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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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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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D Filippetto,
M Bellaveglia,
M Castellano,
E Chiadroni,
L Cultrera,
G Di Pirro,
M Ferrario,
L Ficcadenti,
A Gallo,
G Gatti, [......],
B Marchetti,
L Giannessi,
M Labat,
M Quattromini,
C Ronsivalle,
C Marrelli,
M Migliorati,
A Mostacci,
L Palumbo, M Serluca
[show abstract]
[hide abstract]
ABSTRACT: Peak current represents a key demand for new generation electron beam photoinjectors. Many beam applications, such as free electron laser, inverse Compton scattering, terahertz radiation generation, have efficiencies strongly dependent on the bunch length and current. A method of beam longitudinal compression (called velocity bunching) has been proposed some years ago, based on beam longitudinal phase space rotation in a rf field potential. The control of such rotation can lead to a compression factor in excess of 10, depending on the initial longitudinal emittance. Code simulations have shown the possibility to fully compensate the transverse emittance growth during rf compression, and this regime has been experimentally proven recently at SPARC. The key point is the control of transverse beam plasma oscillations, in order to freeze the emittance at its lowest value at the end of compression. Longitudinal and transverse phase space distortions have been observed during the experiments, leading to asymmetric current profiles and higher final projected emittances. In this paper we discuss in detail the results obtained at SPARC in the regime of velocity bunching, analyzing such nonlinearities and identifying the causes. The beam degradation is discussed, both for slice and projected parameters. Analytical tools are derived to experimentally quantify the effect of such distortions on the projected emittance.
Physical Review Special Topics - Accelerators and Beams 09/2011; 14:92804. · 1.52 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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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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A Bacci,
D Alesini,
M Bellaveglia,
M Castellano,
E Chiadroni,
A Cianchi,
M Del Franco,
G Di Pirro,
A Drago,
M Ferrario, [......],
L Palumbo,
A Petralia,
V Petrillo,
M Quattromini,
C Ronsivalle,
A R Rossi,
L Serafini, M Serluca,
V Surrenti,
C Vaccarezza
[show abstract]
[hide abstract]
ABSTRACT: The successful operation of the SPARC injector in the Velocity Bunching (VB) mode has opened new perspectives to conduct advanced beam dynamics experiments with ultra-short electron pulses able to extend the THz spectrum or to drive the FEL in the SASE Single Spike mode. Moreover a new technique called Laser Comb, able to generate a train of short pulses with high repetition rate, has been recently tested in the VB configuration. Up to four electron beam pulses shorter than 300 fs and separated by less than 1 ps have been characterized. In addition two electron beam pulses have been injected in the undulator and a characteristic interference spectrum produced by the FEL interaction in this new configuration has been observed, confirming that both pulses have been correctly matched to the undulator and were both lasing. In this paper we report the experimental results obtained so far.
Free Electron Laser, Shanghai, China; 01/2011
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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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[show abstract]
[hide abstract]
ABSTRACT: a b s t r a c t An analysis of the single-spike FEL radiation in the visible range starting from noise is presented, taking into account realistic characteristics of the electron beam such as emittance and energy spread. A parametric study of the power emitted respect to emittance and energy spread is carried out and the influence of these quantity on the production of a single-spike radiation pulse is shown. Furthermore, we propose some examples of start-to-end simulations in the specific case of the SPARC apparatus from the photocathode to the end of the undulator, describing a possible experiment aimed at generating sub-picosecond light pulses and exploring the single-spike regime.
Nuclear Instruments and Methods 05/2010;
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M Ferrario,
D Alesini,
A Bacci,
M Bellaveglia,
R Boni,
M Boscolo,
M Castellano,
E Chiadroni,
A Cianchi,
L Cultrera, [......],
L Palumbo,
M Quattromini,
C Ronsivalle,
A R Rossi,
J Rosenzweig,
L Serafini, M Serluca,
B Spataro,
C Vaccarezza,
C Vicario
[show abstract]
[hide abstract]
ABSTRACT: In this Letter we report the first experiments aimed at the simultaneous demonstration of the emittance compensation process and velocity bunching in a high brightness electron source, the SPARC photoinjector in INFN-LNF. While a maximum compression ratio up to a factor 14 has been observed, in a particular case of interest a compression factor of 3, yielding a slice current of 120 A with less than 2 microm slice emittance, has been measured. This technique may be crucial in achieving high brightness beams in photoinjectors aiming at optimized performance of short wavelength single-pass free electron lasers or other advanced applications in laser-plasma accelerators.
Physical Review Letters 02/2010; 104(5):054801. · 7.37 Impact Factor
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M Ferrario,
D Alesini,
F Anelli,
M Bellaveglia,
M Boscolo,
L Cacciotti,
M Castellano,
E Chiadroni,
L Cultrera,
G Di Pirro, [......],
A R Rossi,
L Serafini,
O Limaj,
M Moreno, M Serluca,
A Cianchi,
B Marchetti,
C Vicario,
J Rosenzweig,
H Tomizawa
[show abstract]
[hide abstract]
ABSTRACT: The recent successful operation of the SPARC injector in the Velocity Bunching (VB) mode has opened new perspectives to conduct advanced beam dynamics experiments with ultra-short electron pulses able to extend the THz spectrum and to drive the FEL in the SASE Single Spike mode. In addition a new technique called Laser Comb, able to generate a train of short pulses with high repetition rate, has been recently tested in the VB configuration. In this paper we report the experimental results obtained so far.
IPAC, Kyoto, Japan; 01/2010
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V Petrillo,
Università Di Milano,
Italy A Bacci,
L Serafini,
Italy M Boscolo,
M Ferrario,
C Vaccarezza,
Italy G Dattoli,
L Giannessi,
M Labat,
C Ronsivalle,
Italy S Pagnutti,
P Ottaviani,
Enea Bologna,
Italy L Palumbo, M Serluca
[show abstract]
[hide abstract]
ABSTRACT: We describe a possible experiment aimed at generating sub-picosecond high brightness electron bunches with the SPARC photoinjector, which produce optical single spike radiation pulses in the regime of self-amplified spontaneous emission. The main purpose of the experiment is the production of short electron bunches as long as few SASE cooperation lengths by means of the Velocity Bunching technique. The measure of the properties of the electron beam, the determination of shape and spectrum of the radiation pulse and the validation of the single spike scaling laws will be analysed in order to foresee future operations at shorter wavelength with SPARX. We present in this paper start-to-end simulations of the beam production and FEL performance, statistical analysis and behaviour on the harmonics. The experience gained from this experiment will help in the configuration of the VUV and X-ray FEL SPARX to obtain FEL pulses below 10 fs.
2009 FEL conference, www.jacow.org; 08/2009
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M Ferrario,
D Alesini,
M Bellaveglia,
M Benfatto,
R Boni,
M Boscolo,
M Castellano,
E Chiadroni,
A Clozza,
L Cultrera, [......],
B Carré,
D Garzella,
M Labat,
G Lambert,
H Merdji,
P Salières,
O Tchebakoff,
Cea Saclay,
Dsm / Drecam,
France M Rezvani Jalal
[show abstract]
[hide abstract]
ABSTRACT: The SPARC project foresees the realization of a free electron laser operating at 500 nm driven by a high brightness photo-injector at a beam energy of 150-200 MeV. The SPARC photoinjector is also the test and training facility for the recently approved VUV/soft X-ray FEL project named SPARX [1]. The second stage of the commissioning, that is currently underway, foresees a detailed analysis of the beam matching with the linac in order to confirm the theoretically prediction of emittance compensation based on the "invariant envelope" matching, the demonstration of the "velocity bunching" technique in the linac and the characterisation of the spontaneous and stimulated radiation in the SPARC undulators. In this paper we report the experimental results obtained so far.
Particle Accelerator Conference, Vancouver, Canada; 01/2009
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I Boscolo,
F Castelli,
S Cialdi,
V Petrillo,
Università Di Milano,
Milano A Bacci,
L Serafini,
Milano Italy,
R Bonifacio,
M Boscolo, [......],
L Giannessi,
C Ronsivalle,
Enea Frascati,
Italy,
L Palumbo, M Serluca,
Università La,
Sapienza Roma,
J S Rosenzweig,
Reiche
[show abstract]
[hide abstract]
ABSTRACT: The single spike operation regime has been analysed in the case of the SPARC injector and free-electron-laser. Four different beams at 50 pC are studied, with different production condition and performance.
EPAC08; 01/2008
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M Ferrario,
D Alesini,
M Bellaveglia,
R Boni,
M Boscolo,
M Castellano,
E Chiadroni,
A Clozza,
L Cultrera,
G Di Pirro, [......],
Usa M E Couprie,
France M Bougeard,
B Carré,
D Garzella,
M Labat,
G Lambert,
H Merdji,
P Salières,
O Tchebakoff,
A R Rossi
[show abstract]
[hide abstract]
ABSTRACT: The SPARC project foresees the realization of a high brightness photo-injector to produce a 150-200 MeV electron beam to drive 500 nm FEL experiments in various configurations, a Thomson backscattering source and a plasma accelerator experiment (these last two ones jointly with the project PLASMONX). The SPARC photoinjector is also the test facility for the recently approved VUV FEL project named SPARX. As a first stage of the commissioning, a complete characterization of the photoinjector has been accomplished with a detailed study of the emittance compensation process downstream the gun-solenoid system: this lead to the first direct experimental demonstration of emittance oscillations in a drift. The second stage of the commissioning, that is currently underway, foresees a detailed analysis of the beam matching with the linac in order to confirm the theoretically prediction of emittance compensation based on the "invariant envelope" matching and the demonstration of the "velocity bunching" technique in the linac. SASE and SEEDING experiments are foreseen by the end of the current year. In this paper we report the experimental results obtained so far and the scientific program for the near future.
EPAC, Genova, Italy; 01/2007
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M. Ferrario,
D. Alesini,
A. Bacci,
M. Bellaveglia,
R. Boni,
M. Boscolo,
P. Calvani,
M. Castellano,
E. Chiadroni,
A. Cianchi, [......],
M. Quattromini,
C. Ronsivalle,
A.R. Rossi,
J. Rosenzweig,
L. Serafini, M. Serluca,
B. Spataro,
H. Tomizawa,
C. Vaccarezza,
C. Vicario
[show abstract]
[hide abstract]
ABSTRACT: A new technique, named “laser comb”, was tested during the last SPARC run. It is able to produce electron pulse trains with a charge of some hundreds pC, a repetition rate of some terahertz, and a sub-picosecond length. This technique is based on the velocity bunching configuration of the SPARC injector. It can be useful to drive pump and probe free-electron laser experiments, to generate coherent excitation of plasma waves in plasma accelerators, and to produce narrow band terahertz radiation. In this paper, we describe the experimental results achieved so far and provide a comparison with simulations.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 637(1). · 1.21 Impact Factor
