TEMPERATURE-DEPENDENT IRREVERSIBILITY MAGNETIC-FIELDS OF HIGH-TC SUPERCONDUCTING BIPBSRCACUO TAPES IN THE MAGNETIC-FLUX DENSITIES UP TO 30-T IN THE TEMPERATURE-RANGE FROM 33-K TO 90-K

Temperature-dependent irreversibility magnetic fields, H(irr)(T) were measured for four samples of silver-sheathed Bi1.8Pb0.4Sr2Ca2.2Cu3O(x) tapes having 3 levels of zero-field, 77 K critical current density, J(co), in magnetic flux densities up to 30 T and in the temperature range from 33 to 90 K. The measurements were performed for two orientations of the tape plane, the plane parallel to the applied magnetic field direction and that perpendicular to the applied field. The measurements show that H(irr) increases with J(co), implying that H(irr) is strongly dependent on the morphology of the superconductors. H(irr) was obtained at 27.9 T and 54.7 K for the sample with J(co) = 298 A/mm2 at 77.3 K.