Design of the Ess RFQs and Chopping Line

The chopping line is a critical part of the ESS linac in term of technical realisation of the choppers and preservation of the beam qualities. A new optimised design of the ESS RFQs and chopping lines is reported. The beam dynamics has been optimised with H- beam currents up to 100-mA to have safety margin with respect to the ESS goals. The first RFQ transmits almost 99.7% of the beam up to 2 MeV. The line with two choppers allows a perfect chopping between 2 bunches. The second RFQ accelerates the particles up to 5 MeV with a transmission close to 100%.