Characterization of the Superconducting to Normal Transition
of HTS Coated Conductors by Ultra-Fast Pulsed Current Measurements

Frédéric Sirois, Senior Member, IEEE,
Jonathan Coulombe, Member, IEEE and Antoine Bernier

Abstract— In this paper, we present measurements of the superconducting to normal transition (extended V-I curves) of commercial coated conductors with and without stabilizing copper layer. These measurements were realized with a custom developed ultra-fast regulated pulsed current measurement (PCM) system. Currents between 5 to 10 times the critical current of commercial wires (up to 1000 A) can be applied for a period as short as 5080 μs, limiting the energy released in the sample to a fraction of a Joule. For such short pulses, the temperature increase of the sample is relatively small, which allows characterizing the electrical resistivity of high temperature superconductors (HTS) at high current densities and electric fields. The data obtained will be used to develop more accurate models of HTS in the overcritical current regime, which is crucial for the development of simulation tools of sufficient quality to be used for optimizing the design of superconducting fault current limiters. The PCM technique is also a very powerful tool for investigating the transient thermal behavior of coated conductors, whose better understanding is required in order to devise reliable fault current limiters based on this technology. So far, the measurements have been restricted to 77K and self-field, but further works will extend the range of measurements to higher fields and temperatures.

Index Terms— Fault current limiters, high-temperature superconductors, magnetic thermal factors, pulse measurements, thin films.

Manuscript received August 17, 2008; revised Month XX, 2008.
This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Fonds Québécois de la Recherche sur la Nature et les Technologies (FRQNT)
F. Sirois, J. Coulombe and A. Bernier are with Ecole Polytechnique de ´Montréal, Montréal, QC H3C 3A7, Canada (e-mails: f.sirois@polymtl.ca, jonathan.coulombe@polymtl.ca, antoine.bernier@polymtl.ca).

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