Funneling in LANL high intensity linac designs

The Los Alamos design approach to Accelerator driven transmutation applications is based on high power proton linacs. Most of the accelerators that have been studied have one important element in common. That component is a funnel, where beams from two separate but identical front end linac systems are merged to form a collinear beam of twice the initial beam intensity. The nominal linac design for Accelerator Transmutation of Waste (ATW) consists of an ion source-injector/Radio Frequency Quadrupole (RFQ)/Drift Tube Linac (DTL) combination operating at 350 MHz. The output beam at 20 MeV from each of the DTLs is then funneled to a single high energy linac operating at 700 MHz which accelerates the beam to 800 MeV. In this paper, we present the rationale behind the choice of funneling to achieve higher beam intensity, a beam dynamics design, and simulation results through the funnel section, together with the present experimental status of funneling