RF linacs providing cw proton beams of 30–250 mA at 800–1600 MeV, and cw deuteron beams of 100–250 mA at 35–40 MeV, are needed as drivers for factory neutron sources applied to radioactive waste transmutation, advanced energy production, materials testing facilities, and spallation neutron sources. The maintenance goals require very low beam loss along the linac. Optimization of such systems is complex; status of beam dynamics aspects presently being investigated is outlined.