| Paper |
Title |
Page |
| MOPPH054 |
FERMI @ Elettra: A Seeded FEL Facility for EUV and Soft X-Rays
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166 |
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- J. N. Corlett, L. R. Doolittle, W. M. Fawley, S. M. Lidia, G. Penn, I. V. Pogorelov, J. Qiang, A. Ratti, J. W. Staples, R. B. Wilcox, A. Zholents
LBNL, Berkeley, California
- E. Allaria, C. J. Bocchetta, D. Bulfone, F. C. Cargnello, D. Cocco, P. Craievich, G. D'Auria, M. B. Danailov, G. De Ninno, S. Di Mitri, B. Diviacco, M. Ferianis, A. Galimberti, A. Gambitta, M. Giannini, F. Iazzourene, E. Karantzoulis, M. Lonza, F. M. Mazzolini, G. Penco, L. Rumiz, S. Spampinati, G. Tromba, M. Trovo, A. Vascotto, M. Veronese, M. Zangrando
ELETTRA, Basovizza, Trieste
- M. Cornacchia, P. Emma, Z. Huang, J. Wu
SLAC, Menlo Park, California
- W. Graves, F. X. Kaertner, D. Wang
MIT, Middleton, Massachusetts
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We describe the conceptual design and major performance parameters for the FERMI FEL project funded for construction at the Sincrotrone Trieste, Italy. This user facility complements the existing storage ring light source at Sincrotrone Trieste, and will be the first facility to be based on seeded harmonic cascade FELs. Seeded FELs provide high peak-power pulses, with controlled temporal duration of the coherent output allowing tailored x-ray output for time-domain explorations with short pulses of 100 fs or less, and high resolution with output bandwidths of the order of meV. The facility uses the existing 1.2 GeV S-band linac, driven by electron beam from a new high-brightness rf photocathode gun, and will provide tunable output over a range from ~100 nm to ~10 nm, and APPLE undulator radiators allow control of x-ray polarization. Initially, two FEL cascades are planned, a single-stage harmonic generation to operate over ~100 nm to ~40 nm, and a two-stage cascade operating from ~40 nm to ~10 nm or shorter wavelengh, each with spatially and temporally coherent output, and peak power in the GW range.
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| TUPPH021 |
Q-Switch Techniques Implemented at the ELETTRA Storage-Ring Free Electron Laser
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360 |
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- F. Curbis, F. Curbis
Università degli Studi di Trieste, Trieste
- M. B. Danailov, G. De Ninno, B. Diviacco, L. Romanzin, M. Trovo
ELETTRA, Basovizza, Trieste
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In a storage-ring FEL the gain can be calculated measuring the rise-time of giant pulses, produced by the interaction between the light stored in the optical cavity and an electron beam with low energy-spread (cold beam). This interplay produces the heating of the beam. Therefore, after the generation of a single giant pulse, the overlap between electrons and radiation is periodically prevented for a time necessary to dump the energy spread and recover the cold-beam condition. For this purpose two different methods are implemented at Elettra. In the first, modifying the radio-frequency of the ring, the change of the revolution time of electrons avoids the temporal overlap between the electron beam and the optical field in the mirror cavity. The second method relies on a mechanical gating (chopper) which intercept the light produced during previous interactions, inducing a periodic emptying of the optical cavity. The gain can be also estimated using an indirect formula after measuring the electron-beam energy spread and bunch length. In this paper we compare the different techniques mentioned above for the case of the Elettra SR-FEL.
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| THPPH026 |
Design of a Two-Stage Laser Pulse Shaping System for FEL Photoinjectors
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617 |
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- M. B. Danailov, A. A. Demidovich, R. Ivanov
ELETTRA, Basovizza, Trieste
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Temporal pulse shaping is one of the most important requirements to photoinjector lasers needed in the majority of FEL projects. The laser pulses commonly requested for excitation of the photocathode are in the UV (around 260 nm) and have flat-top shape of duration in the 5-10 ps range. More complex pulse shapes like "water-bags" and ramps have also been proposed recently, indicating that the pulse shaping scheme must offer flexibility in generating different shapes. In this paper we present an approach which combines the two main pulse shaping techniques, namely acousto -optic dispersive filter (DAZZLER) and Fourier-based 4-f system. The DAZZLER is inserted between the seed mode-locked oscillator and the amplifier and is used for preliminary shaping in the infrared, while the final pulse shape and duration are determined by a 4-f system incorporating deformable mirror positioned after the harmonic conversion to UV. The paper provides simulations and experimental results on designed and measured pulses of both flat-top and asymmetric (ramp) type, comparing solutions based on different distribution of amplitude and phase shaping between the two parts of the shaping setup.
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