SHIELDED GRADIENT COIL ASSEMBLY

A shielded gradient coil assembly (40) to generate a gradient magnetic field, the assembly comprises a plurality of radially inner and outer coaxial cylindrical surfaces (11, 12), a gradient field coil arrangement on the radially inner cylindrical surfaces (11) including a longitudinal gradient field coil system (131) having one or more axial circumferential electrically conducting hollow z-field windings having a smaller transverse cross-section and a transverse gradient field coil system (132) having hollow (x,y)-field electrical conductors having a smaller transverse cross-section and arranged as saddle coils on the surfaces of the inner cylindrical surfaces (11). A gradient shield coil arrangement is provided on the radially outer cylindrical surfaces (12) including a longitudinal gradient shield coil system (141) having one or more axial circumferential electrically conducting hollow z-shield windings having a larger transverse cross-section and a transverse gradient shield coil system (142) having solid electrical conductors arranged as saddle coils on the surfaces of the outer cylindrical surfaces (12). In this way an optimum combination is achieved of efficient direct and indirect cooling of the conductors while keeping eddy current effects at a low level.