A superconducting electrical machine includes at least one re-entrant end including at least two segments. The at least two segments are continuous. At least one re-entrant end may be included in a stator of the superconducting electrical machine, the stator being disposed substantially coannular with a longitudinal axis. At least one re-entrant end may also be included in a rotor of the superconducting electrical machine, the rotor being configured to rotate about a longitudinal axis. A first segment is substantially perpendicular to a plane parallel to the longitudinal axis, and a second segment is coannular with the longitudinal axis. Heat distal from rotor windings and/or stator windings encounters a thermal resistance provided by the at least two segments as the heat travels towards the rotor windings and/or stator windings.