Hardware:Magnet

First Generation Magnet (CAS)

The B0 field is created by a small 0.19T permanent magnet weighing about 13kg. The two N45M (NdFeB) rare-earth magnet disks are 15cm in diameter and held 4cm apart with an iron yoke, which also provides a flux-return path for the magnetic field, containing the field to the gap between the pole pieces (and inside the iron). The magnet was designed and constructed by the group of Prof. Yang Wenhui of the Institute of Electrical Engineering of the Chinese Academy of Sciences in Beijing. Design and construction was supervised by Wang Zheng. The CAS group also shimmed the magnet to ~50ppm homogeneity over 1cm DSV. The right photo shows the magnet in the shielded box with the RF coil and 1cm dia. sample tube in place.

First generation magnet at 0.19T with gradient coil and RF in place.

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Second Generation Magnet (MGH)

A second generation magnet with 0.4T field strength was built at MGH in late 2014. The magnet uses a pair of 6" diameter, 1" thick discs of N45M ordered from Applied Magnets. To see the specific magnetic pucks used click here.

The yoke and pole pieces are made from AISI 1018 steel. The preferred material would have been low carbon AISI 1008 steel but this grade of steel was not readily available in the needed stock sizes.

Magnet cross section dimensions. Depth is 6.25".

Second generation magnet shown with gradient and RF coil installed. B0 field strength is 0.4T.