JPH0793059B2 - AC superconducting wire - Google Patents

Description

The present invention relates to a structure of a 50/60 Hz AC superconducting wire.

(Prior art and its problems) As a conventional 50/60 Hz AC superconducting wire, for example, seven superconducting element wires (1) as shown in FIG. 3 (a) are twisted together, and FIG. Such as stainless steel, Kyupro Nikkeru, and other non-superconducting wires (3) surrounded by superconducting element wires (1)
6 twisted together, or as shown in FIG. 7C, there are 13 superconducting wires (1) formed into a flat rectangular twisted wire and impregnated with a resin (2) such as epoxy resin. . The thickness of the conventional superconducting wire is determined only by the current capacity. For example, in order to increase the current capacity, 7 to 19 wires,
The current capacity has been increased by increasing the number of strands to 36. However, when the thickness of the superconducting wire becomes large, heat is generated due to AC loss, the current capacity does not increase, and since the superconducting element wires are too close to each other, the heat density and distribution in the superconducting wire cannot be lowered.

(Problems to be Solved by the Invention) As a result of examining the above problems, the present invention has developed a structure of a superconducting wire having a large current capacity by reducing the heat generation density inside the superconducting wire.

(Means and Actions for Solving Problems) In the present invention, superconducting wires are assembled, and a part or all of the voids of the wires are resin-impregnated, and within 1.0 mm from the center of the assembled superconducting wires. Is a free surface in contact with liquid helium, and the ratio of superconducting element wires to the superconducting element wires excluding resin is 30 to 50%, and three or more superconducting element wires are not adjacent to each other. is there.

Aspects of the present invention will be described below with reference to the sectional views of the superconducting wire shown in FIGS. As shown in FIG. 1 (a), a superconducting wire with an outer diameter of about 0.1 mm, in which a number of filaments such as NbTi are embedded in a Kyupro nickel (1)
And a non-superconducting wire (3) made of stainless steel or Kyupro Nikel, etc. is preliminarily insulated and coated with polyester on the outer circumference, and the non-superconducting wires are assembled so that three or more superconducting element wires are not adjacent to each other and the mutual voids are made of epoxy resin, etc. This is a superconducting wire (4) impregnated with the above resin. At this time, the resin to be impregnated may be enough to fill the voids, and FIG.
As described above, the entire circumference of the equivalent diameter of the superconducting wire may be impregnated. This is because when a large number of superconducting wires are assembled, the vibration of the coil becomes large, and therefore it is better to increase the thickness of the resin layer in order to prevent this.

In addition, 1.0 m from the center of the superconducting wires assembled in the present invention
The fact that there is a free surface in contact with liquid helium within m means, for example, in the case of a round wire, the diameter (A) of the superconducting wire shown in Fig. 1 (b), in the case of a rectangular wire the thickness (B), and in the case of a hexagonal wire. Second
As shown in the figure, the equivalent diameters (C) are 2.0 mm or less, respectively, and when the equivalent diameters (C) are exceeded, AC Ig / DC Ic becomes 50% or less and the effective effect disappears.

Further, in the present invention, the ratio of the superconducting wire to the superconducting wire excluding the resin is set to 30 to 50% because the current density of the conductor is reduced below 30%, and the superconducting wire exceeds 3% when the ratio exceeds 50%. This is because more than two adjacent structures are formed and the heat source density is increased and the heat generation rate is higher than the cooling rate and quenching (transition from superconducting to normal conducting). 1 (c) and 2 are a collection of superconducting wires and non-superconducting wires.

Further, in the present invention, in addition to NbTi alloy wire as the superconductor
Nb ₃ Sn compound wire can also be applied, but in this case, it is necessary to use ceramics for the wire insulation and replace the coil spacer and winding frame with alumina or the like.

(Example) An example of the present invention will be described below.

A 7,000 NbTi filaments with a diameter of 0.5 μm were embedded in 9-1 Kyupro Nikel and a non-superconducting wire made of stainless steel with a diameter of 0.1 mm and a superconducting wire with a diameter of 0.1 mm was preliminarily insulation-coated with polyester to a thickness of 10 μm. The following superconducting wire was produced using these strands. Table 1 shows the specifications of the superconducting wire.

The following alternating current coil was produced using the above superconducting wire. The specifications are shown in Table 2.

The coil was vacuum-impregnated with an epoxy resin, and the resin in the spacer portion was removed to form a liquid helium flow channel (duct). Therefore, the resin (2) is filled between the wires as shown in FIGS. 1 and 2. An energization test was performed at 50 Hz using these coils. The results are shown in Table 3.

As is clear from Table 3, the present invention can be designed with a large current capacity and can achieve AC Ig / DC Ic 95 to 100%.

(Effects) As described above, according to the present invention, the heat generation density inside the superconducting material is reduced, so that a superconducting wire having a large current capacity can be obtained, and an extremely remarkable effect is industrially exhibited.

[Brief description of drawings]

1 to 3 are sectional views of superconducting wires showing an embodiment of the present invention. 1 ... Superconducting element wire, 2 ... Resin, 3 ... Non-superconducting wire, 4
…… Superconducting wire, 5 …… Reinforcing wire.

Claims (1)

[Claims] 1. Superconducting wires are assembled, and a part or all of the voids between the wires are impregnated with resin, and there is a free surface within 1.0 mm from the center of the assembled superconducting wires that liquid helium contacts. A superconducting wire for alternating current, wherein the ratio of superconducting element wires to the superconducting element wires excluding resin is 30 to 50% and three or more superconducting element wires are not adjacent to each other.