Transport Properties of Single MgB2 Filaments Extracted From Multifilamentary Conductors

Using an electrochemical bath, copper and nickel metals and alloys are removed in multifilamentary MgB
₂
conductors to leave single MgB
₂
filaments surrounded by an Nb sheath. Starting from a 0.55-mm 36-filament-diameter conductor, the etched filaments are 60 μm in diameter. Seven wires were characterized by transport critical current measurement, and one investigated further by resistivity when progressively etched. Their radial location in the original multifilamentary wire structure is then used to explore if the critical current is sensitive to the deformation process. The average critical current of the outer layer of filaments is 35% higher than the inner layers. The average filament critical current was 32 A which is within 10% of the 36 filament wire critical current per filament when adjusted for self-field.