Conceptual design of a low-β SC proton linac

In this paper we discuss the conceptual design of a low-β superconducting proton linac based on multi-gap spoke resonator structures. We have demonstrated the feasibility of using superconducting accelerating structures throughout a proton linac for high-peak current applications. The injection energy for this linac is assumed to be 6.7 MeV, which equals the output energy of the CW RFQ built for the Low-Energy Demonstration Accelerator now operating at Los Alamos. The beam is accelerated to 109 MeV using multi-gap spoke resonators. Both 2-gap and 3-gap cavities are used in three accelerating sections with geometric-β values, of 0.175, 0.2, and 0.34. Higher beam energies can be achieved by transitioning to elliptical superconducting cavities to further accelerate the beam. Preliminary beam dynamics simulation results are shown and discussed