A Stack of YBCO Annuli, Thin Plate and Bulk, for Micro-NMR Spectroscopy

A new annulus magnet, the latest in a series of compact magnets being developed for NMR spectroscopy applications at the MIT Francis Bitter Magnet Laboratory, was built and tested in a bath of liquid nitrogen at 77 K. The magnet, YP2800, a stack of 2800 thin YBCO plate annuli, each either 40- or 46-mm square and 0.08-mm thick with a 26-mm bore, is an upgraded version of the two earlier plate annulus magnets, YP750 (750 plates) and YP1070 (1070). This paper presents construction details and test results of YP2800. Its spatial field homogeneity and temporal stability were measured, analyzed, and compared with those of YP750 and YP1070. Also, four YBCO bulk annuli, each 26-mm i.d., 46-mm o.d., and 5.2-mm thick, were added to YP2800 and their impacts on field strength and homogeneity were investigated experimentally.