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Transport critical current densities and n factors in mono- and multifilamentary MgB2/Fe tapes and wires using fine powders

Research paper by H. L. Suo, P. Lezza, D. Uglietti, C. Beneduce, V. Abacherli, R. Flukiger

Indexed on: 07 Aug '02Published on: 07 Aug '02Published in: Physics - Superconductivity



Abstract

Mono- and multifilamentary MgB2/Fe tapes and wires with high transport critical current densities have been prepared using the powder-in-tube (PIT) process. The fabrication details are described. The effect of powder grain sizes and recrystallization temperature on jc has been investigated. At 25K and 1 T, jc values close to 105 A/cm2 were measured, while jc of 106 A/cm2 were extrapolated for 4.2K/0T in our monofilamentary tape. MgB2/Fe tapes exhibit high exponential n factors for the resistive transition: n ~ 80 and 40 were found at 5 T and 7 T, respectively. The highest transport jc values obtained so far in MgB2/Fe wires with 7 filaments were 1.1 * 105 A/cm2 at 4.2 K and in a field of 2 T, which is still lower than for monofilamentary tapes. Improved deformation and recovering processing is expected to lead to higher jc values.