Current distribution and ac loss for a superconducting rectangular strip with in-phase alternating current and applied field

The case of ac transport at in-phase alternating applied magnetic fields for a superconducting rectangular strip with finite thickness is investigated. The applied magnetic field is considered to be perpendicular to the current flow. We present numerical calculations assuming the critical-state model of the current distribution and ac loss for various values of aspect ratio, transport current and applied field amplitude. A rich phenomenology is obtained due to the highly nonlinear nature of the critical state. We perform a detailed comparison with the analytical limits and we discuss their applicability for the actual geometry of superconducting conductors. A dissipation factor is defined, which allows a more detailed analysis of the ac behaviour than the ac loss. Finally, we measure the ac loss and compare it with the calculations, showing a significant qualitative and quantitative agreement without any fitting parameters.