JPH04335503A - Superconducting coil - Google Patents

Abstract

PURPOSE:To prevent superconducting characteristics from decreasing even upon application of thermal strain due to thermal heat cycle and mechanical strain due to the electromagnetic force of a coil itself. CONSTITUTION:This coil comprises an oxide superconductor 2 wound in a coil form, a container 3 which contains the superconductor 2, and a ceramics- filled part 4 to fix the superconductor 2 in the container 3 by hardening it after being cast into the container 3.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a high-temperature superconducting coil formed by winding an oxide superconducting wire into a coil.

0002

[Prior Art and Problems to be Solved by the Invention] A high-temperature superconducting material known as a ceramic superconductor can be used as a thin tape-shaped wire by plastic working it in a metal-coated state. It is being considered. By combining such plastic working and heat treatment, a tape-shaped oxide superconducting wire having a high critical temperature can be obtained. Applications of such tape-shaped oxide superconducting wires to busbar conductors, cable conductors, coils, etc. are being studied.

However, such oxide superconducting wires have a problem in that they are susceptible to mechanical strain due to their characteristics. Therefore, a coil formed of an oxide superconducting wire suffers from thermal distortion caused by heat cycles and mechanical distortion caused by the electromagnetic force of the coil itself, resulting in a reduction in performance.

[0004] An object of the present invention is to provide a superconducting coil that can reduce such thermal distortion and mechanical distortion.

[0005]

[Means for Solving the Problems] A superconducting coil according to the present invention includes an oxide superconducting wire wound into a coil, a container for storing the superconducting wire, and an oxide superconducting wire that is hardened after being injected into the container. and a filled ceramic part for fixing the superconducting wire inside the container.

[0006] In the present invention, the container housing the superconducting wire is preferably made of a non-magnetic material such as stainless steel or ceramics.

[0007] The material for the filling ceramic portion injected into the container preferably contains at least one material selected from the group consisting of Portland cement, silica cement, slag cement, and alumina cement.

[0008] Furthermore, the superconducting wire used in the present invention preferably has a conductive metal layer on the outside of the oxide superconductor.

FIG. 1 is a sectional view showing an embodiment of the present invention. Referring to FIG. 1, an oxide superconducting wire 2 is wound around a stainless steel bobbin 1 in a coil shape. This coiled oxide superconducting wire 2 is housed in a stainless steel container 3 together with a stainless steel bobbin 1. After being stored in the stainless steel container 3, ceramics such as cement are injected into the stainless steel container 3 and hardened to form the filled ceramic part 4.

0010

[Operations and Effects of the Invention] The superconducting coil according to the present invention has the following features:
Since the oxide superconducting wire wound into a coil is fixed by the filled ceramic portion, the behavior of the wire during heat cycles due to temperature differences can be suppressed and mechanical strain can be reduced. Furthermore, since the coiled oxide superconducting wire is fixed by the filled ceramic portion, it provides mechanical reinforcement against the electromagnetic force of the coil itself, and can prevent the performance of the coil from deteriorating.

Therefore, the superconducting coil according to the present invention can be applied to ultra-high magnetic field magnets in liquid helium or the like. In addition, oxide superconducting wires are known to be superior to current metal-based and compound-based superconducting wires in high magnetic fields. Or it can be used as an inner coil.

0012

[Example] Thickness 0.15mm, width 4mm, length 3.0m
A double pancake coil was fabricated by stacking 10 silver-coated Bi-based superconducting wires. This double pancake coil was placed in a stainless steel container with a thickness of 3 mm, silica cement was injected, and after completely hardening, the performance was confirmed in liquid nitrogen. The critical current was 35A.

[0013] This high-temperature superconducting coil was immersed in liquid helium, and an external magnetic field was applied for measurement. When 6 Tesla is applied as an external magnetic field, the Ic of the superconducting coil is 350
A, and the maximum magnetic flux density was 3600 Gauss. The electromagnetic force at this time was 164 kg/cm2. After that, I checked the performance again in liquid nitrogen and found that Ic was 35A.
No deterioration in coil performance was observed.

For comparison, a double pancake coil similar to that used in the above example was prepared, and its performance was confirmed by immersing it in liquid nitrogen as it was. Critical current Ic is 7
0A, and the maximum magnetic flux density Bm was 720 Gauss. This was measured in liquid helium by applying an external magnetic field. When an external magnetic field of 6 Tesla was applied, the Ic of the high superconducting coil was 250 A, and the Bm was 2570 Gauss. The electromagnetic force at this time was 164 kg/cm2.

[0015] After this, the performance was confirmed again in liquid nitrogen in the same manner as in the above example, and the Ic was 32A.
Bm was 329 Gauss, and the coil performance had deteriorated.

As is clear from the above examples and comparative examples, according to the present invention, it is possible to obtain a high temperature superconducting coil whose performance does not deteriorate due to thermal heat cycles or mechanical distortion caused by electromagnetic force.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

[Explanation of symbols]

1 Stainless steel bobbin 2 Oxide superconducting wire 3 Stainless steel container 4 Filled ceramic part

Claims (1)

[Claims] Claims: 1. An oxide superconducting wire wound into a coil, a container for storing the superconducting wire, and an air gap between the container and the oxide superconducting wire by being injected into the container and hardening. A superconducting coil comprising: a filled ceramic portion formed in a superconducting coil;