Quench Degradation Limits and Mechanisms of High Current Density Ag/Bi-2223Superconducting Tapes

Quench degradation properties are important issues in understanding the stability of high-temperature superconductors (HTS). With a growing interest in Ag-alloy- sheathed BiSr2Ca2Cu3O8+x (Bi2223) as an implementable HTS for commercial applications in high-field magnets, it is crucial that its quench behavior and degradation limits, including conditions that decrease its critical current, are well understood. However, there still is a knowledge gap for Ag/Bi2223 tapes. This investigation aims to experimentally determine quench degradation behaviors and the temperature limit that can be used to develop an effective quench protection system. Short samples of control-overpressure processed (CTOP), high current density Bi2223 from Sumitomo were quenched with a local heater at 77 Kelvin. Under varied quenching conditions, the voltage and temperature changes were recorded and analyzed to identify any correlation. Preliminary results suggest that the Bi2223 samples showed a highly significant sensitivity to temperature during quenching, exhibiting irreversible decreases in critical current at \u3c 200 sensitivity to temperature during quenching, exhibiting irreversible decreases in critical current at \u3c 200 Kelvin