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

Abstract

The case of ac transport at in-phase alternating applied magnetic fields for a superconducting rectangular strip with finite thickness has been investigated. The applied magnetic field is considered 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 metastable 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. We also define a loss factor which allow a more detailed analysis of the ac behavior than the ac loss. Finally, we compare the calculations with experiments, showing a significant qualitative and quantitative agreement without any fitting parameter.

Superconducting wire subject to synchronous oscillating excitations: Power dissipation, magnetic response, and low-pass filtering

“…It can be used either for evaluating the non-coupled dependence LðB max y Þ or the ac/dc coupling LðB max y ; I dc tr Þ. Comparisons reveal the important fact that a naive linear superposition of contributions due to either type of excitation is only appropriate for high strengths of the magnetic field and moderate, or low, currents; a finding which adds to previous work dealing with the infinite slab, 17 or rectangular strip geometry, 18 and sheds new light on the validity of approximate formulae at the same time. Consequently, approximations such as LðB max y Þ þLðI max tr Þ and LðB max y ; I dc tr Þ can drastically under-or overestimate the true losses.…”

Potential and limits of numerical modelling for supporting the development of HTS devices

“…A variant of the method, called MMEV, was later introduced by Sanchez [24] and generalized by Pardo [25] to include current constraints.…”

Utilizing Triangular Mesh With MMEV to Study Hysteresis Losses of Round Superconductors Obeying Critical State Model

“…The computational tool based on the MMEV utilized in this work follows similar principles as the one in [26]- [28]. To extend it for triangular elements, one only needs to know how to compute the vector potential caused by a homogeneous current in a triangular element.…”

“…The coefficients are calculated before running the algorithm. The details are given in [26] and [31] as well as the functional to minimize when also applied field is considered. In function WHERETOADD, by taking the first nonsaturated element i, we calculate the magnetic energy variation (2) due to the hypothetical addition of ΔJ into the element.…”

“…Derivation of (4) can be found in [26]. Integration is done in such a way that A m (r) is computed at element barycenter and assumed constant for the element.…”