Magnetic shield
AssigneesMagnetic Shields Limited, The University of Nottingham
InventorsDavid Woolger, James Chalmers, Joseph Farmer, Eliot Dawson, Richard Bowtell, Matthew Brookes, Niall Holmes, Paul Glover
Life of this patent
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Abstract
An active magnetic shield system, including an array of magnetic field sensors arranged to sense a local magnetic field. An array of magnetic field elements are arranged produce a magnetic field. Each magnetic field element has a unit coil for mounting to a plurality of surfaces arranged in at least 3 planes to define an enclosed cancellation volume, and to produce a vector magnetic field pattern.
Claims20
An active magnetic shield system, comprising:
- an array of magnetic field sensors arranged to sense a local magnetic field,
- an array of magnetic field elements arranged produce a magnetic field of −20 nT to +20 nT, the array of magnetic field elements comprising a first set of unit coils and a second set of unit coils, wherein the first set of unit coils is arranged on a first plane and the second set of unit coils is arranged on a second plane spaced from and opposite the first plane, defining a cancellation volume therebetween;
- the first set of unit coils comprising a first plurality of unit coils arranged in at least a 2 by 2 grid in the first plane and at least one further unit coil overlapping the first plurality of unit coils;
- and
- the second set of unit coils comprising a second plurality of unit coils arranged in at least a 2 by 2 grid in the second plane and at least one further unit coil overlapping the second plurality of unit coils;
- wherein each unit coil comprises a coil wire path arranged to produce a vector magnetic field pattern,
- a current source arranged to provide a controlled current to each unit coil, and
- a processor configured to perform
- a feedback algorithm for controlling the current source for each unit coil to minimise the sensed local magnetic field.
A method of producing an active magnetic shield, the method comprising
- generating a magnetic field by
- providing an array of magnetic field elements, the array comprising a first set of unit coils and a second set of unit coils, wherein the first set of unit coils is arranged on a first plane and the second set of unit coils is arranged on a second plane spaced from and opposite the first plane, defining a cancellation volume therebetween, the first set of unit coils comprising a first plurality of unit coils arranged in at least a 2 by 2 grid in the first plane and at least one further unit coil overlapping the first plurality of unit coils;
- and the second set of unit cols comprising a second plurality of unit coils arranged in at least a 2 by 2 grid in the second plane and at least one further unit coil overlapping the second plurality of unit coils;
- specifying a set of coil parameters in each of the unit coils,
- applying current in each of the unit coils over a grid of target points spanning a target volume,
- calculating a field per unit current generated by each of the unit coils at each target point,
- mapping the calculated field per unit current to a target magnetic field,
- determining optimal coil currents for each of the unit coils, and
- comparing the magnetic field generated to the target magnetic field.
Dependencies are inferred from the claim text.