JPS5946578A - Vacuum vessel of nuclear fusion device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum vessel for a nuclear fusion device, in particular, it is formed by alternately arranging thick and thin bellows parts, and the entire outer periphery of the bellows part is covered by a cylindrical part. The present invention relates to a vacuum vessel for a nuclear 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 you can see, the tokamak-shaped fusion device is oriented in the torus direction (φ
) 1 generates a strong toroidal magnetic field (Bi) 2, a toroidal coil 3 generates a plasma current (I
, ) 4'if-, a current transformer coil 6 generated in the current transformer magnetic field (Bf) 5, a vertical magnetic field that controls the position of the plasma 7 in balance with the hoop force etc. due to the plasma current (I ri 4) (B8) It is roughly composed of a vertical magnetic field coil 9 that generates 8, a vacuum vessel 10 that generates plasma 7 inside, etc. In particular, the vacuum vessel 10 is configured to change the current due to the temporal change in the current of the current transformer coil 6. Due to the fluid action, the vacuum container 10
Plasma current (Ip) 4' in torus direction (ψ) 1
Since the structure is such that high-temperature, high-density plasma 7 can be obtained by generating e and the resulting Joule loss, it is necessary to have a sufficiently large electrical resistance in the torus direction 1 relative to the electrical resistance of plasma 7. There is. Therefore, generally, the vacuum container 10 has a plurality of thick parts 11 in the torus direction 1.
It is a composite structure in which thin bellows portions 12 are alternately arranged to form a substantially annular shape, and most of the electrical resistance is ensured by the bellows portions 12.

Furthermore, in order to ensure the full electrical resistance, the bellows portion 12 must not only be made thinner, but also have a longer total extension in the torus direction 1, and the height and number of the ridges of the bellows portion 12 must be increased. In addition to the load of the vacuum force, a large eddy current (i,) is induced and flows in the vacuum vessel 10 when the plasma current (Ip) 4, vertical magnetic field CB, ) 8, etc. suddenly changes, and this eddy current (i , ) interlink with various magnetic fields and generate electromagnetic force.

This will all be explained using FIG. The drawing shows the details of the thick wall part 11 and the bellows part 12 of the vacuum container 10. As shown in the drawing, the torus direction 1 of the thick wall part 11 and the bellows part 12 is
Since the electrical resistances of the eddy current <r,>14 are largely different, most of the eddy current <r,>14 flows throughout the thick-walled part 1. especially,
The small circumferential direction (θ) 15 component of the eddy current (i,) 14 interlinks with the toroidal magnetic field (B*) 2, so a large electromagnetic force (
F') occurs in the direction shown by the arrow. A similar load is generated on the bellows portion 12, so it is important to ensure the full strength of the bellows portion 12, but it is difficult to design a bellows portion 12 that achieves both strength and resistance.

As a solution to such problems, it is possible to support and fix the middle of the bellows part 12, which is elongated in the torus direction 1, with an electrically insulated and highly rigid structure. A method for this purpose is proposed in Japanese Patent No. 55-154495.

FIG. 4 shows all the examples in Japanese Patent Application Laid-open No. 55-15449i'5.

In the figure, it is composed of a cylindrical part 17 protruding from the thick wall part 11 of the vacuum container 10 so as to cover the bellows part 12, a support ring 18 fixed in the middle of the bellows part 12, an insulator 19, an insulating bolt 20, etc. In addition, the strength of the bellows portion 120 is ensured by supporting the support ring 18 on the highly rigid cylindrical portion 17 via an insulator 19 and an insulating bolt 20.

This example is effective as a method of reinforcing the bellows portion 12, but as shown in FIG.
As a result, a large eddy current (i,) 14 flows into the cylindrical portion 17 which is fixed to the thick walled portion 11, which has a long length in the torus direction. The electromagnetic force (f) is generated and the cylindrical part 17 is deformed, and this deformation of the cylindrical part 17 gives forced deformation to the bellows part 12, so the stress in the bellows part 12 is equivalent to this forced deformation. The disadvantage is that it gets bigger.

The present invention has been made in view of the above-mentioned points, and its purpose is to fully reinforce the bellows at its outer periphery.
To provide a vacuum vessel for a nuclear fusion device which can reduce eddy current induced in the cylindrical part even if it is covered with a cylindrical part, and can therefore eliminate all stress generated in the bellows part.

The present invention provides electrical insulation means for the direction of flow of eddy currents generated in a vacuum vessel, which is formed in a substantially circular shape by alternately arranging a plurality of thick walled parts and bellows parts. The intended purpose is achieved by applying it to the cylindrical part that covers the outer periphery of the protruding bellows part.

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 portion. Therefore, the present invention takes advantage of the characteristics of eddy currents, applies electrical insulation means to the cylindrical part in the direction of flow of eddy currents, and prevents the eddy currents from circulating from the thick part to the cylindrical part. be.

The present invention will now be described in detail based on embodiments shown in the drawings. Note that the same reference numeral 't-' will be used for the same reference numeral as in the prior art.

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.

The thick part 11 and the cylindrical part F of the vacuum vessel in this embodiment shown in the drawing are connected to each other by welding, and the cylindrical part 17 is
A gap 22 is provided intermittently in the small circumferential direction (15) on the side near the thick part 11 as an electrical insulating means with respect to the small circumferential direction (15). )x+
Since the gap 22 only needs to function as electrical insulation in the flow direction, the width of the gap 22 in the torus direction (ψ) 1 may be as small as possible, and it is not necessarily necessary to provide it in a plane perpendicular to the torus direction (ψ) 1. It is something.

By having such a configuration of this embodiment, J, thick wall portion 1
Eddy current (i,) 1 trying to flow from the 1 side to the cylindrical part 17
4, the flow path of J is blocked by the gap 22, and the cylindrical part 1
The eddy current induced in the cylindrical portion 17 is significantly reduced, and therefore no strong electromagnetic force is generated in the cylindrical portion 17, and the bellows portion is not deformed, so the stress in the bellows portion is significantly reduced. become.

Incidentally, in order to arrange the void most effectively as an electrical insulation means, it is sufficient to provide the void so as to be perpendicular to the flow path of the eddy current (i,), so as shown in FIG. In the vicinity of the fixed portion between the portion 11 and the cylindrical portion 17, the gap 223 is formed in the small circumferential direction (
15, that is, the vertical magnetic field (B,) that confines the plasma.
8, and on the tip end side in the torus direction of the cylindrical portion 17, it is preferable to provide the gap 22ba-) to the lath direction (ψ)1, that is, substantially parallel to the lines of magnetic force of the toroidal magnetic field (Bi) due to the plasma current.

In addition to the above-mentioned voids, although not particularly shown, the welding portion connecting the thick portion 11 and the cylindrical portion 17 may be made intermittently.
Of course, even if a gap is formed between the two, the same effect as described above can be obtained.

According to the vacuum vessel for a nuclear fusion device of the present invention explained above,
Electrical insulation means for the flow direction of eddy currents generated in a vacuum container formed in a substantially circular shape by alternately arranging a plurality of thick walled parts and bellows parts is provided on the outer periphery of the bellows parts by protruding outward from the pre-thickened wall parts. Because it is applied to the cylindrical part that covers the
The eddy current flowing from the thick part to the cylindrical part is blocked by the electrical insulation means, and the eddy current induced in the cylindrical part is significantly reduced, so that the stress generated in the bellows part covered by the cylindrical part can be reduced. , it is very effective when used in this kind of vacuum container.

[Brief explanation of the drawing]

Figure 1 is a plan view schematically showing a tokamak-type nuclear fusion device with a partial cross-section of its vacuum vessel, Figure 2 is a cross-sectional view in the small circumferential direction, and Figure 3 is a conventional fusion device used in the device. FIG. 4 is a partial perspective view of a vacuum container for explaining eddy currents, etc. in a vacuum container (9), and FIG. is a partial perspective view of a vacuum vessel for explaining eddy currents etc. in the configuration of FIG. 4, FIG. 6 is a partial perspective view showing an embodiment of the vacuum vessel for a nuclear fusion device of the present invention, and FIG. FIG. 7 is a partial perspective view of a vacuum vessel for a nuclear fusion device showing another embodiment of the invention. 3... Toroidal coil, 6... Current transformer coil, 7
... Prada 7.9... Vertical magnetic field coil, 10...
・Vacuum container, 11... Thick wall part, 12... Bellows part, 14... Eddy current, current)

Claims (1)

[Scope of Claims] 1. A cylindrical part that is formed into a substantially annular shape by alternately arranging a plurality of thick-walled parts and bellows parts, and that protrudes outward from the thick-walled parts, and the outer peripheral part of the bellows part. 1. A vacuum container for a nuclear fusion device configured to cover a vacuum container for a nuclear fusion device, characterized in that an electric insulating means for the flow direction of an eddy current generated in the vacuum container is applied to the entire cylindrical portion. 2. The vacuum vessel for a nuclear fusion device according to claim 1, wherein the electrical insulation means with respect to the eddy current flow direction is constructed by providing a gap in a part of the cylindrical portion. 3. The vacuum vessel for a nuclear fusion device according to claim 2, wherein a plurality of the voids are provided substantially intermittently at an end of the cylindrical portion near the thick walled portion. 4. The electrical insulation means with respect to the flow direction of the eddy current is performed by intermittent welding when connecting the thick wall part and the cylindrical part to form a gap in a part between the thick wall part and the cylindrical part. The vacuum vessel for a nuclear fusion device according to claim 1, characterized in that the vacuum vessel is made of aluminum.