High intensity studies on the ISIS synchrotron, including key factors for upgrades and the effects of half integer resonance
Warsop CM., Adams DJ., Gardner ISK., Jones B., Mathieson RJ., Payne SJ., Pine BG., Prior CR., Rees GH., Seville A., Smith HV., Thomason JWG., Williamson RE.
ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Operation centres on a high intensity proton synchrotron, accelerating 3×1013 ppp from 70-800 MeV, at a rep. rate of 50 Hz. Studies are under way looking at many aspects of high intensity behaviour with a view to increasing operational intensity, identifying optimal upgrade routes and understanding more about fundamental intensity limitations. Present work is assessing the possibility of increasing beam power by raising injection energy into the existing ring (to ∼180 MeV), with a new optimised injector. Progress on calculations and simulations for the main high intensity topics is presented, including: space charge and emittance evolution in the transverse and longitudinal planes, beam stability, and injection optimisation. Of particular interest is the space charge limit imposed by half integer resonance, for which the latest experimental and simulation results are reviewed.