Frequency-Dependence and Anisotropy of AC Losses of Bi2223/Ag and YBCO-Coated Conductors

AC transport losses in YBCO-coated conductor and Bi2223/Ag were measured by use of an electrical method. The measurements were carried out at 77 K, with the frequency of ac transport currents ranging from 45 to 3800 Hz. The dependence of ac losses on frequency and the dc background magnetic field were also presented and analyzed. It is found that ac losses of high-temperature superconductor tapes decrease with the frequencies below a specific value and increase with the frequencies above this turning point. It is also found that the existence of Ni-W substrate makes the YBCO-coated conductor have smaller losses under dc background magnetic field up to 80 mT than under self-field.