Low-stray-field permanent magnet arrangement for mr apparatuses

Magnet arrangement in a magnetic resonance apparatus with a permanent magnet system configured to generate a homogeneous magnetic field in a z-axis direction in a measuring volume, the permanent magnet system comprising:

• magnet elements, pole piece elements and yoke elements of magnetic material arranged cylinder-symmetrically with respect to the z axis,
• wherein the yoke elements comprise a first lid, a second lid and at least one hollow cylindrical drum arranged axially between the lids with respect to the z axis,
• wherein the yoke elements enclose the measuring volume both axially and radially,
• wherein the magnet elements each comprise at least one pair of cylinder-symmetrical axial magnets and one pair of cylinder-symmetrical radial magnet rings,
• wherein the axial magnets are each arranged axially adjoining a side of the first lid facing towards the measuring volume and/or adjoining a side of the second lid facing towards the measuring volume,
• wherein the axial magnets are arranged radially within the radial magnet rings and respectively axially further away from the measuring volume than the radial magnet rings, and
• wherein:
• external diameter of the axial magnets≦internal diameter of the radial magnet rings.