The influence of viscous flux flow on AC losses of high Tc superconductors

✍ Scribed by S. Takács; F. Gömöry; P. Lobotka

• Book ID: 104356374
• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 388 KB
• Volume: 165-166
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/s0921-4526(09)80285-8

✦ Synopsis

The frequency dependence of AC susceptibility was measured in the frequency range 27 Hz -100 kHz on polycrystalline YBaCuO samples with both considerable and vanishing contribution of intragranular currents. The intergranular currents lead to the frequency dependence obtained from the extreme flux flow model (i.e., vanishing role of pinning forces) for frequencies above 10 kHz. This is true for the field amplitudes both below and above the penetration field. The intragranular currents have a more complicated frequency dependence, this dependence being in a strong discrepancy with the theoretical calculations for low field amplitudes. Some of the results can be explained by calculating the field penetration and AC losses including both pinning and viscous forces on flux lines, assuming Kim's field dependence for the critical current density.