1B-a09

Limiting current-carrying characteristics of Ag-sheathed Bi₂Sr₂CaCu₂O₈ tape

Limiting current-carrying characteristics of Ag-sheathed Bi₂Sr₂CaCu₂O₈ tape

V.R. Romanovskii^A^B, G. Nishijima^A, S. Awaji^A, Ken-ichiro Takahashi^A, @K. Watanabe^A

IMR, Tohoku University^A, Kurchatov Institute^B

The quench parameters of Ag/Bi₂Sr₂CaCu₂O₈ tape have been studied in detail. The limiting margin of the stable current distribution is characterized by voltage-current characteristic of composite superconductor with typical parameters. The E-J relation is described by power law E=Ec(J/Jc)ⁿ, where the linear temperature function of the critical current Jc(T) was used. It allows to use simple steady-state model and derive the current, temperature and electric field before the quench using analytical formulae. It was shown that stable values of the current and electric field before quench higher than standard determined critical current and voltage. It was also found that considerable overheating of the tape before the quench may take place without loss of superconductivity. The quench parameters as a function of the heat transfer coefficient, resistivity of matrix, volume fraction of superconductor are investigated.