Field dependence of transport J_c for MgB₂ superconducting wire by suspension spinning

The field dependence of transport J_c or MgB₂ superconducting wire by suspension spinning was examined at 4.2 K in magnetic field up to 10 T. The suspension spinning of commercially available MgB₂ powder was examined to fabricate a long superconducting MgB₂ wire. The as-drawn filaments were pressed and pyrolyzed to remove volatile components. The filamentary samples were then cold-pressed, enveloped by an iron sheet with a pellet of mixed powder of Mg and B or with Mg powder, and vacuum-sealed in a fused quartz tube and sintered. The J_c of the sample was strongly dependent on the starting materials and sintering condition. Although the transport J_c value was low such as 4500 A/cm² at 4.2 K and self-field, the J_c value of more than 200 A/cm² was maintained by applying the field of 10 T.