JPH04291702A - High temperature superconducting coil - 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]

The present invention relates to a high-temperature superconducting coil in which pancake coils made of tape-shaped oxide superconducting wires are arranged adjacent to each other.

0002

2. Description of the Related Art In recent years, ceramic-based, ie, oxide-based superconductors have attracted attention as superconducting materials exhibiting higher critical temperatures. Among them, yttrium is 90K.
, the bismuth type has a high critical temperature of about 110K, and the thallium type has a high critical temperature of about 120K, and their practical use is expected. Applications of these high-temperature superconducting materials to cables, buspers, power leads, coils, etc. are being considered.

[0003] Coils are mainly produced by separately heat-treating single pancake coils or double pancake coils, stacking these coils with an insulating material in between, and placing a copper plate or a coil covering material between adjacent coils. The coils were connected by soldering using the same metal wire.

0004

[Problems to be Solved by the Invention] However, when the pancake coils of oxide superconductors are connected using solder in this way, a resistance of 10-7Ω to 10-8Ω occurs at the connecting portion.
A contact resistance of Ω occurs, resulting in a coil that generates Joule loss.

[0005] For this reason, in conventional superconducting coils, it has been impossible to achieve the persistent current mode as an ideal operating condition.

An object of the present invention is to provide a high temperature superconducting coil capable of achieving persistent current mode.

[0007]

[Means for Solving the Problems] The high temperature superconducting coil of the present invention has pancake coils made of metal-coated tape-shaped oxide superconducting wires arranged adjacent to each other, and the ends of the adjacent coils are connected to each other. It is characterized by being connected using an oxide superconductor.

[0008]

[Operation] In the high temperature superconducting coil of the present invention, the ends of adjacent pancake coils are connected by an oxide superconductor. Therefore, the superconductors are bonded to each other, and the contact resistance becomes zero. This allows persistent current mode to be achieved.

[0009] By achieving the persistent current mode, power consumption can be significantly reduced, and the magnet can be put to practical use in crystal pulling magnets, MRI magnets, and the like.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing pancake coils arranged adjacent to each other. Referring to FIG. 1, pancake coil 1 and pancake coil 2 are arranged adjacent to each other. The tape-shaped oxide superconducting wire constituting the pancake coils 1 and 2 is a tape-shaped wire having a silver coating 4 around an oxide superconductor 3. The silver coating on the ends 1a and 2a of the pancake coils 1 and 2, respectively, is stripped off to expose the ends 3a and 5a of the oxide superconductor, as shown in FIG. The silver coating is stripped off over a few mm to 10 mm. A superconducting wire for connection is placed on the ends 3a and 5a of the oxide superconductors exposed in this way, and the oxide superconductors 3a and 5a are electrically connected.

FIG. 3 is a perspective view showing this state. The connecting superconducting wires 7 and 8 are made of oxide superconductors 9 and 1.
0 coated with silver. The oxide superconductors 9 and 10 of the connecting superconducting wires 7 and 8 are in contact with the oxide superconductors 3a and 5a at the ends of the respective pancake coils, so that the adjacent pancake coils 1 and 2 An electrical connection is made between them.

In the state shown in FIG. 3, the connection between the oxide superconductors is made more reliable by wrapping a silver tape or the like around it and heat-treating the connection area while applying surface pressure.

FIG. 4 is a perspective view showing another embodiment according to the present invention. Referring to FIG. 4, respective ends 11a and 12 of adjacent pancake coils 11 and 12
a are connected by overlapping high temperature superconductors 13 and 14. As in this embodiment, the ends of the pancake coils may be directly overlapped and connected with the high temperature superconductor exposed, without using a separate high temperature superconductor for connection.

An experimental example in which a pancake coil as shown in FIG. 3 was created will be described below.

[0015] Bi:Pb:Sr:Ca:Cu=1.80
:0.41:2.01:2.18:3.02. Oxide and carbonate were mixed and heat treated to prepare a powder mainly consisting of 2212 phase and superconducting phase. This was degassed at 760° C. for 3 hours in a reduced pressure atmosphere of 6 torr. These powders have an outer diameter of 12 mm and an inner diameter of 8 mm.
Coated with 1mm silver, wire drawn to 1mm, 0.18m
It was rolled to a thickness of m.

[0016] This wire was heat treated at 845°C for 50 hours and sintered. Using this wire, pancake coils were made, placed adjacent to each other as shown in Figure 1, and the silver coating was removed from each terminal as shown in Figure 2. Their bodies overlapped. 0.2mm from above
Press and wrap with silver tape with a thickness of
Heat treatment was performed for 50 hours.

[0017] When the critical current of the wire joint of the high temperature superconducting coil thus obtained was measured, the critical current was 30 to 40 A at liquid nitrogen temperature. It was found that the critical current is equivalent to the critical current of this wire at liquid nitrogen temperature.

[0018] This shows that according to the invention, a persistent current mode is achieved.

[0019]

According to the present invention, the connecting portions of each pancake coil can be brought into a superconducting state, and a persistent current mode can be achieved. This allows a persistent current to flow through the coil, significantly reducing power consumption, and providing a stable magnetic field.

Therefore, according to the present invention, it can be put to practical use as a coil for crystal pulling furnaces, MRI, NMR, and the like.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing pancake coils arranged adjacent to each other.

FIG. 2 is a perspective view showing a state in which the coating at the end of the pancake coil is removed to expose the oxide superconductor.

FIG. 3 is a perspective view showing an embodiment according to the present invention.

FIG. 4 is a perspective view showing another embodiment according to the invention.

[Explanation of symbols]

1, 2 Pancake coils 1a, 2a End portion 3a of superconducting wire of pancake coil
, 5a Oxide superconductors 7, 8 with exposed ends of the oxide superconducting wire, superconducting wires 9, 10 for connection, oxide superconductor portion 11 of the superconducting wire for connection,
12 Pancake coil

Claims (1)

[Claims] 1. A high-temperature superconducting coil in which pancake coils made of metal-coated tape-shaped oxide superconducting wires are arranged adjacent to each other, and the ends of the adjacent coils are connected with an oxide superconductor. A high-temperature superconducting coil.