Development of a downsized proton accelerator system for compact neutron sources

In order to facilitate the widespread use of neutrons in industrial applications, it is important to provide a compact, semi-ready-made neutron source that a company and a factory can easily install. We are therefore developing a compact neutron source system utilizing a downsized proton accelerator as an entry level model for industrial use and materials development, which consists of a proton source, a four-vane radio frequency quadrupole linear accelerator (RFQ) and a lithium target for neutron production by the Li ( p,n ) 3 7 Be 4 7 reaction. An RFQ is suitable to accelerate protons in the low energy region because it accepts DC beams extracted from the proton source and accelerates effectively to the design energy with bunching and focusing using the electric fields. Furthermore, it is possible to design the RFQ with a higher frequency than conventionally used owing to technological advances in high power solid-state RF amplifiers. We investigated the specifications for 500 MHz and 650 MHz through beam trajectory and electromagnetic simulations and fabricated a 2.5 MeV prototype of the 500 MHz type with a 2.45 GHz ECR proton source.