Current and voltage distribution in composite superconductors with resistivebarriers - symmetric case

Abstract

An equivalent symmetric scheme with distributed parameters isproposed, aiming to simulate the current and voltage distribution in compositehigh-Tc superconductors with thin resistive barriers around the filaments.There are three longitudinal parallel branches in the scheme representing thesuperconducting core, the metallic inner matrix around this core and the outermetallic matrix. Transversal current flow is controlled by two interlayerelements: one represents the barrier inserted between the outer and innermatrices, while the second simulates the interface resistance between innermatrix and the superconducting core. The superconducting core may be fullyresistanceless, but it can be found eventually in the resistive state.Two cases are discussed: first, the transport current is supplied into thecomposite conductor through the outer matrix and, second, the transportcurrent flowing fully in the superconducting core is forced to leave it due tosome distortion of superconductivity.The governing relation in the scheme is the product of thematrix-superconductor interface conductance and the inner matrix resistanceper unit length. Solution of the scheme leads to results that depend on thefollowing dimensionless relations: the ratio of the barrier to thematrix-superconductor interface conductances per unit length, the ratio ofthe outer to the inner matrix resistances per unit length and the ratio of theeventually resistive core resistance to the inner matrix resistance per unitlength.The analytical results offer the possibility to calculate the longitudinalvoltage distribution on the outer matrix surface and by this means to followthe current distribution in the conductor cross section. They also allow oneto calculate the typical current transfer lengths between the elements.