The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 24, 2004
Filed:
Jun. 09, 2003
Bruker Biospin AG, Faellanden, CH;
Abstract
A magnet assembly for generating a magnetic field (H) in the direction of a z axis in a working volume (AV) comprises an actively shielded superconducting magnet coil system (M) and at least one current path (P , . . . , Pn) which is superconductingly closed in the operating state. The actively shielded superconducting magnet coil system (M) has a radially inner partial coil system (C ) and a radially outer partial coil system (C ) disposed coaxially with respect to each other. An external device supplies current to the current paths (P , . . . , Pn) to charge each path to a respective current (IP , . . . , IPn) in the operating state. When optimizing the fringe field behavior outside of the magnet system, the overall magnitude of magnetic dipole moments of the current paths (P , . . . , Pn), charged to their respective operating currents (IP , . . . , IPn), is at least 0.1% of the magnitude of the magnetic dipole moment of the charged partial coil system (C ). When charging the current paths (P , . . . ,Pn) to their respective operating current (IP , . . . , IPn), the resulting change &Dgr; of the coefficient of second order (H ) of the polynomial expansion of the magnetic field (H) of the magnet assembly is given by: |&Dgr; |<max (0.25T/m , 0.9·|H (M)|), wherein H (M) designates the coefficient of second order of the polynomial expansion of the magnetic field of the actively shielded superconducting magnet coil system (M) in the operating state. This permits compensation for deviations of the fringe field of the magnet assembly from its design values due to deviations of coil parameters from their design values, through an appropriate design of the additional current paths (P , . . . , Pn) and setting their currents to a suitable value.