Patent ID: 7692426

Claim:
A magnetic resonance apparatus comprising: a basic field magnet that generates a basic magnetic field in an examination volume, said basic field magnet comprising superconducting coils contained in a helium reservoir cooled with liquid helium, an outer vacuum chamber forming a further reservoir surrounding said helium reservoir with a vacuum between said outer vacuum chamber and said helium reservoir, and a cryoshield between the outer vacuum chamber and the helium reservoir, said basic field magnet defining an inner chamber in which said examination volume is located, said outer vacuum chamber having an outer vacuum chamber exterior surface; a gradient coil located in said inner chamber of said basic field magnet, said gradient coil generating a gradient magnetic field in said examination volume resulting in generation of scatter fields that elevate a temperature of said liquid helium in said helium reservoir; and said outer vacuum chamber comprising a coating applied directly to said outer vacuum chamber exterior surface with no gap between said coating and said outer vacuum chamber exterior surface, said coating having a high electrical conductivity greater than an electrical conductivity of steel or stainless steel that counteracts elevation of said temperature of said liquid helium in said helium reservoir.