System for magnetic field distortion compensation and method of making same

A method of manufacturing a magnetic resonance imaging (MRI) apparatus comprising:

• providing a helium vessel;
• forming a thermal shield around the helium vessel;
• disposing the helium vessel and the thermal shield within a vacuum vessel;
• forming an eddy current compensation assembly comprising a matrix of symmetrical pairs of closed loops on at least one surface of one of the vacuum vessel, the helium vessel, and the thermal shield;
• and
• assembling the vacuum vessel, the helium vessel, and the thermal shield to form a cryostat to house a superconducting magnet.

A magnetic resonance imaging (MRI) apparatus comprising:

• a plurality of superconducting coils having a bore therethrough;
• a plurality of bucking coils positioned about the bore;
• a cryostat comprising:
• a helium vessel sized to surrounding the plurality of superconducting coils and the plurality of bucking coils;
• a thermal shield surrounding the helium vessel;
• and
• a vacuum vessel surrounding the thermal shield;
• a coldhead extending through the vacuum vessel and the thermal shield;
• and
• an eddy current compensation assembly coupled to the cryostat, the eddy current compensation assembly comprising a matrix of closed loops arranged to passively generate compensation currents that substantially mitigate positive and negative eddy currents induced within the cryostat from mechanical vibrations generated by the coldhead.