Reduced filament coupling in Bi(2223)/BaZrO3/Ag composite tapes

Interfilamentary coupling properties of Bi2223/Ag tapes with oxide barriers subjected to AC perpendicular magnetic field

“…For the composite multifilamentary superconducting wire with normal metal matrix, it is widely known that the coupling current loss Q c per-cycle in the matrix part show the maximum at a coupling frequency f c , which is related to the decay time constant of a coupling current, s c with following equation [4][5][6][7]10]:…”

“…To achieve a significant loss reduction by decoupling the filaments, therefore, f c should at least be higher than f op [4][5][6][7][8][10][11][12]. To estimate f c for both tapes, Fig.…”

“…Most popular method for introducing barriers is the coating of oxide powder on the surface of monocore wire [5][6][7][8][9][10][11][12][13][14][15][16]. The oxide material usable as barriers should be highly-resistive, non-poisonous to Bi2223 phase formation during heat treatment, and also should be deformable during cold working such as drawing and flat rolling.…”

“…The oxide material usable as barriers should be highly-resistive, non-poisonous to Bi2223 phase formation during heat treatment, and also should be deformable during cold working such as drawing and flat rolling. BaZrO 3 is known to be effective to increase the matrix resistivity and also to decouple the filaments, but they cause significant degradation of critical current density (J c ) due to their poor ductility [5,7,9]. The tapes with SrCO 3 barriers show reasonably good transport properties [10,11], but it has been pointed out that SrCO 3 barriers is not sufficient to increase transverse resistivity and to suppress the filament coupling [10].…”

Fabrication and characterization of Bi2223 tapes with Al2O3 barriers for reduction of AC losses

“…The measured AC losses for all tapes are composed of the hysteresis loss (Q h ) in the filaments and the coupling current loss (Q c ). The Q c component per-cycle shows the maximum at characteristic frequency f c [4][5][6][7][8][9][11][12][13][14]. If the tape geometries and applied field direction are identical, the f c values are proportional to only the transverse resistivity (q t ) of tape.…”