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J Barros,
C Evain,
L Manceron,
J-B Brubach,
M-A Tordeux,
P Brunelle,
L Nadolski,
A Loulergue, M-E Couprie,
S Bielawski,
C Szwaj,
P Roy
[show abstract]
[hide abstract]
ABSTRACT: We present the first high resolution (10(-3) cm(-1)) interferometric measurements in the 200-750 GHz range using coherent synchrotron radiation, achieved with a low momentum compaction factor. The effect of microbunching on spectra is shown, depending on the bunch current. A high signal-to-noise ratio is reached thanks to an artifact correction system based on a double detection scheme. Combined to the broad emitted spectral range and high flux (up to 10(5) times the incoherent radiation), this study demonstrates that coherent synchrotron radiation can now be used for stability-demanding applications, such as gas-phase studies of unstable molecules.
The Review of scientific instruments 03/2013; 84(3):033102. · 1.52 Impact Factor
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L. Giannessi,
M. Bellaveglia,
E. Chiadroni,
A. Cianchi, M.E. Couprie,
M. Del Franco,
G. Di Pirro,
M. Ferrario,
G. Gatti,
M. Labat,
G. Marcus,
A. Mostacci,
A. Petralia,
V. Petrillo,
M. Quattromini,
J. V. Rau,
S. Spampinati,
V. Surrenti
[show abstract]
[hide abstract]
ABSTRACT: We report measurements demonstrating the concept of the free-electron laser (FEL) superradiant cascade. Radiation (lambda_rad = 200 nm) at the second harmonic of a short, intense seed laser pulse (lambda_seed = 400 nm) was generated by the cascaded FEL scheme at the transition between the modulator and radiator undulator sections. The superradiance of the ultrashort pulse is confirmed by detailed measurements of the resulting spectral structure, the intensity level of the produced harmonics, and the trend of the energy growth along the undulator. These results are compared to numerical particle simulations using the FEL code GENESIS 1.3 and show a satisfactory agreement.
Physical Review Letters 01/2013; 110:044801. · 7.37 Impact Factor
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L. Giannessi,
M. Bellaveglia,
E. Chiadroni,
A. Cianchi, M. E. Couprie,
M. Del Franco,
G. Di Pirro,
M. Ferrario,
G. Gatti,
M. Labat,
G. Marcus,
A. Mostacci,
A. Petralia,
V. Petrillo,
M. Quattromini,
J. V. Rau,
S. Spampinati,
V. Surrenti
Physical Review Letters 01/2013; 110:044801. · 7.37 Impact Factor
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L. Giannessi,
M. Bellaveglia,
E. Chiadroni,
A. Cianchi, M. E. Couprie,
M. Del Franco,
G. Di Pirro,
M. Ferrario,
G. Gatti,
M. Labat,
G. Marcus,
A. Mostacci,
A. Petralia,
V. Petrillo,
M. Quattromini,
J. V. Rau,
S. Spampinati,
and V. Surrenti
[show abstract]
[hide abstract]
ABSTRACT: We report measurements demonstrating the concept of the free-electron laser (FEL) superradiant cascade. Radiation (lambda_rad = 200 nm) at the second harmonic of a short, intense seed laser pulse (lambda_seed = 400 nm) was generated by the cascaded FEL scheme at the transition between the modulator and radiator undulator sections. The superradiance of the ultrashort pulse is confirmed by detailed measurements of the resulting spectral structure, the intensity level of the produced harmonics, and the trend of the energy growth along the undulator. These results are compared to numerical particle simulations using the FEL code GENESIS 1.3 and show a satisfactory agreement.
Physical Review Letters 01/2013; 110:044801. · 7.37 Impact Factor
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N. Joly,
M. Labat,
J. Travers,
K. Mak,
F. Tani,
G. Gatti,
T. Tanikawa,
G. De Ninno,
B. Mahieu,
F. Ciocci,
A. Petralia,
V. Petrillo,
J.V. Rau,
S. Bielawski,
M. Quattromini,
L. Giannessi,
P. St. J. Russell, M.-E. Couprie
[show abstract]
[hide abstract]
ABSTRACT: Instead of seeding a free electron laser in the UV-VUV with a frequency doubled or tripled laser or high order harmonics, here we investigate and present the first results on seeding the SPARC-FEL with a fibre-based tunable ultraviolet source. The seed generation system consists of a kagome hollow-core photonic crystal fibre filled with noble gas. Diffraction-limited DUV pulses of >50 nJ and fs-duration which are continuously tunable from below 200 nm to above 300 nm are generated. The process is based on soliton-effect self-compression of the pump pulse down to a few optical cycles, accompanied by the emission of a resonant dispersive wave in the DUV spectral region. The quality of the compression highly depends on the pump pulse duration, and ideally, pulses <60 fs should be used. Our experimental set-up and associated GENESIS simulations enable us to study the utility of the seed tunability, and the influence of the seed quality, on the performance of the SPARC-FEL in the 200-300 nm range.
34th Intern. Free-Electron Laser Conference, Nara, Japan.; 08/2012
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L Giannessi,
M Artioli,
M Bellaveglia,
F Briquez,
E Chiadroni,
A Cianchi, M E Couprie,
G Dattoli,
E Di Palma,
G Di Pirro, [......],
A Petralia,
V Petrillo,
L Poletto,
M Quattromini,
J V Rau,
J Rosenzweig,
E Sabia,
M Serluca,
I Spassovsky,
V Surrenti
[show abstract]
[hide abstract]
ABSTRACT: Higher order harmonic generation in a free-electron laser amplifier operating in the superradiant regime [R. H. Dicke, Phys. Rev. 93, 99 (1954).] has been observed. Superradiance has been induced by seeding a single-pass amplifier with the second harmonic of a Ti:sapphire laser, generated in a β-Barium borate crystal, at seed intensities comparable to the free-electron laser saturation intensity. Pulse energy and spectral distributions of the harmonics up to the 11th order have been measured and compared with simulations.
Physical Review Letters 04/2012; 108(16):164801. · 7.37 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: In a Storage Ring Free Electron Laser (SRFEL) there is a
strong interdependence between the laser beam and the electron
beam from which the laser is generated. The Super ACO storage ring
has a second Radio Frequency (RF) cavity at the 5th harmonic of
the main RF cavity. It is used to shorten the bunch length,
thereby enhancing the laser gain. Employing this RF harmonic
cavity instabilities are observed with a strong effect on both the
laser radiation properties and the electron beam behaviour. In
this paper, we first present beam characteristics of Super-ACO as
influenced by the harmonic cavity, and the instabilities of the
beam due to this RF cavity. Then we discuss the FEL properties in
presence of the harmonic RF cavity. In general the harmonic cavity
functions as intended, and it is observed that the laser
suppresses the instabilities caused by the harmonic cavity in the
absence of the FEL.
The European Physical Journal D 04/2012; 32(1):83-93. · 1.48 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Cryogenic permanent magnet undulators take benefit from improved
magnetic properties of RE2Fe14B (Rare Earth based
magnets) at cryogenic temperatures for achieving short period high
magnetic field. In particular, using Praseodymium instead of Neodymium
generally employed for insertion devices avoids limitation due to Spin
Reorientation Transition phenomenon. Magnetic properties of magnet
samples (Nd2Fe14B and
Pr2Fe14B) versus temperature have been
investigated and applied to a 20 mm period
Nd2Fe14B (BH50) and to a 18 mm period
Pr2Fe14B (CR53) systems. Four period undulators
have been built, characterised and compared to the models.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 02/2012; 669:1-6. · 1.21 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: We propose to produce femtosecond pulses of soft x-ray coherent undulator radiation in a storage ring for user pump–probe experiments using two energy exchanges between a picosecond relativistic electron bunch and two external ultra-short laser pulses. The coherent emission is generated thanks to the two laser–electron interactions that modulate the longitudinal charge distribution of the electron bunch at a harmonic of the laser wavelength, such as in the echo-enabled harmonic generation in free-electron lasers. Application to the SOLEIL storage ring in the soft x-ray range leads to coherent radiation and improvement of the flux of the photons by several orders in magnitude compared to the conventional slicing scheme. This is also accompanied by a significant enhancement of the signal-to-noise ratio.
New Journal of Physics 01/2012; 14(2):023003. · 4.18 Impact Factor
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Journal of Physics Conference Series 01/2012; 359(1):012002.
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M Labat,
M Bellaveglia,
M Bougeard,
B Carré,
F Ciocci,
E Chiadroni,
A Cianchi, M E Couprie,
L Cultrera,
M Del Franco, [......],
L Poletto,
M Quattromini,
J V Rau,
C Ronsivalle,
E Sabia,
M Serluca,
I Spassovsky,
V Surrenti,
C Vaccarezza,
C Vicario
[show abstract]
[hide abstract]
ABSTRACT: The injection of a seed in a free-electron laser (FEL) amplifier reduces the saturation length and improves the longitudinal coherence. A cascaded FEL, operating in the high-gain harmonic-generation regime, allows us to extend the beneficial effects of the seed to shorter wavelengths. We report on the first operation of a high-gain harmonic-generation free-electron laser, seeded with harmonics generated in gas. The third harmonics of a Ti:sapphire laser, generated in a gas cell, has been amplified and up-converted to its second harmonic (λ(rad)=133 nm) in a FEL cascaded configuration based on a variable number of modulators and radiators. We studied the transition between coherent harmonic generation and superradiant regime, optimizing the laser performances with respect to the number of modulators and radiators.
Physical Review Letters 11/2011; 107(22):224801. · 7.37 Impact Factor
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L Giannessi,
D Alesini,
P Antici,
A Bacci,
M Bellaveglia,
R Boni,
M Boscolo,
F Briquez,
M Castellano,
L Catani, [......],
L Serafini,
M Serluca,
I Spassovsky,
B Spataro,
V Surrenti,
C Vaccarezza,
M Vescovi,
C Vicario,
Sincrotrone Trieste,
Area Science
[show abstract]
[hide abstract]
ABSTRACT: SPARC (acronym of ''Sorgente Pulsata ed Amplificata di Radiazione Coerente'', i.e. Pulsed and Amplified Source of Coherent Radiation) is a single pass free-electron laser designed to obtain high gain amplification at a radiation wavelength of 500 nm. Self-amplified spontaneous emission has been observed driving the amplifier with the high-brightness beam of the SPARC linac. We report measure-ments of energy, spectra, and exponential gain. Experimental results are compared with simulations from several numerical codes.
Physical Review Special Topics - Accelerators and Beams 06/2011; 14:060712. · 1.52 Impact Factor
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R Bachelard,
P Mercère,
M Idir, M-E Couprie,
M Labat,
O Chubar,
G Lambert,
Ph Zeitoun,
H Kimura,
H Ohashi,
A Higashiya,
M Yabashi,
M Nagasono,
T Hara,
T Ishikawa
[show abstract]
[hide abstract]
ABSTRACT: The single-shot spatial characteristics of the vacuum ultraviolet self-amplified spontaneous emission of a free electron laser (FEL) is measured at different stages of amplification up to saturation with a Hartmann wavefront sensor. We show that the fundamental radiation at 61.5 nm tends towards a single-mode behavior as getting closer to saturation. The measurements are found in good agreement with simulations and theory. A near diffraction limited wavefront was measured. The analysis of Fresnel diffraction through the Hartmann wavefront sensor hole array also provides some further insight for the evaluation of the FEL transverse coherence, of high importance for various applications.
Physical Review Letters 06/2011; 106(23):234801. · 7.37 Impact Factor
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T. Togashi,
E.J. Takahashi,
K. Midorikawa,
M. Aoyama,
K. Yamakawa,
T. Sato,
A. Iwasaki,
S. Owada,
T. Okino,
K. Yamanouchi, [......],
T. Ohshima,
Y. Otake,
T. Shintake,
H. Tanaka,
T. Tanaka,
K. Togawa,
H. Tomizawa,
T. Watanabe,
M. Yabashi,
T. Ishikawa
[show abstract]
[hide abstract]
ABSTRACT: We first generated seeded FEL radiation in the EUV region at 6L2 nm with the 13th harmonic of a Ti:sapphire laser. We observed single-peak spectra with drastic enhancements of intensity by nearly three-orders of magnitude.
Lasers and Electro-Optics (CLEO), 2011 Conference on; 06/2011
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[show abstract]
[hide abstract]
ABSTRACT: Seeding a Free-Electron Laser (FEL) drastically improves the temporal coherence of the self-amplified spontaneous emission and reduces the saturation length, even with very low-intensity seed. We report here on the achievement of single-shot nonlinear harmonics from the 2nd to the 7th order at 23 nm, on the FEL of the SCSS Test Accelerator operated at 150 MeV and seeded at 160 nm with harmonics generated in gas. In particular, a clear intensity enhancement leading to saturation effect observations and temporal coherence improvement for both odd and even harmonics are highlighted due to the seeding. Single-shot measurements both in spatial (vertical) and spectral domains are compared to analytical theory and numerical simulations.
EPL (Europhysics Letters) 04/2011; 94(3):34001. · 2.17 Impact Factor
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L Giannessi,
A Bacci,
M Bellaveglia,
F Briquez,
M Castellano,
E Chiadroni,
A Cianchi,
F Ciocci, M E Couprie,
L Cultrera, [......],
A R Rossi,
V Rossi Albertini,
E Sabia,
M Serluca,
S Spampinati,
I Spassovsky,
B Spataro,
V Surrenti,
C Vaccarezza,
C Vicario
[show abstract]
[hide abstract]
ABSTRACT: We report the first experimental implementation of a method based on simultaneous use of an energy chirp in the electron beam and a tapered undulator, for the generation of ultrashort pulses in a self-amplified spontaneous emission mode free-electron laser (SASE FEL). The experiment, performed at the SPARC FEL test facility, demonstrates the possibility of compensating the nominally detrimental effect of the chirp by a proper taper of the undulator gaps. An increase of more than 1 order of magnitude in the pulse energy is observed in comparison to the untapered case, accompanied by FEL spectra where the typical SASE spiking is suppressed.
Physical Review Letters 04/2011; 106(14):144801. · 7.37 Impact Factor
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L Giannessi,
A Bacci,
M Bellaveglia,
F Briquez,
M Castellano,
E Chiadroni,
A Cianchi,
F Ciocci, M E Couprie,
L Cultrera, [......],
I Spassovsky,
B Spataro,
V Surrenti,
C Vaccarezza,
C Vicario,
La Roma,
P Sapienza,
Aldo Le,
Moro,
Area Science
[show abstract]
[hide abstract]
ABSTRACT: We report the first experimental implementation of a method based on simultaneous use of an energy chirp in the electron beam and a tapered undulator, for the generation of ultrashort pulses in a self-amplified spontaneous emission mode free-electron laser (SASE FEL). The experiment, performed at the SPARC FEL test facility, demonstrates the possibility of compensating the nominally detrimental effect of the chirp by a proper taper of the undulator gaps. An increase of more than 1 order of magnitude in the pulse energy is observed in comparison to the untapered case, accompanied by FEL spectra where the typical SASE spiking is suppressed.
Physical Review Letters 01/2011; · 7.37 Impact Factor
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L. Giannessi,
A. Petralia,
G. Dattoli,
F. Ciocci,
M. Del Franco,
M. Quattromini,
C. Ronsivalle,
E. Sabia,
I. Spassovsky,
V. Surrenti, [......],
J. Rosenzweig,
S. Spampinati,
M. Labat,
F. Briquez, M. E. Couprie,
B. Carré,
M. Bougeard,
D. Garzella,
G. Lambert,
C.Vicario
[show abstract]
[hide abstract]
ABSTRACT: We report on the recent activity at the SPARC FEL
where both SASE and seeded FEL dynamics are studied.
The SPARC FEL has been operated in full saturation in
SASE mode, by combining the velocity bunching
compression technique to increase the peak current, with
the idea proposed in [1] and consisting in a taper of the
undulator field to compensate the chirp in the longitudinal
phase space.
In seeded mode the FEL has been operated both as a
single amplifier and as a single stage cascade doubling the
frequency of the input seed at 400nm. We report on the
main results obtained in both the configurations.
32nd International Free Electron Laser Conference, Malmö, Sweden; 08/2010
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Infrared Millimeter and Terahertz Waves (IRMMW-THz), 2010 35th International Conference on; 01/2010
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L Giannessi,
A Petralia,
G Dattoli,
F Ciocci,
M Del Franco,
M Quattromini,
C Ronsivalle,
E Sabia,
I Spassovsky,
V Surrenti, [......],
M Labat,
F Briquez, M E Couprie,
Fr B Carré,
M Bougeard,
D Garzella,
Cea Saclay,
Dsm / Drecam,
Lambert Loa,
Fr C Vicario
[show abstract]
[hide abstract]
ABSTRACT: The SPARC FEL has been configured to test different cascaded FEL configurations with a seed generated in gas. In the framework of the DS4 EUROFEL collaboration, a research work plan at the SPARC FEL test facility aiming at the investigation of seeded and cascaded FEL configurations was implemented [1]. The main goal of the collaboration was to study the amplification and the harmonic generation process of an input seed signal, obtained as higher order harmonics generated in gases [2,3]. We describe here the first experimental results, which were recently obtained.
Free Electron Laser, Malmo, Sweden; 01/2010
