Status of the Activities on the $\hbox {Nb}_{3} \hbox {Sn}$ Dipole SMC and of the Design of the RMC

As part of the European project EuCARD, the aim of the short model coil (SMC) dipole magnet is to perform R&D on the Nb₃Sn coil fabrication technology while testing Nb₃Sn superconducting cables. The baseline design features two double-layer racetrack coils, within a support structure based on bladders and keys technology and surrounded by an aluminum shell. The last magnet assembled up to now of the SMC series (SMC3a) was tested in 2011 and it reached a peak field of 12.5 T in the coil, corresponding to approximately 90 % of the short sample limit. Following the successful test of SMC3a, modifications were implemented in the design of the coil parts and support structure in order to accommodate wider cables. While making a valid contribution to the development of the Nb₃Sn magnets technology, the final goal of the high field magnet project is to design, build, and test the FRESCA 2 magnet. Based on the SMC structure, the racetrack model coil represents an upgrade of the SMC in order to test a FRESCA 2 cable. The first part of this paper describes the status of activities on the SMC project, the design changes for the future SMC, and their predicted magnet parameters. The second part is dedicated to the description of the magnetic and mechanical design of the racetrack model coil.