The properties required of a conductor for pulsed magnet coils are tensile strength in excess of 1 GPa combined with electrical conductivity 50% of that of copper at 77 K. Six approaches have been investigated: copper alloys, macrocomposites, microcomposites, cables, interlayer reinforcement and external reinforcement.
Copper stainless steel macrocomposites and copper niobium and copper silver microcomposites gave 77 K tensile strengths of 1.2 to 1.3 GPa coupled with adequate conductivity to withstand 70 T pulses.
A series of coils with optimized fibre composite reinforcement and commercial soft copper wires as well as Glidcop wires have been designed, manufactured and tested. Record fields up to 70 T in a 12 mm bore and 62 T in a 24 mm bore have been achieved for pulse durations of the order 10 ms. In combination with a straightforward stress strain analysis, coil tests to destruction have provided the necessary data on the mechanical behaviour of construction materials that were needed to refine the coil design.
An experimental high strength cable consisting of pearlitic steel wires around a copper core has been developed. Coils made with this cable have reproducibly generated peak fields up to 55 T in a 17 mm bore. It was determined that in its present form this cable is not yet a practical alternative to other coil construction methods. However, the excellent material performance is an incentive for the continuation of this development.
A family of ultra-high strengh, high conductivity conductors will be developed for the construction of coils for producing pulse and quasi stationary magnetic fields up to 100 tesla. External and internal reinforcement of copper, using the technology for multi-filamentary superconductors, will provide strength without sacryficing
superconductivity. Coils will be fabricated using these conductors. Coils construction, insulation, and impregnation techniques will be additional variables under study. Completed coils will be tested at the collaborating laboratories.
Funding SchemeCSC - Cost-sharing contracts
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