| 摘要 |
A method and apparatus for passively shimming a magnet. A magnetic field produced by the magnet is measured and modeled in the form of a Legendre polynomial expansion having a predetermined number of harmonic terms. The degree of non-homogeneity in the measured field is determined by examining the harmonic terms. A shim is then designed to correspond to a magnitude change of a harmonic term of the polynomial expansion in order to improve the homogeneity of the magnetic field. A metal plate is connected to or placed near a pole of the magnet, the shim is placed against the metal plate, and a plastic plate is attached to the metal plate such that the shim is held in place in a predetermined location against the metal plate.
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