Open and shielded supercondutive magnet

摘要

The assembly (112) includes magnetizable, cylindrically shaped pole piece (114) with longitudinal axis (116) and annular shaped ring (118). The assembly (128) includes magnetizable and cylindrically shaped pole piece (130) and annular shaped ring (134). A shielding coil (142) is provided coaxially aligned with axis (132). The shielding coil is provided radially outward from the main coil (140). The ring (118) has an inner end (120) and outer end (122). A shielding coil (126) is coaxially aligned with axis (116). The shielding coil (126) carries a shielding electric current. The axes (116,132) of pole pieces (114,130) are coaxial. The assembly (128) also includes a magnetizable generally annular shaped ring (134). The ring has inner end (136) and outer end (138). The assembly (128) includes a generally annular shaped superconductive main coil (140) coaxially aligned with axis (132). The main coil (140) carries a main electric current.