| 摘要 |
PURPOSE:To reduce the diameter of a device by executing complete diamagnetic magnetic shield composed of a superconductive material to a main coil device while installing cancel coil devices on both sides of the main coil device. CONSTITUTION:A superconducting magnetic shield 9 consists of an Nb-Ti multilayer thin-film, and a main coil device 1' is covered with the magnetic shield 9 under the state in which the magnetic shield 9 is dipped into liquid He. Consequently, a leakage magnetic field A2'' in the radial direction of a magnetic field generated from the device 1' is suppressed by the complete diamagnetic shield of the shield 9, thus remarkably reducing the size of the magnetic field A2''. A magnetic field A2' leaking to the outside from a magnetic field generating space 3 is diminished markedly or brought to zero by an opposite magnetic field a2'' generated by cancel devices 8 mounted on both sides of the device 1'. That is, a magnetic field A2'-a2' is brought to zero approximately. Accordingly, the diameter of the active shield type superconducting magnet device is scaled down, thus facilitating installation, then reducing the cost of equipment. |
