Magnetic resonance imager with helium recondensing

A cryogen recondensing system with a mechanical cryocooler utilizing a rare earth displacer for a magnetic resonance imager superconducting magnet comprising:

• a sleeve surrounding said cryocooler rare earth displacer;
• said sleeve being magnetically coupled to the magnetic fields generated by the movement of said rare earth displacer;
• said sleeve including a lead alloy which provide superconducting flow of currents induced in said shield by said magnetic fields;
• and
• high thermal conductivity members along the surface of said sleeve;
• said superconducting current flow opposing said induced magnet fields to shield said superconducting magnet from said magnetic fields generated by said movement of said rare earth displacer;
• and
• said cryocooler thermally connected to cryogen recondensing means.