Status of the R&D on the Rectangular Cable in Copper Conduit Conductor for the MADMAX Dipole

For the superconducting dipole of the MADMAX project, a rectangular Cable-in-Conduit Conductor (CICC) with copper jacket will be used. In particular, a copper hollow profile produced by conform process will be used for the jacket. However, the need of high level of compaction to increase the elastic limit of the jacket makes the initial cross section (dimensions and shape) of the profile unknown a priori. Moreover, the need for a rounded rectangular hole at the end of the compaction process to minimize the stress in the jacket represents a further challenge. For these reasons, a compaction model developed at CEA Paris-Saclay has been used to predict the profile cross section. Then, short profile samples have been iteratively machined and compacted to demonstrate the feasibility of having the desired jacket cross section, in particular a rounded rectangular hole. The yield strength and the residual resistivity ratio (RRR) of the samples have been also measured before and after the compaction process to evaluate the effect of the cold working achieved. In the present work, this R&D activity will be presented and the results will be discussed.