Stripping foil simulations for ISIS injection upgrades

ISIS, the pulsed neutron and muon spallation source located at the Rutherford Appleton Laboratory (UK), currently delivers a mean beam power of 0.2 MW to target. A 70 MeV H-linear accelerator feeds into a 50 Hz, 800 MeV proton synchrotron (through a 0.3 μm aluminium oxide stripping foil), accelerating up to 3×1013protons per pulse. Potential injection scheme upgrades, aiming to raise average beam power towards 0.5 MW with a new 180 MeV linear accelerator, are being studied. Detailed consideration of the injection stripping foil forms a key element of this study: scattering, stripping efficiency and foil lifetime are significant factors in determining loss levels, which consequently limit operational intensity. This paper describes the identification of a suitable stripping foil specification for successful 180 MeV H-charge exchange injection into the ISIS synchrotron. A simulation code was developed to investigate electron stripping, scattering events and temperature rises, in order to witness their subsequent effect on foil lifetime. ANSYS models were also used to investigate the heat transfer and temperature distribution within thin foils. Copyright © 2011 by IPAC'11/EPS-AG.