This project has been established by the Electrical Power Engineering Group at the University of Southampton, and its collaborators the National Grid Company and Pirelli Cables to address some fundamental issues associated with the application of superconducting technology.
Within existing superconducting equipment designs LN2 is used as both the coolant and electrical insulator. Primarily this project is concerned with power transmission and the potential difficulty for all types of superconducting equipment at the ambient/cryogenic boundary. There exists the potential for electrically weaker thermal bubbles of gas nitrogen to form due to thermal influx either from the outside of a termination or through the conductor.
This project will undertake a fundamental study of the bubble dynamics through the life-cycle stages of nucleation/growth/break-off/rise from surface. A purpose built cryostat has been designed and manufactured in-house enabling investigation of bubble dynamics for a range of different samples and conditions including; liquid nitrogen temperature, heat influx regime, pressure (to 20bar), surface materials and geometries.
This study is currently focused on the examination of the influence of electric fields upon the bubbles and LN2; the pre-breakdown, partial discharge and breakdown for the conditions simulated and materials/geometries realistic to the application of superconductivity technology. The project will furnish the University of Southampton and its collaborators with design data that can only be obtained through such extensive experimental validation.