ENERGY SPREAD IN BTW ACCELERATING STRUCTURES AT ELETTRA

The FEL project FERMI@ELETTRA will use the existing 1.0 GeV Linac, based on Backward Travelling Wave (BTW) structures, to produce VUV radiation between 100-10 nm. The project will be articulated in two different phases (100-40nm/40-10nm) and will require high quality beam with short bunches (500/160 fsec). Hence, wakefield effects have to be considered with respect to the electron beam quality. The single bunch energy spread induced by the short-range longitudinal wakefield is analyzed and results of start-to-end simulations are reported.