JP2001326117A - High-temperature superconducting coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-temperature superconducting coil which is protected against deterioration due to repeated cooling. SOLUTION: A filament winding pipe, on which filaments are wound, making an angle of 0 to 40 deg. with a cylindrical axis is used as a winding frame, having a thermal expansion coefficient of 17×10 -6 to 80×10-6 in its circumferential direction, and a high-temperature superconducting coil uses this winding frame.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-temperature superconducting coil using a winding form having a coefficient of thermal expansion in the circumferential direction of 17 × 10 ⁻⁶ or more and 80 × 10 ⁻⁶ or less.

[0002]

2. Description of the Related Art A glass fiber reinforced composite material (GFR) is used for a high-temperature superconducting coil formed by winding an oxide superconductor along a bobbin.
P) etc. are used. However, the thermal expansion coefficient of high-temperature superconducting material is about 27 × 10 ^-6 , and the thermal expansion coefficient of GFRP reel is 6.9 × 10
^In the case of such a coil, once cooled, the superconducting characteristics deteriorate due to the difference in the thermal expansion coefficient between the bobbin and the superconducting material.

[0003]

The characteristic deterioration of the high-temperature superconducting coil due to repeated cooling is caused by a smaller thermal expansion coefficient in the circumferential direction of the bobbin than that of the high-temperature superconducting material. An object of the present invention is to provide a high-temperature superconducting coil in which the coefficient of thermal expansion in the circumferential direction of a bobbin is increased so that deterioration due to repeated cooling does not occur.

[0004]

That is, the present invention is a high-temperature superconducting coil using a winding form having a coefficient of thermal expansion in the circumferential direction of 17 × 10 ⁻⁶ or more and 80 × 10 ⁻⁶ or less. More specifically, the above high-temperature superconducting coil uses a filament winding pipe having a winding angle of the fiber of 0 to 40 ° with respect to a cylindrical axis as a winding frame.

The winding frame for a high-temperature superconducting coil used in the present invention has a thermal expansion coefficient in the circumferential direction of 17 × 10 ^-6 or more and 80 × 10 ^-6.
Hereinafter, a reel having a size of preferably 22 × 10 ⁻⁶ or more and 50 × 10 ⁻⁶ or less is preferable. When the thermal expansion coefficient of the bobbin is 17 × 10 ⁻⁶ or less, the wound high-temperature superconductor undergoes tensile deterioration due to small shrinkage during cooling of the bobbin. On the other hand, if it is 80 × 10 ⁻⁶ or more, the cooling shrinkage of the bobbin is too large, so that the fixability of the high-temperature superconductor deteriorates.

The reinforcing fibers of the fiber-reinforced composite material for the bobbin include fibers such as polyethylene, polyparaphenylenebenzbisoxazole (PBO), aramid, polyarylate, and glass fiber. Especially polyethylene fiber, PBO
Fibers and aramid fibers are desirable because they exhibit a large positive coefficient of thermal expansion in the radial direction. These fibers may be mixed and reinforced.

On the other hand, all matrix resins show positive expansion. As the matrix resin used here, epoxy resin, unsaturated polyester resin, vinyl ester resin,
Urethane resins and urethane acrylate resins can be used, but epoxy resins are particularly preferred.

A preferred form of reinforcing the composite material is a filament winding (FW) pipe. The winding angle is preferably 0 to 40 °, preferably 10 to 35 ° with respect to the cylindrical axis. Winding angle 40 ~ 90
In °, the thermal expansion coefficient in the circumferential direction of the bobbin becomes small or negative, so that the high-temperature superconducting material undergoes tensile deterioration during cooling. 0
At 4040 °, the coefficient of thermal expansion in the circumferential direction of the ^bobbin exhibits a large positive value of 17 × 10 ⁻⁶ or more, so that deterioration of the high-temperature superconductor can be prevented.

The mixing ratio of the fibers and the matrix resin in the composite material is preferably 20 to 85%, more preferably 30 to 70%, as a fiber volume ratio (Vf). If Vf is less than 20%, the effect of reinforcing fibers is hardly exhibited, and if it exceeds 85%, the matrix resin is hardly impregnated and the mechanical properties as a composite material are undesirably deteriorated. As described above, the coefficient of thermal expansion of the FW pipe made of a composite material
It is determined by the winding angle, Vf, fiber type, etc.

In this manner, the coefficient of thermal expansion in the circumferential direction is 17 × 10
^-6 or more and 80 × 10 ^-6 or less, so that a bobbin that does not deteriorate the high-temperature superconductor during cooling can be obtained.

The high-temperature superconductor used in the present invention may be a bismuth-based oxide superconductor such as Bi2212, Bi2223 or an yttrium-based oxide superconductor such as YBCO.
The shape of the superconductor may be a wire or a tape.

In this way, a high-temperature superconducting coil that does not deteriorate due to repeated cooling can be manufactured.

[0013]

EXAMPLES (Examples 1 to 6) A high-temperature superconducting coil used in the present invention was produced as follows. Winding frame is outer 55mm / inner diameter 5
The pipe was 0 mm in length and 40 mm in length. This is molded by the FW method, and high-strength polyethylene (Toyobo,
Registered trademark: Dyneema), PBO (Toyobo, registered trademark: Zylon) fiber, aramid (Kevlar 49), and glass fiber (Nittobo, E-glass) are used. Epoxy resin was used in the following ratio as a matrix. Epicoat 827 (oiled shell) 100 parts Epicure YH300 (oiled shell) 80 parts EMI-24 (oiled shell) 1 part . The winding angle is 0 °
A product having an angle of 4040 ° was prepared, and this was designated as Examples 1 to 6. As the high-temperature superconducting material, a Bi2223 silver sheathed round wire and a tape wire were used.

(Comparative Examples 1 to 5) The FW winding angle of the winding frame is 45 to 90.
° was used. This is referred to as Comparative Examples 1 to 5.

[0015]

[Table 1]

The coefficient of thermal expansion in the circumferential direction of the bobbin was measured in a temperature range of 77 to 300 K with a strain gauge attached to the outer periphery of the bobbin.

Deterioration of the high-temperature superconducting coil due to cooling is performed by conducting an electric current test in a state where the coil is immersed in liquid nitrogen.
Observed by the change in the quench current density.

[0018]

According to the present invention, it has become possible to manufacture a high-temperature superconducting coil which does not deteriorate due to repeated cooling.

[Brief description of the drawings]

[Figure 1] Repetitive cooling characteristics of various high-temperature superconducting coils using Bi2223 silver sheathed round wire.

FIG. 2 shows the repetitive cooling characteristics of various high-temperature superconducting coils using Bi2223 silver sheathed tape wires.

Claims (2)

[Claims] 1. A thermal expansion coefficient in a circumferential direction of 17 × 10 ⁻⁶ or more and 80 × 10 or more.
A high-temperature superconducting coil characterized by using a winding frame having a ^{diameter of -6} or less. 2. The high-temperature superconducting coil according to claim 1, wherein a filament winding pipe having a fiber winding angle of 0 to 40 ° with respect to a cylindrical axis is used as a winding frame.