A persistent-mode magnet, assembled from superconducting annuli, provides a micro coil NMR, in which compactness and manufacturability are provided for a variety of applications. An annular magnet for micro NMR can include a YBCO-annulus Helmholtz coil, for example, that can energized by a magnet system...http://www.google.co.uk/patents/US7859374?utm_source=gb-gplus-sharePatent US7859374 - Annular magnet system for magnetic resonance spectroscopy
