Abstract: 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.

Abstract: A superconductor magnet system (2) includes a cryostat (4), a superconductor bulk magnet (5), and a cryogenic cooling system (12). The bulk magnet (5) has at least N axially stacked bulk sub-magnets (6a-6c), with N?3. Between each two axially neighboring bulk sub-magnets, an intermediate body (7a-7b) is arranged. The intermediate bodies (7a-7b) are made from a non-metallic thermal insulator material. The cryogenic cooling system (12) is adapted for independently controlling the temperature of each bulk sub-magnet (6a-6c), and has, for each bulk sub-magnet, a temperature sensor (16a-16c) for sensing the temperature of the respective bulk sub-magnet and an adjustment unit (13a-13c) for adjusting a heating power and/or a cooling power at the respective bulk sub-magnet.

Abstract: 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.

Abstract: 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 (I0) to the charger magnet, to generate an externally applied magnetic field, wherein a temperature Tbulk of the bulk magnet exceeds a bulk magnet critical temperature Tc; applying an auxiliary electrical current (I1, . . . ) to the field correction unit, thus generating an auxiliary magnetic field applied to the bulk magnet from within the superconductor bore, wherein Tbulk>Tc; lowering Tbulk below Tc; turning off the electrical current at the charger magnet, wherein Tbulk<Tc, and turning off the auxiliary electrical current at the field correction unit, wherein Tbulk<Tc; and removing the bulk magnet from the charger bore while Tbulk<Tc.

Abstract: Charging method for a superconductor magnet system with reduced stray field, weight and space includes: arranging the system within a charger magnet bore; with Tmain>Tmaincrit and Tshield>Tshieldcrit, applying a current Icharger to the charger magnet and increasing Icharger to a first current I1>0; lowering a main superconductor bulk magnet temperature Tmain to an operation temperature Tmainop, with Tmainop<Tmaincrit, while keeping Tshield>Tshieldcrit; lowering Icharger to a second current I2<0, thereby inducing a persistent current IPmain in the main magnet; lowering a shield magnet temperature Tshield to an operation temperature Tshieldop, with Tshieldop<Tshieldcrit; increasing Icharger to zero, thereby inducing a persistent current IPshield in the shield magnet; removing the magnet system from the charger bore, and keeping Tmain?Tmainop with Tmainop<Tmaincrit and Tshield?Tshieldop with Tshieldop<Tshieldcrit; where: Tmaincrit: main magnet critical temperature and Tshieldcrit: shie

Abstract: A method for charging a superconductor bulk magnet includes: step a) charging the magnet charger system so as to generate a first magnetic field in the sample volume, the superconductor bulk magnet having a temperature T>Tc (300); step b) cooling the superconductor bulk magnet to a temperature T<Tc (400); step c) discharging the magnet charger system, which inductively charges the superconductor bulk magnet, such that the superconductor bulk magnet traps a second magnetic field in the sample volume (500). In step a), the field adjustment unit is set such that the first magnetic field generated by the magnet charger system in the sample volume includes a homogeneous magnetic field component and at least one non-homogeneous magnetic field component (300). The non-homogeneous field component is chosen so that the second magnetic field of step c) has a higher homogeneity than the first magnetic field of step a) in the sample volume.

Abstract: A superconductor magnet system (2) includes a cryostat (4), a superconductor bulk magnet (5), and a cryogenic cooling system (12). The bulk magnet (5) has at least N axially stacked bulk sub-magnets (6a-6c), with N?3. Between each two axially neighboring bulk sub-magnets, an intermediate body (7a-7b) is arranged. The intermediate bodies (7a-7b) are made from a non-metallic thermal insulator material. The cryogenic cooling system (12) is adapted for independently controlling the temperature of each bulk sub-magnet (6a-6c), and has, for each bulk sub-magnet, a temperature sensor (16a-16c) for sensing the temperature of the respective bulk sub-magnet and an adjustment unit (13a-13c) for adjusting a heating power and/or a cooling power at the respective bulk sub-magnet.

Abstract: Charging method for a superconductor magnet system with reduced stray field, weight and space includes: arranging the system within a charger magnet bore; with Tmain>Tmaincrit and Tshield>Tshieldcrit, applying a current Icharger to the charger magnet and increasing Icharger to a first current I1>0; lowering a main superconductor bulk magnet temperature Tmain to an operation temperature Tmainop, with Tmainop<Tmaincrit, while keeping Tshield>Tshieldcrit; lowering Icharger to a second current I2<0, thereby inducing a persistent current IPmain in the main magnet; lowering a shield magnet temperature Tshield to an operation temperature Tshieldop, with Tshieldop<Tshieldcrit; increasing Icharger to zero, thereby inducing a persistent current IPshield in the shield magnet; removing the magnet system from the charger bore, and keeping Tmain?Tmainop with Tmainop<Tmaincrit and Tshield?Tshieldop with Tshieldop<Tshieldcrit; where: Tmaincrit: main magnet critical temperature and Tshieldcrit: shie

Abstract: A superconductor magnet apparatus (2) includes a superconductor bulk magnet (9), a cryostat (7) and a ferromagnetic shielding body (11). The bulk magnet has a superconductor bore (10), an axis (z) of rotational symmetry, and a maximum outer diameter ODbm in a plane perpendicular to the z axis. The superconductor bore has a minimum cross-sectional area Sbo in a plane perpendicular to the z axis. The cryostat has a room temperature bore (8), 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 (12), 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 ODbm/3. For an average cross-sectional area Sfb of the shielding body, Sfb?2.5*Sbo, and the shielding body is arranged within the cryostat.

Abstract: A superconductor magnet apparatus (2) includes a superconductor bulk magnet (9), a cryostat (7) and a ferromagnetic shielding body (11). The bulk magnet has a superconductor bore (10), an axis (z) of rotational symmetry, and a maximum outer diameter ODbm in a plane perpendicular to the z axis. The superconductor bore has a minimum cross-sectional area Sbo in a plane perpendicular to the z axis. The cryostat has a room temperature bore (8), 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 (12), 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 ODbm/3. For an average cross-sectional area Sfb of the shielding body, Sfb?2.5*Sbo, and the shielding body is arranged within the cryostat.

Abstract: 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 (I0) to the charger magnet, to generate an externally applied magnetic field, wherein a temperature Tbulk of the bulk magnet exceeds a bulk magnet critical temperature Tc; applying an auxiliary electrical current (I1, . . . ) to the field correction unit, thus generating an auxiliary magnetic field applied to the bulk magnet from within the superconductor bore, wherein Tbulk>Tc; lowering Tbulk below Tc; turning off the electrical current at the charger magnet, wherein Tbulk<Tc, and turning off the auxiliary electrical current at the field correction unit, wherein Tbulk<Tc; and removing the bulk magnet from the charger bore while Tbulk<Tc.