Diviacco, B.
(Bruno Diviacco)

TUCOS04 Coherent Harmonic Generation using the ELETTRA Storage Ring Optical Klystron
Giovanni De Ninno, Miltcho B. Danailov, Bruno Diviacco, Mario Ferianis, Mauro Trovò (Elettra, Basovizza, Trieste), Luca Giannessi (ENEA C.R. Frascati, Frascati - Roma)

The standard process leading to CHG using single-pass devices or storage rings is based on the up-frequency conversion of a high-power laser focused into the first undulator of an optical klystron. The seeding signal, which is necessary to produce the modulation of the electron density and hence to induce the coherent emission, may be provided by an external laser or, in the case of storage-ring oscillators, by the FEL itself. The latter configuration has been recently implemented at ELETTRA allowing to generate the third harmonic of an intra-cavity signal at 660 nm. In the first part of this paper, we report about the set of measurements that have been performed, for different experimental set-ups, with the aim of characterizing the power as well as the spectral and temporal characteristics of the obtained radiation. As for seeding using an external laser, a detailed campaign of simulations, reported in the second part of the paper, shows that the ELETTRA optical klystron is also well suited for the investigation of this configuration. These results make the ELETTRA FEL an ideal test-facility in view of CHG experiments planned on dedicated next-generation devices.

MOPOS25 Electron beam simulations for the FERMI project at ELETTRA
Simone Di Mitri, Rene Johan Bakker, Carlo Joseph Bocchetta, Paolo Craievich, Gerardo D'Auria, Giovanni De Ninno, Bruno Diviacco, Lidia Tosi, Victor Verzilov (Elettra, Basovizza, Trieste)

FERMI at ELETTRA is a project aims at the construction of a single-pass user facility for the spectral range from 100 nm to 10 nm. Starting point is the existing 1.2 GeV, 3-GHz linac. Downstream of the linac two undulator beamlines will serve the wavelength range from 100 nm to 40 nm, and 40 nm to 10 nm, respectively. The former beamline will be based on a single-stage HGHG scheme while for the latter a double stage HGHG scheme is foreseen. This paper discusses results from start-to-end simulations for the former beamline, including the option of HGHG. Care has been taken to include realistic models for the injector, accelerating structures, and undulator beamline.

THPOS08 Experiments on the Synchronization of an Ultrafast Cr:LiSAF Laser with the ELETTRA Storage Ring and FEL Pulses
Mario Ferianis, Miltcho B. Danailov, Giovanni De Ninno, Bruno Diviacco, Mauro Trovò (Elettra, Basovizza, Trieste), Marcello Coreno (CNR-IMIP, Basovizza (TS)), Gamal Elsayed Afifi (NILES, Cairo)

The techniques for synchronizing ultrafast lasers to external radio frequency reference sources are well established and characterized in the literature. However, data lack on the minimum light-to-light jitter which can be achieved in different synchrotron operation modes when an external laser is locked to the storage ring master clock. Here we present first results for the synchronization of an ultrafast Cr:LiSAF laser with electromagnetic radiation coming from the Elettra storage ring in four bunch and multi-bunch mode. In addition, data on the synchronization of the same laser with the Elettra FEL pulses, both in free running and Q-switching regime, are reported. In our experiments, laser-to-RF locking was continuously monitored using a built-in phase detection. The laser light to storage ring light locking was characterized by simultaneous acquisition of two/three pulse trains by a streak camera. In addition, pulse jitter was determined by processing of the signal of fast photodiodes monitoring the different light beams.

THPOS09 Electron-Beam Stabilization for the European Storage-Ring Free-Electron Laser at Elettra
Mauro Trovò, Daniele Bulfone, Miltcho B. Danailov, Giovanni De Ninno, Bruno Diviacco, Vincenzo Forchi`, Marco Lonza (Elettra, Basovizza, Trieste), Luca Giannessi (ENEA C.R. Frascati, Frascati - Roma)

The temporal structure of the storage-ring free-electron laser at Elettra shows high sensitivity to electron-beam instabilities. In fact, even small beam orbit oscillations (of the order of few microns) may perturb the FEL dynamics and periodically switch off the laser. In order to improve the FEL operation and performance, a longitudinal multi-bunch feedback and a local orbit feedback have been activated. This paper reports on the beneficial effect of these feedback systems. Plans for a future "slow" longitudinal feedback are also briefly described.