Cryogenic compressive deformation properties of superconducting coil packs simulated for helical coils on LHD [Large Helical Davice] program

An electromagnetic force of above 10 MN/m will act on the helical coils in the Large Helical Device. To investigate the deformation properties of the helical coils, the coil pack, which consists of 16 superconductors, was prepared and a compressive mechanical test was carried out at 4.2 K. Also, the apparent rigidity was discussed on the basis of the mixture law. The results show that the gaps between the electric insulation spacer and the superconductor give rise to hysteresis on the compressive load-deformation curve on the first cycle. The estimated result of the coil pack rigidity gives good agreement with the experiment. (Author)