Self-Field Effects in a Josephson Junction Model for Jc in REBCO Tapes

Abstract

We have modeled the effects of self-field on the critical current density Jc in high temperature superconducting REBCO tapes, by considering them as a collection of Josephson junctions (JJs) in parallel. We have used a 2D JJ framework for each junction and included their component self-field effects using the well known expression for the magnetic field produced by a thin strip. We provide computational and analytic expressions for the spatial distribution of Jc, enabling us to calculate the critical current of coated conductors over the whole field range. We find that Jc in self field for thin tapes is broadly independent of the width but strongly dependent on the thickness of the tape. For example, if a tape thickness is doubled, even if Jc is unchanged in high field, we expect the self-field Jc to drop by ∼ 20 % because of the larger self-field produced. Our results are compared to experimental results for technological coated conductors from the literature and good agreement is found.