Beam dynamics design for alternating phase focusing proton Linac for a compact accelerator-based neutron source

A prototype Canadian compact accelerator-driven neutron source is proposed for installation at the University of Windsor. The source is based on a high-intensity compact proton RF linear accelerator (Linac) that delivers an average current of 10 mA of protons at 10 MeV to the target. The accelerator consists of a short radio frequency quadrupole, followed by an efficient drift tube Linac (DTL) structure. This study compares the alternating phase focusing (APF) DTL with other DTL variants, such as Alvarez and Crossbar H-mode (CH) DTLs, using KONUS and negative synchronous phase beam dynamics. The APF-DTL design employs an RF phase variation for transverse and longitudinal beam focusing, avoiding magnetic lenses. A detailed optimization of the synchronous phases yielded a configuration that minimizes emittance growth, though the APF-DTL showed increased sensitivity to transverse emittance constraints. The results suggest that while APF-DTL offers operational simplicity, more standard DTL variants such as Alvarez and CH-KONUS provide better beam quality and power efficiency for high-intensity applications like CANS.