Superconducting Properties and Microstructure of ${\rm V}_{3}{\rm Ga}$ Multifilamentary Wires Through a PIT Process Using High Ga Content Compounds

We have reconsidered V₃Ga compound wire for future fusion reactor application. 14 MeV fast neutrons will be formed during the deuterium-tritium fusion reaction, consequently future fusion reactors will be constructed using low activation materials wherever possible. V₃Ga compound has a short radioactive decay time and it will be one of the candidate superconductors with both low activation and high field properties so called ldquolow activation superconducting materialsrdquo. The present critical current density, J _c, is insufficient for large fusion magnet. We investigated a new PIT process, using high Ga content compound, in order to improve superconducting properties. The upper critical field, H _c2, of the samples using high Ga content Cu-Ga compounds, was increased with increasing Ga content, and measured 22.5 T when was used 50 at%Ga compound powder. Moreover, the effect of Mg addition into the powder filament was also investigated. The small amount of Mg addition within 1 at%, was improved H _c2 to about 23.0 T. The Ga content dependence and the Mg addition effect on the superconducting properties in the new PIT process are reported in this paper.