JPS62271308A - superconducting cable conductor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention and Field of Industrial Application] This invention relates to a superconducting cable conductor used for generating a high magnetic field.

[Conventional technology] Nuclear fusion boloidal coils and energy storage magnets
Since the system is operated in pulse mode, a high-field, large-capacity conductor with low loss in a fluctuating magnetic field is required. As such a high-magnetic-field, large-capacity shielding conductor, a conductor having a cable structure in which superconducting wires are twisted together is generally used. The reason why a conductor with such a cable structure is used is that by dividing the conductor into strands and reducing the twist bits of the strands, it is possible to reduce loss induced by a fluctuating magnetic field.

[Problems to be solved by the invention] However, with such a cable conductor, superelectric! !
There is a problem in that a coupling current is induced and flows between the strands, resulting in loss. In order to reduce such coupling current, methods such as coating the wire with an electrically insulating film have been used in some cases, but this method reduces the metallic coupling between the wires. gone,
This is not preferable for the effective functioning of the stabilizing material.

When a coupling current flows between the IP4 conductive strands, the temperature of the conductor rises due to heat generation due to the loss, and the conductor transitions from a superconducting state to a normal conductive state, resulting in the problem of poor superconducting stability.

Furthermore, the conventional JIB conductive wire has a stabilizing material on the outer periphery and is composed only of CU, which has low strength, so it has the disadvantage that fatigue cracks are likely to occur on the surface due to repeated electromagnetic force caused by fluctuating magnetic fields. There was also.

In addition, it is an object of the present invention to provide a superconducting cable conductor in which 1q loss due to coupling current is significantly reduced and fatigue strength is increased.

[Means for solving the problems] In the ffl conductive cable conductor of the present invention, the first embodiment
As shown in Fig. 2 and Fig. 2, Fe containing 5 mri% or more and 25% by weight or less of Cr in the outer periphery of the compound superconducting strand.
-A Cr alloy layer is provided. Here, the reason why the Cr concentration in the l"e-Cr alloy layer was limited to 5% to 25% by weight is because if it is less than 5% by weight, the electrical resistance value at extremely low temperatures is not large enough, and the loss due to the coupling current is This is because if the reduction becomes insufficient and exceeds 25% by weight, processability during extrusion or wire drawing will decrease.

[Function 1] The ultra-RFI cable conductor of the present invention has F on its outer periphery.
A c-Cr alloy layer is provided. Since the e-Cr alloy layer has a high electrical resistance, the coupling current flowing between the superconducting wires can be reduced, and the loss can be reduced in a gentle manner.

Furthermore, fatigue cracks usually occur on the surface of a super-XS wire and propagate internally, but in the conductor of this invention, the surface is Fe-
No cracks occur because it is reinforced with a Cr alloy layer. As shown in Figure 2, outside the Fe-Cr alloy layer? Even when a Cu portion with a low degree of A is provided, cracks stop at the l''c-Cr alloy layer and do not propagate further inside.

[Embodiment] FIG. 1 is a sectional view showing an embodiment of the present invention. In FIG. 1, a superconducting wire 1 includes an Nb s Sn multifilamentary wire portion 2 with a Cu-Sn alloy as a matrix, and the Nb5
a stabilizing Cu section 3 disposed around the Sn multifilamentary wire section 2;
'i:a-C provided around the stabilizing CLI section 3
It is composed of an r-alloy layer 4.

FIG. 2 is a sectional view showing another embodiment of the invention.

As shown in FIG. 2, in this invention, the Fe-Cr alloy layer 4 is divided into an inner stabilized CLI portion 3a and an outer stabilized CLI portion 011.
It can also be provided between the portions 3b.

The superconducting cable conductor of the present invention can be produced, for example, by extrusion and wire drawing of a composite billet. An experimental example of this creation method will be described below.

Between the inner Cu pipe and the outer Cu pipe, 1:e-
Insert the %Cr alloy vibrator for 13m, then insert the inner CI+
Inside the vibrator, there are 15 Nb multifilamentary wires (55 Nb cores) with a hexagonal cross-section Cu-13m %Sn alloy matrix.
One bottle was densely packed. After filling, the inside was evacuated in a vacuum chamber, and the upper and lower portions were electron beam welded to obtain a composite pellet. In addition, in this combined billet, Cu pipe and C
1l -3n alloy matrix Nl) In order to prevent the Sn in the Cu-Sn alloy from diffusing into the Cu vibe, one Nb sheet (I+1) was wound in multiple layers between the multifilamentary wire part and the Nl-3n alloy matrix.

After extruding the composite billet, it was processed into a wire rod while repeating intermediate softening to obtain a wire rod with a diameter of 1,2111111φ. When the cross section of the wire was inspected with a metallurgical microscope, Fe-
The Cr alloy layer was uniformly plastically worked, and no defects such as local breakage were observed.

The obtained superconducting strands were fabricated into a bundle type conductor as shown in FIG. 3 and a shaped rectangular twisted conductor as shown in FIG. The bundle type conductor is made by twisting 3 x 3 x 3 x 7 wires to form a stranded wire conductor 6, which is inserted into a stainless steel conduit tube 5, and the void ratio in the conduit tube 5 is 4.
1471 was processed and created so that it would be 0%.

In addition, the molded rectangular twisted body was produced by twisting seven strands of wire to form a stranded wire conductor 6, twisting 30 flat wires onto a stainless steel strip reinforcing material 7, and then roller-forming.

The twisting processability of all the conductors was good. Twisting again! ! When the wire was removed from the conductor after II and inspected under a microscope, no defects were found.

When coils were made from these conductors and energized to generate a magnetic field, it was confirmed that the loss was small in a fluctuating magnetic field, and the stability of continuous conduction was good.

In order to evaluate the effect of reducing loss due to coupling current in the present invention, Nb*Sn superconducting strands (11 mφ) having the cross-sectional structure shown in FIG. 2 were prepared, and a 3×3×4 bundle-type conductor cable was prepared. By changing the filling factor of the strands, the liquid helium filling factor in the bundle type conductor can be increased by 2.
The current loss as a cable was measured by varying the weight from 0 to 50 ω%.

The loss time constant is normalized by the loss time constant of the wire and is shown in FIG. For comparison, a conventional cable without an Fe-Cr alloy layer was also measured in the same manner. This result is also shown in FIG.

As is clear from FIG. 5, it has been confirmed that the cable conductor of the present invention has a significantly smaller increase in loss due to cable construction than the conventional cable.

In the above explanation, Nb 3 is used as the compound superconducting wire.
Sn super? [Although the explanation was made using an in wire, ■.

When a Qa superconducting strand and a Nb or All superconducting strand are used as a compound superconducting strand, it can be produced in the same manner, and the same effect can be achieved.

〔Effect of the invention〕

Since the superconducting cable conductor of the present invention is provided with the l''e-Cr alloy layer having high electrical resistance on its outer periphery, loss due to coupling current flowing between the strands can be significantly reduced.

Therefore, the loss is small in the modified eJliti field, and the stability of the superconductor is also excellent.

Furthermore, since an e-Cr alloy layer is provided on the outer periphery of the superconducting wire for reinforcement, fatigue strength can also be increased.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention. FIG. 2 is a sectional view showing another embodiment of the invention. FIG. 3 is a sectional view showing an example of a bundle type conductor. FIG. 4 is a sectional view showing an example of a molded rectangular twisted conductor. FIG. 5 is a diagram showing the relationship between the liquid helium filling rate and the loss time constant ratio during energization in the cable conductor of the present invention and the conventional cable conductor. In the figure, 1 is a superconducting wire, 2 is a multifilamentary wire portion, 3 is a stabilizing Cub, and 4 is a Fe-Cr alloy layer.

Claims (4)

[Claims] (1) At least 5% by weight25 on the outer periphery of the compound-based superconducting wire
A superconducting cable conductor, characterized in that it is provided with an Fe-Cr alloy layer containing not more than % by weight of Cr. (2) The superconducting cable conductor according to claim 1, wherein the compound-based superconducting strand is a Nb_3Sn superconducting strand. (3) The superconducting cable conductor according to claim 1, wherein the compound-based superconducting strand is a V_3Ga superconducting strand. (4) The superconducting cable conductor according to claim 1, wherein the compound-based superconducting strand is a Nb_3Al superconducting strand.