Speaker
Description
The China Spallation Neutron Source (CSNS) is a high-power proton accelerator facility dedicated to neutron scattering research. In the second phase, CSNS-II, the injection energy will be raised from 80 MeV to 300 MeV, and the Linac repetition rate will double from 25 Hz to 50 Hz—with 25 Hz allocated to the RCS and the remaining 25 Hz reserved for other applications. Based on the CSNS-II Linac, a Fixed-Field accelerator (FFA) is proposed to support specialized applications involving broadband white light neutrons and muons. The FFA will further boost the beam energy from 300 MeV to 600 MeV before directing it onto a target, thereby generating the intense neutron and muon fluxes required for these experiments. This paper presents a comprehensive overview of the FFA physical design, including the lattice, beam injection and extraction, beam dynamics, error correction, beam optics, collimation, beam loss control, nonlinear effects, etc. A preliminary design proposal for the 600 MeV FFA based on the CSNS-II Linac is presented. In addition, progress in the development of several key technologies will be presented, including large-aperture multi-stage variable-gradient magnets, high-gradient magnetic-alloy accelerating structures, large-aperture thin-wall vacuum chambers, high-voltage kicker with short rise time, and large-aperture specially-shaped beam position monitor systems, etc.