Design of a fast cycled low loss 6 T model dipole cooling at 1.9 K

The option being considered for the FCC-hh high energy injector is a superconducting synchrotron replacing the CERN SPS. The new machine would operate in a cycled mode also to feed experimental areas, much like the SPS nowadays. Due to this specific cycled operation, innovative design and development approaches is required to cope with the AC losses in the superconducting cables and iron yoke. The research joins experience accumulated at CERN and JINR in the design and operation of large systems operated at 1.9 K and in fast ramped and cycled magnets respectively. Minimization of the cycling power losses is particularly important. Total thermal losses should be limited to tentatively < 2 W/m at 4.2 K equivalent. The magnet design, and the results of preliminary tests on a candidate NbTi-wire for building a model magnet are presented and discussed.