Effect of twisting on strain tolerance of Bi-2212 multifilamentary round wires

Silver sheath Bi2Sr2Ca1Cu2Ox superconducting multifilamentary round wires h aving various twist pitch lengths and an untwisted one were fabricated by t he oxide powder-in-Ag-tube method. The twisting process to a pitch length o f 4.5 mm at a diameter of 1.45 mm did not influence the superconducting cri tical current density J(c) whose value was about 90000 A/cm(2) at 4.2 K, 0 T. The J(c) of the twisted wires is less sensitive to bending strain as twi st pitch length becomes shorter. This phenomenon is explained by the calcul ated results that the filament's curvature, which is added by the bending, becomes less as pitch length becomes shorter. (C) 1999 American Institute o f Physics. [S0021-8979(99)02404- 4].