JP4016549B2 - Superconducting wire and superconducting coil device using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internal forced cooling type superconducting wire using aluminum as a stabilizing material, and a superconducting coil device using the superconducting wire.
[0002]
[Prior art]
Conventional superconducting wires using metal-based superconductors, such as NbTi alloys and Nb ₃ Sn compounds, have a low electrical resistivity at an extremely low temperature around 4.2 K, which is the operating temperature, in order to stabilize the superconducting state. As a stabilizing material, it is necessary to have a configuration in which a superconductor is embedded therein, and high-purity aluminum or oxygen-free copper has generally been used as the stabilizing material. Furthermore, in order to use such a superconducting wire in the internal forced cooling type, a superconducting wire having a structure in which a passage for flowing cooling helium is provided in the stabilizing material is considered as an advanced technology.
[0003]
FIG. 8 is a cross-sectional view showing an internal forced cooling type aluminum stabilized superconducting wire as the advanced technology described in Japanese Patent Application No. 11-200043, for example. In FIG. 8, 1 is a superconducting structure in which a superconductor is embedded in copper. An element wire 3 is a stabilizing material made of high-purity aluminum in which the superconducting element wire 1 is embedded, and 12 is a cooling hole provided in the stabilizing material 3. Aluminum is used as a stabilizing material because of its low electrical resistance, and its electrical resistivity near 4.2 K is required to be about 1/300 or less of room temperature.
[0004]
In order to obtain the superconducting wire having such a configuration, the superconducting element wire 1 manufactured in advance is continuously supplied to the aluminum composite extrusion apparatus, the needle is positioned and formed to form the cooling hole 12, and the extrusion process is performed. Then, the aluminum conductor 3 is coated around the superconducting element wire 1, and a superconducting wire having a cooling hole 12 formed in the stabilizer is continuously manufactured.
[0005]
The superconducting wire thus constructed is wound to form a superconducting coil, and about 4.5K supercritical pressure helium is circulated through the cooling hole to cool to a very low temperature, and the coil is brought into a superconducting state. It is used for the purpose.
[0006]
[Problems to be solved by the invention]
Since the conventional superconducting coil device is constructed and manufactured as described above, it is necessary to hold the superconducting element wire 1 and the cooling hole needle in a predetermined position in the cross section in the stabilizing material. Their position is unstable, and there is a problem that the superconducting wire enters into the cooling hole.
[0007]
The present invention has been made to solve the above-described problems, and can obtain a superconducting wire that can be manufactured in a dimensionally stable and inexpensive manner, and a superconducting coil device that uses the superconducting wire. For the purpose.
[0008]
[Means for Solving the Problems]
The superconducting wire according to the present invention is obtained by embedding a superconducting element wire, which is a composite of copper and a metallic superconductor, and a metal tube in an aluminum stabilizing material.
[0009]
The superconducting wire and the metal tube are adjacent to each other.
[0010]
In addition, a plurality of superconducting wires are twisted around a metal tube.
[0011]
Further, a groove having a depth of ½ or more of the diameter of the superconducting element wire is provided on the outer periphery of the metal tube, and the superconducting element wire is embedded in the groove.
[0012]
Further, a groove is provided on the inner surface of the metal tube.
[0013]
The material of the metal tube is aluminum.
[0014]
The material of the metal tube is a high electrical resistance material.
[0015]
The high electrical resistance material is austenitic stainless steel.
[0016]
The superconducting coil device according to the present invention uses the superconducting wire.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a superconducting element wire that is a composite of copper and a metallic superconductor, 2 is a metal tube arranged in parallel to the superconducting element wire 1, and 3 is embedded in the superconducting element wire 1 and the metal tube 2. It is an aluminum stabilizer.
[0018]
In order to obtain a superconducting wire having such a configuration, a superconducting wire 1 and a metal tube 2 manufactured in advance are bundled and continuously supplied to an aluminum composite extrusion device. A superconducting wire having a structure embedded in aluminum in a state where the superconducting wire 1 and the metal tube 2 are in close contact with each other is continuously manufactured.
[0019]
In the present invention, needles are not required to form the cooling holes required in the prior art, their relative positions are stable, and there is a possibility that the superconducting wires may enter the cooling holes. Not at all.
[0020]
The superconducting wire 1 may be simply bundled in parallel with the metal tube 2 or may be bundled with a thin metal wire such as a copper wire or an aluminum wire. Furthermore, as shown in FIG. 2, it may be wound around the metal tube 2. The metal tube 2 must naturally be airtight in order to allow helium to flow through it.
[0021]
The superconducting wire constructed in this way is wound to form a superconducting coil, and about 4.5K supercritical pressure helium is circulated in the cooling hole, for example, to cool to a very low temperature, and the coil is brought into a superconducting state. Never energize it and use it for the intended purpose.
[0022]
Embodiment 2. FIG.
In the first embodiment, the case where there is one superconducting element wire 1 has been described. However, as shown in FIG. 3, a plurality of superconducting element wires are twisted around the metal tube 2 so that the metal tube is connected to the core. Since the twisted wire 1a is configured, a superconducting wire having a larger current carrying capacity and a superconducting coil device using the superconducting wire can be obtained.
[0023]
Embodiment 3 FIG.
In the first and second embodiments, the case where the outer periphery of the metal tube has a smooth cylindrical surface is illustrated. However, as shown in FIG. 4, at least 1/2 of the diameter of the superconducting element wire 1 on the outer periphery of the metal tube 2a. Since the groove having the above depth is provided, and the superconducting element wire 1 is embedded and bundled in the groove and supplied to the extruder, the mutual position of the superconducting element wire and the metal tube is further dimensionally determined at the time of extrusion. A stable, good yield, inexpensive and long superconducting wire and a superconducting coil device using the same can be obtained.
[0024]
Embodiment 4 FIG.
In the first to third embodiments, the case where the inner surface of the metal tube 2b is smooth is illustrated. However, as shown in FIG. 5, a groove is provided on the inner surface of the metal tube 2b to increase the surface area of the inner surface of the metal tube. As a result, it is possible to obtain a superconducting wire that has better cooling characteristics and is small and inexpensive, and a superconducting coil device using the same.
[0025]
Embodiment 5 FIG.
In the first to fourth embodiments, the material of the metal pipe is not particularly mentioned. Usually, however, the helium pipe at the terminal portion is joined as a coil, and thus there is reliability such as brazing and the construction is easy. An oxygen-free copper tube may be used. Oxygen-free copper tubes are also convenient as cooling tubes because they are easy to manufacture as long tubes and are inexpensive. However, when the superconducting coil device is used, when the magnetic field, the coil energization current, and the cooling tube dimensions are large, the aluminum stabilizer and the copper cooling tube are different metals, so there is some heat generation in the superconducting coil. When the superconducting wire becomes normal conducting, a Hall electric field represented by the formula (1) is generated in the cross section of the superconducting wire between the stabilizing material and the metal tube.
[0026]
E _H = B × J _T × R (1)
[0027]
In Equation (1), B (T) is the magnetic field applied to the superconducting wire, E _H (V / m) is the potential gradient generated in the cross section of the superconducting wire, that is, the Hall electric field, and J _T (A / m ² ) is Since the superconductor has become a normal conductor, the current density of the transport current inside each of the stabilizer and the metal pipe, R (m ³ / C) is the stabilizer aluminum and copper of the metal pipe material. It is a unique Hall coefficient. The relationship between E _H , B, and J _T is as shown in FIG. In the figure, for E _H and J _T , the generated materials are added as additional subscripts Al and Cu. A Hall voltage whose approximate value is represented by Equation (2) is generated by the Hall electric field represented by Equation (1).
[0028]
V _H ≒ E _H × L _C (2)
[0029]
In Equation (2), E _H (V / m) is the Hall electric field, V _H (V) is the Hall voltage, L _C (m) is the representative length of the metal tube, for example, the diameter of the tube (indicated by d in the figure). ). Depending on the dimensions of the metal tube and the electrical resistivity of the material, the Hall current _JH shown in FIG. 6 flows in the metal tube and the aluminum stabilizer. In an extremely low temperature state, the electrical resistance is extremely small, that is, 1/300 or less of room temperature in the case of aluminum and 1/100 or less in the case of copper. Therefore, the Hall current generated by the Hall electric field is extremely May grow. When the Hall current is increased to the same level as the transport current, a larger Joule loss occurs in the stabilizing material than in the case where only the transport current shunted from the superconducting wire flows through the stabilizing material, which in turn increases the superconducting stability. Reduce. This means that the limit of the current capacity that can be stably energized is greatly reduced, and the performance of the superconducting wire is greatly impaired.
[0030]
Therefore, in the present embodiment, in order to prevent deterioration of the superconducting wire stability due to the Hall electric field as described above, the metal tube 2c is made of phosphorous deoxidized copper which is copper having a relatively large resistance. At an extremely low temperature, the electrical resistance of phosphorous-deoxidized copper is about 10 times that of oxygen-free copper, and the electrical resistance of the circuit through which the hole current flows is increased and the hole current is reduced compared to the case where the metal tube is oxygen-free copper. Therefore, the superconducting stability is not greatly impaired. Moreover, the phosphorous-deoxidized copper has the same ease of brazing as oxygen-free copper, and the manufacturing advantages are maintained.
[0031]
By doing in this way, the superconducting wire which has a required characteristic and the superconducting coil apparatus using the same can be obtained cheaply.
[0032]
Embodiment 6 FIG.
In this embodiment, pure aluminum is used as a material for the metal tube. FIG. 7 shows a pipe joint portion of the cooling pipe of the superconducting coil terminal portion in the present embodiment.
[0033]
Since the metal pipe 2 embedded in the stabilizing material 3 is connected to the cooling pipe at the end, the metal pipe portion is exposed from the stabilizing material and connected to the pipe 4 via the pipe joint 5. When normal oxygen-free copper is adopted as the metal pipe material embedded in the superconducting wire, the connection part between the metal pipe 2 and the pipe joint 5 is performed by brazing.
[0034]
On the other hand, if the metal pipe material is aluminum, the pipe joint 5 can also be made of aluminum, and the connection between the metal pipe and the pipe joint can be welded with higher reliability. In the case where pressure resistance is required for the metal tube, an aluminum alloy may be adopted as the metal tube material.
[0035]
Further, if the metal tube material is aluminum, it is the same material as the stabilizing material. Therefore, the Hall electric field described in the fifth embodiment is the same between the stabilizing material portion and the metal tube portion and cancels out. Does not flow, the superconducting stability of the superconducting wire does not deteriorate, and the current carrying capacity characteristic does not deteriorate. Aluminum tubes are convenient as cooling tubes because they are easy to manufacture as long tubes and are inexpensive.
[0036]
By doing in this way, the superconducting wire which has a required characteristic and the superconducting coil apparatus using the same can be obtained cheaply.
[0037]
Embodiment 7 FIG.
In the present embodiment, austenitic stainless steel is used as the metal tube material. By doing in this way, similarly to the said Embodiment 6, reliable welding can be employ | adopted for joining of a cooling pipe and piping in a superconducting coil terminal part.
[0038]
Although the Hall electric field described in Embodiment 5 is generated, the electric resistance of the metal tube at an extremely low temperature is 5000 times larger than that of oxygen-free copper, so that the hole current hardly flows and the superconducting stability of the superconducting wire is impaired. Furthermore, there is no reduction in the current capacity of the superconducting wire.
[0039]
By doing in this way, the superconducting wire which has a required characteristic and the superconducting coil apparatus using the same can be obtained cheaply.
[0040]
【The invention's effect】
Since the superconducting wire according to the present invention has a superconducting element wire, which is a composite of copper and a metallic superconductor, and a metal tube embedded in a stabilizing material made of aluminum, the production yield is good and the cost can be reduced. Have
[0041]
Further, since the superconducting element wire and the metal tube are adjacent to each other, the relative positioning between the superconducting element wire and the metal tube is facilitated, and the manufacturing yield is improved and the manufacturing can be performed at low cost.
[0042]
Further, since a plurality of superconducting wires are twisted around the metal tube, there is an effect that the current carrying capacity can be increased.
[0043]
Further, since a groove having a depth of ½ or more of the diameter of the superconducting element wire is provided on the outer periphery of the metal tube, and the superconducting element wire is embedded in the groove, the relative relationship between the superconducting element wire and the metal tube is increased. Since positioning is further facilitated, the manufacturing yield is further improved.
[0044]
In addition, since the groove is provided on the inner surface of the metal tube, the cooling characteristic can be improved.
[0045]
Further, since the material of the metal tube is aluminum, there is an effect that it is possible to prevent a decrease in superconducting stability due to a hole current.
[0046]
Further, since the material of the metal tube is a high electrical resistance material, there is an effect that it is possible to prevent a decrease in superconducting stability due to a hole current.
[0047]
Further, since the high electrical resistance material is austenitic stainless steel, it has an effect of preventing the deterioration of the superconducting stability due to the hole current.
[0048]
Since the superconducting coil device according to the present invention uses the superconducting wire, the yield of the superconducting wire is improved, so that the device can be manufactured at low cost.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.
FIG. 2 is a perspective view showing Embodiment 1 of the present invention.
FIG. 3 is a cross-sectional view showing a second embodiment of the present invention.
FIG. 4 is a sectional view showing Embodiment 3 of the present invention.
FIG. 5 is a sectional view showing Embodiment 4 of the present invention.
FIG. 6 is a cross-sectional view showing a related situation of a Hall electric field, a magnetic field and a Hall current.
FIG. 7 is a sectional view showing Embodiment 6 of the present invention.
FIG. 8 is a cross-sectional view showing a conventional superconducting coil device.
[Explanation of symbols]
1 superconducting wire, 1a stranded wire, 2, 2a, 2b metal tube,
3 Stabilizer, 4 Piping, 5 Piping joint, 12 Cooling hole.

Claims (9)

A superconducting wire in which a superconducting wire, which is a composite of copper and a metal-based superconductor, and a metal tube are bundled and embedded in a stabilizing material made of aluminum. Claim 1 Symbol placement superconducting wire a plurality of superconducting strands, characterized in that twisted around a metal tube. 3. The superconducting device according to claim 1, wherein a groove having a depth of ½ or more of a diameter of a superconducting element wire of a metal tube is provided, and the superconducting element wire is embedded in the groove. line. The superconducting wire according to any one of claims 1 to 3 , wherein a groove is provided on an inner surface of the metal tube. The superconducting wire according to any one of claims 1 to 4, wherein the metal tube is made of phosphorous deoxidized copper. The superconducting wire according to any one of claims 1 to 4 , wherein a material of the metal tube is aluminum. The superconducting wire according to any one of claims 1 to 4 , wherein the metal tube is made of a high electrical resistance material. The superconducting wire according to claim 7, wherein the high electrical resistance material is austenitic stainless steel. A superconducting coil device using the superconducting wire according to any one of claims 1 to 8 .

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