JPH04322412A - Superconducting coil - Google Patents

Abstract

PURPOSE:To realize a superconducting coil ensuring high reliability of a bending part of superconduction conductor having a small radius of curvature. CONSTITUTION:In a superconducting coil formed by forming a superconductor (8) by bundling a plurality of superconducting wires (1) with a conduit (10) and then coiling such superconductor, a slit (11) is provided to the total circumference or a part of the cross section of the conduit (10) to form a bending part (9) having a small radius of curvature such as crossover part or a leadout part and the bending part (9) is coupled with a cover (12) to form a shape of the bending part (9).

Description

[Detailed description of the invention]

[Object of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting coil in which the structure of a bending part with a small radius of curvature, such as a transition part or an outlet part of the coil, is improved.

0003

2. Description of the Related Art There is a type of superconducting conductor in which a plurality of superconducting wires are bundled together in a conduit, and a cryogenic coolant is flowed into a space having a predetermined porosity of the conduit. This is generally called a cable-in-conduit type superconducting conductor. In this case, supercritical pressure helium is used as the refrigerant, but from the viewpoint of the stability of its physical properties, helium at a pressure of about 5 to 10 atmospheres is generally used.

FIG. 5 is a cross-sectional view of such a cable-in-conduit type superconducting conductor (8). (1) is superconducting wire, (2) is stainless steel conduit, (3)
is stainless steel tape, (4) is electrical insulation material, (5)
is the space through which the refrigerant flows, and this space ratio is determined from the viewpoint of the stability of the conductor. The conduit (2) restrains the movement of the multiple thin superconducting wires (1) that would cause the superconducting state to be destroyed, and forms a pressure boundary for the refrigerant, and
It has the function of sharing the load against the generated electromagnetic force.

[0005] When such a superconducting conductor (8) is used to create a coil with a large current, high magnetic field, and high current density, such as a magnetic field coil for a nuclear fusion device, the cross-sectional dimension of the conductor is naturally large. In addition, since the wall thickness of the conduit (2) also increases, it becomes difficult to form bent portions with a small radius of curvature, such as conductor transition portions and lead-out portions. Furthermore, in the manufacturing process of cable-in-conduit type conductors,
Since the material of the conduit (2) is considerably work hardened and the elongation of the material is reduced, there is also the problem that cracks occur in the conduit (2) during the molding process of the lead portion.

[0006] For this reason, conventionally, a method has been proposed in which the bent portion is formed by means as shown in FIG. That is, in FIG. 6, the conduit at the bent part is removed and only a plurality of superconducting wires are used to form the bent part (9), and this is connected to a spacer (6) made of FPR (fiber reinforced plastic) and a fixing member (
7).

Problems with such a conventional configuration are as follows.

(a) Superconducting wire (1) by electromagnetic force etc.
When it moves, frictional heat is generated, which breaks the superconducting state (that is, quenches it). cable in
In a conduit type conductor, in order to restrict the movement of the superconducting wire (1) due to electromagnetic force, etc., the superconducting wire (1) is significantly compacted by reducing the cross section of the conductor during the conductor manufacturing process. However, when the conduit is removed as shown in Figure 6, the compaction in that part is released and the superconducting wire (1) becomes easier to move.
Therefore, quenching is likely to occur.

(b) The FRP spacer (6) is intended to fix the superconducting wire (1) and restrict its movement, but due to problems such as the bridging effect of a large number of superconducting wires, It is difficult to securely secure the superconducting wire.

0010

[Problems to be Solved by the Invention] As described above, in the configuration of conventional superconducting coils with bending parts with a small radius of curvature, such as the leading part or the transition part, the fixing force of the superconducting wire is not sufficient, so There is a limit to its applicability to coils that are subject to strong excitation or that require rapid excitation.

The present invention has been made in view of the above circumstances, and provides high reliability that enables the necessary forming to obtain the necessary magnetic field accuracy without changing the fixing force for multiple superconducting wires during manufacturing. An object of the present invention is to provide a superconducting coil having a bent portion with a small radius of curvature, such as a lead-out portion or a transition portion.

[Configuration of the invention]

[0013]

[Means for Solving the Problems] In order to achieve the above object, in the present invention, at a bending part with a small radius of curvature such as a leading part or a transition part of a superconducting coil, a first means is to make a conduit intersect with a conductor axis. A superconducting coil is constructed by making a slit in the superconducting conductor, and fixing the superconducting conductor by engaging the bent portion in the groove of the cover, and determining the shape of the bent portion. Also, as a second means, in addition to the first means,
When covering a bent part with a cover, the cover should be
The space between the conduit and the cover is filled with a stainless steel spacer, and the ends of the cover, the conduit, and the split surfaces of the cover are sealed and welded to form a superconducting coil.

[0014]

[Operation] In the first means of the present invention, only slits are made in the conduit in the cross section of the superconducting conductor, so that the fixing force to the superconducting wire during manufacture is not released. Therefore, even if a varying magnetic field acts, the superconducting wire will not move and the superconducting coil will not quench. Furthermore, by making slits in the conduit, bent parts with a small radius of curvature, such as opening parts or transition parts, can be formed freely without applying undue strain to the conduit, which has undergone work hardening and whose elongation has decreased. Therefore, it is easy to fit and fix the superconducting conductor into the groove provided in the cover by machining in advance. According to the second method, the cover of the first method is divided into two along the bending plane to cover the bent portion, and the gap between the cover and the conduit is filled with a stainless steel spacer, so that the superconducting wire is Since the cover end and the conduit and the divided surfaces of the cover are sealed and welded together, the refrigerant of the superconducting wire does not leak, and a superconducting coil with a large current value can be provided.

[0015]

【Example】

(Example 1) The first example of the present invention will be described below with reference to FIG.
, and FIG. 2. FIG. 1 is a longitudinal cross-sectional view of the opening portion which is the bent portion (9) of this embodiment, and FIG. 2 is a perspective view showing only the conduit of the superconducting conductor from FIG. 1. Figure 1
In FIG. 2, (10) is a rectangular cross-section conduit made of stainless steel (hereinafter simply referred to as a conduit), (11
) is a slit, (12) is a stainless steel cover divided into two parts, and (13) is a groove. The end of the cover (12), the conduit (10), and the split surface between the two covers are fixed by welding.

The opening part is made by bending, but in this case, as shown in FIG.
Make two slits (11) on the sides and shape. That is,
The outlet portion of the coil has a polygonal line shape with the slit (11) as a node. The cover (12) is divided into two parts, and a groove (13) in a predetermined shape set from the viewpoint of reducing the error magnetic field is provided on the inside of the cover (12).
can be fitted.

The method for assembling the opening part is as follows. That is, the cover (12) splits the superconducting conductor (8) into two.
Fit it into the groove (13) of the cover (12).
The splitting surface, the cover (12) and the conduit (10) are welded to complete the process.

In such a configuration, the conduit (1
The number of slits (11) inserted into the superconducting wire (1
), the superconducting wire (1) will not deteriorate due to bending of the lead portion. Further, since the slit (11) is placed in a cross section intersecting the conductor axis, the compaction applied during conductor manufacture to prevent movement of the superconducting wire (1) is not released. Further, since the groove (13) and the conduit (10) fit together, the superconducting conductor (8) can be reliably fixed by welding the two halves of the cover (12). Therefore, a superconducting coil using a cable-in-conduit type superconducting conductor with a large current value can be obtained.

(Embodiment 2) A second embodiment is shown in FIGS. 3 and 4. Slits (11) are made in the conduit (10) at several places (5 places in the figure) in the circumferential direction, bent at a predetermined radius, and then a cover (split into two) is placed over the conduit (10) to secure a flow path for the cooling medium. 12) and cover with conduit (1
0) and the cover (12), and seal the welded part (14) between the cover end and the conduit, and between the dividing surfaces (17) of the cover (12).
), the structure is welded and joined.

[0020] With such a configuration, the conduit (1
0), there is no reduction in the cross-sectional area of the flow path due to bending, and since the thickness of the stainless steel spacer can be adjusted, the groove width of the cover (12) can be machined with ease and accuracy. (10), superconducting wire (1
) remains restrained, so no loosening occurs, and the cooling space (5) does not decrease.

Therefore, the cooling performance is high because there is no reduction in the cross-sectional area of the refrigerant flow path, and the superconducting wire (1) does not move due to electromagnetic force during energization, and it is easy to manufacture and has a large current value. - A superconducting coil using an in-conduit superconducting conductor can be obtained.

[0022]

[Effects of the Invention] As described above, in the present invention, a slit is made in the conduit and the conduit is fitted into the cover to form a bent part such as an exit part or a transition part of a superconducting coil, so the radius of curvature is small. We have created a superconducting coil that can be formed to obtain the necessary magnetic field precision without compromising the fixing force for multiple thin superconducting wires at the bending section, thus increasing the reliability of the bending section such as the lead-out section or the transition section. can be provided. If the second aspect is adopted, the machining accuracy during manufacturing becomes easier.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view showing the main parts of a first embodiment of the present invention.

FIG. 2 is a perspective view showing essential parts of the conduit in FIG. 1;

FIG. 3 is a vertical sectional view showing the main parts of a second embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view taken along line IV-IV in FIG. 3;

FIG. 5 is a cross-sectional view of a cable-in-conduit type superconducting conductor common to the conventional and present invention.

FIG. 6 is a vertical cross-sectional view showing the main parts of a conventional example.

[Explanation of symbols]

1...Superconducting wire 8...Superconducting conductor 9...Bending part 10... Conduit 11...Slit 12...Cover 14...Seal welding part 16...Stainless steel spacer 17...Divided plane

Claims (2)

[Claims] Claim 1: A superconducting conductor is formed by bundling a plurality of superconducting wires with a conduit, and in a superconducting coil wound with this, a slit is made in the entire circumference or a part of the cross section of the conduit to form a transition part or an exit part, etc. A superconducting coil characterized in that a bent portion having a small radius of curvature is formed, and the shape of the bent portion is determined by engaging the bent portion with a cover. [Claim 2] The bent part is covered with a cover divided into two along the bending plane, a stainless steel spacer is filled in the gap between the conduit and the cover, and the end of the cover and the divided surfaces of the conduit and the cover are seal-welded to each other. The superconducting coil according to claim 1.