JPH05217433A - Superconductor - Google Patents

Abstract

PURPOSE:To prevent the movement of superconducting element wires within a conduit and at the same time maintain a path for a coolant to flow, by fixing the element wires with a thermohardening type insulating tape wound in a spiral form in the direction of the length thereof on the outer circumference of a secondary twisted wire in which a plurality of superconducting element wires are twisted. CONSTITUTION:A superconducting element wire 11 is formed with an extremely thin multi-core superconducting wire of NbTi or Nb3Sn being surrounded with a stabilization material such as Cu, Al or the like. Three pieces of the element wires 11 are twisted to make a primary twisted wire 12, and three pieces of the primary twisted wires 12 are twisted to make a secondary twisted wire 13. A thermohardening type insulating tape is wound on the twisted wire 13 in a spiral form along in the direction of the length thereof. A plurality of the twisted wires 13, the circumference of which the insulating tape 14 is applied to, are twisted to make a subcable 15. In this case, six pieces of subcables 15 are twisted and then housed in the conduit 16. The superconducting wire is made by drawing. Thereby, the movement of the element wire 11 is restricted by the thermohardening type insulating layer 18. However, there is not present the layer 18 all over the space between the element wires 11, so that a path for a coolant to flow can be maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a forced cooling type superconducting conductor for forcibly feeding and cooling supercritical helium.

[0002]

2. Description of the Related Art A forced-cooling type superconducting conductor that cools by using forced convection of a single-phase flow such as supercritical helium or a cryogenic fluid is a hollow conductor, a cable-in-conduit conductor, or a combination thereof. There is a conductor. The hollow conductor is configured such that a large number of ultra-fine multi-core superconducting wires are assembled and integrated with a stabilizing material by solder or the like, and a hole is formed in the central portion thereof so that helium as a refrigerant can be pumped. As shown in FIG. 3, the cable-in-conduit conductor 8 includes a secondary twisted wire 2, a tertiary twisted wire 3, which is formed by twisting a plurality of superfine multicore superconducting wires 1 of NbTi or Nb ₃ Sn many times. 4th twisted wire 4 and 5th twisted wire 5 and multiple twists in a cable shape, SUS
Is contained in a strong conduit (tube) 6 made of a material, an incoloy material, a Ti material, or an alloy thereof, and the refrigerant flows into a space 7 surrounded by the inner wall of the conduit 6 other than the superconducting element wire. (U.S. Pat. No. 4,336,420
Specification: Jun. 22, 1982).

In this type of superconducting conductor, since the superconducting element wire 1 in the conduit 6 moves in the conduit 6 by an electromagnetic force to generate heat, the element wire temperature is prevented from rising to cause superconducting breakdown (quenching). The surface of the superconducting element wire 1 is thinly coated with solder, and when the wires are twisted, they are point-contacted with each other, and soldered and fixed at the portions where they contact each other to prevent them from moving.
Further, the movement of the strands is restrained by covering the outer circumference of the cable in which the twisted wires are bundled several times with a high electric resistance material having good heat conduction characteristics. Further, the pipe diameter is squeezed to be as small as possible (generally around 35 to 40%) so that the ratio of the refrigerant flow passage area to the cross-sectional area of the cable space in the conduit 6 (hereinafter referred to as void ratio) is as small as possible. It was

[0004]

As described above, in the conventional superconducting conductor, the superconducting element wires in the conduit are solder-coated and the movement of the superconducting element wires is restricted, but the electrical conductivity between the superconducting element wires is reduced. Due to the connection, the coupling loss with respect to a fluctuating magnetic field is large, and quenching may occur due to this internal heat generation.Therefore, if the wires are not electrically coupled but only fixed by twisting, the bending radius and electromagnetic There is a drawback that the wire becomes easy to move in places where the force is strong.

Therefore, in the conventional superconducting conductor, the void ratio is made as small as possible in order to prevent the easiness of movement of the wire, but the wire loss and the hydraulic diameter become small at the time of manufacturing the conductor, and the pressure loss increases, As a result, other drawbacks such as a very large loss of the circulation pump and an increase in the temperature of the refrigerant due to a temperature rise due to pressure loss have occurred.

As a method for compensating for the above-mentioned drawbacks, instead of soldering and fixing to the outer circumference of the superconducting element wire, an adhesive agent is applied and adhered and fixed to each other (JP-A-2-2978).
No. 08 gazette) has been proposed, but in this method, when the wires are bonded to each other, the refrigerant flow path between the superconducting wires is blocked, the refrigerant does not flow, and the cooling characteristics are significantly deteriorated. There was a problem of causing (superconducting breakdown).

The present invention has been made to solve the above problems, and an object of the present invention is to prevent the movement of the superconducting element wire in the conduit and to secure the refrigerant passage to provide a stable superconducting conductor having excellent cooling characteristics. To provide.

[0008]

In order to achieve the above object, the present invention stores a stranded wire made of NbTi or Nb ₃ Sn ultrafine multifilamentary superconducting wire in a high strength stainless steel pipe. In a cable-in-conduit type superconducting conductor for forcedly cooling a refrigerant by forcing it into a pipe, a thermosetting insulating tape is provided on the outer periphery of a secondary stranded wire formed by twisting a plurality of superconducting element wires forming the stranded wire. It is characterized in that the superconducting wires are fixed to each other by spirally winding in the longitudinal direction.

[0009]

According to the superconducting conductor of the present invention, since the movement of the superconducting element wire is restrained to the minimum and the refrigerant flow path between the element wires is secured, excellent stability and cooling characteristics can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 (a) is a sectional view of an embodiment of the present invention, and FIG. 1 (b) is an enlarged view of part A of FIG. 1 (a).
In FIG. 1, 11 is a superconducting element wire, which is NbTi or N
An extra fine multi-core superconducting wire of b ₃ Sn is surrounded by a stabilizing material such as Cu or Al, and an electrical insulating material is inserted if necessary. As shown in FIG. 2, three superconducting wires 11 are twisted to form a primary twisted wire 12, and three primary twisted wires 12 are twisted to form a secondary twisted wire 13. A thermosetting insulating tape 14 is spirally wound around the outer periphery of the secondary twisted wire 13 along the longitudinal direction. The secondary stranded wire 13 thus provided with the insulating tape 14 on the outer periphery is stranded many times as in the conventional example shown in FIG.

In the case of this embodiment, six sub cables 15 are twisted and housed in the conduit 16, and the superconducting conductor 20 is manufactured by dicing to a predetermined void ratio. After the superconducting conductor 20 has been manufactured, the superconducting conductor 2 can be processed in an appropriate process of coil manufacturing.
0 is heated to cure the thermosetting insulating tape 14, and the superconducting element wires 11 are fixed in units of secondary twisted wires. The superconducting conductor 20 after curing is as shown in FIG. 1 (a), and an enlarged portion A is shown in FIG. 1 (b).

The hardened insulating layer 18 fixes the superconducting element wire 11 in the state of the primary twisted wire 12, whereby the superconducting element wire 1 is formed.
It restrains the movement of 1. However, since there is no hardened insulating layer 18 between all the superconducting wires 11, the coolant flow path 17 can be secured. Therefore, even if a coil is formed and electricity is applied, the superconducting element wire 11 hardly moves and has excellent stability and good cooling characteristics can be obtained.

Although the winding pitch of the thermosetting insulating tape is not specified in this embodiment, if it is tightly wound or lap wound, the cooling surface area is reduced, and the current is unbalanced or shunted. By winding, the cooling surface area can be prevented from decreasing, and uneven flow and diversion problems can be reduced. In this case, the pitch of the skip winding is the third stranded wire (3 ³ It is preferable that the pitch is 1/3 or less of the twist pitch of the main twist. Further, the same effect as that of the above-mentioned embodiment can be obtained even if the secondary twisted wire is formed by two twists, four twists such as four twists.

[0015]

As described above, according to the present invention, the movement of the superconducting element wire in the conduit can be prevented and the coolant flow path can be secured, so that the superconducting conductor having a stable and excellent cooling characteristic can be provided. ..

[Brief description of drawings]

FIG. 1 (a) is a cross-sectional view of an embodiment of the present invention, and FIG. 1 (b) is an enlarged view of part A of FIG. 1 (a).

FIG. 2 is a perspective view of a part of the secondary stranded wire of FIG.

FIG. 3 is a diagram showing a manufacturing process of a conventional superconducting conductor.

[Explanation of symbols]

11 ... Superconducting element wire, 12 ... Primary stranded wire, 13 ... Secondary stranded wire,
14 ... Thermosetting insulating tape, 15 ... Sub cable, 1
6 ... Conduit, 17 ... Refrigerant flow path, 18 ... Cured insulating layer,
20 ... Superconducting conductor.

Claims (1)

[Claims] 1. A cable-in-conduit in which a stranded wire made of an NbTi or Nb ₃ Sn ultrafine multi-core superconducting element wire is housed in a tube made of high-strength stainless steel, and a refrigerant is forced into the tube for forced cooling. Type superconducting conductor, a thermosetting insulating tape is wound spirally around the outer periphery of a secondary stranded wire in which a plurality of superconducting element wires forming the stranded wire are twisted, and the superconducting element wires are mutually wound. A superconducting conductor characterized by being fixed.