GB2142771A

GB2142771A - Toroidal coil apparatus

Info

Publication number: GB2142771A
Application number: GB08415878A
Authority: GB
Inventors: Kazuo Kuno; Tadashi Ichihara; Shintaro Fukumoto; Daisaburo Nagata
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1983-06-21
Filing date: 1984-06-21
Publication date: 1985-01-23
Also published as: JPS604203A; DE3422567C2; GB8415878D0; GB2142771B; DE3422567A1

Abstract

A toroidal coil apparatus comprising: a plurality of split support frames 30a, b which contain the coils 1, and which are radially arranged in an erect manner, connecting portions consisting of recesses 32 on one frame part and projections 31 on the other frame part, these projections and recesses being so constructed as to fit to each other; and inversion preventing beams (8) that are connected to the neighboring support frames near the connecting portions. <IMAGE>

Description

SPECIFICATION Coil apparatus The present invention relates to a large coil apparatusfor generating a strong magnetic field used for apparatus for nuclear fusion, and particularly to a support frame construction for supporting coils.

First, a conventional apparatus will be de scribed'below with reference to a toroidal construction for a torus-type apparatus for nuclear fusion. In a toroidal magnetic field generating apparatus employed for the torustype nuclear fusion apparatus, in general, a toroidal magnetic field is generated by permitting heavy currents to flow in the same direction through a plurality of coils arranged in a torus circle. An intense electromagnetic force is generated in the toroidal coils owing to the interaction between the magnetic field and the currents flowing in the coils.The electromagnetic force can be divided into a force for expanding the coils, a centripetal force that works to collect a plurality of toroidal coils toward the center thereof as a whole, and an inverting force that is generated by the interaction of the' electromagnetic force and a poloidal magnetic field and that acts to move the toroidal coils outwards. In the toroidal magnetic field generating apparatus, a problem exists with regard to how to support the electromagnetic forces that act on the coils and how to. minimize the stress or deformation generated in the coils.

In a conventional apparatus having a small scale as shown in Figs. 1 and 2, toroidal coils 1 are contained in coil support frames 2, and are secured onto a rack 3 by bolts 4.

In. the case of an apparatus of a large scale as shown in Figs. 3 to 5, a plurality of coil support frames 2 containing toroidal coils 1 are collected in a precise radial form with the inner sides thereof located towards the center side, and wedge surfaces S formed on both sides of the inner sides of the coil support frames 2 are intimately joined to each other, so that the electromagnetic force is correctly received via the wedge surfaces S so that the apparatus can withstand an intense electromagnetic force. To support the weight of the toroidal coils 1, force from the heat and electromagnetic force, furthermore, the coil support frame 2 consists of a C-shaped upper support member 2b and an L-shaped lower support member 2a that are coupled together by connection members 2c, 2d.The thus constructed coil support frame 2 is secured onto the rack 3 by bolts 4, in order to support the toroidal coils 1. To cope with the inverting force, inversion preventing beams 8 are installed among the neighbouring coils in the tbrus direction. as shown in Fig. 6 to produce rigidity relative to the neighbouring coils.

In either case, mechanical strength of the toroidal coils 1 composed of copper is mostly dependent upon the coil support frames 2.

Fig. 7 is a sectional view of the conventional coil support frame 2. A conductor 11 constituting the toroidal coil 1 is wound several turns, wrapped in an inter-layer insulator 12, wrapped in an insulator 1 3 to insulate from grounding, and is inserted in a frame 21 which consitutes a major portion of the coil support frame 2 and which has a U-shaped in cross section. Then, a cover-like frame 22 is secured by bolts 5 to firmly contain the toroidal coil 1 in the coil support frame 2. Depending upon the construction of the coil, intensity of electromagnetic force and economical aspect, the cover-like frame 22 will be secured by bolts as shown in Fig. 8(a) or will be secured by welding as shown in Figs. 8(b) and 8(c).The conventional toroidal coil 1 is constructed as described above, and intense electromagnetic forces F and Fr generated in the conductor 11 are transmitted to the coil support frame 2 via insulators.

It is, however, a recent trend to construct coils in large sizes, to allow heavy currents to flow for extended periods of time resulting in an increase in the expanding force and in coil temperature. Also, heavy currents are in allowed to flow the poloidal coils resulting in an increase in the inverting force. Therefore, the conventional coil support construction is no longer capable of withstanding the stress and displacement exerted on the coils. Moreover the mechanical strength of the coil support frames 2 supporting the coils is no longer sufficient. Particularly, the coil support frame 2 having a two-split construction is no longer capable of providing sufficient strength and allows large displacement to occur.Further, accompanying the diversifying study of nuclear fusion many instruments for observing plasma are installed, making it difficult to freely arrange the inversion preventing beam 8. Accordingly, it is now becoming difficult to support the increasing inverting force.

The present invention was accomplished in view of the defects inherent in the abovementioned conventional art, and has for its object to provide a coil apparatus in which the coil support frames are split near the positions where the inversion preventing beams will be arranged, and th coil support frames which are split are connected relying upon an insert construction, in order to reduce the stress and displacement caused by the inverting force acting on the coils and the coil support frames.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a plan view which schematically illustrates a conventional coil apparatus employed in a small nuclear fusion apparatus; Figure 2 is a section view along the line ll-ll in Fig. 1; Figures 3 to 5 are a plan view, a sectional side view, and a plan view illustrating schematically a conventional coil apparatus employed in a large nuclear fusion apparatus; Figure 6 is a plan view showing a conventional construction for preventing the coil apparatus from inverting; Figures 7, 8(a), 8(b) and 8(c) are section views illustrating the state for supporting the coils relying upon the conventional coil support frames; Figures 9 and 10 are a side view and a disassembled view illustrating a coil support construction for a coil apparatus according to an embodiment of the present invention; and Figures ii and 12 are diagrams showing the stress distribution of the coil support frame according to the present invention.

In the drawings, the same reference numerals denote the same or corresponding portions.

An embodiment of the present invention will be described below in conjunction with Figs. 9 to 1 2. The toroidal coil 1 is inserted in coil support frames 30a, 30b that are split into two at the portions of inversion preventing beams 8. A convex portion 31 is formed at the connecting portion of the coil support frame 30a, and a concave portion 32 is formed at the connecting portion of the coil support frame 30b to engage with the convex portion 31. After the concave portion 32 and the convex portions 31 are fitted to each other, the coil support frames 30a, 30b are firmly secured together by bolts 33. As will be understood from stress values at each of the portions shown in Figs. 11 and 1 2, the coil support frames 30a, 30b should most suitably be split at the portions of inversion preventing beam 8.In order to improve the workability, furthermore, a groove 34 for inserting the toroidal coil 1 is linearly cut near the split portion of the coil support frame 30b. After the toroidal coil 1 is inserted, wedges 35 are driven to tightly couple the toroidal coil 1 and the coil support frame 30b together. Furthermore, in order to avoid an excessive inverting force from exerting on the split portions of coil support frames 30a, 30b, the convex portion 31 is provided for the coil support frame 30a and the concave portion 32 is provided for the coil support frame 30b. The coil support frames 30a, 30b are then- firmly fastened together by bolts 33.

Described below is how to support the coils.

The toroidal coil 1 is wrapped in an inter-layer insulator and in a ground insulator, and is inserted in the coil support frames 30a, 30b.

The wedge 35 is then driven between the toroidal coil 1 and the groove 34 in the coil support frame 30b to tightly couple them together. Then, the convex portion 31 and the concave portion 32 of the coil support frames 30a, 30b are fitted together the coil support frames 30a, 30b are tightly coupled together and are rigidly secured by bolts 33. The cover-like frame 22 is then welded in a manner as shown in Fig. 8(c) to complete a whole construction of coil support frames 30a. 30b.

As described above, the coil support frames 30a, 30b are split at the portions of inversion preventing beams 8, and are provided with the convex portion 31 and concave portion 32 which are to be fitted together, and are firmly secured together by bolts 33. Therefore, the connecting portions exhibit greatly increased rigidity, so that reduced stress and displacement stemming from the inverting force are exerted on the toroidal coil 1 and on the coil support frames 30a, 30b. Moreover, the wedge 35 is driven between the toroidal coil 1 and the groove 34 in the coil support frame 30b, so that the toroidal coil 1 and the coil support frame 30a are intimately coupled together to exhibit increased rigidity.

Although the above-mentioned embodiment has dealt with the case of a D-type toroidal coil apparatus. the invention can also be adapted to a circular-type toroidal coil apparatus to obtain the same effects as the abovementioned embodiment.

According to the present invention as described above, the coil support frames are split near the portions where the inversion preventing beams are to be arranged, and the connecting portions of the coil support frames are fitted to each other. Therefore, the coil and the coil support frames can be tightly coupled together to enhance the rigidity thereof. It is thus possible to obtain a coil apparatus in which the coil and the coil support frames receive reduced stress and displacement that stem from the inverting force.

Claims

1. A coil apparatus comprising: a plurality of split-type support frames which consist of a plurality of frames, which contain the coils, and which are radially arranged in an erect manner with the inner sides thereof being located on the center side; connecting portions consisting of convex portions provided for the frames of one side and concave portions provided for the frames of the other side, said convex and concave portions being so constructed as to fit to each other; and inversion preventing beams that are connected to the neighboring support frames near the connecting portions.

2. A coil apparatus as set forth in claim 1, wherein said coils are toroidal 'coils.

3. A toroidal coil apparatus comprising a plurality of toroidally arranged coil support frames disposed radially and erect with their radially inner sides adjacent the centre of the apparatus, each coil support frame being split into a radially inner and a radially outer part which are interconnected by connecting means comprising a recess provided in one such part and a mating projection provided on the other such part, and bracing members disposed between adjacent coil support frames at or near the said connecting means of said frames.

4. A coil apparatus as set forth in claim 1, 2 or 3 wherein wedge surfaces are formed on both sides of each of said support frames on the inner side thereof, and are intimately joined to each other.

5. A coil apparatus as set forth in any preceding claim, wherein said support frame and said coil are intimately coupled together by means of at least-one wedge.

6. A coil apparatus as set forth in any preceding claim, wherein said connecting portions or means are firmly fastened together by bolts.

7. A toroidal coil apparatus substantially as herein described with reference to Figs. 9 to 1 2 of the accompanying drawings.