JPS6156851B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a superconducting magnet used in nuclear fusion devices and the like, and more particularly to a superconducting magnet with improved attachment of a spacer that constitutes a flow path for cooling a superconducting coil.

In recent years, devices that utilize superconductivity have been widely adopted, such as magnetic levitation, energy storage, rotating electric machines, and nuclear fusion devices.

In particular, torus-type fusion devices have become significantly larger, and the coils used in these devices must generate a strong magnetic field to confine high-temperature plasma; Large superconducting coils will become essential for nuclear fusion devices.

Generally, a superconducting state is created by cooling the coil to an extremely low temperature with a coolant such as liquid helium or supercritical helium. For this reason,
Superconducting coils are typically housed in a vacuum-insulated container.

An example of a superconducting coil is shown in FIGS. 1 and 2. That is, a plurality of superconducting coils 2 wound in a pancake shape, a cryogenic container 1 housing them, a spacer 3 located between the plurality of superconducting coils 2, and a spacer 3 located between the coils 2 and the cryogenic container 1. It is composed of a fixing member 4. This spacer 3 constitutes a flow path for a coolant such as liquid helium to efficiently cool the superconducting coil 2, and also provides electrical insulation between adjacent superconducting coils. This serves to secure the containers 1 and provide electrical insulation.

As shown in FIG. 3, a conventional spacer 4 is bonded to a superconducting coil 2 using an insulating varnish or the like.
In this way, electrical insulation between the superconducting coils and a coolant flow path are formed. In addition, a fixing member 4 is inserted into the gap between the superconducting coil and the inner and outer diameter sides of the cryogenic container,
Secure the coil in a cryogenic container. Usually, this member has a rectangular cross-sectional shape, and is arranged in consideration of its position and interference with the spacer 3 so as not to close the refrigerant passage.

In the superconducting coil configured as above,
As shown in FIG. 3, in the conventional coil that generates a relatively small electromagnetic force, the fixing member 4 is relatively easily placed in a place where the spacer 3 is placed between the superconducting coils 2 and does not interfere with the spacer. I was able to place it.

However, in large superconducting coils that generate strong electromagnetic force, such as in nuclear fusion devices, the hoop force that acts on the coil itself and the attraction force that acts between adjacent coils are also strong. Therefore, when a coil is fixed in a cryogenic container, a strong force is applied to the fixing member or the spacer placed between the coils, so these must have sufficient strength. Since the fixing member or spacer comes into direct contact with the coil, it must also be made of a material with good insulation properties. In general, insulators such as FRP are relatively weak in strength compared to structural metal materials, so when placing them as fixing members or spacers, it is necessary to place as many as possible without interfering with the flow of refrigerant. It needs to be strong and durable. For this reason, it has become difficult to arrange the fixing member and the spacer without interference, as in the past. That is, as shown in FIG.
As a result, the number of fixed members 4 to be arranged increases, and the spacers 3 and fixed members 4 are arranged partially or completely overlapping each other.

Therefore, as shown in FIG. 5, the spacer 3 and the fixing member 4 interfere, causing the coil 2 and the container 1 to
A bubble reservoir 5, which is a triangular dead end, is created in the refrigerant passage between the two, and the bubbles in the refrigerant that are trying to escape upward are accumulated here, and cooling is expected to be locally reduced. In the worst case, this may cause the superconducting state to not be maintained.

An object of the present invention is to provide a superconducting coil having good cooling characteristics by appropriately considering the arrangement or shape of the spacer between adjacent superconducting coils and the fixing member between the coil and the container.

According to the present invention, a tapered groove is provided in the arrangement or the fixing member so that the attachment portion between the spacer and the fixing member does not become a dead end.

An embodiment of the present invention will be described with reference to FIG.

That is, the refrigerant guide surface D of the fixing member 4 is arranged so as to match the end of the refrigerant guide surface 3G of the spacer 3, which corresponds to the outlet C of the refrigerant flow path. By doing this, the outlet C of the flow passage becomes a horizontal surface, so that the bubbles generated during heat exchange of the refrigerant do not stay in this part and flow upward as shown by the arrow. Therefore, deterioration in cooling of the coil 2 due to air bubbles is prevented, and safe operation can be continued.

7 and 8 show other embodiments of the present invention, and the difference from FIG. 6 is that the spacer 3
A tapered groove E, which is the same as the slope of the spacer 3 and serves as a refrigerant guide surface, is provided in the fixing member 4 on the extension of the spacer 3 to eliminate the stagnant part of air bubbles, and the cooling of the coil 2 is reduced by circulating the refrigerant as shown by the arrow. It is designed to prevent this.

[Brief explanation of the drawing]

Fig. 1 is an external side view of a superconducting magnet, Fig. 2 is a sectional view taken along the line A-A in Fig. 1, Figs. 3 and 4 are transverse plan views showing conventional superconducting magnets, and Fig. 5 is a 6 and 7 are cross-sectional plan views showing the main parts of the superconducting magnet according to the present invention, and FIG. 8 is a side view of the central part viewed from the fixing member side of FIG. 7. be. 1...Cryogenic container, 2...Superconducting coil, 3...
...Spacer, 4...Fixing member, E...Tapered groove.

Claims (1)

[Claims] 1. Equipped with a cryogenic container that houses a superconducting coil and a refrigerant that cools the superconducting coil,
a spacer located between adjacent superconducting coils and arranged substantially along the radial direction of the superconducting coils;
In a superconducting magnet having a fixing member disposed in a gap between the cryogenic container and the superconducting coil and in contact with the spacer, a refrigerant guide surface of the fixing member that is connected to a refrigerant guide surface of the spacer is in a horizontal direction or more. A superconducting magnet characterized in that it is configured so that: