2026-09-23T05:14:43Zhttps://api.repository.cam.ac.uk/server/oai/requestoai:www.repository.cam.ac.uk:1810/1047852024-06-26T13:41:32Zcom_1810_34587com_1810_34586com_1810_256064col_1810_34589col_1810_205358
Numerical modelling of current transfer in nonlinear anisotropic conductive media
10.17863/CAM.14188
Baranowski, Robert Paul
Current transfer behaviour in anisotropic superconducting bodies is the central topic of
this thesis and focuses on the effect that the nonlinearity of the electric field dependence
upon the local current density value and anisotropy have on the nature of current transport.
The main motivation for this work was the desire for a better understanding of the
conceptually difficult behaviour of current transport in superconducting bodies and
examines current transfer quantitatively for a number of important problems on the
macroscopic and microscopic scale. This behaviour is examined both experimentally and
using computer models. The successful development of a powerful, robust and adaptable
numerical model for analysing the complex current transfer behaviour has been the
primary aim of this work.
The range of parameters appropriate to macroscopic models of the Bi-2212 CRT system
has been experimentally examined using a specifically constructed apparatus for the
measurement of current transport characteristics. A study of the self-field properties of the
Bi-2212 CRT material using a new experimental technique and mathematical analysis is
presented and has allowed the importance of the self-field effect in the numerical model to
be assessed. An essential requirement for the practical application of high current
superconducting devices is the development of low resistance current contacts. The
research presented examines this macroscopic current transfer problem and aims to
explain experimentally observed current transfer characteristics at high applied currents.
Existing models cannot explain these characteristics. Current transfer on the microscopic
scale is also examined. Models of current transfer have been developed from descriptions
of specific microstructures that are thought to characterise the microstructure of Bi-2223
and Bi-2212 silver-sheathed tapes. This thesis specifically presents modelling of current
transfer between c-axis, low-angle c-axis and edge-on c-axis tilt oriented grain interfaces;
the principal current transfer paths between individual current elements of the
microstructural models of current flow in polycrystalline HTSs.
University of Cambridge
1999-04
Thesis
Doctoral
Doctor of Philosophy (PhD)
en
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Current transfer
superconductivity
finite element modelling
critical currents