JPH0250565B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a superconducting wire used in a superconducting coil of a superconducting magnet such as a nuclear fusion reactor, and particularly to a type of superconducting wire that is forcedly circulated and cooled by a cooling medium.

Recently, a so-called hollow superconducting wire with a cooling medium passage formed in the center of its cross section has been used, and a cooling medium such as supercritical pressure helium is forced to circulate in the cooling medium passage to forcibly cool the superconducting wire from the inside. Various coils have been proposed. A hollow superconducting wire used in such a superconducting coil is, for example, as shown in FIG. A type in which strands 3A are embedded, or a type in which ultrafine multicore superconducting strands 3B are wound or twisted around the outer surface of a stabilizing base material 2 made of copper or the like, which also has a rectangular cross section, as shown in Fig. 2. Furthermore, as shown in FIG. 3, grooves 4 are formed on the outer surface of the stabilizing base material 2 having a rectangular cross section, and shaped superconducting wires 3C are fitted and fixed in each groove 4. There are things etc.

In superconducting magnets using such forced cooling type superconducting wires, the cooling medium is forced to circulate inside the conductor, so each part is evenly cooled, and the coil is compact and has high mechanical strength. However, on the other hand, since the superconducting wires are cooled indirectly through a stabilizing base material such as copper, the cooling efficiency is low, which may cause some problems. There is a problem in that when a heat spot occurs in a part of the superconducting wire and the superconducting properties are lost, the recovery is delayed.

On the other hand, as shown in FIG. 4, a large number of superconducting strands 3B are housed inside a rectangular cylindrical body 6, and a cooling medium such as liquid helium is allowed to flow through the gaps 7 between the superconducting strands. A bundle type superconducting wire has also been proposed, and in this case, superconducting wire 3B
Direct cooling is performed by bringing the cooling medium into direct contact with the surface. However, in this type of superconducting wire, it is extremely difficult to allow the coolant to flow smoothly, and the flow of the coolant can locally become stagnant, causing the temperature to rise, creating heat spots, or causing the heat spots to recover quickly. There is a drawback that it is not carried out.

Therefore, the present inventors took advantage of the above-mentioned hollow superconducting wire and the direct cooling type superconducting wire shown in FIG. 4 to achieve a high overall cooling efficiency and good local stability. A superconducting wire with a structure that can withstand electromagnetic force was proposed in Japanese Patent Application No. 1-31244. An example of this proposed superconducting wire is shown in FIG.

In FIG. 5, inside the stabilizing base material 10, which is hollow and has a rectangular cross section and is made of a highly conductive material such as copper, copper alloy, high-purity aluminum, or aluminum alloy, Nb-Ti alloy, Nb-Ti-Ta A plurality of superconducting wires 11 made of an alloy-based superconducting material such as an alloy or a compound-based superconducting material such as Nb ₃ , Sn, V ₃ Ga, Nb ₃ Ge, etc. are accommodated. The outside of the stabilizing base material 10 is covered with a rectangular cross-sectional outer covering made of copper, stainless steel, titanium, titanium alloy, etc., with an appropriate number of separators 12 made of the same material as the stabilizing base material 10 or stainless steel, etc. surrounded by 13
A coolant flow path 14 is secured between the outer surface of the stabilizing base material 10 and the inner surface of the jacket 13 by the separator 12 . Furthermore, the stabilizing base material 10 includes:
A plurality of communicating passages 15 in the shape of round holes, long holes, or slits are formed to communicate the cooling medium flow path 14 on the outside with the space on the inside. Therefore, the cooling medium such as supercritical pressure helium flowing through the cooling medium flow path 14 flows through the communication path 15 to stabilize the base material 1.
The cooling medium flows into the gap 16 between the superconducting strands 11 inside the 0, and comes into direct contact with the superconducting strands 11. A flow of the cooling medium also occurs in the inter-wire gaps 16 of the superconducting wires 11 inside the stabilizing base material 10.

In the above-proposed superconducting wire, overall cooling is achieved by a steady flow of the cooling medium flowing through the cooling medium channel 14 outside the stabilizing base material 10, so that it is similar to the case of the conventional hollow superconducting wire. Uniform cooling is performed, and since the linear cooling medium comes into contact with the superconducting wire 11 itself inside the stabilizing base material 10 and is directly cooled, the cooling efficiency is high, and the cooling efficiency is high. A communication path 15 is connected to the inner cooling medium.
Because the superconducting wire is exchanged by flowing in and out through There is very little delay in cooling, and therefore the total cooling efficiency is excellent, and at the same time, steady stability and transient stability are also extremely excellent. In addition, in the superconducting wire proposed above, when a disturbance occurs and the superconducting state is broken and a magnetic flux flow state occurs, the current is shunted to the stabilizing base material, so heat is generated even in the stabilizing base material. However, since the heat generated by this stabilizing base material is also cooled by the cooling medium on the outside,
Compared to the conventional bundle type direct cooling method shown in Figure 4, the superconducting state can be recovered quickly, and as mentioned above, the cooling medium inside and outside the stabilizing base material can flow in and out through the communication path. In order to
Even if the aggregate structure of the superconducting strands in the stabilizing base material is such that the cooling medium does not flow smoothly in the longitudinal direction, such as a braided structure or a formed strand structure, there is no particular problem; Since there are no restrictions on the aggregate structure of the superconducting wire, there is a high degree of freedom in its design.Also, since the superconducting wire is placed in the center of the superconducting wire, the superconducting wire will not be affected by the bending strain when it is wound around a coil such as a magnet. Compared to conventional superconductors, there is little deterioration in the characteristics of the wire, and since the superconducting wire is protected by the outer stabilizing base material, damage and deterioration of the superconducting wire due to electromagnetic force from the outside is effectively prevented. It has much superior characteristics compared to wire.

In addition, in the superconducting wire shown in FIG.
7B are stacked in two layers and accommodated in the stabilizing base material 10, and the two-layer superconducting wire aggregates 17A, 17B
A thin tape 18 made of a high-low conductive material such as Cypronickel is inserted between the two layers, so that the superconducting wire assemblies 17A and 17B in each layer do not come into direct contact with each other. With this configuration, it is possible to prevent deterioration of superconducting properties when a coupling current flows between each layer and the excitation speed is extremely high, such as in pulse drive. Furthermore, in the superconducting wire shown in FIG. 5, superconducting wire aggregates 17 in each layer
A, 17B and the stabilizing base material 10 are also interposed with a thin tape 19 made of the same high-resistance conductive material as described above.
It plays a role in preventing coupling current from flowing between both layers via the . However, in order to simplify the drawing, in FIG. 5, the tape 19 is shown provided on the entire outer surface of each layer 17A, 17B, but in reality, it is shown that the tape 19 is provided on the entire outer surface of each layer 17A, 17B, but in reality, the tape 19 is provided so as not to obstruct the inflow of the cooling medium from the communication path 15. It is usual to form a space as appropriate.

As described above, the proposed superconducting wire has better cooling efficiency and stability than conventional superconducting wires, and also has excellent mechanical strength against external bending forces, etc., and is useful for various electrical applications in addition to nuclear fusion. It is ideal for various uses such as energy storage, magnetic resonance absorption, magnetic separation, etc., especially for superconducting wires for large-sized, high-field magnets, and is especially suitable for tapes 18 made of high-resistance conductive materials containing superconducting wires in multiple layers. In the case where a conductive tape or 19 is inserted, the coupling current between each layer is prevented by the high-resistance conductive tape, making it ideal for pulse applications using large currents. However, when the present inventors conducted further research for practical application, it was found that the above proposed superconducting wire still had the following problems.

As mentioned above, in the proposed superconducting wire, the separator 12 is provided between the stabilizing base material 10 and the jacket 13, and the separator 12 secures the cooling medium flow path 14. The separator 12 for securing the medium flow path 14 is
As shown in FIG. 6, a round wire or a rectangular wire (rectangular wire in the figure) is wound around the outside of the stabilizing base material 10 in an open spiral. However, since the stabilizing base material 10 has a rectangular cross section as shown, when the round wire or rectangular wire is wound around the stabilizing base material 10, each edge of the stabilizing base material 10 Lifting up in some parts is unavoidable. Then, when the stabilizing base material 10 and the separator 12 are covered with the outer sheath 13 in such a state that the separator 12 is lifted up at the edge portion, and further wound into a coil shape to form a magnet, superconducting Twisting occurs throughout the wire, and the stabilizing base material 1
Deformation may occur in the superconducting strands inside the wire.
Further, when providing the separator 12 by winding a round wire or a flat wire in an open spiral around the outside of the stabilizing base material 10, it is difficult to bring the round wire or flat wire into close contact with the stabilizing base material 10 by simply winding it. It is difficult to stabilize the gap between the stabilizing base material 10 and the separator 12 due to the electromagnetic force generated when the outer sheath 13 is coated and molded and then wound around a coil for use in a magnet etc. and energized. This allows movement of the hardened base material 10 and its inner layer material, which causes quenching to occur.

Therefore, in order to eliminate the above inconvenience,
After winding the round wire or the rectangular wire around the outside of the stabilizing base material 10, it is necessary to press the wound round wire or the like toward the outer surface of the stabilizing base material 10 so as to bring it into close contact. However, such round wires etc. are stabilized by the base material 10.
When pressing toward the outer surface of the stabilizing base material 10, the stabilizing base material 10 is deformed by the pressing force, and the superconducting wires inside the stabilizing base material 10 are disadvantageously damaged.

This invention was made in view of the above circumstances, and it is possible to stabilize the separator provided between the stabilizing base material and the jacket when manufacturing the superconducting wire described in the above-mentioned Japanese Patent Application No. 57-45795. An object of the present invention is to provide a method for forming a separator that can be molded in close contact with a stabilized base material without damaging the inside of the stabilized base material.

That is, the present invention provides a method for forming a separator in which a plurality of superconducting strands are housed inside a stabilizing base material having a hollow shape and a rectangular cross section, and between the stabilizing base material and an outer sheath surrounding it. A separator is disposed, and the separator ensures a continuous cooling medium flow path in the longitudinal direction of the stabilizing base material, and a communication path is formed in the stabilizing base material to communicate between the inside and outside of the stabilizing base material. The separator of the forced cooling type superconducting wire is configured such that the cooling medium flowing through the cooling medium flow path flows into the gap between the superconducting strands in the stabilizing base material through the communication path to directly cool the superconducting strands. In forming the separator, a hollow pipe, which is the material of the separator, is wound in an open spiral around the stabilizing base material, and the wrapped pipe is pressed against the stabilizing base material. This is characterized in that the pipe is molded into a flat shape, and at the same time, the pressing force causes the pipe to come into close contact with the stabilizing base material to form a separator.

The method for forming a separator of the present invention will be explained in more detail below.

FIG. 7 is a diagram showing the procedure of a method for forming a separator according to the present invention. As shown in Figure 7A,
First, a hollow pipe 20 is wound around the outer surface of the stabilizing base material 10 in an open spiral. In this embodiment, the hollow pipe 20 has a hollow part 2 inside.
1 and a circular cross section are used. Next, the pipe 20 wound around the outer surface of the stabilizing base material 10 as described above is pressed against the outer surface of the stabilizing base material 10 using, for example, a rolling roll. Since the pipe 20 is hollow as described above, it is easily deformed by being pressed in this way and is formed into a flat shape. In this case, hollow part 2
It is preferable for the inner surface of the pipe 20 forming the tube 1 to be in a state where the inner and outer sides are joined when viewed from the stabilizing base material 10, as shown in FIG. 7B, so that there is no room for deformation later. When deformed when electromagnetic force is applied (when energized), a corresponding dimensional margin is created, causing wire movement. Therefore, collapsing the pipe should be done during the manufacturing process and not during the action of electromagnetic forces.

In this process, the pipe 20 is brought into close contact with the outer surface and edge portion of the stabilizing base material 10. In addition, since the hollow pipe 20 has a hollow part 21, its deformation resistance is low, and is 1/3 to 1/20 of that of a normal round wire.
Therefore, even if this hollow pipe 20 is pressed against the stabilizing base material 10 and molded, the stabilizing base material 10 will not be deformed. Therefore, the superconducting wires 11 inside the stabilizing base material 10 will not be damaged.

As explained above, according to the present invention, when forming a separator for a forced cooling superconducting wire, a hollow pipe is used as a material for the separator, and the hollow pipe is attached to a stabilizing base material. After winding, the separator is formed by pressing against the stabilizing base material and at the same time it is in close contact with the stabilizing base material, which prevents the separator from lifting up from the stabilizing base material. is gone,
Therefore, even if the superconducting wire manufactured in this way is wound into a coil for use in a magnet etc. and energized, the stabilizing base material and the superconducting wire inside it will not move due to the action of electromagnetic force. There is no such thing as quenching. In addition, since a hollow pipe was used as the material for the separator, even if the hollow pipe was pressed against the stabilizing base material so that it was in close contact with the outer surface of the stabilizing base material, the hollow pipe itself would deform and remain stable. Since it is in close contact with the stabilizing base material and absorbing its pressing force, the stabilizing base material itself will not be deformed, and the superconducting wires inside the stabilizing base material will not be damaged.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views showing an example of a conventional hollow superconducting wire, FIG. 4 is a cross-sectional view showing an example of a conventional directly cooled superconducting wire, and FIG. 5 is a cross-sectional view showing an example of a conventional directly cooled superconducting wire. FIG. 6 is a perspective view showing an example of the proposed superconducting wire, FIG. 6 is a perspective view showing the stabilizing base material and separator in the superconducting wire of FIG. 5, and FIG. 7 is a step-by-step diagram showing an example of the separator forming method of the present invention. FIG. 10... Stabilizing base material, 11... Superconducting wire, 1
3...Outer cover, 14...Cooling medium passage, 15...Communication path, 20...Pipe, 21...Hollow part.

Claims (1)

[Scope of Claims] 1. A plurality of superconducting strands are housed inside a hollow stabilizing base material with a rectangular cross section, and a separator is provided between the stabilizing base material and an outer sheath surrounding it. The separator forms a cooling medium flow path continuous in the longitudinal direction of the stabilizing base material, and the stabilizing base material has a communication path that communicates between the inside and outside of the stabilizing base material, and the cooling medium Forming the separator of a forced cooling type superconducting wire configured such that the cooling medium flowing through the flow path flows into the gap between the superconducting wires in the stabilizing base material through the communication path to directly cool the superconducting wires. In doing so, a hollow pipe, which is the material of the separator, is wound in an open spiral around the stabilizing base material, and the wrapped pipe is pressed against the stabilizing base material to form a flat shape. 1. A method for forming a separator in a forced cooling superconducting wire, characterized in that the pipe is molded into a superconductor, and at the same time the pipe is brought into close contact with a stabilizing base material by the pressing force to form a separator.