program abstracts
Saturday, 3F-12, 10:35-10:45
Impact of Coated Conductor Architecture on Conductor Stability and ac Loss for Power Applications
Robert Duckworth
Yifei Zhang, Fred List
Oak Ridge National Laboratory
Ph: (865) 574-2735, fax: (865) 574-2735, duckworthrc@ornl.gov
Conductor stability and ac loss are two inter-related operational issues that can complicate the introduction of coated conductors in to high temperature superconducting applications. With respect to conductor architecture, conductor stability and ac loss are currently being explored in as-manufactured coated conductors as well as prototype conductor geometries. In as-manufactured coated conductors, materials that are used for stabilization have been shown to influence conductor stability at either steady state and/or transient operating conditions. Stabilization can be utilized to either limit faults and suppress temperature rise, but the thickness and material properties can impact the ac loss on a single tape basis and more importantly when multiple conductors are integrated into a given device geometry. In prototype conductor geometries, different methods are being pursued to produce filamentary conductors that reduce ac loss. Processes that lead to low ac loss could compromise conductor stability due to the lack of current sharing between filaments. To improve the viability of low ac loss geometries, conductor stability needs to be part of the evaluation for a given conductor architecture. Work at ORNL has been directed at establishing the connection between low ac loss and conductor stability through a series of simulations and experiments on geometries with and without electrical connections between the filaments. With respect to the concept of continuous stabilization between filaments, ac loss has been measured in a series of samples with different coatings between silver and YBCO filaments. It was found that low ac loss can be maintained through the manipulation of the interface conditions between the YBCO and silver and through the addition of high resistive materials between YBCO filaments and silver. However, a threshold was identified where the interface conditions cause a significant drop in conductor stability during fault currents.
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