Third harmonic ac susceptibility of superconducting strips and disks

Abstract

Third harmonic ac susceptibility of superconducting strips and disks with finite thickness (cross-sections 2 a×2 b) in a perpendicular magnetic field Ha = H0sin(ωt) has been calculated. The flux creep effects have been taken into account by using a power-law electric field E(j) = Ec(j/jc)n. Detailed results are present for different thickness b and creep exponents n, which are compared with those derived from the Bean critical state model and from numerically solving the flux creep equation for infinite slab in parallel field. In the limits of b/a≫1 and n→∞ the results from the parallel situation and the Bean model are reproduced, respectively.