JPS6256472B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum vessel for a nuclear fusion device, and more particularly to a vacuum vessel for a nuclear fusion device, which is formed by alternately arranging thick and thin bellows parts, and covering the outer periphery of the bellows part with a cylindrical part. The present invention relates to a vacuum container for a fusion device.

As a typical torus-shaped fusion device employing this kind of vacuum vessel for fusion devices, a tokamak-type fusion device is schematically shown in FIGS. 1 and 2.

As shown in the figure, the tokamak-type fusion device has a strong toroidal magnetic field (B _t )2 in the torus direction ()1.
a toroidal coil 3 that generates a current transformer, a current transformer coil 6 that generates a plasma current (I _p ) 4 by current transformer action and a current transformer magnetic field (B _f ) 5, and a hoop by the plasma current (I _p ) 4 A vertical magnetic field (B
_z ) It is generally composed of a vertical magnetic field coil 9 that generates 8, a vacuum vessel 10 that generates Prusma 7 therein, and the like. In particular, the vacuum vessel 10 generates a plasma current (I _p ) 4 in the torus direction ( ) 1 within the vacuum vessel 10 due to the current transformer action caused by the temporal change in the current of the current transformer coil 6, and its joule loss Since the structure is such that a higher temperature and higher density plasma 7 can be obtained, it is necessary to have a sufficiently large electrical resistance in the torus direction 1 compared to the electrical resistance of the plasma 7. Therefore, generally, the vacuum container 10 has a plurality of thick parts 1 in the torus direction 1.
It is a composite structure in which thin bellows parts 1 and thin bellows parts 12 are alternately arranged to form a substantially annular shape, and most of the electrical resistance is ensured by the bellows parts 12. Furthermore, in order to ensure electrical resistance, the bellows part 1
In addition to thinning the bellows portion 2, it is necessary to increase the total extension in the torus direction 1, and it is necessary to increase the height and number of the ridges of the bellows portion 12. In addition to the load of the vacuum force, large eddy currents ( _ie ) are induced and flow in the vacuum vessel 10 when the plasma current (I _p ) 4 or the vertical magnetic field (B _z ) 8 suddenly changes, and this eddy current (i _e ) is interlinked with various magnetic fields and receives a large electromagnetic force.

This will be explained using FIG. This figure shows the details of the thick wall part 11 and the bellows part 12 of the vacuum vessel 10. As shown in the figure, the electric resistance of the thick wall part 11 and the bellows part 12 in the torus direction 1 is significantly different, so that the vortex Most of the current (i _e ) 14 is in the thick part 1
It flows in a circular manner within 1. In particular, eddy current (i
Since the small circumferential direction (θ) 15 component of _e ) 14 interlinks with the toroidal magnetic field (B _t ) 2, a large electromagnetic force F is generated in the direction shown by the arrow. Bellows part 12
A similar load is generated on the bellows portion 12, so it is important to ensure the strength of the bellows portion 12, but it is difficult to design a design that achieves both strength and resistance value.

As a solution to this problem, the middle of the bellows part 12, which is longer in the torus direction 1, is
Supporting and fixing using an electrically insulated and highly rigid structure is considered, and such a method is proposed, for example, in Japanese Patent Application Laid-Open No. 154495/1983.

FIG. 4 shows an example of this in Japanese Patent Application Laid-open No. 154495/1983.

In the figure, the vacuum container 1 is placed so as to cover the bellows part 12.
It is composed of a cylindrical part 17 protruding from the thick wall part 11 of 0, a support ring 18 fixed to the middle of the bellows part 12, an insulator 19, an insulating bolt 20, etc. The strength of the bellows portion 12 is ensured by supporting it on a highly rigid cylindrical portion 17 via bolts 20.

Although this example is effective as a method of reinforcing the bellows portion 12, as shown in FIG. As a result, a large eddy current ( _ie ) 14 flows into the thick wall portion 11 from the thick wall portion 11 side, and a large electromagnetic force f is also generated in the cylindrical portion 17, deforming the cylindrical portion 17. Since this applies forced deformation to the bellows portion 12, there is a drawback that the stress in the bellows portion 12 becomes considerably large due to this forced deformation.

The present invention has been made in view of the above-mentioned points, and its purpose is to cover the outer circumference of the bellows portion with a cylindrical portion in order to reinforce the bellows portion. It is an object of the present invention to provide a vacuum vessel for a nuclear fusion device, which can reduce eddy currents caused by eddy currents and, therefore, reduce stress generated in a bellows portion.

The present invention takes into consideration the characteristics of eddy currents that occur in a vacuum container that is formed into a substantially annular shape by alternately arranging a plurality of thick-walled parts and bellows parts, and has developed a thick-walled part of a cylindrical part that covers the outer periphery of the bellows part. The intended purpose is achieved by intermittently providing gaps extending in the circumferential direction of the cylindrical portion near the portion where the cylindrical portion is fixed. That is, in general, the cylindrical part that supports the bellows part is required to have sufficient rigidity, so it is usually fixed to the thick part by welding or the like. Therefore, eddy currents due to the changing magnetic field circulate through the thick portion and the cylindrical portion. In addition, in this case, the magnitude of the eddy current is approximately proportional to the length in the torus direction including the thick walled part and the cylindrical part, and due to its nature, the eddy current is concentrated at the end in the torus direction, that is, the cylindrical part. Since it flows in the direction of the small circumference, electromagnetic force due to interaction with the toroidal magnetic field is also concentrated in the cylindrical part. Therefore, in consideration of the characteristics of eddy current, the present invention intermittently provides gaps extending in the circumferential direction of the cylindrical part near the fixed part with the thick part of the cylindrical part that covers the outer periphery of the bellows part. The air gap makes it difficult for eddy currents to circulate from the thick part to the cylindrical part.

Hereinafter, the present invention will be explained in detail based on embodiments shown in the drawings. Incidentally, the same reference numerals are used for the same parts as in the past.

FIG. 6 shows an embodiment of the present invention. The detailed structure is almost the same as that of the conventional one, and here, the relevant connecting part between the thick part 11 and the cylindrical part 17 will be schematically illustrated and explained.

Thick wall part 11 of the vacuum container in this embodiment shown in the figure
and the cylindrical part 17 are connected to each other by welding, and the cylindrical part 17 is provided with a small circumferential direction (θ) 15, that is, a vertical magnetic field (B _z ) 8 for confining the plasma, near the fixed part with the thick-walled part 11. A plurality of gaps 22 are provided that extend substantially in parallel, and these gaps 22 are provided intermittently in the small circumferential direction (θ) 15.

By having the configuration of this embodiment as described above,
The eddy current (i _e ) 14 that attempts to flow from the thick walled portion 11 side to the cylindrical portion 17 is blocked by the air gap 22, and the eddy current induced in the cylindrical portion 17 is significantly reduced. Since no large electromagnetic force is generated in the cylindrical portion 17 and no deformation is applied to the bellows portion, the stress in the bellows portion becomes extremely small.

In order to arrange the void 22 most effectively, it is sufficient to provide the void so as to be perpendicular to the flow path of the eddy current ( _ie ), so as shown in FIG. In the vicinity of the fixed part 17, an air gap 22a is provided in the small circumferential direction (θ) 15, that is, almost parallel to the vertical magnetic field ( _Bz ) 8 that confines the plasma, and the air gap 22a is provided on the opposite side to the side where this air gap 22a is provided. Cylindrical part 1 of
On the tip side in the torus direction of No. 7, the air gap 22b is made to extend in the axial direction in the torus direction ()1, that is, almost parallel to the magnetic field lines of the toroidal magnetic field (B _t ) due to the plasma current, and intermittently in the circumferential direction. It is preferable to provide the space between the gaps 22a.

According to the vacuum vessel for a nuclear fusion device of the present invention described above, the characteristics of eddy currents generated in the vacuum vessel formed in a substantially annular shape by alternately arranging a plurality of thick-walled parts and bellows parts are taken into consideration. , gaps extending in the circumferential direction of the cylindrical part are intermittently provided near the fixed part with the thick part of the cylindrical part that covers the outer periphery of the bellows part, so that the flow from the thick part to the cylindrical part is intermittently provided. The eddy current is blocked by the air gap and the eddy current induced in the cylindrical part is significantly reduced, so the stress generated in the bellows part covered by the cylindrical part can be reduced, which is extremely effective when used in this type of vacuum container. It is effective for

[Brief explanation of the drawing]

Figure 1 is a plan view schematically showing a tokamak-type nuclear fusion device with a part of its vacuum vessel in section, Figure 2 is a cross-sectional view in the small circumferential direction, and Figure 3 is a conventional FIG. 4 is a partial sectional view of the vacuum container showing the vicinity of the cylindrical portion covering the bellows portion in a conventional vacuum container; FIG. FIG. 6 is a partial perspective view showing an embodiment of the vacuum container for a nuclear fusion device of the present invention, and FIG. FIG. 1 is a partial perspective view of a vacuum vessel for a nuclear fusion device showing an example. 3... Toroidal coil, 6... Current transformer coil, 7... Plasma, 9... Vertical magnetic field coil, 1
0... Vacuum container, 11... Thick wall part, 12... Bellows part, 14... Eddy current, 17... Cylindrical part, 2
2, 22a, 22b... void.

Claims (1)

[Scope of Claims] 1. A plurality of thick-walled parts and bellows parts are arranged alternately to form a substantially annular shape, and a cylindrical part protruding outward from the thick-walled parts covers the outer peripheral part of the bellows part. In the vacuum vessel for a nuclear fusion device configured to cover the outer periphery of the bellows part, a gap extending in the circumferential direction is intermittently provided in the cylindrical part near a fixed part with the thick part of the cylindrical part that covers the outer periphery of the bellows part. A vacuum vessel for a nuclear fusion device, characterized in that: 2 Separately from the void extending in the circumferential direction of the cylindrical portion, the void extending in the axial direction of the cylindrical portion is provided at the end of the cylindrical portion on the opposite side from the side where the void extending in the circumferential direction is provided. The nuclear fusion device according to claim 1, wherein the voids extending in the axial direction of the cylindrical portion are located in the voids extending in the circumferential direction. Vacuum container for equipment.