Mechanical Properties Evaluation of Large Scale Superconductors in High Magnetic Field and Large Current under Cryogenic Temperatute.

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Large scale plasma devices, such as the Large Helical Device, the Wenderstein 7-X and the International Thermo-nuclear Experimental Reactor, have been planed and started to fabrication. These large devices require the large scale superconducting magnet to generate high magnetic fields. Since huge electro-magnetic forces will act on the superconducting magnet during the operation, the mechanical deformation behavior must estimate before fabrication. For this purpose, the several kinds of measurements for the deformation evaluation have been carried out in this study.1.NbTi superconductor which had a copper ratio of 1.0 to 2.0, was deformed locally at room temperature, and then was cooled into liquid helium. In this case, a recovery after quenching was delayd because of the increase of an electrical resistance of copper. On the other hand, when the superconductor was deformed at cryogenic temperature, the recovery occurred in a normal way. From these results, it was recognized that the changes of the electric property of a stabilizer were affected by the mechanical deformation and it should be noted on the magnet design and fabrication.2.The superconductors which was used for the Large Helical Device had a rather stability to mechanical deformation. The coil deformation would be estimated by the mechanical test using a coil pack.3.An excitation test of Inner Vertical coil of the Large Helical Device was carried out, and the deformation during cooling period and excitation test was measured successfully. In the deformation measurement, cable wires should be considered not to be affected by magnetic field.