Compact superconducting magnet configuration with active shielding having a shielding coil contributing to field formation

摘要

Superconducting magnet configuration (4) with active shielding for generating a homogeneous magnetic field (B o) in an examination volume (4b), comprises: radially inner superconducting main field coil (1) comprising unstructured solenoid coil or several radially nested unstructured solenoid coils; superconducting shielding coil (2) disposed coaxially and radially exterior to main field coil; ferromagnetic field formation device (3) disposed radially within main field coil; and ferromagnetic shielding body surrounding main field coil and shielding coil in radial and axial direction. Superconducting magnet configuration (4) with active shielding for generating a homogeneous magnetic field (B o) in an examination volume (4b), comprises: a radially inner superconducting main field coil (1) which is disposed rotationally symmetrically about z-axis and having an axial length (L haupt), the main field coil comprising an unstructured solenoid coil or several radially nested unstructured solenoid coils, which are driven in a same direction; a superconducting shielding coil (2) disposed coaxially and radially exterior to the main field coil, the shielding coil generating a magnetic field in the examination volume which is directed substantially opposite to a magnetic field generated by the main field magnet in the examination volume, the shielding coil having an axial length (L abs) which is smaller than the axial length L hauptof the main field coil, where a combined axial magnetic field profile generated by the main field coil and the shielding coil has a field strength minimum along the z-axis in a center of the examination volume and a field strength maximum on each side of the center; a ferromagnetic field formation device (3) disposed radially within the main field coil; and a ferromagnetic shielding body surrounding the main field coil and the shielding coil in a radial and axial direction, where a combined axial magnetic field profile generated by the ferromagnetic field formation device and the ferromagnetic shielding body has a field strength maximum along the z-axis in the center of the examination volume and a field strength minimum on both sides of the center.