Patent ID: 8258903

Claim:
A superconducting, actively shielded magnet, comprising: a housing filled with a cryogen, said housing being located with respect to a center of symmetry; a first superconducting coil module in said housing that generates a homogenous magnetic field in a homogenous magnetic field direction in a volume outside of said housing and enclosed by said first superconducting coil module; a second superconducting coil module in said housing surrounding said first superconducting coil module, that generates a reducing magnetic field that reduces a scatter magnetic field in an environment that encompasses said first and second superconducting coil modules; and a third superconducting coil module located in said housing relative to said first and second superconducting coil modules, that generates a compensation gradient field that substantially compensates an interference gradient field at least in said volume to substantially reduce an effect of said interference gradient field in said volume.