Testing of high temperature superconductors for cryogenic current lead applications

As part of a developmental effort to bring the technology of high-temperature superconducting current lead to practical applications, device-size high-temperature superconductor (HTSC) samples supplied by various vendor sources were tested. The tests include measurements of DC transport critical current I/sub c/, current density (J/sub c/), and electrical joint resistance (R/sub c/) under externally applied magnetic field in a LN/sub 2/ bath, as well as the effects of thermal cycling on these parameters for one selected sample. Dependence of R/sub c/ on temperature was also evaluated. Based on these tests, a set of HTSC bars was ordered and used in a prototype multiple lead assembly. This lead assembly demonstrated experimentally a two to one reduction in heat leak. The work related to the testing of the HTSC samples is addressed.<>