MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
Relation of n-Value to Critical Current for Local Sections and Overall Sample in a SmBCO Coated Conductor Pulled in Tension
Shojiro OchiaiHiroshi OkudaShinji NaganoMichinaka SuganoSang-Song OhHong-Soo HaKozo Osamura
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2014 Volume 55 Issue 3 Pages 549-555

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Abstract

Under application of tensile stress to a SmBCO (SmBa2Cu3O7−δ) coated conductor sample consisting of series electric circuit of local sections, the relation of voltage–current curve, critical current and n-value of the sections to those of overall sample was studied. The change in critical current and n-value with increasing applied stress was different from section to section due to the difference in damage behavior of the SmBCO layer among the sections. When the difference in extent of damage among the sections was small, the voltages developed in all sections contributed to the voltage of overall sample. In this case, the critical current and n-value of overall sample were within the range of the highest and lowest values among the sections. On the other hand, when the damage in one section was far severer than that of other sections, the voltage developed in the most severely damaged section largely contributed to the overall voltage, and hence the voltage–current curves of the most severely damaged section were almost the same as those of overall sample. In this case, critical current of the overall sample was slightly higher and n-value of the overall sample was lower than the critical current and n-value of the most severely damaged section. Accordingly, the decrease in n-value with decreasing critical current in overall sample was sharper than that in sections. This phenomenon was accounted for by the increase in shunting current at cracked part at higher voltage in the most severely damaged section.

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© 2013 The Japan Institute of Metals and Materials
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