| 摘要 |
PURPOSE:To enhance performance and to reduce a size and a light by combining a ceramic superconductor, a metal superconductor, and disposing the ceramic superconductor on a high magnetic field region and the metal superconductor on a low magnetic field region. CONSTITUTION:In order to prevent adverse influence of an electromagnetism of a high magnetic field generating magnet 7 to an external field, a shield unit 8 of a ceramic superconductor 1 and a shield unit 9 of a metal superconductor 2 are disposed in superposition in a cryostat 3 cooled with liquid helium(L- He). In this case, since the unit 8 of the superconductor 1 is disposed at the high magnetic field side, i.e., the magnet 7 side, the unit 8 shields most of the magnetism generated from the magnet 7, and weak magnetism of a trap magnetic field, etc., of itself is shielded by the unit 9. Further, since the shielding operation is generated by a shielding current in the high magnetic field, the unit 8 of the superconductor 1 is used. Thus, the thickness of a ferromagnetic shield unit is reduced to be decreased in size and weight. |
