JPH05234741A - Superconducting magnet structure - Google Patents

Abstract

PURPOSE:To generate a higher and uniform magnetic field without reducing a current density by incorporating a partly parallel component to a generated magnetic field direction of an entire magnet in an energizing direction to be energized by a stripelike member. CONSTITUTION:A silver tape (stripelike member) 1 has a parallel blind part (silver exposed part) for mounting a lead as indicated by hatching. The tape 1 also has a shape having displaced parts 2a-2c continued as steps in a direction crossing an extension line direction of the member. The tape 1 is wound in a coil state to form a four-continuous-layer pancake coil. After current leads 3a, 3b and potential leads 4a-4e are attached to the obtained composite coil, when it is energized in a magnetic field, a resistance of about 10<-13>OMEGA.m to be used as criteria of the coil at the time of energizing 182A is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is constructed by winding or laminating a band-shaped member having a surface coated with a superconducting material, and utilizing the generation of a high magnetic field, various physical property measuring devices, magnetic levitation trains, nuclear fusion. The present invention relates to a superconducting magnet structure used as a device or the like. The superconducting material used in the present invention includes rare earth elements-alkaline earth elements-
Various oxide superconducting materials including copper oxide, or
Examples thereof include superconducting compounds such as Nb ₃ Ga and V ₃ Ga, but in the following description, the Bi-based oxide superconductor will be mainly described.

[0002]

2. Description of the Related Art Since rare earth element-alkaline earth element-copper oxide ceramics have been attracting attention as oxide superconductors, superconducting phenomena have been studied for many complex oxides. For example, a Bi-based oxide has a superconducting transition temperature (hereinafter simply referred to as Tc) of 80 K (low temperature phase) or 11
It is considered to be a promising substance with a high Tc such as 0 K (high temperature phase). This oxide is easily oriented by partially melting and then cooling on a silver substrate, and is practical even in a high magnetic field near 4.2 K. Sufficient critical current density (hereinafter referred to as Jc)
Is known to show.

Superconducting magnets, which utilize a persistent current phenomenon realized by a superconducting material, generate a large magnetic field by flowing a large current without consuming electric power, are various physical property measuring devices, magnetic levitation trains, Applications to nuclear fusion devices and the like are being promoted.

When considering the application of a superconducting substance to a superconducting magnet, it is an essential requirement to make the superconducting substance linear or strip-shaped. For example, in the case of a Bi-based oxide superconducting material, in addition to forming a wire drawing coil by the conventionally known silver sheath method (Kazuyuki Shibuya et al., Spring Meeting of the 1991 Spring Low Temperature Engineering Superconductivity Society, P232), dip it on the surface of silver tape A superconducting magnet is formed by a method such as coating by a coating method or a doctor blade method and then coiling (Junichi Shimoyama et al., Autumn 1991 Low Temperature Engineering Superconductivity Society Lecture Summary, P5), etc. Has been reported to be successfully eliminated and to exhibit high Jc even under a high magnetic field.

[0005]

However, the superconducting magnets reported so far have a so-called single pancake structure, and a laminated structure essential for generating a higher and more uniform magnetic field has been reported. Absent. One of the causes is that the superconducting connection between single pancakes cannot be easily performed. In addition, for example, in a Bi-based oxide superconductor, after the partial melting heat treatment, the Bi-based oxide is crystallized and becomes extremely weak against strain, and cracks easily occur due to handling, and Jc tends to decrease. Another reason is that it is difficult to add a step for laminating after the melt heat treatment. Therefore, it has been desired to realize a superconducting magnet structure having a Jc similar to that of a conventional single pancake even with a laminated structure. The present invention has been made under such circumstances, and an object thereof is to provide a laminated structure type superconducting magnet structure capable of generating a higher and more uniform magnetic field without lowering Jc. It is in.

[0006]

The present invention which has achieved the above object is a superconducting magnet structure constituted by winding or laminating a belt-shaped member having a surface coated with a superconducting substance. The superconducting magnet structure is characterized in that the energizing direction energized by has a component that is partially parallel to the direction of the magnetic field generated by the entire magnet. A specific example of the strip-shaped member forming the superconducting magnet structure is one having a continuous shape with a displacement portion in the direction intersecting the extension line direction of the strip-shaped member as a step.

[0007]

The present invention is constructed as described above, but in short, the present inventors constructed a single pancake by constructing it so that the energizing direction has a component partially parallel to the direction of the magnetic field generated by the entire magnet. It has been found that a superconducting magnet that can generate a higher and more uniform magnetic field that shows a comparable Jc and that is comparable to a laminated structure can be integrated.
The present invention has been completed.

The structure, action and effect of the present invention will be described in more detail with reference to the following examples, but the following examples do not limit the present invention, and any design changes may be made in view of the spirit of the preceding and the following. Also included in the technical scope of the present invention. For example, in the examples described below, the case where the Bi-based oxide superconductor is coated on the silver tape by the dip coating method is shown, but the present invention is not limited to such a case, and the case where another oxide superconductor is coated. , Or Sn or Ga on the Nb or V tape surface
Is hot dip plated and then diffused to form Nb ₃ Sn or
The present invention also includes technical applications such as forming a superconducting compound such as V ₃ Ga.

[0009]

EXAMPLES First, the present inventors cut the silver tape 1 (strip-shaped member) having the shape shown in FIG. The tape thickness at this time is
The tape width was 50 μm, the tape width was 19 mm, and the total length was 6.0 mm. Figure 1
In the figure, the hatched portion means a blind portion (silver exposed portion) for attaching the lead wire. Further, this silver tape 1 has a continuous shape with displacement portions 2a to 2c in the direction intersecting the extension line direction of the strip-shaped member as steps. The silver tape shown in FIG. 1 was wound into a coil as shown in FIG. 2 to obtain a four-layer laminated pancake coil. At this time, the coil inner diameter: 13 mm, outer diameter: 60 mm, coil length:
It was a coarse roll of 80 mm.

On the other hand, the molar ratio of each element is Bi: Sr: Cu:
The powder (Bi-2212 type powder) prepared by the solid-phase reaction method with Pb = 2: 2: 1: 2 was used as an organic thickener (polyvinyl butyral) and an organic solvent (butanol). Mix to form a slurry. After immersing the coil shown in FIG. 2 in this slurry, pulling up (dip coating),
By drying, each side has a thickness of about 60 μm, width
A 19 mm thick film was formed. Then, first in air, gradually heat up to 500 ° C to remove the solvent and then heat up to 887 ° C to remove Bi-
By partially melting the 2212 phase and then slowly cooling it,
A coil having a structure in which Bi-2212 phase crystals were densely laminated on the surface of the silver tape was obtained. The heat treatment pattern at this time is shown in FIG. The thickness of the superconducting layer was about 20 μm on each side.

After inserting an insulator between the coils, the outer diameter 28
mm and inner diameter of 13 mm, and finally fixed by pouring wax. After the current leads 3a and 3b and the potential leads 4a to 4e were attached to the obtained composite coil as shown in FIG. 4, each terminal (by DC 4 terminal method) was inserted in a superconducting magnet at 4.2K. P _{1 to} P ₅ ) The IV characteristics between them are investigated,
At the same time, the generated magnetic field was detected by the Hall element installed in the center of the coil.

As a result of energizing the composite coil in a magnetic field of 4.2 K and 5.0 T, resistance generation corresponding to 10 ^-13 Ω · m used as the criteria of the coil was observed when 182 A was energized. The central magnetic field of the coil observed at the same time was 5.27T.
This means that this composite coil generated a magnetic field of 0.27T. The central magnetic field calculated from the shape and configuration of this coil was 0.284 T, which was almost in agreement with the actually measured value. Table 1 shows the critical current (Ic) between the terminals. The Ic of the coil at this point is 182 A, and the Jc of the superconducting part is
The current was 1.37 × 10 ⁴ A / cm ² , and the current flow was from the end (position + shown in FIG. 4) to the end (− shown in FIG.
Position) was performed in series.

[0013]

[Table 1]

From these results, the composite coil has 4
It is clear that the entire continuous stack exhibits superconductivity,
Span between pancakes (steps 2a to 2 shown in FIG. 1)
It was found through c) that the superconducting laminated state was completely established. The present invention has made it possible to integrally manufacture a superconducting multi-layer pancake relatively easily under the condition that the superconducting connection technology has not been established so far, and thereby, the persistent current mode of the superconducting magnet can be obtained. Driving is also possible. Next, various examples of the present invention will be shown.
First, three silver tapes 1 (thickness: 50 μm) each having the pattern shape shown in FIGS. 5 to 7 were cut.

The silver tape shown in FIGS. 5 and 6 has a structure basically similar to that of the silver tape shown in FIG. 1, but the one shown in FIG. 5 has displacement portions 2a to 2c. 6 extends in a direction inclined with respect to the silver tape, and the one shown in FIG. 6 is obtained by changing the width of each layer of the silver tape. Moreover, what is shown in FIG. 7 is cut in a zigzag shape. Then, one of the silver tapes was dipped in the slurry prepared in the same manner as described above, then pulled up (dip coat) and dried to obtain Bi having a thickness of about 100 μm.
A system oxide film was formed. This was sandwiched between the remaining two silver tapes, and wound or laminated in the shapes shown in FIGS. 8 to 10 (72 in FIG. 10) to form composite coils 5a to 5c. At this time, one pair of sandwich-shaped three silver tapes was sandwiched with one glass tape insulating material.

Next, for each coil, first 50 in air.
After gradually heating to 0 ° C. to remove the solvent, the system was heated to 887 ° C. to partially melt the Bi type-2212 phase and further slowly cooled to form a flat type Bi type-2212 phase crystal parallel to the silver tape surface. A coil having a densely laminated structure was obtained. At this time, the thickness of the superconducting layer was about 35 μm per surface.
Finally, it was fixed by pouring wax. Regarding the obtained composite coils 5a and 5b, the IV characteristics were examined by the DC 4-terminal method while being inserted in the superconducting magnet at 4.2 K, and at the same time, the generated magnetic field was detected by the Hall element installed in the center of the coil. did.

As a result, the composite coil shown in FIG.
a, 4.2 K, 5 T external magnetic field, Ic 115 A (Criteria: 10 ^-13 Ω · m), central magnetic field 0.24 T,
The distance at which the magnetic field strength was −5% from the central magnetic field was 6 mm from the coil center. The composite coil shown in FIG. 9 has an Ic: 105 A in an external magnetic field of 5b, 4.2 K, 5T.
(Criteria: 10 ^-13 Ω ・ m), central magnetic field is 0.18
T, the distance at which the magnetic field strength was -5% from the central magnetic field was 18 mm from the coil center. The composite coil shown in FIG. 9 was obtained by changing the tape width in each layer. Such a coil has the advantage that the uniform magnetic field space can be changed as necessary.

On the other hand, the composite coil shown in FIG. 10 becomes superconducting as a whole, and Ic = 73 A (Criteria: 10
^-13 Ω · m) was confirmed in the absence of a 4.2 K magnetic field. The composite coil shown in FIG. 10 is a so-called baseball coil magnet. Further, it is possible to easily form a deformed magnet such as a saddle type magnet by devising the cut shape of the silver tape. The present invention has an advantage that even a deformed magnet, which has been conventionally difficult to form with an oxide material, can be formed into a laminated shape relatively easily. In each of the composite coils 5a to 5c shown in FIGS. 8 to 10, the orientation plane can be increased or decreased by adjusting the number of dip-coated silver sheets and non-dip-coated silver tapes, and Ic can be easily changed. be able to.

[0019]

The present invention is constructed as described above, and enables a higher and more uniform magnetic field generation without lowering the current density, and is a laminated structure type superconducting device equivalent to one in which single pancakes are laminated. A magnet structure was realized.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a cut shape of a silver tape.

FIG. 2 is a perspective view showing an appearance when the silver tape having the shape shown in FIG. 1 is temporarily wound into a coil.

FIG. 3 is a graph showing an example of a heat treatment pattern in an example.

FIG. 4 is a perspective view showing a lead wire connection state of a composite coil when an IV characteristic is investigated.

FIG. 5 is a plan view showing another example of the cut shape of the silver tape.

FIG. 6 is a plan view showing still another example of the cut shape of the silver tape.

FIG. 7 is a plan view showing another example of the cut shape of the silver tape.

8 is a perspective view showing an appearance when the silver tape having the shape shown in FIG. 5 is wound to form a composite coil 5a.

9 is a perspective view showing an appearance when the silver tape having the shape shown in FIG. 6 is wound to form a composite coil 5b.

FIG. 10 is a perspective view showing an appearance when the silver tapes having the shape shown in FIG. 7 are laminated to form a composite coil 5c.

[Explanation of symbols]

 1 Silver Tape (Band-shaped member) 2a to 2c Stepped portion 3a, 3b Current lead 4a to 4b Potential lead 5a to 5c Composite coil

Front page continued (72) Inventor Toshio Eki 1-5-5 Takatsukadai, Nishi-ku, Kobe City Kobe Steel Works Seishin Research Center (72) Inventor Yoshio Masuda 1-5 Takatsukadai, Nishi-ku, Kobe No. 5 Stock Company, Kobe Steel Seishin Research Area

Claims (2)

[Claims] 1. A superconducting magnet structure constituted by winding or stacking a strip-shaped member coated on the surface with a superconducting substance, wherein the energizing direction along the strip-shaped member is the magnetic field direction of the entire magnet. A superconducting magnet structure characterized in that it has a partly parallel component. 2. The superconducting magnet structure according to claim 1, wherein the strip-shaped member has a continuous shape with a displacement portion in a direction intersecting the extension line direction of the strip-shaped member as a step.