Comparison of voltage–current characteristics of high quality Bi-2223 tapes with Hall-sensor measurements and computed current density distributions

The critical current reduction caused by the self-field of the current is measurable on modern HTS tapes. The current density reduction is strongest near the tape edges due to tape geometry and strong anisotropy. In voltage ( V)–current ( I) measurement the self-field also increases with rising current. In this paper V( I) measurements are simulated with Finite Element Method to study the evolution of the current density distribution in increasing self-field. The computations are based on local magnetic flux density dependent current density-electric field characteristics, which have been derived from V( I) characteristics measured at external magnetic fields. Current densities determined with least squares method from measured magnetic flux density profiles are compared to the computed ones. The results show good correlation between the power law model calculations and measurements, but only with current amplitudes bigger than half of the critical current.