earticle

영어

The Mg-Powder-Compaction (MPC) process is proposed to fabricate the MgB2 superconducting wires. Mg powder wall, similar to the Mg metal tube, inside the Nb outer sheath has been made and the stochiometric B powder was inserted into the wall. Even though the very high MgB2 core density of 2.53 g/cm3 is obtained, the superconducting area fraction of MgB2 is not high enough for the applications. In this work, an advanced MPC process was adopted by adding Mg powder into B powder. The Mg powder wall in the initial wire was fabricated by controlling the wall thickness while maintaining a constant density, and the mixture of B and Mg powder was filled into the Mg powder wall with the same filling density. It is found that the reduction in the area of the Mg powder wall proceeds similar to the wire, and the Mg powder wall is well maintained at the final wire diameter, which is advantage for the fabrication of long wires. With the advanced MPC process, as the added Mg is increased the densities of MgB2 core is decreased and the porous structure is formed, it is found that the area fraction of superconducting MgB2 increase up to the 37.7 % with the improved high critical current density (Jc) and the engineering critical current density (Je).