Bruker Switzerland Ag

Stephen Alfred March

Joerg Hinderer

Franck Borgnolutti

Stephan Heiss

Robert Schauwecker

Rainer Pietig

Pierre-Alain Bovier

Dmitry Eshchenko

Jörg Hinderer

Kenneth J Günter

A method is provided for homogenizing a magnetic field profile of a superconductor magnet system having a cryostat with a room temperature bore, a superconductor bulk magnet with at least three axially stacked bulk sub-magnets, arranged coaxially with the room temperature bore, and a cryogenic cooling system for cooling the superconductor bulk magnet. The cryogenic cooling system independently controls the temperature of each bulk sub-magnet to provide different respective temperatures to the sub-magnets and thereby provide the sub-magnets with different relative currents such that a first subset of the bulk sub-magnets are almost magnetically saturated, and a second subset of the bulk sub-magnets are significantly away from magnetic saturation. By controlling a heating power and/or a cooling power at the bulk sub-magnets without measuring the temperatures of the bulk sub-magnets, the respective currents of the bulk sub-magnets are changed to increase a homogeneity of the field profile.

Method for homogenizing a magnetic field profile of a superconductor magnet system

A superconductor magnet system () includes a cryostat (), a superconductor bulk magnet (), and a cryogenic cooling system (). The bulk magnet () has at least N axially stacked bulk sub-magnets (-), with N&#x2265;3. Between each two axially neighboring bulk sub-magnets, an intermediate body (-) is arranged. The intermediate bodies (-) are made from a non-metallic thermal insulator material. The cryogenic cooling system () is adapted for independently controlling the temperature of each bulk sub-magnet (-), and has, for each bulk sub-magnet, a temperature sensor (-) for sensing the temperature of the respective bulk sub-magnet and an adjustment unit (-) for adjusting a heating power and/or a cooling power at the respective bulk sub-magnet.

Superconductor magnet system, with individual temperature control of axially stacked bulk sub-magnets

A superconductor bulk magnet magnetizing method providing a more homogenous trapped magnetic field includes: placing the bulk magnet inside a charger bore of an electrical charger magnet; placing a field correction unit inside a superconductor bore of the bulk magnet; applying an electrical current (I) to the charger magnet, to generate an externally applied magnetic field, wherein a temperature Tof the bulk magnet exceeds a bulk magnet critical temperature T; applying an auxiliary electrical current (I, . . . ) to the field correction unit, thus generating an auxiliary magnetic field applied to the bulk magnet from within the superconductor bore, wherein T&#x3e;T; lowering Tbelow T; turning off the electrical current at the charger magnet, wherein T&#x3c;T, and turning off the auxiliary electrical current at the field correction unit, wherein T&#x3c;T; and removing the bulk magnet from the charger bore while T&#x3c;T.

Method for magnetizing a superconductor bulk magnet, with generating an auxiliary magnetic field in the superconductor bore

Charging method for a superconductor magnet system with reduced stray field, weight and space includes: arranging the system within a charger magnet bore; with T&#x3e;Tand T&#x3e;T, applying a current Ito the charger magnet and increasing Ito a first current I&#x3e;0; lowering a main superconductor bulk magnet temperature Tto an operation temperature T, with T&#x3c;T, while keeping T&#x3e;T; lowering Ito a second current I&#x3c;0, thereby inducing a persistent current IPin the main magnet; lowering a shield magnet temperature Tto an operation temperature T, with T&#x3c;T; increasing Ito zero, thereby inducing a persistent current IPin the shield magnet; removing the magnet system from the charger bore, and keeping T&#x2264;Twith T&#x3c;Tand T&#x2264;Twith T&#x3c;T; where: T: main magnet critical temperature and T: shield magnet critical temperature.

Method for charging a superconductor magnet system, with a main superconductor bulk magnet and a shield superconductor bulk magnet

A superconductor magnet apparatus () includes a superconductor bulk magnet (), a cryostat () and a ferromagnetic shielding body (). The bulk magnet has a superconductor bore (), an axis (z) of rotational symmetry, and a maximum outer diameter ODin a plane perpendicular to the z axis. The superconductor bore has a minimum cross-sectional area Sin a plane perpendicular to the z axis. The cryostat has a room temperature bore (), the bulk magnet is arranged within the cryostat and the room temperature bore is arranged within the superconductor bore. The shielding body has a shielding bore (), the bulk magnet is arranged within the shielding bore and the shielding body extends beyond the bulk magnet at each axial end by at least OD/3. For an average cross-sectional area Sof the shielding body, S&#x2265;2.5*S, and the shielding body is arranged within the cryostat.

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Zurich, Switzerland

Stephen Alfred March