Abstract: There is provided a multipole magnet for deflecting a beam of charged particles. The multipole magnet comprises a plurality of ferromagnetic poles and a plurality of permanent magnet assemblies to supply a magnetomotive force to the ferromagnetic poles. At least one of the permanent magnet assemblies has a plurality of discrete permanent magnet positions and a plurality of permanent magnets each fixed in one of the permanent magnet positions.

Abstract: A multipole magnet for deflecting a beam of charged particles, comprising: a plurality of ferromagnetic poles arranged in a pole plane; a plurality of permanent magnets each having a magnetisation direction, and each being arranged to supply magnetomotive force to the plurality of ferromagnetic poles to produce a magnetic field along the pole plane in a beamline space between the poles; and a plurality of ferromagnetic flux conducting members arranged to channel magnetic flux from at least one of the plurality of permanent magnets; wherein the multipole magnet comprises an even number of ferromagnetic poles, each pole being arranged to diametrically oppose another of the poles in the pole plane along a pole axis, wherein each of the plurality of permanent magnets is associated with at least one of the plurality of poles and the magnetisation direction of each permanent magnet isorientated in the pole plane at an angle of at least 45° relative to the pole axis of the associated pole.

Abstract: A multipole magnet for deflecting a beam of charged particles, comprising: a plurality of ferromagnetic poles arranged in a pole plane; a plurality of permanent magnets each having a magnetisation direction, and each being arranged to supply magnetomotive force to the plurality of ferromagnetic poles to produce a magnetic field along the pole plane in a beamline space between the poles; and a plurality of ferromagnetic flux conducting members arranged to channel magnetic flux from at least one of the plurality of permanent magnets; wherein the multipole magnet comprises an even number of ferromagnetic poles, each pole being arranged to diametrically oppose another of the poles in the pole plane along a pole axis, wherein each of the plurality of permanent magnets is associated with at least one of the plurality of poles and the magnetisation direction of each permanent magnet isorientated in the pole plane at an angle of at least 45° relative to the pole axis of the associated pole.