JPH0225243B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a superconducting magnet used in a cryogenic atmosphere, such as a superconducting magnet for a nuclear fusion reactor.

[Technical background of the invention and its problems]

There are two types of superconducting magnets: the immersion cooling method and the forced cooling method.The forced cooling method allows for large current density;
It also has many advantages that are difficult to obtain with immersion cooling methods, such as increasing the strength of the coil against electromagnetic force.

FIG. 1 shows a conventional forced cooling superconducting magnet. A tubular conductor in which a plurality of superconducting wires 1 are passed through a rectangular or round sheath tube 2 is wound up in a pancake or solenoid manner, and the surface of the sheath tube 2 is covered with an insulating material (not shown) to generate electromagnetic force. The insulating material 3 is impregnated with, for example, epoxy resin, and then hardened and housed in the coil container 4 in order to maintain its strength. The space other than the superconducting wire 1 inside the sheath tube 2 is cooled by flowing a refrigerant.

In general, the sheath tube 2 of the tubular conductor is designed to withstand not only external forces such as electromagnetic force but also a sudden increase in the pressure inside the tube due to the quench phenomenon of the superconducting wire 1.
determines the shape of In particular, in the case of a square shape, rounded surfaces are usually formed to prevent stress concentration at the corners.

However, due to the rounded corners of the sheath tube 2, large gaps are formed and there are parts where the insulating material 3 is more than other parts. If the coil is overfilled, cracks are likely to occur, which are further aggravated by thermal contraction when the coil is cooled.
Such cracks weakened the coil strength, creating a very problematic drawback.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned drawbacks, and provides a superconducting magnet that prevents cracks from occurring in portions of a tubular conductor where the amount of insulating material formed is larger than other portions, such as the corners of the sheath pipe. The purpose is to

[Summary of the invention] That is, a filling made of an inorganic material and an organic material is filled into a large gap formed at a corner of a sheath tube, and then the filling is buried by vacuum impregnating the entire space with an insulating material. It is something.

[Embodiments of the invention]

An embodiment of the present invention shown in the drawings will be described below. In FIG. 2, parts having the same functions as those in FIG. 1 are designated by the same reference numerals, and their explanations will be omitted. As shown in Fig. 3, a filler 5 made of an inorganic material and an organic resin having a cross section slightly smaller than the gap is inserted into the gap formed by the rounded corner of the sheath pipe 2 of the tubular conductor, and the coil is successively inserted into the gap. After winding, the insulating material 3 is vacuum impregnated with an organic resin such as epoxy resin.

As shown in Fig. 4, the filling 5 has a relatively large rounded surface and is filled with inorganic materials such as felt, glass fiber, silica powder, etc., and epoxy resin, etc. as shown in a, b, and c in the voids formed by the relatively large rounded surface. Linear shapes with a square, round, or diamond cross section made of organic resin;
In addition, short glass threads or glass fibers are used in the gaps formed by relatively small rounded surfaces, as shown in d.

Next, the action will be explained. In the large gap formed at the corner of the sheath tube 2, a pawl 5 formed to a size corresponding to the gap is inserted at the stage of coil winding. By this operation, the large voids are almost entirely filled with the strong material 5, and the micro voids are filled with the insulating material 3 by vacuum impregnation. In the coil formed in this way, since the entire gap is not made of a single piece of insulating material 3, cracks are less likely to occur throughout the gap, and the center portion is made of a strong pawl 5. Since this is guaranteed, even if a slight defect occurs in the insulating material 3 in the minute gap between the pawl 5 and the sheath tube 2, there will be no problem in terms of strength. Furthermore, by using the same material as the insulating material 3 impregnated with the organic resin for the pawl 5, the amount of change due to thermal contraction during cooling of the coil is reduced, and cracks are less likely to occur. Note that although the sheath tube 2 has been described above as having a rectangular shape, the same applies to a round shape as well.

〔Effect of the invention〕

As described above, according to the present invention, the gap formed between the tubular conductors in a superconducting magnet is filled with a filler made of an inorganic material and an organic resin, and the filler is embedded by vacuum impregnating the whole with the organic resin. Therefore, cracks are less likely to occur, and even if cracks occur, the strength is guaranteed by the filler and the coil strength is not weakened, which is an excellent effect.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing a conventional superconducting magnet, FIG. 2 is a vertical cross-sectional view showing an embodiment of the superconducting magnet of the present invention, and FIG. Figures 4a, b, c and d are perspective views showing the form of the nail in Figure 2, respectively. 1... Superconducting wire, 2... Sheath tube, 3... Insulating material, 4... Container, 5... Filler.

Claims (1)

[Scope of Claims] 1. A superconducting magnet in which a plurality of superconducting wires are passed through the tube and a tubular conductor is wound to allow a refrigerant to flow into a space other than the superconducting wires and housed in a container. A superconducting magnet characterized by having a filling made of a material and an organic resin embedded therein. 2. The superconducting magnet according to claim 1, wherein the claws are square wire-shaped. 3. The superconducting magnet according to claim 1, characterized in that the claws have a round wire shape. 4. The superconducting magnet according to claim 1, characterized in that the claws are in the form of fibers.