Full penetration current variation of a superconducting tube

Abstract

It is well known that the critical current density Jc of a superconducting material depends on the magnetic field B. If magnetic independent Jc is chosen for analytical calculation of current distribution, the critical current Ic0 corresponds to full penetration current Ip. Ic0 is a measured current with 1μV/cm criterion and Ip is a calculated current. The aim of this paper is to present Ip variation of superconducting tube. To calculate Ip, which is depending on the material itself, a linear function Jc(B) is sufficient to obtain realistic values by analytic way. We need to have a linear Jc(B) law (Jc(B)=JC0.(1-|B|/BJ0) that is close to the measured Jc(B) characteristics presented in this paper. The linear Jc(B) law chosen was used for the calculation of the distribution of both magnetic field B(r, t) and the current density J(r, t). These distributions allow the analytical calculation of Ip. We present the variation of Ip with material characteristics and geometric parameters of the tube. The two main results are presented. Ip decreases when BJ0 increases for same JC0. Ip increases when the tube internal radius Rin increases for same tube section. For AC losses versus current curves, Ip is the frontier between low and high losses. So the present results, allow designing future transport current superconducting cable.