Abstract
The possibility of rescaling (or calibrating) of the magnetization results to predict the transport critical current density (Jc) of commercial coated conductors (REBCO tapes) is discussed from both the experimental and theoretical point of view. For this purpose the critical current density in tapes from three different producers was investigated by means of transport and magnetization measurements, in perpendicular magnetic fields of 0.25 T – 2 T at temperatures 65 K – 77 K. Two kinds of samples were tested in the magnetization measurements – square samples 2 × 2 mm2 cut from the central parts of the tapes and elongated rectangular samples of the full tape width (4 mm nominally) and 8 mm length. The transport measurements were performed on full-width samples in a subcooled liquid nitrogen bath. The presented results show that it is possible to empirically rescale the measured magnetization data on the basis of a single transport measurement, achieving the overall accuracy of the transport Jc prediction between 4% and 10% for different tested tapes. Simple theoretical justification and analysis of the empirical scaling is presented, based on the critical state model with the power law current-voltage relation considered to account for different level of electric field in the transport and magnetization measurements.
Highlights
Technical high temperature superconducting wires of the 2nd generation, the Coated Conductors (CC’s) [1,2,3], are being studied and tested for applications in a wide range of working temperatures [4,5,6,7]
Commercial coated conductors, called REBCO tapes, of 4 mm nominal width from three manufacturers were investigated in the study: SCS4050-AP wire from Superpower Inc., HCN 04150 tape from SuNAM Co., Ltd. (‘Sunam’) and the REBCO tape produced by SuperOx company (‘Superox’) [20,21,22]
The article presents a comparison of experimental Jc(B) dependences determined in magnetization and transport measurements in the temperature range 65 K – 77 K for commercial coated conductors of three different industrial manufacturers
Summary
Technical high temperature superconducting wires of the 2nd generation, the Coated Conductors (CC’s) [1,2,3], are being studied and tested for applications in a wide range of working temperatures [4,5,6,7]. The difficulties connected with the heat generation are often at least partially overcome by physically narrowing the CC original width, reducing the required transport current, or by employing pulsed transport current measurement methods [15,16,17,18]. Another alternative represent the contactless magnetization measurements where sample heating is avoided, offering in general much broader interval of available magnetic fields and temperatures than the transport ones. The goal of the presented work was to explore the possibility of substituting the transport critical current measurements with the magnetization ones for commercially available CC’s at higher temperatures and lower fields. The most important aspects are discussed in this paper, with the aim to test whether, and to which extent, could a scaling factor determined at one temperature be possibly used in a broader temperature interval
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