Transverse ac susceptibility of superconducting bars with elliptical cross-section and constant critical-current density

The complex ac susceptibility ? = ?'?j ?'' of an infinitely long hard superconducting bar with an elliptical cross-section of semi-axes a and b is numerically calculated with a uniform ac field applied along the b axis, based on the critical-state model with a constant Jc. Normalized to the exact low-field limit of ??', ?0, ??' and ?'' as functions of the field amplitude Hm normalized to the exact full penetration field Hp are given in tables and figures for 0.01?b/a?100. It is shown for any value of b/a that, with increasing Hm/Hp, ?'' is proportional to and inversely proportional to Hm at and , respectively. Defining a characteristic point as where ?'' takes its maximum ?''m, it is shown that, with increasing b/a, ?''m/?0 increases from 0.188 to 0.229, whereas Hm(?''m)/Hp increases from 0.35 to 1.18 and ??'(?''m)/?0 displays a minimum at b/a?0.5. The results are used for comparing with some experimental data of a mono-filamentary Bi-2223/Ag tape.

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