JPH0467327B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention aims to prevent the movement of a conductor due to electromagnetic force, which is the cause of quenching, in a superconducting coil. Conventional methods for fixing stranded wires in superconducting coils include (1) applying tension while winding the stranded wires; (2) After winding, compress it from the outside with reinforcing wire. (3) Impregnate with epoxy resin after winding. (4) Insert thermal insulation between the windings. However, with these methods, it is not possible to fix the stranded wire, and among them, in the case of epoxy resin impregnation according to (3), although the movement of the wire can be suppressed, heat shrinkage occurs as the wire is cooled after impregnation. At this time, the quench was caused by the heat released when the crack occurred. Furthermore, since the refrigerant and the superconducting wire do not come into direct contact, it is necessary to select a large margin for the stabilization conditions, which reduces the overall current density of the coil. especially
Wind & Reat type coils have a high temperature section (700℃
Because the magnet wire is processed in the vicinity), the winding expands or contracts significantly as it heats and cools, making it difficult to maintain a constant spacing between the windings by epoxy impregnation alone, making it difficult to obtain a highly homogeneous magnet. It was hot. As a result of intensive research in view of the current situation, the present invention has developed a superconducting coil that is formed by winding a superconducting conductor and that more firmly fixes the conductors between the coils to prevent quenching and improves mechanical strength. It is something. That is, the present invention provides a superconducting coil in which rectangular shaped stranded wire is wound around the outer periphery of a thin non-magnetic pipe whose hollow part has a shape other than a perfect circle, in which a fluid that hardens or solidifies at 300°C or less is injected into the hollow part. The superconducting coil is characterized in that the stranded wires are fixed by expanding the pipe. To explain the present invention with reference to the drawings, conductor wires 2 are twisted around the circumference of a thin non-magnetic metal tube 1 as shown in FIG. 1a, and then the metal tube and the conductor are twisted together as shown in FIG. Roll and form into a flat shape. In this case, it is necessary to provide a small gap 3 in the metal tube. Further, as shown in FIG. 2a, after a thin non-magnetic metal tube 1 is formed into a flat shape, conductor wires 2 are twisted and formed around the outer periphery of the tube. Note that, in this case and similar to the above, a gap is provided in the metal tube. After that, the above-mentioned molded stranded wire is wound into a coil, for example, on a cylindrical bobbin, and the outer periphery is covered with a GFRP tube for reinforcement, or an insulating material is inserted, and a metal wire such as SUS is wrapped around the outer circumference for reinforcement. Wrap something around it and tie it up. At this time, both ends of the wire are brought out to the outside and the area around them is reinforced. Filling fluid 4 is poured into the metal tube from the other end by leaving one end of the stranded wire open or in a suction state. Once the metal tube is filled with fluid, one end is sealed and sealed, and pressure is applied from the open end. The tube 1 is filled with the fluid until it expands as shown in FIG. 2b.
After charging, the open end is also sealed, and the fluid is hardened or solidified by heating to a temperature of 300° C. or lower to obtain the superconductor of the present invention. In the present invention, austenitic steel tubes, titanium alloy tubes, copper alloy tubes, aluminum alloy tubes, etc. are used as the non-magnetic metal tubes, and the wall thickness of the tubes must be such that they can be easily expanded by press-fitting fluid. Although it is necessary, it differs depending on the material of the metal tube. Normally, the wall thickness is preferably about 0.1 to 1.0 mm. Further, the shape of the metal tube is not particularly limited as long as the cross section is other than a perfect circle, and any shape that can increase the cross-sectional area by pressurizing fluid into the tube may be used. For example, an oval
It may be rectangular or flat, or it may have a wedge-shaped inner surface or an uneven surface as shown in FIG. The fluid to be filled in the metal tube may be any pressure medium for adding internal pressure to the tube, such as a low melting point metal or silicone resin that has good thermal conductivity and a coefficient of linear expansion that is close to that of a superconducting wire and generates little gas. , epoxy resin, wax, etc. are preferred. In addition, the solidification or coagulation temperature of the fluid is 300℃.
The reason for this is that if the temperature is 300°C or higher, the superconducting properties will deteriorate at the temperature during solidification or solidification. Next, examples of the present invention will be described. Example A strand 2 having 24 Nb cores as shown in FIG.
The wire was compressed using a tag head to form the hollow portion 3 into a flat shape having a thickness of 0.2 mm in the thickness direction as shown in FIG. In this case, after winding, tighten the outside with SUS304 wire with an outer diameter of 0.8 mmφ, and then heat it to 700℃.
After performing diffusion heat treatment for 3 days, the wire was cooled to room temperature to obtain a rectangular shaped stranded wire. Thereafter, as shown in Figure 2a, while reducing the pressure at one end of the formed stranded wire of the coil, epoxy resin 4 was injected from the other end of the SUS tube to fill the inside of the tube with the epoxy resin, and then the pressure was reduced. One end of the tube was closed, and the tube 1 was further pressurized to 6 atmospheres to bulge out as shown in FIG. In addition, in order to compare with the coil of the present invention, the above molded stranded wire was impregnated with epoxy resin from the outside and heated at 150°C.
After curing for 4 hours, two solenoid coils were produced. An energization test was conducted to test the performance of the superconducting coil of the present invention and the superconducting coil of the comparative example thus obtained. The results are shown in Table 1.

[Table]
As detailed above, according to the present invention, the superconducting wire is firmly fixed, the wire does not sway due to electromagnetic force and does not quench, and the hollow part in the metal tube is filled with an insulating material such as epoxy resin. By doing so, when used as a pulsed magnet, it has remarkable effects such as a marked improvement in stability.

[Brief explanation of the drawing]

Figure 1 shows the process of rectangular forming stranded wire in the superconducting coil of the present invention, where a is a cross-sectional view before compression, b is a cross-sectional view after compression, and Figures 2 to 4 show various steps in the present invention. Fig. 3 shows a bulged state of a flat-formed stranded wire having the shape of , where a is a cross-sectional view of the flat tube before pressurization, and b is a cross-sectional view of the flat tube after pressurization and expansion. 1...Metal tube, 2...Conductor strand, 3...Gap, 4...Filling material.

Claims (1)

[Claims] 1. A superconducting coil formed by winding rectangular shaped stranded wire around the outer periphery of a thin non-magnetic pipe whose hollow part has a shape other than a perfect circle, wherein the hollow part is heated to 300°C. A superconducting coil characterized in that the stranded wires are fixed by injecting a fluid that hardens or solidifies below to expand the pipe. 2. The superconducting coil according to claim 1, wherein the thin non-magnetic pipe has a thickness in the range of 0.1 to 1.0 mm. 3. The superconducting coil according to claim 1, wherein the thin non-magnetic pipe has an elliptical shape or a rectangular flat shape. 4 Materials for thin-walled non-magnetic pipes include austenitic stainless steel pipes, titanium alloy pipes, copper alloy pipes,
The superconducting coil according to claim 1, characterized in that it is made of an aluminum alloy tube. 5. The superconducting coil according to claim 1, characterized in that the fluid that hardens or solidifies at 300° C. or lower is made of a low melting point metal such as lead, wax, silicone resin, or epoxy resin.