Development of 2 km-Class Carbon-Doped MgB2 Wire With Uniform Critical Current Property

초록

Kilometer-scale carbon-doped MgB2 superconducting wires were fabricated using a three-dimensional vibrating powder-filling powder-in-tube process and systematically evaluated for uniformity and performance. The optimized process enabled fabrication of a 2.1 km-long 18-filament conductor with a critical current density (J(c)) of 1.13 & times; 10(5) A/cm(2) at 20 K and 2 T, showing only similar to 2% variation along its length. Carbon substitution enhanced high-field performance primarily through impurity scattering, while the n-value demonstrated a strong proportionality with J(c) across all measured conditions. This correlation establishes the n-value as not only a research parameter but also a practical quality-control metric for industrial wire production. The combined achievements of process innovation and transport uniformity highlight the feasibility of MgB2 conductors for MRI magnets, high-field research magnets, and superconducting power transmission.

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