Status and perspectives of the fermi fel facility (2019)

FERMI is the seeded Free Electron Laser (FEL) user facility at the Elettra laboratory in Trieste, operating in the VUV to EUV and soft X-rays spectral range; the radiation produced by the seeded FEL is characterized by wavelength stability, low temporal jitter and longitudinal coherence in the range 100-4 nm. During 2018 a dedicated experiment has shown the potential of an Echo Enabled Harmonic Generation (EEHG) scheme to cover most of this spectral range with a single stage cascade [1]. Such a scheme, combined with an increment of the beam energy and of the accelerator performances, could extend the FERMI operating range up to the oxygen K-edge. With this future perspective, we present the development plans under consideration for the next 3 to 5 years. These include an upgrade of the linac and of the existing FEL lines, consisting in the conversion of FEL-1 first, and FEL-2 in a second moment, into EEHG seeded FELs.