STRAIN TOLERANCE OF DOCTOR-BLADE-PROCESSED BI2SR2CA1CU2O8-DELTA TAPES

The strain tolerance of doctor blade tapes of the high-temperature superconductor Bi2Sr2Ca1Cu2O8-delta have been studied to determine the suitability of these materials for magnet conductors. Critical currents that are on the order of 150 000 A/cm2 in zero magnetic field fall by about 30% with 0.1% bending strain and by a factor of 6 with 0.2% bending strain. At 20 T, critical currents fall with strain by approximately the same factor as at 4.2 K, but the critical currents fall with field somewhat faster. These bending strain results have a character quite different from Nb3Sn bronze process material in that there is essentially no prestress from the Cu jacket and there seems to be only a very small reversible range where the sample is within the elastic limit.