embodiment 9 FIG.
The heating conditions at the time of solder connection construction of the end connection portions of the superconducting conductors 1a and 1b will be described. If solder is supplied and applied after the heating conditions at the time of solder connection construction are maintained for a predetermined time after reaching a predetermined temperature, wetting and penetration of the solder is improved. FIG. 9 is a diagram for explaining the heating conditions at the time of solder connection construction in the ninth embodiment. The flow of hydrogenated nitrogen gas into the superconducting conductors 1a and 1b and inside the end portions is the same as in the eighth embodiment. After making the inside of superconducting conductors 1a and 1b and the inside of the end thereof into a predetermined gas atmosphere, the end is heated as shown in FIG. By holding this heating temperature, the oxide film on the copper surface can be removed. During this heating temperature holding process, the oxide film on the surface of the copper plate inserted between the end face where the superconducting stranded wire is connected is removed by the reduction action of hydrogen. By performing the solder supply operation, the penetration of the solder material to the joint surface is good and good soldering can be performed.

  As described above, in the ninth embodiment, in the soldering of the end connecting portions of the superconducting conductors 1a and 1b, hydrogenated nitrogen gas is contained in an inert gas atmosphere containing hydrogen, or inside and inside the superconducting conductors 1a and 1b. Since the soldering is performed after the temperature is maintained at a predetermined temperature, the oxide film that obstructs the penetration of the solder is removed, the permeability of the solder is improved, and as a result, the soldering quality is improved and the quality is improved. The superconducting conductor device and a superconducting coil device using this superconducting conductor device can be obtained.

Embodiment 10 FIG.
When soldering is performed after the heating temperature condition at the time of solder connection construction is maintained for 30 seconds after reaching 300 ° C., solder wetting and penetration are improved. Table 4 explains heating temperature conditions in the tenth embodiment. The contact angle shown above is compared as an index of solder permeability. The inventors measured the contact angle when the PbSn solder was placed on a gold-plated copper plate and heated to 250 ° C. and 300 ° C. in a hydrogenated nitrogen atmosphere. The results are shown in Table 4.

  According to Table 4, when the soldering temperature is 250 ° C., the contact angle is 90 degrees or more, whereas when the soldering temperature is 300 ° C., the contact angle is 1 degree or less, and the contact angle is dramatic. Decreased. The soldering temperature may be 300 ° C or higher.

  As described above, in the tenth embodiment, in soldering the superconducting conductors 1a and 1b at the end connecting portions, hydrogenated nitrogen gas is allowed to flow in an inert gas atmosphere containing hydrogen or inside the superconducting conductors 1a and 1b and inside the end portions. However, after maintaining at a predetermined temperature, 300 ° C. heating was maintained for 30 seconds as a condition for soldering, so that the oxide film that hinders solder penetration was removed, and the solder permeability was improved. As a result, the soldering quality is improved, and there is an effect that a superconducting conductor device having high joining performance and quality with uniform joining and a superconducting coil device using this superconducting conductor device can be obtained.

Embodiment 11 FIG.
A method for supplying solder to the interface of the connecting portion will be described. When the solder is supplied from the outer periphery of the interface of the connecting portion along the copper plate to be inserted, so-called soldering, the penetration of the solder is improved. FIG. 10 is a longitudinal sectional view showing a method of manufacturing the superconducting conductor device in the eleventh embodiment. By inserting the thread-like solder 11 from the outer periphery of the copper plate 9 inserted between the end connection portions of the heated superconducting conductors 1a and 1b, the molten solder permeates the interface. Compared with so-called place solder in which solder is placed in advance at the interface, the surface area of the solder is large and the solder does not flow, so the oxide film is at the interface where it is desired to join, and the wettability of the solder is not good. On the other hand, the solder of the eleventh embodiment has a small surface area and melts and the portion having a fresh surface where the oxide film on the surface is broken flows and penetrates, so that the solder has good permeability.

  Thus, in the eleventh embodiment, since solder is supplied from the outer periphery of the conductor connecting portion in the soldering of the end connecting portion of the superconducting conductors 1a and 1b, the oxide film that hinders the penetration of the solder is removed, Improved solder penetration, resulting in improved soldering quality, low electrical resistance, uniform bonding with high bonding performance and quality, and a superconducting coil device using this superconducting device There is an effect that can.

Embodiment 12 FIG.
The process of the part which the copper plate 9 inserted in a connection part interface protrudes to an outer periphery from a junction part is demonstrated. If this projecting part is cut off after soldering, the assembly work after soldering becomes easy. FIG. 11 is a longitudinal sectional view showing a method of manufacturing the superconducting conductor device in the twelfth embodiment. An outer tube 6 is installed in the conductor connection portion for mechanical reinforcement of the joining interface and airtightness against the coil external vacuum at the joining interface. If the outer tube 6 is structured to be in close contact with the outer periphery of the terminal tubes 4a and 4b of the conductor connection portion, the mechanical structure becomes strong.

  When the outer periphery of the interposer copper plate 9 is cut off between the conductor connection portion joint surfaces, the inner surface of the outer tube 6 directly mechanically supports the outer surfaces of the conductor connection portion terminal tubes 4a and 4b, thereby obtaining a strong outer tube 6 mounting structure. it can. As described above, in the twelfth embodiment, since the protruding portion from the outer peripheral end of the joining portion of the intercalated copper plate of the superconducting conductor connecting portion is cut out, the reliability of the mechanical strength of the conductor connecting portion and the reliability of the vacuum airtightness are obtained. As a result, there is an effect that a high-quality superconducting conductor device is obtained.

Embodiment 13 FIG.
The type of superconductor will be described. When the superconductor is applied to a material that requires heat treatment for producing a high-temperature superconductor after forming a winding shape of a superconducting coil such as Nb ₃ Sn, for example, there is an effect of improving the wettability of the solder. _Nb 3 Sn generation heat treatment of a superconducting coil using Nb ₃ Sn superconductors are prolonged heat treatment even 100-500 hours at a high temperature of 600 to 700 ° C. In this heat treatment process, if the inside of the metal tube of the superconducting conductor is isolated from the atmosphere inside the furnace, and a clean inert gas, for example, Ar gas, is circulated inside the metal tube, it is inevitable in the process of manufacturing a superconducting stranded wire. Organic matter adhering to the surface can be almost completely removed by the baking effect.

Although the organic substance adhering to the surface of the superconducting stranded wire inhibits the wettability of the solder to the surface of the superconducting stranded wire, this removal treatment can prevent a decrease in the wettability. Table 5 shows an example of measurement results of the amount of oil and fat adhering to the surfaces of the Nb ₃ Sn superconducting wire subjected to the organic substance removal treatment during the Nb ₃ Sn generating heat treatment and the Nb ₃ Sn superconducting wire not experiencing the generating heat treatment.

As shown in Table 5, the effect of the organic substance removal treatment combined with the Nb ₃ Sn generation heat treatment is remarkable, and the organic substance is almost completely removed. Accordingly, the penetration effect of the solder in the longitudinal direction of the conductor is increased. As described above, in the thirteenth embodiment, since soldering is applied to the junction of the conductor connection portion of the superconducting coil that is subjected to the superconductor generation heat treatment at a high temperature such as Nb ₃ Sn after coil forming, an organic substance that inhibits solder wetting As a result, the solder penetrates more reliably over a wide range, and as a result, the soldering quality is improved.

Embodiment 14 FIG.
In the first embodiment, the case where the internal forced cooling type superconducting conductor in which the superconducting stranded wire is housed in the metal tube is used has been described. However, the superconducting stranded wire is exposed and applied to a superconducting conductor having no metal tube. However, there is an effect that a superconducting conductor device having excellent cooling performance can be obtained. Superconducting conductors that use metal tubes are usually applied to superconducting coil devices that require high strength and high voltage resistance performance, while superconducting coil devices that are directly exposed to a stationary liquid refrigerant such as liquid helium. In comparison, the cooling performance is insufficient. A case will be described in which the cooling performance is more emphasized and applied to the conductor connection part of the superconducting coil device in which the stranded wire is directly exposed to the refrigerant liquid.

FIG. 12 is a perspective view showing a main part of the superconducting conductor device according to the fourteenth embodiment. The end of the superconducting stranded wire is covered with the terminal tube 4. The configuration of the end portions of the terminal tube and the superconducting stranded wire and the form of solder bonding are the same as in the first embodiment. As described above, in the fourteenth embodiment, since the soldering with the copper plate interposed is applied in the conductor connecting portion of the superconducting coil using the superconducting conductor composed only of the stranded wire, the coil cooling performance is higher and the performance is increased. There is an effect that a superconducting conductor device having a high level can be obtained.

It is a longitudinal cross-sectional view which shows the superconducting conductor apparatus in Embodiment 1 of this invention. FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. It is the BB line cross-sectional view of FIG. FIG. 3 is a perspective view of a main part of the superconducting conductor device in the first embodiment. It is a characteristic view which shows the copper plate buckling load with respect to copper plate thickness, and a copper plate electrical resistance. FIG. 5 is a longitudinal sectional view showing a superconducting conductor device in a third embodiment. It is a characteristic view which shows the relationship between the applied magnetic flux density with respect to the kind of solder, and an electrical resistivity. It is a longitudinal cross-sectional view which shows the manufacturing method of the superconducting conductor apparatus in Embodiment 8. It is a figure explaining the heating conditions at the time of the solder connection construction in Embodiment 9. FIG. It is a longitudinal cross-sectional view which shows the manufacturing method of the superconducting conductor apparatus in Embodiment 11. It is a longitudinal cross-sectional view which shows the manufacturing method of the superconducting conductor apparatus in Embodiment 12. It is a longitudinal cross-sectional view which shows Embodiment 12 of this invention. It is a perspective view which shows the principal part of the superconducting conductor apparatus in Embodiment 14. FIG.

Explanation of symbols

1a, 1b Superconducting conductor 2a, 2b Superconducting stranded wire 3a, 3b Conduit 4a, 4b Circular terminal tube 6 Outer tube 7a, 7b Refrigerant outlet tube 8 Arrow 9 Copper plate 10 Junction 11 Threaded solder 14 Heater 20 Hydrogenated nitrogen gas container 21a, 21b Reduced diameter portion.

Claims (14)

  A forced-cooling type superconducting conductor having a superconducting stranded wire and a conduit surrounding the superconducting stranded wire to form a refrigerant flow path, wherein opposite ends of the superconducting conductors connected in the longitudinal direction are in the longitudinal direction of the superconducting conductor A superconducting conductor device in which a copper plate is interposed between the cut end portions of the superconducting conductor, and both the end portions of the superconducting conductor and the copper plate are butt-joined with solder.   The superconducting conductor device according to claim 1, wherein the copper plate has a thickness of 50 μm to 300 μm. The size of the copper plate is larger than the diameter of the opposing end portion of the superconducting conductor when the opposing end portions of the superconducting conductors to be connected are circular,
3. The superconducting conductor device according to claim 1, wherein when the opposing end portion of the superconducting conductor is non-circular, the superconducting conductor device is larger than a maximum passing dimension of the opposing end portion of the superconducting conductor.   The superconducting conductor device according to any one of claims 1 to 3, wherein the copper plate is plated with gold.   The superconducting conductor device according to any one of claims 1 to 4, wherein the solder material contains 95 wt% or more of Sn.   The superconducting conductor device according to any one of claims 1 to 4, wherein the solder material contains P.   A superconducting conductor having a superconducting stranded wire, the opposite ends of the superconducting conductors connected in the longitudinal direction being cut at substantially right angles to the longitudinal direction of the superconducting conductor, and the superconducting conductor ends cut. A superconducting conductor device in which a copper plate is interposed between the ends of the superconducting conductors and the copper plate.   A forced-cooling type superconducting conductor having a superconducting stranded wire and a conduit surrounding the superconducting stranded wire to form a refrigerant flow path, wherein opposite ends of the superconducting conductors connected in the longitudinal direction are in the longitudinal direction of the superconducting conductor A copper plate is interposed between the cut end portions of the superconducting conductor, and both the end portions of the superconducting conductor and the copper plate are butt-joined with solder in an inert gas atmosphere containing hydrogen. A method of manufacturing a superconducting conductor device.   9. The method of manufacturing a superconducting conductor device according to claim 8, wherein an inert gas containing hydrogen is caused to flow inside the conduit of the superconducting conductor and the ends of the superconducting conductors and the copper plate are butt-joined by solder.   A forced-cooling type superconducting conductor having a superconducting stranded wire and a conduit surrounding the superconducting stranded wire to form a refrigerant flow path, wherein opposite ends of the superconducting conductors connected in the longitudinal direction are in the longitudinal direction of the superconducting conductor The superconducting conductor ends are cut at a substantially right angle, a copper plate is interposed between the cut ends of the superconducting conductors, and after holding a part or the whole to be joined with solder at a predetermined temperature for a predetermined time, A method of manufacturing a superconducting conductor device in which the copper plates are butt-joined with solder.   The method for manufacturing a superconducting conductor device according to claim 10, wherein the temperature of the portion to be joined with solder is set to 300 ° C. or higher.   A forced-cooling type superconducting conductor having a superconducting stranded wire and a conduit surrounding the superconducting stranded wire to form a refrigerant flow path, wherein opposite ends of the superconducting conductors connected in the longitudinal direction are in the longitudinal direction of the superconducting conductor A copper plate is interposed between the cut ends of the superconducting conductor, and a thread-like solder is supplied from the outer periphery of the portion to be joined with the solder, between the ends of both the superconducting conductors and the copper plate. Of manufacturing a superconducting conductor device in which butt is joined with solder.   The method for manufacturing a superconducting conductor device according to any one of claims 8 to 12, wherein a portion protruding from the joining portion of the end portion of the superconducting conductor after joining with solder is deleted.   The superconducting device according to any one of claims 8 to 13, wherein organic substances adhering to the surface of the superconducting stranded wire are thermally decomposed and removed during heat treatment for generating a superconducting material at a high temperature of the superconducting material of the superconducting conductor. A method for manufacturing a conductor device.

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