| Paper |
Title |
Page |
MOP073 |
Chirped Pulse Amplification in a Seeded Free-electron Laser: Design of a Test Experiment at FERMI |
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- G. De Ninno, E. Allaria, I. Cudin, M.B. Danailov, A.A. Demidovich, S. Di Mitri, E. Ferrari, D. Gauthier, L. Giannessi, N. Mahne, G. Penco, L. Raimondi, P. Rebernik Ribič, C. Spezzani, L. Sturari, C. Svetina, M. Zangrando
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
- H. Dacasa, B. Mahieu, P. Zeitoun
LOA, Palaiseau, France
- M. Fajardo
IPFN, Lisbon, Portugal
- E. Ferrari
Università degli Studi di Trieste, Trieste, Italy
- F. Frassetto, L. P. Poletto
LUXOR, Padova, Italy
- D. Gauthier
University of Nova Gorica, Nova Gorica, Slovenia
- L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
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In solid-state lasers, frequency chirping is employed to stretch a short pulse prior to amplification, mitigating the problems related to high power in the active medium. After amplification, the chirp is compensated in order to recover short pulse duration and, hence, high peak power. Chirped pulse amplification (CPA) in seeded FEL’s relies on a similar principle: the seed pulse is stretched in time before interacting with the electron beam. This permits one to create bunching on a larger number of electrons, and to (approximately) linearly increase the output energy of the generated FEL pulse. In ideal conditions, the chirp carried by the phase of the seed pulse is transmitted to the output phase of the FEL pulse. Chirp compensation after the last undulator allows production of a short (ideally Fourier-transformed) pulse and, therefore, a larger peak power with respect to what obtained, for the same conditions, in standard (i.e., no-chirp-on-the-seed) operation mode. In this paper, we present the preparatory studies (i.e., numerical simulations and compressor design), which have been carried out at FERMI, in view of performing the first test experiment of CPA on a seeded FEL.
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| MOP077 |
Measurements of the FEL-bandwidth Scaling with Harmonic Number in a HGHG FEL |
227 |
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- E. Allaria, M.B. Danailov, W.M. Fawley, E. Ferrari, L. Giannessi
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
- E. Ferrari
Università degli Studi di Trieste, Trieste, Italy
- L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
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In this work we report recent measurements done at FERMI showing the dependence of the FEL bandwidth with respect to the seed laser harmonic at which the FEL is operated. Comparison of FEL spectra for different Fourier-limit seed and chirp pulses is also reported.
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| TUB02 |
Generation of Intense XVUV Pulses with an Optical Klystron Enhanced Self- amplified Spontaneous Emission Free Electron Laser |
332 |
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- G. Penco, E. Allaria, G. De Ninno, E. Ferrari, L. Giannessi
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
- G. De Ninno
University of Nova Gorica, Nova Gorica, Slovenia
- L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
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Fermi is a seeded FEL operating in high gain harmonic generation mode. The FEL layout is constituted by a modulator and six radiators separated by a dispersive section. The modulator and the radiators can be tuned to the same resonant frequency to set up an asymmetric optical klystron configuration where self amplified spontaneous emission can be generated and studied. This paper presents the experiment consisting in the analysis of the enhancement of the self-amplified spontaneous emission (SASE) radiation by the dispersion in the optical klystron. The FEL pulses produced with the optical klystron configuration are several order of magnitude more intense than in pure SASE mode with the dispersion set to zero, The experimental observations are in good agreement with simulation results and theoretical expectations. A comparison with the typical high-gain harmonic generation seeded Fel operation is also provided.
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Slides TUB02 [12.835 MB]
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| TUP085 |
FERMI Status Report |
564 |
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- M. Svandrlik, E. Allaria, F. Bencivenga, C. Callegari, F. Capotondi, D. Castronovo, P. Cinquegrana, M. Coreno, R. Cucini, I. Cudin, G. D'Auria, M.B. Danailov, R. De Monte, G. De Ninno, P. Delgiusto, A.A. Demidovich, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, P. Finetti, L. Fröhlich, P. Furlan Radivo, G. Gaio, D. Gauthier, F. Gelmetti, L. Giannessi, M. Kiskinova, S. Krecic, M. Lonza, N. Mahne, C. Masciovecchio, M. Milloch, F. Parmigiani, G. Penco, L. Pivetta, O. Plekan, M. Predonzani, E. Principi, L. Raimondi, P. Rebernik Ribič, F. Rossi, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, C. Spezzani, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
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FERMI, the seeded FEL located at the Elettra laboratory in Trieste, Italy, is now in regular operation for users with its first FEL line, FEL-1, which covers the wavelength range between 100 and 20 nm. We will give an overview of the typical operating modes of the facility for users and we will report on the status of beamlines and experimental stations. Three beamlines are now opened for users, three more are in construction. Meanwhile, the second FEL line of FERMI, FEL-2, a HGHG double stage cascade covering the wavelength range 20 to 4 nm is still under commissioning; we will report on the latest results in particular at the shortest wavelength, 4 nm in the fundamental.
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| THA02 |
Experimental Characterization of FEL Polarization Control with Cross Polarized Undulators |
644 |
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- E. Ferrari, E. Allaria, G. De Ninno, B. Diviacco, D. Gauthier, L. Giannessi, G. Penco, C. Spezzani
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
- J. Buck, M. Ilchen
XFEL. EU, Hamburg, Germany
- G. De Ninno, D. Gauthier
University of Nova Gorica, Nova Gorica, Slovenia
- L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
- Z. Huang, A.A. Lutman
SLAC, Menlo Park, California, USA
- G. Lambert, B. Mahieu
LOA, Palaiseau, France
- J. Viefhaus
DESY, Hamburg, Germany
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Polarization control of the coherent radiation is becoming an important feature of recent and future short wavelength free electron laser facilities. While polarization tuning can be achieved taking advantage of specially designed undulators, a scheme based on two consecutive undulators emitting orthogonally polarized fields has also been proposed. Developed initially in synchrotron radiation sources, crossed polarized undulator schemes could benefit from the coherent emission that characterize FELs. In this work we report the first detailed experimental characterization of the polarization properties of an FEL operated with crossed polarized undulators in the Soft-X-Rays. Aspects concerning the average degree of polarization and the shot to shot stability are investigated together with a comparison of the performance of various schemes to control and switch the polarization
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Slides THA02 [5.383 MB]
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| MOB01 |
Pulse Control in a Free Electron Laser Amplifier |
9 |
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- L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
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Funding: Work supported by MIUR (DM1834 RIC.4-12-2002 and Grants No. FIRB- RBAP045JF2 and No. FIRB-RBAP06AWK3), and by the EU Commission in the Sixth Framework Program, Contract No. 011935- EUROFEL.
A significant progress has been made in controlling the properties of the radiation emitted by a FEL amplifier. Experiments have demonstrated the possibility both to increase the temporal coherence and to reduce the amplifier length to reach saturation, by seeding it with an external source. This may be a solid state, short pulse, laser (Ti:Sa,OPA..), doubled or tripled in a crystal, or a high order harmonic pulse generated in gas. The coherence improvement and the increased compactness of the source are only the first beneficial offspring of this marriage between the optical laser world and that of FELs. Non-linear effects in the seeded FEL dynamics may be exploited to shorten the pulse length beyond that allowed by the FEL natural gain bandwidth. Multiple seed pulses can be used to generate pulses whose temporal distance and properties are also controlled. Similarly, the FEL gain can be adapted to match the seed properties by tailoring the electrons phase space to generate ultra-short output pulses at unparalleled intensities. I had the honor (and luck) to participate in many relevant experiments at the SPARC and FERMI FELs and I will give my personal overview.
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Slides MOB01 [29.932 MB]
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| MOP077 |
Measurements of the FEL-bandwidth Scaling with Harmonic Number in a HGHG FEL |
227 |
| |
- E. Allaria, M.B. Danailov, W.M. Fawley, E. Ferrari, L. Giannessi
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
- E. Ferrari
Università degli Studi di Trieste, Trieste, Italy
- L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
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In this work we report recent measurements done at FERMI showing the dependence of the FEL bandwidth with respect to the seed laser harmonic at which the FEL is operated. Comparison of FEL spectra for different Fourier-limit seed and chirp pulses is also reported.
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| MOP079 |
Generation of Multiple Coherent Pulses in a Superradiant Free-Electron Laser |
233 |
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- X. Yang, S. Seletskiy
BNL, Upton, Long Island, New York, USA
- L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
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We analyze the structure of the tail of a superradiant pulse, which is constituted by a train of sub-pulses with decaying amplitudes. We show how a trailing pulse, with pi phase advance from the leading pulse, is generated at the falling edge of the leading superradiant pulse, where the corresponding phase space is deeply saturated and the electrons become de-trapped by the reduced ponderomotive potential. Once the trailing pulse gains enough energy, it generates a second trailing pulse, and the process takes place again. By performing detailed simulations of the resulting electron phase space distribution and the FEL pulse spectral and temporal structure with PERSEO, we confirm that the deformation and re-bunching of the longitudinal phase space create a sequence of pulses. These results are compared to 3D simulations using the FEL code GENESIS 1.3 showing a good agreement.
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MOP080 |
Two Color Experiments at SPARC: External and Intra-bunch Seeding |
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- D. Alesini, M.P. Anania, M. Bellaveglia, M. Castellano, E. Chiadroni, D. Di Giovenale, G. Di Pirro, M. Ferrario, A. Gallo, G. Gatti, R. Pompili, S. Romeo, V. Shpakov, C. Vaccarezza, F. Villa
INFN/LNF, Frascati (Roma), Italy
- M. Artioli
ENEA-Bologna, Bologna, Italy
- A. Bacci, A.R. Rossi
Istituto Nazionale di Fisica Nucleare, Milano, Italy
- M.C. Carpanese, F. Ciocci, G. Dattoli, E. Di Palma, L. Giannessi, A. Petralia, E. Sabia, I.P. Spassovsky
ENEA C.R. Frascati, Frascati (Roma), Italy
- A. Cianchi
INFN-Roma II, Roma, Italy
- F. Filippi, A. Giribono
INFN-Roma, Roma, Italy
- L. Innocenti
Università di Roma II Tor Vergata, Roma, Italy
- N.S. Mirian, V. Petrillo
Universita' degli Studi di Milano & INFN, Milano, Italy
- A. Mostacci
Rome University La Sapienza, Roma, Italy
- J.V. Rau
ISM-CNR, Rome, Italy
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The FEL-SPARC operation with two bunches at different energies has been characterized using different tools. The effect of the e-beam matching on the SASE operation has been explored by controlling the transport with an ad hoc developed control system, allowing either the transport in matching conditions and in different configurations. Since the two bunches have, at the entrance of the undulator, different phase space characteristics we used this effect as a knob to enhance or suppress one or the other FEL mode. We investigated the effect of seeding on both frequencies and observed beating waves, furthermore we observed effects of intra-bunch seeding when only one of the modes is seeded.
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| TUB02 |
Generation of Intense XVUV Pulses with an Optical Klystron Enhanced Self- amplified Spontaneous Emission Free Electron Laser |
332 |
| |
- G. Penco, E. Allaria, G. De Ninno, E. Ferrari, L. Giannessi
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
- G. De Ninno
University of Nova Gorica, Nova Gorica, Slovenia
- L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
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Fermi is a seeded FEL operating in high gain harmonic generation mode. The FEL layout is constituted by a modulator and six radiators separated by a dispersive section. The modulator and the radiators can be tuned to the same resonant frequency to set up an asymmetric optical klystron configuration where self amplified spontaneous emission can be generated and studied. This paper presents the experiment consisting in the analysis of the enhancement of the self-amplified spontaneous emission (SASE) radiation by the dispersion in the optical klystron. The FEL pulses produced with the optical klystron configuration are several order of magnitude more intense than in pure SASE mode with the dispersion set to zero, The experimental observations are in good agreement with simulation results and theoretical expectations. A comparison with the typical high-gain harmonic generation seeded Fel operation is also provided.
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Slides TUB02 [12.835 MB]
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| THA02 |
Experimental Characterization of FEL Polarization Control with Cross Polarized Undulators |
644 |
| |
- E. Ferrari, E. Allaria, G. De Ninno, B. Diviacco, D. Gauthier, L. Giannessi, G. Penco, C. Spezzani
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
- J. Buck, M. Ilchen
XFEL. EU, Hamburg, Germany
- G. De Ninno, D. Gauthier
University of Nova Gorica, Nova Gorica, Slovenia
- L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
- Z. Huang, A.A. Lutman
SLAC, Menlo Park, California, USA
- G. Lambert, B. Mahieu
LOA, Palaiseau, France
- J. Viefhaus
DESY, Hamburg, Germany
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Polarization control of the coherent radiation is becoming an important feature of recent and future short wavelength free electron laser facilities. While polarization tuning can be achieved taking advantage of specially designed undulators, a scheme based on two consecutive undulators emitting orthogonally polarized fields has also been proposed. Developed initially in synchrotron radiation sources, crossed polarized undulator schemes could benefit from the coherent emission that characterize FELs. In this work we report the first detailed experimental characterization of the polarization properties of an FEL operated with crossed polarized undulators in the Soft-X-Rays. Aspects concerning the average degree of polarization and the shot to shot stability are investigated together with a comparison of the performance of various schemes to control and switch the polarization
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Slides THA02 [5.383 MB]
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