Ring simulation and beam dynamics studies for ISIS upgrades 0.5 to 10 MW

© 2014 CC-BY-3.0 and by the respective authors. Various upgrade routes are under study for the ISIS spallation neutron source at RAL in the UK. Recent work has concentrated on upgrading the injector, increasing injection energy from 70 to 180 MeV, and studying the challenging possibility of reaching powers up to 0.5 MW in the existing 800 MeV RCS. Studies for the longer term are exploring the possibilities of a 5 MW, 3.2 GeV RCS that could form part of a new stand-alone 10 MW next generation “ISIS II” facility. A central part of these ring studies is the use of computer simulations to guide designs, for example optimising the injection painting configuration and providing an indication of expected loss levels. Here we summarise the computer models used, indicate where benchmarking has been possible, describe optimisations and results from studies, and outline the main uncertainties. Understanding the limitations in high power RCS accelerators is an important part of determining optimal facility designs for the future.