Temperature dependence of the ac loss in YBCO superconducting tapes fabricated by the IBAD-PLD technique was investigated. The ac loss was measured with a saddle-shaped pickup coil by applying a magnetic field perpendicular to the wide surface. Temperature dependence of the critical current, Ic, versus the magnetic field, B, characteristics was estimated from the magnetization curves observed. By defining Bb(T) as a specific value of B at the breaking point of the Ic-B curve in logarithmic scale at the respective temperature, T, Ic for 0≤B<Bb was nearly constant independent of B, and Ic for B>Bb decreased in proportion to the (1-γ)th power of B, where γ is a pin parameter of the Irie-Yamafuji model and 0<γ<1. In addition, the temperature dependencies of Bb and zero field Ic were almost identical and γ had no temperature dependence. We found that the normalized Ic-B curves by the zero field Ic at the respective temperature, Ic0(T), coincide with one master curve regardless of temperature. This means that the Ic-B characteristics of YBCO superconducting tapes are scaled with temperature. Consequently it was clarified that the magnetization and the ac loss are scaled with temperature. The magnetization curves and the ac loss versus field amplitude curves, which are normalized by using Ic 0(T), coincided with one master curve for any temperature from 4.2 to 77K. This fact is very useful in the design of YBCO superconducting systems because it is possible to estimate the ac loss at any temperature only if we know the field amplitude dependence of the ac loss at some temperature, e.g., 77K, and the temperature dependence of zero field I c.
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Condensed Matter Physics
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry