Bruker Switzerland Ag

Michele Zaffalon

Nicolas Freytag

Roger Meister

Robert Schauwecker

Pierre-Alain Bovier

Florian Helbing

An NMR apparatus having a magnet coil system for generating a homogeneous magnetic field comprises a superconducting magnet arranged within a vacuum vessel in the cold region of a cryostat, and a shim system containing shim elements arranged outside the vacuum vessel. The superconducting magnet has a first mechanical connection point to the vacuum vessel via a magnet suspension, and the shim system has a second mechanical connection point to the vacuum vessel via a positioning element. On at least one portion of a path along the vacuum vessel from the first connection point to the second connection point and/or on at least one portion of a path along the positioning element from the second connection point to the shim system, a regulating element for regulating thermally caused changes in length is arranged on the relevant path. Magnetic field homogeneity can thus be kept largely stable.

Active reduction of temperature induced shim drift in NMR magnet systems

A temperature-control system for an NMR magnet system. A permanent magnet arrangement () with a central air gap () generates a homogeneous static magnetic field inside the air gap. A probehead () transmits RF pulses and receives RF signals from a test sample (). An H0 coil changes the amplitude of the static magnetic field. A shim system () in the air gap further homogenizes the magnetic field. A first insulation chamber () surrounds and thermally shields the permanent magnet arrangement and includes an arrangement () controlling a temperature T1 of the first insulation chamber. The shim system, the H0 coil and the NMR probehead are arranged outside the first insulation chamber in the air gap. A heat-conducting body () is arranged between the shim system and the H0 coil on one side and the permanent magnet arrangement on the other, thereby enhancing field stability and suppressing drift.

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Zürich, Switzerland

Michele Zaffalon