2000 年 35 巻 2 号 p. 87-94
The superconducting magnets on Maglev vehicles when running vibrate mechanically due to electromagnetic disturbance from the ground coils. Therefore, the current leads fixed on the superconducting coil, which is vibrating at about 98m/s2 (=10g), are also required to endure the vibration. We executed dynamic vibration tests for two types of current leads (straight & arc types) which had a multi-stacked configuration of Ag-sheathed Bi2223 tapes impregnated with epoxy resin in a concaved reinforcing gutter. We evaluated the straight-type lead for an operating current of 700A after every vibration test in liquid nitrogen for one hour under the dynamic strain deformation of 50-100μ on the surface of the reinforcing material covering the current lead. We could not detect degradation of the current lead by vibration through the total cycles of 3.9×106 after continuous vibration tests. We also executed vibration tests for arc-type current leads which were combined with an actual energized superconducting coil for a Maglev. Large accelerations of these current leads occurred at frequencies of 308 and 375Hz. In spite of the maximum acceleration of 600-700m/s2 generated by actuating the excessive force on a superconducting coil for two seconds, which occurred on these current leads carrying 500A, the superconductivity of the current leads did not shift to normal conductivity. There was no damage to either type of current lead during these vibration tests. So we confirmed the good prospect for the application of these current leads to actual Maglev superconducting magnets.