JPH06260335A - High temperature superconducting magnet - Google Patents

Abstract

(57) [Abstract] [Purpose] In a pancake type high temperature superconducting coil, a higher magnetic field is applied to obtain a high magnetic field. [Composition] In a high-temperature superconducting magnet formed by stacking pancake-shaped coils, a cross-sectional area of a conductor forming a coil at both ends of the magnet in the axial direction is made larger than a cross-sectional area of a conductor forming a coil in the middle portion. did. By increasing the coil conductor cross-sectional area at both ends in the coil axial direction, a higher current is caused to flow therethrough, and as a result, the amount of current in the entire coil is increased and a high magnetic field is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnet using a high temperature superconducting wire.

[0002]

2. Description of the Related Art As a coil winding method for a high temperature superconducting magnet, a coil is wound in a solenoid shape, and as shown in FIG. There is one in which the coils are connected to each other by a joint 3 and the coils are attached to each other.

[0003]

Here, when considering the magnetic flux density distribution of the entire pancake coil,
Coil axis direction component of the magnetic field is maximum near the center of the Kuriaboa 5 as shown in FIG. 3 (B _M), the coil radial component B _R of the magnetic field is maximized in the coil axis direction end portions. still,
B _O is the central magnetic field. By the way, as shown in the graph of FIG. 4, in a Bi-based wire or the like, the anisotropy of the critical current I _C is large, and I _C is greatly reduced by the coil radial component of the magnetic field. Therefore, the total I _C is determined by the coils at both ends in the axial direction, and in order to raise this, the number of turns of the coil is earned.
There is a problem that a large number of wire rods are required because there is no choice but to increase the number of laminated pancake coils.

[0004]

The present invention has been made to solve the above-mentioned problems, and is characterized by a high-temperature superconducting magnet formed by stacking pancake-shaped coils in the axial direction of the magnet. The cross-sectional area of the conductors forming the coils at both ends is made larger than the cross-sectional area of the conductors forming the coil in the middle portion.

[0005]

In the above-mentioned conventional structure, since the conductors of the laminated pancake coils have the same cross-sectional area, the current that can flow through the entire coil is regulated by the coils I _C at both ends in the coil axial direction. The magnet of the present invention increases the cross-sectional area of the coil conductor at both ends in the axial direction of the coil, thereby allowing a higher current to flow therethrough, consequently increasing the current amount of the entire coil and obtaining a high magnetic field. As a means for increasing the conductor cross-sectional area at both ends, for example, it is conceivable to use a bundle wire in which two tape wires are stacked. in this case,
Also the I _C of the wire rod 1 sheet of a vertical magnetic field applied to the coil at both ends decreases, because I _C can be increased by the sum of the two sheets, it is possible to increase the amount of current that can be flowed across the coil.
Further, if the number of wire rods of the bundled wire is appropriately selected according to the magnitude of the radial magnetic field, the amount of wire rods can be efficiently saved.

[0006]

EXAMPLES Examples of the present invention will be described below together with comparative examples. FIG. 1 is a schematic diagram showing a magnet. As shown, ten pancake coils 1 are mounted on a copper bobbin 2 and laminated. Each pancake coil is numbered from No. 1, No. 2 ... Such a coil was cooled by a refrigerator having two cooling stages, energized under the following conditions, and the generated magnetic field was measured. As a comparative example, the same electricity was applied to a stack of 20 pancake coils each made of a single conductor.

(Conditions for Example) Conductor: 0.24 × 2.7 mm width Bi-based silver sheath tape electric wire 61 Multi-core wire Pancake coil: 10 sheets laminated No. 1, 2, 9 and 10 use two bundled bundle wires. No3 to 8 are one conductor Coil dimensions: Inner diameter 40φ, Outer diameter 100φ, Height 100m
m Energizing current: 40A Magnetic field generated: 1.2T (at 21K)

(Conditions for Comparative Example) Conductor: 0.24 × 2.7 mm width Bi-based silver sheath tape electric wire 61 Multi-core wire Pancake coil: 20 sheets of laminated layers All one conductor Coil dimensions: Inner diameter 40φ, Outer diameter 100φ, 200m height
m Energizing current: 20A Magnetic field generated: 1.2T (at 21K)

As a result, the coil volume of the comparative example is twice as large as that of the embodiment, and the amount of wire used is also twice that of the embodiment. It is confirmed that the embodiment of the present invention can reduce the amount of wire used for generating the same magnetic field. It was

In the above embodiment, two bundle wires are used. However, as a structure for increasing the conductor cross-sectional area at both ends in the axial direction of the coil, the thickness is the same as that of the tape wire used for the coil in the middle part. , The width may be doubled at both ends.

[0011]

As described above, according to the superconducting magnet of the present invention, it is possible to generate a high magnetic field while being compact. Therefore, it is expected to be effectively used for mobile SC devices such as linear motors and electric vehicles and magnets that require a high magnetic field (15T or more).

[Brief description of drawings]

FIG. 1 is a schematic view of a superconducting magnet.

FIG. 2 is a schematic view showing a conventional pancake magnet.

FIG. 3 is an explanatory diagram of a magnetic flux density distribution generated in a pancake coil.

FIG. 4 is a graph showing the relationship between superconducting current density and applied magnetic field.

[Explanation of symbols]

 1 Pancake coil 2 Copper bobbin 3 Joint 4 Reel 5 Clear bore

Claims (1)

[Claims] 1. In a high-temperature superconducting magnet formed by stacking pancake-shaped coils, a cross-sectional area of a conductor forming a coil at both ends of the magnet in an axial direction is compared with a cross-sectional area of a conductor forming a coil at an intermediate portion of the magnet. High temperature superconducting magnet characterized by being made larger.