Ac losses in multifilamentary high-T-c tapes due to a perpendicular ac magnetic field

Ac losses in mono and multifilamentary high-T-C tapes exposed to a harmonic magnetic field perpendicular to the tape surface are considered. By writin g the ac dissipation in terms of the ac magnetic susceptibility, we have tw o parameters: the imaginary part of the internal ac susceptibility chi " an d the external susceptibility in the Meissner state chi(0) related to the d emagnetization. These two terms of the ac loss formula are analysed in deta il through both theoretical and experimental approaches. We have used finit e-element codes to determine chi(0) for the three tapes under study, and th en we have compared the predictions and the experimental results. Existing theories have been used to calculate chi " as a function of the amplitude o f the ac magnetic field and have been verified through measurements.