The advent of extreme ultraviolet (EUV) and soft x-ray free electron lasers (FELs) has enabled nonlinear optical experiments at wavelengths shorter than the visible-UV range. An important class of experiments is those based on the four-wave-mixing (FWM) approach, which are often based on interactions between pulses at different wavelengths. The exploitation of multiple EUV/soft x-ray wavelengths is not straightforward, but it can significantly expand the range of applications. In this manuscript we report on an experimental approach, based on the concomitant use of a non-collinear split-delay-and-recombination unit (“mini-Timer”) and on a two-color seeded FEL emission scheme (“twin-seed mode”). We used a diamond sample for demonstrating the capability of this setup of generating and detecting a FWM signal stimulated by two-color EUV FEL pulses. This approach can be further exploited for developing experimental methods based on non-linear EUV/x-ray optics.
The seeded FEL FERMI has completed the commissioning of both the FEL lines, and it is now providing the user community with a coherent and tunable UV radiation (from 100 nm to 4 nm) in a number of different configurations. These also include original FEL-pump - FEL-probe schemes with twin-seeded FEL pulses. Among the key systems for the operation of FERMI, there is the femtosecond optical timing system and dedicated longitudinal diagnostics, specifically developed for FERMI. In this paper, after a short review of the FERMI optical timing system and of its routinely achieved performances, we focus on the results obtained from the suite of longitudinal diagnostics (Bunch Arrival Monitor, Electro Optical sampling station and RF deflectors) all operating in single shot and with 10s fs resolution which demonstrate the FERMI achieved performances. The longitudinal diagnostics measurements are compared between these device and other device on shot-to-shot basis, looking for correlations between machine parameters. Finally future challenges in terms of improvement of existing diagnostics, planned installations and possible upgrades are discussed.
Fabio Villa, David Alesini, Maria Pia Anania, Marcello Artioli, Alberto Bacci, Marco Bellaveglia, Mariano Carpanese, Michele Castellano, Alessandro Cianchi, Franco Ciocci, Enrica Chiadroni, Giuseppe Dattoli, Domenico Di Giovenale, Emanuele Di Palma, Giampiero Di Pirro, Massimo Ferrario, Francesco Filippi, Alessandro Gallo, Giancarlo Gatti, Luca Giannessi, Anna Giribono, Luca Innocenti, Najmeh Sada Mirian, Andrea Mostacci, Alberto Petralia, Vittoria Petrillo, Riccardo Pompili, Julietta Rau, Stefano Romeo, Andrea Renato Rossi, Elio Sabia, Vladimir Shpakov, Ivan Spassovsky, Cristina Vaccarezza
We present the experimental evidence of the generation of coherent and statistically stable Free-Electron Laser (FEL) two color radiation obtained by seeding an electron double peaked beam in time and energy with a single peaked laser pulse. The FEL radiation presents two neat spectral lines, with time delay, frequency separation and relative intensity that can be accurately controlled. The analysis of the emission shows a temporal coherence and regularity in frequency significantly enhanced with respect to the Self Amplified Spontaneous Emission (SASE).
L. Badano, E. Ferrari, E. Allaria, S. Bassanese, D. Castronovo, M. Danailov, A. Demidovich, G. De Ninno, S. Di Mitri, B. Diviacco, W. Fawley, L. Frohlich, G. Gaio, L. Giannessi, G. Penco, S. Spampinati, C. Spezzani, M. Trovò, M. Veronese
FERMI is the first user facility based upon an externally seeded free-electron laser (FEL) that delivers a coherent and tunable UV radiation (down to 4 nm at the fundamental) in a number of different configurations. A microbunching instability (MBI) developing in the bunch compressors and in the rest of the linac can degrade the quality of the high brightness electron beam sufficiently to reduce the FEL output intensity and spectral brightness. A laser heater installed in the low energy (100 MeV) part of the FERMI accelerator increases the local energy spread to provide Landau damping against this instability. In this paper we summarize the main results obtained with the FERMI laser heater since it commissioning in 2012. We present the measurement of the reduction of the incoherent energy spread at the linac exit induced by the heating of the electron beam at the beginning of the linac. We also discuss the positive effects of such heating upon the emission of coherent optical transition radiation and the FEL performances both in terms of intensity and spectrum. Moreover, we report about results that have been used to experimentally demonstrate that for transversely uniform heating the local energy spread augmentation is characterized by a non-Gaussian distribution that can be preserved up to the FEL undulator entrance with a significant impact on the performance of high-gain harmonic generation (HGHG) FELs, especially at soft x-ray wavelengths.
The optical klystron enhancement to a self-amplified spontaneous emission (SASE) free electron laser (FEL) has been deeply studied in theory and in simulations. In this FEL scheme, a relativistic electron beam passes through two undulators, separated by a dispersive section. The latter converts the electron-beam energy modulation produced in the first undulator in density modulation, thus enhancing the free-electron laser gain. We report the first experiment that has been carried out at the FERMI facility in Trieste, of enhancement to a SASE FEL by using the optical klystron scheme. XUV photons have been produced with an intensity several orders of magnitude larger than in pure SASE mode. The impact of the uncorrelated energy spread of the electron beam on the optical klystron SASE performance has been also investigated.
P. Finetti, E. Allaria, B. Diviacco, C. Callegari, B. Mahieu, J. Viefhaus, M. Zangrando, G. De Ninno, G. Lambert, E. Ferrari, J. Buck, M. Ilchen, B. Vodungbo, N. Mahne, C. Svetina, C. Spezzani, S. Di Mitri, G. Penco, M. Trovò, W. Fawley, P. Rebernik, D. Gauthier, C. Grazioli, M. Coreno, B. Ressel, A. Kivimäki, T. Mazza, L. Glaser, F. Scholz, J. Seltmann, P. Gessler, J. Grünert, A. De Fanis, M. Meyer, A. Knie, S. Moeller, L. Raimondi, F. Capotondi, E. Pedersoli, O. Plekan, M. Danailov, A. Demidovich, I. Nikolov, A. Abrami, J. Gautier, J. Lüning, P. Zeitoun, L. Giannessi
FERMI, based at Elettra (Trieste, Italy) is the first free electron laser (FEL) facility operated for user experiments in
seeded mode. Another unique property of FERMI, among other FEL sources, is to allow control of the polarization state
of the radiation. Polarization dependence in the study of the interaction of coherent, high field, short-pulse ionizing
radiation with matter, is a new frontier with potential in a wide range of research areas. The first measurement of the
polarization-state of VUV light from a single-pass FEL was performed at FERMI FEL-1 operated in the 52 nm-26 nm
range. Three different experimental techniques were used. The experiments were carried out at the end-station of two
different beamlines to assess the impact of transport optics and provide polarization data for the end user. In this paper
we summarize the results obtained from different setups. The results are consistent with each other and allow a general
discussion about the viability of permanent diagnostics aimed at monitoring the polarization of FEL pulses.
Cristian Svetina, Nicola Mahne, Lorenzo Raimondi, Luca Rumiz, Marco Zangrando, Enrico Allaria, Filippo Bencivenga, Carlo Callegari, Flavio Capotondi, Davide Castronovo, Paolo Cinquegrana, Paolo Craievich, Ivan Cudin, Massimo Dal Forno, Miltcho Danailov, Gerardo D'Auria, Raffaele De Monte, Giovanni De Ninno, Alexander Demidovich, Simone Di Mitri, Bruno Diviacco, Alessandro Fabris, Riccardo Fabris, William Fawley, Mario Ferianis, Eugenio Ferrari, Lars Froehlich, Paolo Furlan Radivo, Giulio Gaio, Luca Giannessi, Maya Kiskinova, Marco Lonza, Benoit Mahieu, Claudio Masciovecchio, Ivaylo Nikolov, Fulvio Parmigiani, Emanuele Pedersoli, Giuseppe Penco, Mauro Predonzani, Emiliano Principi, Fabio Rossi, Claudio Scafuri, Claudio Serpico, Paolo Sigalotti, Simone Spampinati, Carlo Spezzani, Michele Svandrlik, Mauro Trovo, Alessandro Vascotto, Marco Veronese, Roberto Visintini, Dino Zangrando
FERMI@Elettra is the first seeded VUV/soft X-ray FEL source. It is composed of two undulatory chains: the low energy branch (FELl) covering the wavelength range from 20 nm up to 100 nm, and the high energy branch (FEL2, employing a double stage cascade), covering the wavelength range from 4 nm up to 20 nm. At the end of 2012 FELl has been opened to external users while FEL2 has been turned on for the first time having demonstrated that a double cascade scheme is suitable for generating high intensity coherent FEL radiation. In this paper we will share our experience and will show our most recent results for both FERMI FELl and FEL2 sources. We will also present a brand new machine scheme that allows to perform two-colour pump and probe experiments as well as the first experimental results.
S. Di Mitri, E. Allaria, P. Cinquegrana, P. Craievich, M. Danailov, A. Demidovich, G. De Ninno, B. Diviacco, W. Fawley, L. Froelich, L. Giannessi, R. Ivanov, M. Musardo, I. Nikolov, G. Penco, P. Sigalotti, S. Spampinati, C. Spezzani, M. Trovò, M. Veronese
After less than two years of commissioning the FERMI@Elettra free electron laser is now entering into the operation
phase and is providing light to the first user experiments. To reach the final ambitious goals of providing high power
coherent pulses with fundamental wavelengths down to 4 nm, the system will need further studies and additional
commissioning time in 2011 when fine tuning of the major systems such as the electron gun and the main accelerator
will take place. Nevertheless, FERMI is already able to provide light with unique characteristics allowing Users to
perform experiments not possible with other facilities. Based on a 1.5 GeV electron linear accelerator, FERMI@Elettra
has two seeded FEL lines that cover the whole spectral range from 100 nm down to 4 nm with fully coherent pulses. The
use of the high gain harmonic generation scheme initiated by a tunable laser in the UV allows FERMI to produce light
characterized by both transverse and full temporal coherence. The use of specially designed undulators allows full
control of the FEL polarization and can be continuously varied from linear to circular in any orientation or ellipticity.
Here we will report about the first results and the future plans for FERMI@Elettra.
L. Poletto, G. Tondello, S. De Silvestri, M. Nisoli, G. Sansone, S. Stagira, P. Musumeci, M. Petrarca, M. Mattioli, M. Labat, O. Tcherbakoff, M. Bougeard, B. Carré, D. Garzella, G. Lambert, H. Merdji, P. Salières, M. Couprie, D. Alesini, M. Biagini, R. Boni, M. Castellano, A. Clozza, A. Drago, M. Ferrario, V. Fusco, A. Gallo, A. Ghigo, M. Migliorati, L. Palumbo, C. Sanelli, F. Sgamma, B. Spataro, S. Tomassini, C. Vaccarezza, C. Vicario, L. Serafini, S. Ambrogio, F. Ciocci, G. Dattoli, A. Doria, G. Gallerano, M. Germano, L. Giannessi, E. Giovenale, I. Spassovsky, M. Quattromini, A. Renieri, C. Ronsivalle, V. Surrenti, P. Ottaviani, S. Pagnutti, M. Rosetti, A. Dipace, E. Sabia
This communication describes the research work plan that is under implementation at the SPARC FEL facility in the
framework of the DS4 EUROFEL programme. The main goal of the collaboration is to study and test the amplification
and the FEL harmonic generation process of an input seed signal obtained as higher order harmonics generated both in
crystals (400 nm and 266 nm) and in gases (266 nm, 160 nm, 114 nm). The SPARC FEL can be con-figured to test
several cascaded FEL layouts that will be briefly analysed.
C. Vaccarezza, D. Alesini, M. Bellaveglia, S. Bertolucci, M. Biagini, R. Boni, M. Boscolo, M. Castellano, A. Clozza, L. Cultrera, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, D. Filippetto, V. Fusco, A. Gallo, A. Ghigo, S. Guiducci, M. Migliorati, L. Palumbo, L. Pellegrino, M. Preger, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stella, F. Tazzioli, M. Vescovi, C. Vicario, F. Ciocci, G. Dattoli, A. Doria, F. Flora, G. Gallerano, L. Giannessi, E. Giovenale, G. Messina, P. Ottaviani, G. Parisi, L. Picardi, M. Quattromini, A. Renieri, C. Ronsivalle, S. Cialdi, C. Maroli, V. Petrillo, M. Romè, L. Serafini, L. Catani, E. Chiadroni, A. Cianchi, C. Schaerf, P. Musumeci, F. Alessandria, A. Bacci, F. Broggi, C. De Martinis, D. Giove, M. Mauri, L. Ficcadenti, M. Mattioli, A. Mostacci, P. Emma, S. Reiche, J. Rosenzweig
KEYWORDS: Magnetism, Free electron lasers, Electron beams, Particles, Stanford Linear Collider, Superconductors, Diagnostics, S band, Lanthanum, Energy efficiency
The SPARX project consists in an X-ray-FEL facility jointly supported by MIUR (Research Department of Italian
Government), Regione Lazio, CNR, ENEA, INFN and Rome University Tor Vergata. It is the natural extension of the
ongoing activities of the SPARC collaboration. The aim is the generation of electron beams characterized by ultra-high
peak brightness at the energy of 1 and 2 GeV, for the first and the second phase respectively. The beam is expected to
drive a single pass FEL experiment in the range of 13.5-6 nm and 6-1.5 nm, at 1 GeV and 2 GeV respectively, both in
SASE and SEEDED FEL configurations. A hybrid scheme of RF and magnetic compression will be adopted, based on
the expertise achieved at the SPARC high brightness photoinjector presently under commissioning at Frascati INFNLNF
Laboratories. The use of superconducting and exotic undulator sections will be also exploited. In this paper we
report the progress of the collaboration together with start to end simulation results based on a combined scheme of RF
compression techniques.
D. Alesini, S. Bertolucci, M. Biagini, R. Boni, M. Boscolo, M. Castellano, A. Clozza, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, V. Fusco, A. Gallo, A. Ghigo, S. Guiducci, M. Incurvati, C. Ligi, F. Marcellini, M. Migliorati, A. Mostacci, L. Palumbo, L. Pellegrino, M. Preger, R. Ricci, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, F. Tazzioli, C. Vaccarezza, M. Vescovi, C. Vicario, F. Alessandria, A. Bacci, I. Boscolo, F. Broggi, S. Cialdi, C. De Martinis, D. Giove, C. Maroli, V. Petrillo, M. Romè, L. Serafini, D. Levi, G. Medici, M. Mattioli, P. Musumeci, L. Catani, E. Chiadroni, D. Moricciani, F. Ciocci, G. Dattoli, A. Doria, F. Flora, G. Gallerano, L. Giannessi, E. Giovenale, G. Messina, L. Mezi, P. Ottaviani, L. Picardi, M. Quattromini, A. Renieri, C. Ronsivalle, A. Cianchi, C. Schaerf, J. Rosenzweig
SPARC and SPARX are two different initiatives toward an X-ray FEL SASE source at LNF. SPARC is a high gain FEL
project devoted to provide a source of visible and VUV radiation while exploiting SASE mechanism. An advanced
Photo-Injector system, emittance self-compensating RF-gun plus a 150 MeV Linac, will inject a high quality e-beam into
the undulator to generate high brilliance FEL radiation in the visible region at the fundamental wavelength, (530 nm).
The production of flat top drive laser beams, high peak current bunches, and an emittance compensation scheme will be
investigated together with the generation of higher harmonic radiation in the VUV region. SPARX is the direct evolution
of such a high gain SASE FEL towards the 13.5 and 1.5 nm operating wavelengths, at 2.5 GeV. The first phase of the
SPARX project, fiinded by Government Agencies, will be focused on R&D activity on critical components and
techniques for future X-ray facilities as described in this paper.
The techniques for synchronizing ultra fast lasers to external radio frequency reference sources are well established and characterized in the literature. However, there is little data on the actual light-to-light jitter that 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 of the synchronization of an ultra fast Cr:LiSAF laser with synchrotron radiation generated by the ELETTRA storage ring in different filling modes. In addition, data on the synchronization of the same laser with the ELETTRA FEL pulses, both in free running and Q-switching regimes, are reported. In our experiments, laser-to-RF locking was continuously monitored using built-in phase detection. The laser light to storage ring light locking was characterized by simultaneous acquisition of the 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.
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