Abstract: A passive magnetic field shim arrangement including a plurality of shim pairs. For shimming a number of magnetic field harmonics, each shim pair may include a first shim and a second opposite and substantially equal shim, each shim pair being configured for shimming one of the magnetic field harmonics. Each shim pair may include a first shim of order N and a second opposite and substantially equal shim of order N, the first and second shims together defining a magnetic field shim correction of order N?1. Each shim may include one or more shim elements arranged on a non-magnetic tubular support, the tubular supports being dimensioned such that the tubular supports may be arranged concentrically in relation to each other.

Abstract: A passive magnetic field shim arrangement including a plurality of shim pairs. For shimming a number of magnetic field harmonics, each shim pair may include a first shim and a second opposite and substantially equal shim, each shim pair being configured for shimming one of the magnetic field harmonics. Each shim pair may include a first shim of order N and a second opposite and substantially equal shim of order N, the first and second shims together defining a magnetic field shim correction of order N?1. Each shim may include one or more shim elements arranged on a non-magnetic tubular support, the tubular supports being dimensioned such that the tubular supports may be arranged concentrically in relation to each other.

Abstract: In a superconducting magnet arrangement having main magnet windings, a first switch is connected between first and second ends of the main magnet windings, an induction coil has a first end connected to the first end of the main magnet windings and having a second end connected through a second switch to the second end of the main magnet windings, and a further coil capable of magnetically coupling with the induction coil, current flowing in the main magnet windings is adjusted by flux pumping.