Development of the EFDA Dipole High Field Conductor

Following the outcome of the conceptual design phase the EFDA dipole magnet will be made of rectangular Cable-in-Conduit Conductors (CICC) jacketed in 316LN. In order to optimize the required amount of superconductor two different conductor types are used: a high-field (HF) conductor consisting of 144 strands and a low-field (LF) conductor with 108 strands. A high ${\rm J}_{\rm c}$ $\hbox{Nb}_{3}\hbox{Sn}$ strand with a critical current density $\sim 2400\ \hbox{A/mm}^{2}$ (at 4.2 K and 12 T) and an effective filament diameter of $\sim 70\ \mu{\hbox {m}}$ was selected.