Lawrence Berkeley National Laboratory

In order to set up a powerful proton source for a future Neutrino Factory, increasing at the same time the flux of protons available for new and existing facilities, CERN is studying a 2.2 GeV superconducting H- linac for 4 MW beam power, called SPL. The superconducting part of this linac covers the energy range from 120 MeV to 2.2 GeV. Three sections made of 352 MHz cavities with nominal beta of 0.52, 0.7 and 0.8 bring the beam energy up to 1 GeV. From this energy, superconducting cavities from LEP or beta 0.8 cavities can be used up to the final energy of 2.2 GeV. This paper covers the optimisation for the superconducting part, the beam dynamics design principles, the matching between sections, and the results of multiparticle simulations with up to 50 million particles. To demonstrate the stability of the design, matched and mismatched input beams are used.