Evaluation of alumina dispersion strengthened (ODS) copper for possible use in the central solenoid & TF coils for the Compact Ignition Tokamak (CIT)

The tensile, fatigue, and electrical characteristics of small samples of ODS copper indicate that it is an attractive candidate for the conductor in the central solenoid and TF (toroidal-field) coils in the Compact Ignition Tokamak (CIT). It will, however, be necessary to obtain the material in substantially larger sizes than previously produced. The central solenoid requires plates which are about 1900×1900×22 mm (75×75×0.875 in) in size and the TF coils would need plates which are about 120×5300×22 mm (46×210×0.875 in). The status and results from R&D tasks which are underway to prove the feasibility of obtaining these materials and to evaluate the impact of scale-up on the mechanical properties is described. The materials has been obtained in three grades (of different fractional alumina content) in strip, bar, and plate form for initial evaluation. Yield strength, ultimate strength, and fatigue behavior are reported. Review of the results together with metallurgical examination of fractured specimens and the requirements for the tokamak have led to concentration on one grade (0.3-wt.% alumina). Subscale plates have been produced for one of the grades and scale-up to full size is presently underway