• G. De Ninno, E. Allaria, F. Curbis, M.B. Danailov, B. Diviacco, M. Marsi, M. Trovo
  ELETTRA, Basovizza, Trieste
• M. Coreno
  CNR - IMIP, Trieste
• S. Günster, D. Ristau
  Laser Zentrum Hannover, Hannover

Thanks to an intensive technological effort in the framework of the EEC Contract HPRI CT-2001-50025 (EUFELE), the European FEL at ELETTRA was able to break the previous record for the shortest wavelength of an FEL oscillator. Novel solutions were adopted for multilayer mirrors to allow FEL operation in the wavelength region between 160 and 190 nm, which is one of the main targets of the project. The characteristics of the FEL pulses measured at 176 nm (spectral profiles, high intensity, meV bandpass, MHz repetition rate) make it a competitive light source for spectroscopy, in particular for fluorescence studies in the VUV spectral range. Proof of principle experiments have been performed on different types of silica glasses, yielding information on the mechanisms of light absorption in this material.

• F. Curbis, F. Curbis
  Universita degli Studi di Trieste, Trieste
• G. De Ninno
  ELETTRA, Basovizza, Trieste

Coherent harmonic generation can be obtained by means of frequency up-conversion of a high-power external laser focused into the first undulator of an optical klystron. The standard configuration is based on a single-pass device, where the seed laser is synchronized with an electron beam entering the first undulator of the optical klystron after being accelerated using a linear accelerator. As an alternative, the optical klystron may be installed on a storage ring, where it is normally used as interaction region for an oscillator free-electron laser. In this case, removing the optical cavity and using an external seed, one obtains a configuration which is similar to the standard one but also presents some peculiar characteristics. In this paper we investigate the possibility of harmonic generation using the Elettra storage-ring optical klystron. We explore different experimental set-ups varying the beam energy, the seed characteristics and the strength of the optical-klystron dispersive section. We also study the performance sensitivity to fluctuations of some beam parameters and the coherent/incoherent signal ratio for different harmonics. Numerical simulations are performed using different 3-D numerical codes.

• F. Curbis, F. Curbis
  Universita degli Studi di Trieste, Trieste
• G. De Ninno
  ELETTRA, Basovizza, Trieste

Coherent harmonic generation can be obtained by means of frequency up-conversion of a high-power external laser focused into the first undulator of an optical klystron. The standard configuration is based on a single-pass device, where the seed laser is synchronized with an electron beam entering the first undulator of the optical klystron after being accelerated using a linear accelerator. As an alternative, the optical klystron may be installed on a storage ring, where it is normally used as interaction region for an oscillator free-electron laser. In this case, removing the optical cavity and using an external seed, one obtains a configuration which is similar to the standard one but also presents some peculiar characteristics. In this paper we investigate the possibility of harmonic generation using the Elettra storage-ring optical klystron. We explore different experimental set-ups varying the beam energy, the seed characteristics and the strength of the optical-klystron dispersive section. We also study the performance sensitivity to fluctuations of some beam parameters and the coherent/incoherent signal ratio for different harmonics. Numerical simulations are performed using different 3-D numerical codes.