Objectives and content
The proposal research aims at developing a Bi(2223) high temperature superconductor tape for the special purpose to carry alternating currents with minimised losses. These kind of tapes are important for the development of AC loaded devices like superconducting power cables, transformers or energy storage systems (SMES) using high temperature superconducting coils.
The realisation of such low AC loss tapes requires tape properties being completely different from the presently existing Bi(2223) /Ag two component composites. First an enhanced number of superconducting filaments (> 19) with cross section dimensions smaller than 10 m and a filling ratio of > 25 % have to be realized restricting on preparation methods suitable for long lengths. A further modification is a twist of the filaments along the wire with twist pitches in the order of 10 mm without or negligible influence on the transport current capability. A severe disadvantage of the presently used Ag matrix materials is their high electrical conductivity which favours electrical coupling of the filaments. Therefore the most innovative challenge of the present proposal is the development of a multicomponent tape configuration using material combinations which increase the electrical resistance between the filaments by at least two 'orders of magnitude, but maintaining a conductivity along the tape good enough for thermal stabilisation and which still allow oxygen exchange of the filament with the heat treatment atmosphere.
The developed low AC loss Bi(2223) tapes will intensively be investigated with respect to AC losses and mechanical and superconducting behaviour to characterise their properties with respect to practical use. Final tape lengths of e > 100 m with projected transport currents densities of 8000 Acm-2 overall will be tested in power cable arrangements through industrial developers and suppliers to evaluate their improved properties and their potential for industrial application.
Funding SchemeCSC - Cost-sharing contracts
SW7 2BZ London
KT22 7ST Leatherhead
7500 AE Enschede