Critical Current Densities and n-Values of MgB2 Conductors for SMES, MRI, and Low AC Loss Applications

Multifilamentary MgB2 strands (filament numbers 36 to 114) prepared by the in-situ power-in-tube (PIT) route with carbon doping contents of 0, 2, and 3.2% were wound on barrels for transport J(c) and n-value measurement at 4.2 K in fields of up to 12 T. The strand and gauge lengths were 1 m and 0.5 m. Heat treatments at 675? and 650? centered around the melting point of Mg (650?) and both utilized the liquid-solid reaction. A pair of strands, with and without 2% C doping exhibited the J(c) (B) crossover effect. Studied were the dependencies of J(c) on field strength, dopant concentration, and cabling and the dependence of n-value on field strength.

Automated summary

Multifilamentary MgB2 strands (filament numbers 36 to 114) with 0, 2, and 3.2% carbon doping were prepared by the in-situ power-in-tube (PIT) method. These strands were tested for their J(c) and n-value at 4.2 K under magnetic fields up to 12 T. The heat treatments at 675℃ and 650℃, with the liquid-solid reaction, centered around the melting point of Mg (650℃). The J(c) (B) crossover effect was observed in a pair of strands with and without 2% C doping. The study focused on the dependence of J(c) on field strength, dopant concentration, cabling, and the dependence of n-value on field strength.