Temperature of Bi-2223/Ag samples in the resistive section of I– V curves

• Published in: Physica. C, Superconductivity Superconductivity, 2004-01, Vol.401 (1), p.160-164
• Main Authors: Polák, Milan, Kvitkovič, Jozef, Demenčı&#x0301, k, Eduard, Janšák, Lubomil, Mozola, Pavol
• Format: Article
• Language: English
• Subjects: Bi-2223/Ag tapes; Current–voltage curves; Heating
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/j.physc.2003.09.029

We measured I– V curves and temperature of homogeneous short samples of Bi-2223/Ag multifilamentary tape immersed in liquid nitrogen and carrying a transport current in the resistive state. The curves measured with increasing and decreasing current were identical at low values of electric fields up to some microvolts per centimeter only. At electric fields above this value we observed hysteretic behavior of I– V curves in two regions of electric fields. One between 10 and 100 μV/cm, which can be suppressed by a small external magnetic field. At electric fields above ∼1 mV/cm we detected a strong heating of the sample and a sudden drop of the measured voltage at increasing current and heat flux of about 0.4–1 W/cm 2. The voltage drop was always accompanied by a sudden decrease of the sample temperature. We also measured heat transfer characteristic using copper tape with dimensions similar to those of the superconducting samples. Finally, we measured a superconducting sample with an artificial inhomogeneity locally reducing the critical current.