Scaling law for voltage-current curve of a superconductor tape with a power-law dependence of electric field on a magnetic-field-dependent sheet current density

Systematic theoretical study on the voltage (V) vs. current (I) curves of high-T-c superconductor (HTS) thin tapes has not been done till now, although their measurements are frequently used for determining critical current I-c at electric field E equivalent to V/l(v) = E-c = 10(-4) V/m, l(v) being the voltage tap distance. On the other hand, it is well recognized that such tapes obey a power-law dependence of local electric field on local sheet current density with a Kim-model critical sheet current density, from which the V vs. I curve may be calculated as a function of current ramp rate R. Such calculations are carried out in the present work with a scaling law deduced, which states that if E/E-c vs. I/I-c is a solution at given apparent power-law exponent n(a) and R/E-c, then this R/E-c multiplied by a constant C leads to another solution with E/E-c and I/I-c multiplied by C and C-1/na, respectively. In the help of the scaling law, condition-dependent V vs. I may be studied systematically and completely based on a limited amount of numerical computations and V - I curve measurements may be performed under properly controlled conditions to become a more powerful tool for HTS research. (C) 2017 Elsevier B.V. All rights reserved.