The Decrease of the Critical Current of Coated Conductors When a Perpendicular Magnetic Field is Applied: A Josephson Effect Point of View

Abstract

A large decrease is observed in the critical current density of YBCO coated conductors (CC) and related compounds when a strong perpendicular magnetic field is applied. While measurements are generally carried out at 77K only, here we present a magnetic technique permitting to determine the critical current per unit width of conductor (I cr /w) in a large temperature range. We report measurements carried out on various CCs that show that, in addition to the reduction in the critical temperature that can be attributed to the low value of the irreversibility field near T c , the field application results in a large decrease of I cr /w at all temperatures. We ascribe this reduction to the Josephson behaviour of the twin boundaries included in the YBCO layer.

Experiments and FE modeling of stress–strain state in ReBCO tape under tensile, torsional and transverse load

“…The thermometer is attached to the anvil surface close to the pushing area. All the I c data are corrected to a temperature of 77.36 K. Literature data [9] on the critical current versus temperature dependence of SCS4050 tape was used for this correction. A 150 mm length of sample tape is used for the tests.…”

A New Technique for the Determination of the Critical Current Density in Superconducting Films and Flat Samples

“…This is especially detrimental in the case of the coated conductors, whose characterization is seldom carried out far below 77 K, while their very large critical current density at low temperature is interesting for many applications. We have proposed for some time a technique suitable for square films [2,3], based on the measurement of the magnetic moment generated by the current lines persisting in the sample after the application of a magnetic field. Typically with this technique, using a SQUID magnetometer, the measurements time in the whole range of the temperatures below T c with a 1 K interval is of 2 hours.…”