JPH01248090A - Helical vacuum vessel - Google Patents

Abstract

PURPOSE:To prevent generation of restricting stress by a thermal expansion of a helical coil and to avoid generation of stress on a bellows by its torsion, by providing at least one bellows at certain cross sections along a torus direction of a vacuum vessel. CONSTITUTION:When electricity is charged, a helical coil 3 is heated by an electrical resistance of its conductive lead, and expands thermally. On the other hand, an electric current through the helical coil 3 increases, being resulted from generation of a high temperature plasma. Also, the helical coil 3 is being used at higher and higher temperature. An expansion difference between the helical coil 3 and the vacuum vessel is apt to be absorbed by an extension movement of the helical coil 3 sliding along a helical coil groove towards an axial direction of the helical coil. With this movement, the helical coil 3 is apt to expand the vacuum vessel. Therefore, with placement of a bellows at a part of thick wall portion of the helical vacuum vessel, the thermal expansion of the helical coil is not restricted and a thermal stress is not generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a helical vacuum vessel, and more particularly to a helical vacuum vessel having a helical coil wound spirally on its outer surface. .

[Conventional technology]

Generally, a tokamak type vacuum container is
As shown in Japanese Patent No. 74.98, a bellows is provided in a vacuum container to absorb thermal expansion during baking of the vacuum container and to reduce eddy current generated in the vacuum container. However, in the case of a helical vacuum vessel with a helical coil, the absorption of thermal stress generated in the helical coil is
It wasn't taken into consideration.

[Problem to be solved by the invention]

Recent nuclear fusion devices are becoming larger and more precise in order to achieve critical conditions. Furthermore, in order to improve the performance of plasma, the magnetic field for stopping and sending the plasma needs to be made stronger, and the Ml current flowing through the coil is also becoming larger and larger.

In the field of torus-type nuclear fusion, the conditions are similar to those mentioned above, and the strength of the helical coil attached to the helical-type vacuum vessel is also becoming extremely strict.

In contrast, conventional helical vacuum vessels do not take into consideration the thermal expansion stress of the helical coil, and there is a possibility that the helical coil may be destroyed.

The present invention has been made in view of the above-mentioned points, and its purpose is to provide a helical type coil that prevents the helical coil wound around the outer surface of the vacuum container from being destroyed even if there is thermal expansion. We provide vacuum containers.

[Means to solve the problem]

The above purpose is to install a bellows on one cross section of the helical vacuum vessel.
Alternatively, by arranging a thermal elongation absorbing means, and absorbing the thermal elongation of the helical coil itself due to the temperature rise of the helical coil when the helical coil is energized, by stretching the bellows, or by absorbing it by the thermal elongation absorbing means. be done.

Furthermore, this can be achieved by arranging shear pins on the bellows in a direction perpendicular to the axis of the bellows so that the bellows is not twisted when the helical coil is wound around the helical vacuum vessel.

[Effect]

The bellows placed in the helical vacuum vessel is stretched as the helical coil is thermally expanded, and the diameter of the helical vacuum vessel increases. Therefore, the thermal expansion of the helical coil is no longer restrained, and no thermal expansion stress is generated in the helical coil, so that the helical coil will not be destroyed.

Furthermore, by disposing a jerky in the bellows portion, this jerky supports the torsional force that acts on the bellows portion during winding of the helical coil, so that the bellows will not be twisted and destroyed.

〔Example〕

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is an overall view of the helical vacuum vessel.

The helical coil 3 wraps around the vacuum container in a spiral manner around the outer surface of the thick wall portion 2 of the helical vacuum container. Furthermore, this helical coil 3 is embedded in a groove dug in the thick wall portion 2 as shown in FIG. At this time, the magnetic field distribution due to the helical coil 3 is relative to the plasma 5.

Since it is necessary to be symmetrical, all cross sections of the thick portion are arranged symmetrically with respect to the center of the plasma 5. Therefore, when the coils are energized, the helical coils 3 at symmetrical positions repel each other and jump out of the groove of the helical coil 3. To support this, a helical coil support 4 is installed along the outer surface of the helical coil 3.

With the above structure, when the helical coil 3 is energized, the following three problems occur.

(1) Since the helical coil 3 goes around the vacuum vessel while spirally wrapping the outer surface of the thick wall part 2 of the helical vacuum vessel, the developed length of the helical coil 3 is the circumference of the helical vacuum vessel. With the recent increase in the size of helical vacuum vessels, this trend is becoming more and more pronounced.

In this case, when energized, the helical coil 3 generates heat due to the electrical resistance of the conductor of the helical coil 3 and thermally expands.

On the other hand, in order to generate high-performance plasma, the helical coil 3 is supplied with an increased current in order to strengthen the magnetic field of the helical coil. Furthermore, due to the development of high-temperature insulating materials, the helical coil 3 is being used at increasingly high temperatures even though it is cooled by the cooling pipe 6 inside the conductor.

As mentioned above, the ratio of the circumferential length of a helical vacuum vessel to the developed length of a helical coil is increasing, and the operating temperature of a helical coil is increasing. The difference in expansion is extremely large.

(2) In order to improve plasma performance, we will improve the machining accuracy of the helical groove in the thick wall part of the helical vacuum vessel, and
Since mounting precision of the helical coil 3 is required, the gap between the helical coil 3 and the helical coil groove is becoming smaller and smaller, and there is no gap to absorb the difference in thermal engraving of the helical coil.

(3) In order to improve plasma performance, it is necessary to increase the strength of the magnetic field for plasma confinement, and the current flowing through the helical coil 3 increases. Therefore, the electromagnetic force acting on the helical coil 3 increases, and it is necessary to further increase the rigidity of the helical coil support 4. As a result, the helical coil 3 can no longer be thermally expanded in the radial direction.

Due to the above three points, the difference due to thermal expansion between the helical coil 3 and the helical vacuum container is absorbed by the helical coil 3 sliding in the helical coil groove and extending in the axial direction of the helical coil.

As a result, the helical coil 3 tries to push and expand the helical vacuum container. Due to this force, the bellows 1 is arranged in a part of the thick wall part so that the helical type vacuum container expands without resistance. In this way, bellows 1
expands without restricting the thermal expansion of the helical coil 3, so no restraint stress is generated in the helical coil 3 due to thermal expansion restriction.

As a result, the helical coil 3 will not be destroyed.

As explained above, if the bellows is arranged in a part of the thick wall part of the helical vacuum vessel as shown in FIG. 1, the thermal expansion of the helical coil will not be restricted, so no thermal stress will occur.

Furthermore, when the helical coil is wound around the vacuum vessel, a large torsional reaction force is applied to the vacuum vessel. As a result, the vacuum container may become twisted at the bellows portion.

To restrain this torsional force, use a fastening flange.

Placed on both ends of the bellows and fastened with fastening bolts. Furthermore, a shear pin is arranged on the fastening flange to prevent the bellows from twisting.

FIG. 3 shows details of the flange portion.

FIG. 3 is a detailed view of section B in FIG. 1. Bellows 1 is
It is welded to the thick part 2. A fastening flange 8 is connected to the thick portion 2, and the fastening flange 8 is tightened with a fastening bolt 11 via an insulating sleeve 9 and an insulating washer 10 in order to increase electrical resistance. A certain gap is provided between the fastening flange 8 and the fastening bolt 11 so that the bellows 1 can be thermally expanded when the helical coil is thermally expanded, as described above.

In this way, the thermal elongation of the helical coil is absorbed by the axial elongation of the bellows, and the torsional force acting on the bellows during helical coil winding is absorbed by the shear pin. , the bellows will not be damaged.

〔Effect of the invention〕

According to the present invention described above, the thermal expansion of the helical coil can be absorbed by the bellows of the helical vacuum vessel, so that no restraint stress is generated in the helical coil due to thermal expansion. Furthermore, the torsional force of the bellows during helical coil winding can be supported by the shear pin, so no stress due to torsion is generated in the bellows. In this way, a bellows is provided in a part of the helical vacuum container,
By providing the shear pin in the bellows, the strength of the helical coil and the bellows will not be impaired, so there is an effect that a reliable helical type vacuum container can be manufactured.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a helical vacuum vessel showing an embodiment of the present invention, Fig. 2 is a cross-sectional view taken along line A-A in Fig.
It is a detailed view of part B in the figure. 1... Bellows, 2... Thick wall part, 3... Helical coil, 4... Helical coil support, 5... Plasma, 6... Cooling pipe. 1 map prefecture 3 map

Claims (1)

[Claims] 1. A helical type vacuum vessel having a helical coil wound spirally on the outer surface, characterized in that at least one bellows is provided on a certain cross section in the torus direction of the vacuum vessel. Helical vacuum container. 2. The helical type vacuum vessel according to claim 1, wherein the bellows portion is provided with a fastening flange for maintaining the distance between the surfaces of the bellows, and a plurality of shear pins are provided in a toroidal direction. 3. In a helical vacuum container having a helical coil wound spirally on the outer surface, the vacuum container is formed of a thick wall portion and at least one bellows installed in a certain cross section in the torus direction. A helical vacuum container characterized by: 4. In a helical type vacuum vessel equipped with a helical coil wound spirally on the outer surface, at least one layer is provided on a certain cross section in the torus direction of the vacuum vessel to absorb thermal elongation of the helical coil when electricity is applied to the helical coil. A helical vacuum container characterized by being equipped with an absorption means.