Ac losses in multifilamentary high-TCtapes 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 writing the ac dissipation in terms of the ac magnetic susceptibility, we have two parameters: the imaginary part of the internal ac susceptibility χ'' and the external susceptibility in the Meissner state χ 0 , related to the demagnetization. These two terms of the ac loss formula are analysed in detail through both theoretical and experimental approaches. We have used finite-element codes to determine χ 0 for the three tapes under study, and then we have compared the predictions and the experimental results. Existing theories have been used to calculate χ'' as a function of the amplitude of the ac magnetic field and have been verified through measurements.