Fast-bunching design of compact heavy ion RFQ linac

We propose the construction of a compact linac as the injector of a cancer therapy facility at the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS). Based on a traditional setup, a new compact fast-bunching design is first introduced to optimize the 600 keV/u RFQ with a 0.05 pmA ^12C^4+ beam. This shortens the RFQ structure length from the standard design value of 272–230 cm while effectively regulating the particle loss and emittance growth. In addition, a detailed error analysis was performed after the optimization process. The error sources cover input beam parameters errors, machining errors and alignment errors. The simulation results show that the beam loss and emittance growth of the RFQ are acceptable and within typical ranges of error.