Critical Current Density and Current Transfer Length of Multifilamentary MgB₂ Strands of Various Design

In this paper, a series of high-performing powder-in-tube MgB2strands have been prepared. Transport voltage-current measurements were performed to determine the effects of C doping and strand geometry such as filament numbers. The bestJcfor our samples was 1.0 × 105A/cm2at 4.2 K, 7 T, for a strand using B powder with 3% C addition. The current transfer length was also measured for MgB2short wires with Nb chemical barrier and Monel outer sheath. The current transfer length ranged from 2 to 12 mm, and had a correlation with the filament numbers.