Danailov, M.B.
(Miltcho B. Danailov)

TUCOS03 VUV Optics Development for the Elettra Storage Ring FEL
Stefan Guenster, Detlev Ristau (LZH, Hannover), Francesca Sarto (ENEA, Roma), Miltcho B. Danailov, Mauro Trovò (Elettra, Basovizza, Trieste), Alexandre Gatto, Norbert Kaiser (IOF, Jena)

Vacuum ultraviolet optical components for the storage ring FEL at Elettra are under continuous development in the European research consortium EUFELE. Target of the project is the progress to shorter lasing wavelengths in the VUV spectral range. The current status allows lasing with oxide mirror systems down to 190 nm. The main obstacles for the development of optical coatings for shorter wavelengths is the high energetic background of the synchrotron radiation impinging onto the front mirror in the laser cavity. Investigations in single layer systems and multilayer stacks of oxide or fluoride materials demonstrate that fluoride mirrors reach highest reflectivity values down to 140 nm, and oxide coatings possess a satisfactory resistance against the high energetic background irradiation. However, pure oxide multilayer stacks exhibit significant absorption below 190 nm and pure fluoride stacks suffer from strong degradation effects under synchrotron radiation. A solution could be hybrid systems, combining fluoride stacks with oxide protection layers to provide high reflectivity and a robust behaviour under synchrotron radiation load. Results of hybrid systems will be presented.

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.

MOPOS27 Status Report on SPARC Project
Alberto Renieri, Mariano Carpanese, Franco Ciocci, Giuseppe Dattoli, Antonio Di Pace, Andrea Doria, Francesco Flora, Gian Piero Gallerano, Luca Giannessi, Emilio Giovenale, Giovanni Messina, Luca Mezi, Pier Luigi Ottaviani, Simonetta Pagnutti, Giovanni Parisi, Luigi Picardi, Marcello Quattromini, Giuseppe Ronci, Concetta Ronsivalle, Elio Sabia, Mauro Sassi, Alberto Zucchini (ENEA C.R. Frascati, Frascati - Roma), Carlo Joseph Bocchetta, Miltcho B. Danailov, Gerardo D'Auria, Mario Ferianis (Elettra, Basovizza, Trieste), F. Alessandria, A. Bacci, Ilario Boscolo, F. Broggi, S. Cialdi, C. De Martinis, D. Giove, C. Maroli, V. Petrillo, M. Romè, Luca Serafini (INFN Milano, Milano), D. Levi, Mario Mattioli, G. Medici, Pietro Musumeci (INFN Roma, Roma), L. Catani, E. Chiadroni, Sergio Tazzari (INFN-Roma2, Roma), David Alesini, M. Bellaveglia, Sergio Bertolucci, M.E. Biagini, Caterina Biscari, R. Boni, Manuela Boscolo, Michele Castellano, A. Clozza, G. Di Pirro, A. Drago, A. Esposito, Massimo Ferrario, D. Filippetto, V. Fusco, A. Gallo, A. Ghigo, Susanna Guiducci, M. Incurvati, C. Ligi, F. Marcellini, Mauro Migliorati, C. Milardi, Luigi Palumbo, L. Pellegrino, Miro Preger, P. Raimondi, R. Ricci, C. Sanelli, Mario Serio, F. Sgamma, Bruno Spataro, A. Stecchi, A. Stella, Franco Tazzioli, Cristina Vaccarezza, Mario Vescovi, C. Vicario, M. Zobov (INFN/LNF, Frascati (Roma)), A. Cianchi, A. D'Angelo, R. Di Salvo, A. Fantini, D. Moricciani, Carlo Schaerf (Rome University Tor Vergata, Roma), D. H. Dowell, Paul J Emma, C. Limborg-Deprey, D. T. Palmer (SLAC, Menlo Park, California), James B Rosenzweig, Gil Travish (UCLA, Los Angeles, California), Sven Reiche (UCLA/DPA, Los Angeles - California)

We review the status of FEL source activity of the on going SPARC FEL experiment, developed within the framework of a collaboration among ENEA, CNR, INFN, INFM, Sincrotrone Trieste and University of Rome Tor Vergata. The project is aimed at realising a SASE FEL source, operating in the visible (around 500 nm), with an extended range of tunability down to the VUV (100nm) by the use of the mechanism of non-linear harmonic generation. The development of the relevant activities foresees the realisation of an advanced 150 MeV photo-injector source, aimed at producing a high brightness electron beams, needed to drive a SASE-FEL experiment and a 12 m long undulator. We present the status of the design and construction of the injector, of the undulator and of the e-beam transport line. In particular we discuss the choice of the project parameters, their optimisation and the sensitivity of the SPARC performance to any parameter variation. We will show, using start to-end simulations, what is the impact of the e-beam and of the undulator parameters on the characteristics of the output laser field and in particular on the amount of the non linearly generated power at higher harmonics.

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.