Transport performance in Bi2212 cylinders prepared by the diffusion process for current lead application

Bi2212 HTS bulk cylinders have been prepared by the diffusion process for current lead application. The Bi2212 HTS layer is synthesized through a diffusion reaction between a Sr-Ca-Cu oxide substrate and a Bi-Cu oxide coating with Ag addition. The HTS diffusion layer about 150μm in thickness formed around the cylinder 37/29 mm in outside/inside diameter and 200 mm in length. The transport current of the cylindrical specimen exceeds 7,500 A at 4.2 K and self-field, which corresponds to a transport current density of 24,000 A/cm². The total heat loads, including heat leakage conducted through the cylindrical specimen between 4 K and 20 K and between 8 K and 40 K, are estimated to be 100 mW at 5,000 A and 300 mW at 3,000 A, respectively. Present Bi2212 HTS cylinders with large transport current as well as low joint resistance and thermal conductivity, seem to be promising as a current lead for superconducting magnets.