| Budget Amount *help |
¥3,260,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥360,000)
Fiscal Year 2007: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2006: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
At first, the conceptual design of the superconducting magnet in which the supporting structure was used as a protection resistance was advanced. Secondly, the design of the small coil sample for the principle proof was revised. As the results of the examination of a basic specification of the magnet used for the fusion reactor, it was understood that the resistance of tens of μ Ω or more was necessary for the resistance between turns of the magnet to reduce the heat generation during the excitation within the conventional refrigerating power. It means that the resistance only by stainless steels is too small for it. If the resistance is too large oppositely, the shut-off voltage exceeds the allowable value. Therefore, we need the conductive material that has 1, 000 to 100, 0000 times higher resistivity than stainless steels. Such a material was investigated, and conductive ceramics and the conductive resin were made candidates. Although the conductive ceramics can be a candidate for the real magnet, the conductive resin with carbon is selected for the sample from a viewpoint of productivity and easiness of obtaining. A coil sample without the layer-to-layer insulation was produced with the resin.
Since the larger magnetic energy is preferred to prove the quench protection, the solenoid coil with the diameter of about 100mm was selected. The NbTi strands class 200 A in a rectangular section was used. Its copper ratio is three. The coil is pool-cooled, and its winding is insulated from surrounding helium to evaluate the temperature rise when shut-off. Then the bobbin is made of fiber reinforced plastics, and the outside of the winding is wrapped with Kapton tapes. The resistance between layers can be controlled by adjusting the spaces between the bare NbTi strands and by rubbing the conductive resin into the space. Although the winding method to secure the certain space between layers should be improved, the feasibility of the conductive resin was proved.
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