TEMPORAL STABILITY OF CIRCULATING CURRENT IN THIN-FILM TL2BA2CACU2O8 AND YBA2CU3O7

The temporal stability of trapped transport current in annular thin fi lm Tl2Ba2CaCu2O8 (TBCCO) and YBa2Cu3O7 (YBCO) wafers has been accurate ly measured and has been found to be of suitable quality for the strin gent requirements of nuclear magnetic resonance (NMR) magnets, No dete ctable decay, to the limit of the experimental apparatus (210(-14) Om ega), was detected in those wafers with transport current at or below the critical current density J(c). The critical current density, as pr eviously determined from 12 mu m meander lines, was confirmed in a waf er with a width of 1.9 cm, The profile of trapped magnetic field resul ting from induced current was modeled in order to assess its effect on the uniformity of an NMR magnet.