Title :
Field Performance of an Optimized Stack of YBCO Square “Annuli” for a Compact NMR Magnet
Author :
Hahn, Seungyong ; Voccio, John ; Bermond, Stéphane ; Park, Dong-Keun ; Bascuñán, Juan ; Kim, Seok-Beom ; Masaru, Tomita ; Iwasa, Yukikazu
Author_Institution :
Francis Bitter Magn. Lab. (FBML), Massachusetts Inst. of Technol. (MIT), Cambridge, MA, USA
fDate :
6/1/2011 12:00:00 AM
Abstract :
The spatial field homogeneity and time stability of a trapped field generated by a stack of YBCO square plates with a center hole (square “annuli”) was investigated. By optimizing stacking of magnetized square annuli, we aim to construct a compact NMR magnet. The stacked magnet consists of 750 thin YBCO plates, each 40-mm square and 80-μm thick with a 25-mm bore, and has a Ø10 mm room-temperature access for NMR measurement. To improve spatial field homogeneity of the 750-plate stack (YP750) a three-step optimization was performed: 1) statistical selection of best plates from supply plates; 2) field homogeneity measurement of multi-plate modules; and 3) optimal assembly of the modules to maximize field homogeneity. In this paper, we present analytical and experimental results of field homogeneity and temporal stability at 77 K, performed on YP750 and those of a hybrid stack, YPB750, in which two YBCO bulk annuli, each Ø46 mm and 16-mm thick with a 25-mm bore, are added to YP750, one at the top and the other at the bottom.
Keywords :
assembling; barium compounds; copper compounds; magnetic traps; nuclear magnetic resonance; statistical analysis; superconducting magnets; yttrium compounds; YBCO; YBCO square annuli; YBCO square plate; compact NMR magnet; field homogeneity measurement; field performance; magnetized square annuli; multiplate module; optimal assembly; optimized stack; spatial field homogeneity; stacked magnet; statistical selection; temperature 77 K; temporal stability; thin YBCO plate; time stability; trapped field; Magnetic resonance imaging; Nuclear magnetic resonance; Optimization; Saturation magnetization; Stacking; Superconducting magnets; Yttrium barium copper oxide; Compact NMR; YBCO plates; field cooling; field homogeneity; optimization; temporal stability; trapped field;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
DOI :
10.1109/TASC.2010.2103920