STFC/RAL/ASTeC, Chilton, Didcot, Oxon
High power driver rings are examined, using new FFAG designs, based on cells of five, scaling symmetrical pumplet magnets. Apertures are minimized by using large, betatron phase shifts per cell, typically μh ~ 280° and μv ~ 130°. Key aspects are the lengths of the long straight sections, particularly IF Hˉ charge exchange injection is required. Rings are considered for ISIS upgrades and Neutrino Factory proton and muon drivers. both with and without insertions.
STFC/RAL/ISIS, Chilton, Didcot, Oxon
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
ISIS is the spallation neutron source at 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 present ring (~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 latest experimental and simulation results are reviewed. Results from measurement and 3D simulation of the present operational machine are also summarised, along with investigations of the observed loss mechanisms. Finally, future plans are outlined.
