Cryogenic field sensing for compensating magnetic field variations in magnetic resonance imaging magnets

A superconducting magnet includes superconducting magnet coils (C1, C2, C3, C4, C5, C6, S1, S2) disposed inside a magnet cryostat (12). The superconducting magnet coils generate a static (B0) magnetic field when an electric current flows in the superconducting magnet coils. A superconducting B0 compensation circuit (30, 60, 70) is also disposed inside the magnet cryostat, and is coupled with the superconducting magnet coils to passively reduce temporal variations in the B0 magnetic field generated by the superconducting magnet coils. An electric current sensor (40) is also disposed inside the magnet cryostat and is connected to measure electric current flowing in the superconducting B0 compensation circuit. An active B0 compensation component (50) is operatively connected with the electric current sensor to receive the measurement of electric current flowing in the superconducting B0 compensation circuit and to provide active B0 magnetic field compensation based on the measured electric current.