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od 2020-09-20

Title: Novel gradient coils for magnetic resonance microscopy

Source: Spatially Resolved Magnetic Resonance, Eds. Blumler P., Blumich B., Botto R., Fukushima E., WILEY-VCH, Weinheim, New York, Chichester, Brisbane, Singapore, Toronto

Year : 1998

Abstract:

This paper describes three magnetic field gradient coils of considerable simplicity, two for transverse gradient and one for longitudinal gradients. The coaxial arc gradient coil has a simple unit construction of symmetric form. It features a large volume of uniform transverse field gradient, high efficiency and low inductance rapid switching. A prototype coil was first constructed and a smaller coil set was [hen constructed for NMR microscopy, with excellent results. The system may be used for all sizes from microimaging to whole-body MRI. The second transverse gradient coil uses full circle current paths rather than current arcs. It has an even simpler form of construction and has closely similar properties to the coaxial arc transverse gradient coil. A prototype coil set was first made and two smaller coil sets have been made for NMR. microscopy. The longitudinal gradient coil is based on an analysis of the multipole expansion of the external field of a gradient coil system. It is first shown that a Maxwell pair has no hexadecapole moment. The field outside such a pair therefore falls as r-4 from the quad-rupole moment and as r-8 from the 64-pole moment. Using a nested pair of Maxwell pairs the quadrupole term is canceled leaving only the rapid attenuation of the r-8 term, thus providing a simple screened Longitudinal gradient coil.

   (Pobrane:  2023-03-27)