2007 Fiscal Year Final Research Report Summary
Study on high rigid coil structure aiming to minimize the weight of superconducting magnets in fusion reactors
| Project/Area Number |
18560793
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nuclear fusion studies
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| Research Institution | National Institute for Fusion Science |
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Principal Investigator |
TAKAHATA Kazuya National Institute for Fusion Science, Department of Large Helical Device Project, Professor (10216773)
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| Co-Investigator(Kenkyū-buntansha) |
TAMURA Hitoshi National Institute of Fusion Science, Department of Large Helical Device Project, Assistant Professor (20236756)
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| Project Period (FY) |
2006 – 2007
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| Keywords | Superconducting magnet / Fusion reactor / Aluminum-alloy-jacketed superconductor / Friction stir welding / Aluminum alloy / Nb3Sn / Indirect-cooling method |
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| Research Abstract |
Conceptual design studies on a superconducting magnet for a fusion reactor have been performed using indirect cooling and a rigid superconductor in order to reduce the weight and the cost of the magnet. Then the feasibility and the effect on the weight reduction were investigated. We proposed a novel aluminum-alloy-jacketed Nb3Sn superconductor for the rigid superconductor and designed an indirect-cooled coil structure for the heliotron fusion reactor FFHR. From the studies of elimination of steady-state nuclear heating, support of electromagnetic force, and quench protection, it is confirmed that the indirect-cooled coil is a promising candidate for fusion magnets. Stress and strain distributions in the coil of FFHR were calculated by using three dimensional FEM model. The stress and strain were all below the allowable values. The thickness of the support structural of the coil can be more reduced than that of assumed in the FE model. Comparison with conventional conductors indicates that the proposed superconductor has high rigidity and the coil weight can be reduced.
To demonstrate the fabrication process of the aluminum-alloy-jacketed Nb3Sn superconductor, a sub-scale 10 kA-class superconductor was developed. We developed a conductor fabrication process using a recently developed friction stir welding (FSW) technique that uses friction heating. We succeeded in carrying 19 kA at 8 T. The experiments demonstrated the feasibility of this candidate superconductor. The conductor will be wound after the heat treatment of Nb3Sn. Further investigation will be required to develop a winding processes of the conductor without degradation of superconducting properties.
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