Improvements in or relating to electromagnets

摘要

A superconducting electromagnet comprising an annular inner helium container vessel within which the windings of an annular magnet are contained, an outer annular vacuum chamber within which the said inner vessel is contained, and a generally annular hollow thermal shield arranged to enclose the inner vessel and disposed between the said vessel and the said chamber in spaced apart relationship so that the longitudinal axes of the said shield and the magnet are substantially co-extensive, an outer wall of the shield being defined by concentric generally cylindrical mutually spaced inner and outer thermal screens, which in combination define a double wall screen, the shield having a double wall only in a region concentric with the longitudinal axis of the magnet. $$