Critical Current and n-Value of Heterogeneously Cracked Superconducting Tapes, Studied by a Monte Carlo Simulation Method Combined with a Model of Current Shunting at Cracks

Influences of crack size-distribution and specimen length on the critical current and n-value of heterogeneously cracked superconducting tapes were studied by a Monte Carlo simulation method combined with a model of crack-induced current shunting. In simulation, model specimens, constituted of a series of sections having cracks with different size to each other, were used. It was shown by the present simulation that (i) both of the critical current and n-value decrease with increasing width of crack size distribution, (ii) n-value decreases more sensitively to the increase in width of crack size distribution in comparison with the critical current, and (iii) the features (i) and (ii) stated above are enhanced with increasing specimen length. Also, the experimentally observed feature that the width of distribution of critical current decreases with increasing length in heterogeneously cracked superconducting tapes was realized by the present simulation. This result was in good accordance with the reported feature that local information of critical current values in a specimen is diluted when the voltage tap distance is large.