抄録
To achieve a further increase in critical current densities of NbTi multifilamentary superconducting wires for AC use, several wires having the theoretically designed Nb island-type artificial pins introduced into NbTi superconducting filaments were fabricated. Oversaturation phenomena were observed whereby Fp increased in the wide range of magnetic field and the position of peak Fp shifted systematically from the low magnetic field side to the high-field side as the reduction rate of artificial pins increased. High critical current densities, such as 1.42×1010A/m2 at 1T (obtained by wire with a filament diameter of the 0.1μm class) 8.7×109A/m2 at 2T and 6.1×109A/m2 at 3T (obtained by wire with a filament diameter of 0.4μm class) were achieved. Moreover, it was clarified that the field-position of peak Fp was decided by pin interval, ds, if the correlation length I66 was smaller than half of the fluxoid spacing, af. As a result, helpful guideline in designing critical current densities by introducing artificial pins was derived.
