Performance test of Bi-2212HTS current leads prepared by the diffusion process

Bi-2212 HTS bulk conductors have been prepared by the two components diffusion process for current lead application. The Bi-2212 HTS layer is synthesized through a diffusion reaction between a Sr-Ca-Sr oxide substrate and a Bi-Cu oxide coating with Ag addition. The HTS diffusion layer about 150 mum in thickness formed around the cylindrical tube 27/19 mm in outside/inside diameter and 200 mm in length. The transport current of the tubular specimen exceeds 4000 A at 4.2 K and self-field, which corresponds to a transport current density of 20 000 A/cm(2). The Joule heating of the joint at an end of the specimen is estimated to be 200 mW from the overall joint resistance of 12 nU. Therefore, the total heat load, including heat leakage conducted through the tubular specimen between 4 K and 40 K, is expected to be less than 400 mW at 4000 A. Present Bi-2212 HTS conductors with large transport current as well as low joint resistance and thermal conductivity, seem to be promising as a current lead for superconducting magnets.