A wide range E − J constitutive law for simulating REBCO tapes above their critical current

Abstract

When modeling superconducting devices based on rare earth barium copper oxide (REBCO) tapes and operating near or above the critical current value I c, the power-law is not always accurate. In our previous works, we proposed the overcritical current constitutive law, based on a combination of fast pulsed current measurements and finite element analysis. The overcritical current constitutive law was provided in the form of look-up tables and was validated experimentally. We showed that the overcritical current constitutive law could better reproduce experimental measurements than the power-law, and that the power-law predicts a faster quench than the overcritical current constitutive law. In this contribution we use a mathematical expression based on the collective pinning model to analytically describe the overcritical current regime of REBCO tapes based on measurements performed between 77 and 90 K in self-field conditions. The wide-range constitutive law is verified by comparing DC fault measurements with the results of numerical simulations using the overcritical current constitutive law to represent the electrical resistivity of the superconducting layer of REBCO tapes.