Systems, methods and apparatus are provided through which in some
embodiments drift of a magnetic field of a magnetic resonance imaging
(MRI) system is reduced by including a drift compensation coil which
accumulates current at a rate proportional to the decay in the primary
coil via its electromagnetic mutual inductance to the primary coil. In
some embodiments, the drift compensation coil includes reverse turns at
an outer radius, to significantly reduce any exacerbation of the fringe
field during a quench of the primary coil. In further embodiments, the
actively shielded drift compensation coil is complemented with a
non-coupling external disturbance shield coil.