THE ESS ACCELERATOR

In 2003 the joint European effort to design a European Spallation Source resulted in a set of detailed design reports. Lund was agreed as the site in 2009, and a company, ESS AB, hasbeencreatedto design,build andoperateESS. A collaboration has been formed for the accelerator work and an update project has been agreed and financed. Detailed planning for the prototyping in a Prepare-to-Build (P2B) projecthas also started. The currentstatus of the Design Update project for the accelerator will be presented, together with an outline of future work. The baseline for the updated design delivers 5 MW of 2.5 GeV protons to a single target, in 2.86 ms long pulses with a 14 Hz repetition rate. The linac will havea normalconductingfrontend with an ion source, an RFQ and a DTL. The superconducting part starts with spoke cavities followed by two families of elliptical cavities. It will be the first time that spoke cavities are used in a major accelerator. Work is being done to optimize the energy efficiency and to make further use of the heat from the cooling water coming out of the facility. Finally, potential future upgrades of power are considered.