Compact superconducting magnet configuration with active shielding, wherein the shielding coil damps the field maximum of the main coil

摘要

An actively shielded superconducting magnet configuration (M1; M2; M3; 14) for generating a homogeneous magnetic field B0 in a volume under investigation (4b) has a radially inner superconducting main field coil (1) which is disposed rotationally symmetrically about an axis (z axis) and a coaxial radially outer superconducting shielding coil (2) which is operated in an opposite direction. The magnet configuration consists of the main field coil, the shielding coil and a ferromagnetic field-shaping device (3; 18), wherein the ferromagnetic field-shaping device is disposed radially inside the main field coil. The main field coil consists of an unstructured solenoid coil or of several radially nested unstructured solenoid coils (15, 16) which are operated in the same direction. An extension Labs of the shielding coil in the axial direction is smaller than the extension Lhaupt of the main field coil in the axial direction. ⅆ 2 ⅆ z 2 ⁢ B H + A ⁡ ( z ) ⁢ ❘ z = 0 ⁢ ≤0 applies for the axial magnetic field profile BH+A(z) generated by the main field coil and the shielding coil during operation along the z-axis in the center at z=0 and ⅆ 2 ⅆ z 2 ⁢ B F ⁡ ( z ) ⁢ ❘ z = 0 ⁢ ≥0 applies for the axial magnetic field profile BF(z) generated by the ferromagnetic field-shaping device (3; 18) during operation along the z-axis in the center at z=0, wherein the z-axis is oriented in a positive direction of the B0-field. An actively shielded superconducting magnet configuration of considerably simplified structure is thereby provided with a homogeneous and particularly high magnetic field B0 in the volume under investigation.