JPS608778A - 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] [Field of Application of the Invention] The present invention relates to a nuclear fusion device, and in particular, a voloidal magnetic field coil disposed along a donut-shaped vacuum vessel and directly supported by the vacuum vessel. Leap into the fusion device.

[Background of the invention]

Nuclear fusion devices use a magnetic field to trap high-temperature plasma inside a vacuum container, separating it from the container wall. In torus-type fusion devices, a toroidal magnetic field that generates a high magnetic field is used to create a wall of this magnetic field. It is equipped with a poloidal magnetic field coil for stable maintenance of high-temperature plasma or position control. The outline of a nuclear fusion device equipped with this toroidal and voloidal magnetic field coil is shown in FIGS. 1 and 2.

In the drawing, reference numeral 2 denotes a solid-walled container formed into a substantially doughnut-like shape by alternately arranging thick-walled portions 3 and bellows 4, and plasma 1 is confined inside the container.

A plurality of toroidal magnetic field coils 5 surround the vacuum vessel 2 and are arranged at predetermined intervals in the circumferential direction of the torus. On the other hand, the poloidal magnetic field coil 6 is disposed along the vacuum vessel 2 between the vacuum vessel 2 and the toroidal magnetic field coil 5. 8 is a vacuum evacuation device for evacuating the inside of the vacuum container 2, and 9 is an upper and lower pedestal that supports the toroidal magnetic field coil 5 via a support.

In the nuclear fusion device configured in this way, the poloidal magnetic field coil 6 must apply a magnetic field to the plasma 1 in the vacuum vessel 2, so it is better to install it at the smallest possible distance from the vacuum vessel 2. This is advantageous in terms of coupling with the plasma 1, power capacity of the poloidal magnetic field coil 6, and saving limited space. For this reason, the poloidal magnetic field coil 6 is normally attached directly to the outer wall of the vacuum vessel 2 as shown in FIGS. 3 and 4, and the details of the mounting structure are shown in FIG.
The poloidal magnetic field coil 6 is fixedly supported on the vacuum vessel 2 by a support member 12 at a predetermined position in the circumferential direction of the torus.

However, with such a conventional structure, when the temperature of the vacuum container 2 increases due to baking or the like, the vacuum container 2 deforms from the solid line to the dotted line as shown in FIG.

As a result, the attachment point 10 of the Shiboloidal magnetic field coil 6 is set to 11.
Move to. When deformation and displacement occur in the poloidal magnetic field coil 6 in this way, forced displacement is applied to the ciboloidal magnetic field coil 6 due to these relative displacements, and at this time, the stress and strain generated in the poloidal magnetic field coil 6 increase. There was a problem with the strength, which could become excessive.

[Purpose of the invention]

The present invention has been made in view of this, and its purpose is to provide a nuclear fusion device in which the relative thermal displacement between the poloidal magnetic field coil and the vacuum vessel acting on the poloidal magnetic field coil is small.

[Summary of the invention]

In the present invention, the electric resistance of the poloidal magnetic field coil provided along the circumferential direction of the torus of a nearly donut-shaped vacuum vessel that stores plasma therein is made of a conductor larger than that of pure copper, and the coil thermally expand,
This is designed to minimize the difference in thermal displacement between the coil and the vacuum vessel to achieve the so-called purpose.

The present invention will be described in detail. Each symbol is ΔRv Main radial thermal displacement of the vacuum vessel ΔRc Main radial thermal displacement of the coil Δtv Temperature rise of the vacuum vessel Δtc Temperature rise of the coil Rv Main radius of the point of interest of the vacuum vessel FLc Main of the point of interest of the coil The radius αV is the linear expansion coefficient of the vacuum vessel and the linear expansion coefficient αC of the coil.

Poloidal magnetic field coil 6 generated when the temperature of the vacuum container 2 increases
The thermal stress of is caused by the displacement difference between the two.

Here, each torus principal radial displacement is ΔRv
-Δtv-L(v・αV ΔRc−Δtc−ruc・αC, so if Rv=Rc, the displacement difference ΔR becomes ΔR−ΔRv−ΔELc=(Δtv(Iv−Δtcαc) Rv, which is a poloidal To reduce the thermal stress of the magnetic field coil 6, Δtvα
It can be seen that V and ΔtcαC should be made as equal as possible.

For this purpose, it is most effective to match the coefficients of linear expansion of the vacuum vessel 2 and the poloidal magnetic field coil 6, and to equalize their temperatures.

The present invention has been made with this point in mind.

The poloidal magnetic field coil 6 attached to the vacuum container 2 is
Assuming that the vacuum container 2 and the vacuum container 2 are sufficiently heat-insulated, when the vacuum container 2 is baked, the temperature of both will be equal due to heat conduction from the vacuum container, so by making the coefficients of linear expansion approximately equal, Almost no stress is generated in the poloidal magnetic field coil 6, and a good nuclear fusion device can be obtained.

On the other hand, if the heat retention of the poloidal magnetic field coil 6 is insufficient, heating of the poloidal magnetic field coil 6 by heat conduction from the vacuum container cannot be expected, so it is necessary to raise the temperature by energizing the coil itself.

However, since the temperature rise due to normal baking of the vacuum container 2 is 100 C or more, a conventional voloidal magnetic field coil using a copper conductor cannot achieve its purpose unless a large current is passed for a long time.

This is because the conventional design concept of the coil was to reduce Joule loss.

In the present invention, since a material with higher electrical resistance than pure copper is used for the conductor constituting the voloidal magnetic field coil, compared to the conventionally configured coil, it is necessary to obtain the same temperature rise by only one square root of the electrical resistance ratio with pure copper. All you need to do is to flow the following current, and by that amount,
The electromagnetic force generated can be reduced.

For example, if the vacuum vessel and voloidal magnetic field coil are 5US
304, the electrical resistance is about 35 times that of electrolytic copper, so the coil current when energized and heated is about 1/6 of that of a conventional copper coil.

〔Effect of the invention〕

According to the nuclear fusion device of the present invention described above, it is possible to obtain a nuclear fusion device in which the thermal displacement of the voloidal magnetic field coil provided along the circumferential direction of the torus of the donut-shaped vacuum container is small.

[Brief explanation of the drawing]

Figure 1 is a partially sectional plan view of a torus-type fusion device, Figure 2 is a sectional view taken along line A-A, Figure 3 is a plan view of a vacuum vessel with a voloidal magnetic field coil placed 11 meters away, and Figure 4 The figure is a cross-sectional view taken along line BB, FIG. 5 is a cross-sectional view of the vacuum container showing the state in which a conventional voloidal magnetic field coil is attached, and FIG. 6 is a view showing the state after displacement. 1... Plasma, 2... Vacuum vessel, 5... Toroidal magnetism Figure I Figure 2 Figure 3 Figure 4 Figure 5 611

Claims (1)

[Scope of Claims] 1. A substantially donut-shaped vacuum container containing plasma therein, a plurality of toroidal magnetic field coils surrounding the vacuum container and arranged at predetermined intervals in the circumferential direction of the torus; A nuclear fusion device comprising a poloidal magnetic field coil provided along the circumferential direction of a torus of a vacuum vessel, characterized in that the voloidal magnetic field coil is constructed using a conductor having a higher resistance to peeking than pure copper. Nuclear fusion device. 2. The nuclear fusion device according to claim 1, wherein the conductor of the voloidal @Yang coil has a linear expansion coefficient substantially equal to that of the material constituting the vacuum vessel.