Superconducting generator thermal radiation shield having substantially uniform temperature

A superconducting generator having a rotor including a field winding operated at superconducting temperature and a cylindrical electromagnetic shield surrounding and shielding said winding is disclosed. A cylindrical thermal radiation shield disposed between said electromagnetic shield and said field winding to intercept radiation from said shield and re-radiate to the field winding at a lower temperature with a heat transfer mechanism for rapid cooldown of the thermal radiation shield and serving to maintain the thermal radiation shield at substantially uniform temperature throughout its length