The ESS Linac

The European Spallation Source, ESS, uses a linear accelerator to bombard the tungsten target with the high intensity protons beam for producing intense beams of neutrons. The nominal average beam power of the linac is 5 MW with a peak beam power at target of 125 MW. During last year the ESS linac cost was re-evaluated, and to meet the budget a few modifications were introduced to the linac design. One of the major changes is the reduction of the final energy from 2.5 GeV to 2.0 GeV and therefore beam current was increased accordingly to compensate for the lower final energy. As a result the linac is designed to meet the cost objective by taking a higher risk. This paper focuses on the driving forces behind the new design, engineering and beam dynamics requirements of the design and finally on the beam dynamics performance of the linac.