Multifilamentary NbTi with artificial pinning centers: the effect of alloy, pin material, and geometry on the superconducting properties

Low temperature superconductors containing artificial pinning centers (APC) in NbTi have shown critical current densities (below 4 T) substantially higher than metallurgically fabricated and optimized NbTi superconductors. Peak current densities are achieved when the pinning center spacing is matched to the spacing of the flux line lattice (FLL) at field of operation. It is shown that the choice of the superconducting alloy as well as the pin material has a marked effect on both the characteristic pinning force, F/sub p/, and the critical magnetic field, H/sub c2/. In addition, the design approach or geometry, such as the size of the artificial superconducting filament, the area of the pinning material, and the position of the pins, can be important factors in determining the strength of the pinning force on the FLL.<>