Anisotropy of the critical current density in the NbTi filaments of round composite superconductors

Magnetization measurements have been performed on several multifilament NbTi wires in transverse and longitudinal magnetic fields. The ratio of circumferential and axial critical current densities for the individual filaments is deduced from the measurements and appears to be an increasing function of the magnitude of the magnetic field and the amount of cold work in the filaments. The results suggest that filaments may be less stable in longitudinal magnetic fields than calculations utilizing standard critical current data would indicate. Transverse swept field magnetization data confirm the theory of coupling in the composite.