A LINEAR BEAM RASTER SYSTEM FOR THE EUROPEAN SPALLATION SOURCE

The European Spallation Source (ESS) will, when built, be the most intense neutron source in the world. The neutrons are generated by a high power (5 MW) proton beam impacting a rotating W spallation target. To reduce the replacement frequency of components subjected to the full beam current, i.e. the proton beam window (PBW) and the target, means to introduce low peak current densities, i.e. flat transverse beam profiles, are necessary. The ESS will nominally operate with an average (peak) proton current of 2.5 mA (62.5 mA) at 2.0 GeV. The relatively long beam pulse duration of 2.86 ms (at 14 Hz) leaves ample time to facilitate a Lissajous-like, linear raster system that illuminates a footprint area by sweeping an only moderately enlarged linac beamlet. The design, specifications, performance, and benefits of the beam raster system will be described and discussed.