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Title |
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| MOPPH028 |
Future Seeding Experiments at SPARC
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95 |
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- L. Giannessi, S. Ambrogio, F. Ciocci, G. Dattoli, A. Doria, G. P. Gallerano, E. Giovenale, M. Quattromini, A. Renieri, C. Ronsivalle, I. P. Spassovsky
ENEA C. R. Frascati, Frascati (Roma)
- D. Alesini, M. E. 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
INFN/LNF, Frascati (Roma)
- M. Bougeard, B. Carré, D. Garzella, M. Labat, G. Lambert, H. Merdji, P. Salieres, O. Tcherbakoff
CEA, Gif-sur-Yvette
- M.-E. Couprie
SOLEIL, Gif-sur-Yvette
- A. Dipace, E. Sabia
ENEA Portici, Portici (Napoli)
- M. Mattioli
Università di Roma I La Sapienza, Roma
- P. Musumeci, M. Petrarca
INFN-Roma, Roma
- M. Nisoli, G. Sansone, S. Stagira, S. de Silvestri
Politecnico/Milano, Milano
- P. L. Ottaviani, S. Pagnutti, M. Rosetti
ENEA-Bologna, Bologna
- L. P. Poletto, G. T. Tondello
Univ. degli Studi di Padova, Padova
- L. Serafini
INFN-Milano, Milano
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Sources based on high order harmonics generated in gas with high power Ti:Sa lasers pulses represent promising candidates as seed for FEL amplifiers for several reasons, as spatial and temporal coherence, wavelength tunability and spectral range, which extends down to the 10-9m wavelength scale. This communication is devoted to the description of a research work plan that is under implementation at the SPARC FEL facility in the framework of the 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 crystal (400nm and 266 nm) and in gas (266nm, 160nm, 114nm) from a high intensity Ti:Sa laser pulse.
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| MOPPH030 |
X-Rays Generation with a FEL Based on an Optical Wiggler
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99 |
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- A. Bacci, C. Maroli, L. Serafini
INFN-Milano, Milano
- M. Ferrario
INFN/LNF, Frascati (Roma)
- V. Petrillo
Universita' degli Studi di Milano, Milano
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The interaction between high-brilliance electron beams and counter-propagating laser pulses produces X rays via Thomson back-scattering. If the laser source is long and intense enough, the electron beam can bunch on the scale of the X-ray wavelength and a regime of collective effects can establish. In this case the FEL instability can develop and the system behaves like a FEL based on an optical undulator. Coherent X-rays can be irradiated, with a bandwidth thinner than that of the corresponding incoherent emission. The emittance of the electron beam and the non-uniformity of the laser energy limit the growth of the X-ray signal. We analyse with a 3-D code the transverse effects in the emission. The scalings typical of the optical wiggler make possible considerable emission also in violation of the Pellegrini criterion for static wigglers. A generalized form of this criterion is validated on the basis of the numerical evidence. An optimization of the radiation intensity has been done shifting the focus of the beam. The dependence of the radiation on the stability of the laser pulse has been studied.
INFN, Section of MIlan, Via Celoria,16 20133 Milano (Italy)
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| THAAU06 |
Parametric Optimization of a X-Ray FEL Based on a Thomson Source
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517 |
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- L. Serafini, A. Bacci, C. Maroli, V. Petrillo, A. R. Rossi
INFN-Milano, Milano
- M. Ferrario
INFN/LNF, Frascati (Roma)
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We present a study based on a parametric optimization for a Thomson Source operated in FEL mode. This deals with the proposed scheme to use a high energy laser pulse colliding with a high brightness electron beam of low to medium energy electrons undulating in the incoming laser field may emit in a FEL coherent mode as far as some conditions are satisfied. A set of simple analytical formulas taking into account 3D effects is derived to express these conditions in terms of three free parameters, namely the wavelength of the laser, the amplitude of the ripples in the laser field, and the peak current of the eletron beam. A few examples of possible operating points are compared with results of 3D numerical simulations, showing the FEL coherent emission of X-rays in the 0.1 to 5 nm range with tens of MeV high brightness electron beams coliding with high energy laser pulses.
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Talk
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| THPPH070 |
Optimum Beam Creation In Photoinjectors Using Space-Charge Expansion
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752 |
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- M. P. Dunning, A. M. Cook, R. J. England, J. B. Rosenzweig
UCLA, Los Angeles, California
- M. Bellaveglia, M. Boscolo, L. Catani, A. Cianchi, G. Di Pirro, M. Ferrario, D. Filippetto, G. Gatti, L. Palumbo, C. Vicario
INFN/LNF, Frascati (Roma)
- S. M. Jones
Jet Propulsion Laboratory, Pasadena, California
- P. Musumeci
INFN-Roma, Roma
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It has recently been shown that by illuminating a photocathode with an ultra-short laser pulse of appropriate transverse profile, a uniform density, ellipsoidally shaped bunch is dynamically formed, which then has linear space-charge fields in all dimensions inside of the bunch. We study here this process, and its marriage to the standard emittance compensation scenario that is implemented in most modern photoinjectors. It is seen that the two processes are compatible, with simulations indicating that a very high brightness beam can be obtained. The scheme has produced stimulus for a series of experiments at the SPARC injector at Frascati in 2006-2007. An initial time-resolved experiment has been performed involving Cerenkov radiation produced at an aerogel. We discuss the results of this preliminary experiment, as well as plans for future experiments to resolve the ellipsoidal bunch shape at low energy. Future measurements at high energy based on fs resolution RF sweepers are discussed, and prospects for using the very low longitudinal emittance beam in a future bunch compressor to produce 10 micron long beams are evaluated.
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| THPPH031 |
Commissioning of the SPARC Photo-Injector
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637 |
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- M. Bellaveglia, D. Alesini, S. Bertolucci, M. E. Biagini, R. Boni, M. Boscolo, M. Castellano, A. Clozza, L. Cultrera, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, L. Ficcadenti, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, A. Ghigo, S. Guiducci, M. Incurvati, C. Ligi, M. Migliorati, A. Mostacci, L. Palumbo, L. Pellegrino, M. A. Preger, R. Ricci, C. Sanelli, F. Sgamma, B. Spataro, F. Tazzioli, C. Vaccarezza, M. Vescovi, C. Vicario
INFN/LNF, Frascati (Roma)
- A. Bacci, I. Boscolo, F. Broggi, S. Cialdi, D. Giove, M. Mauri, A. R. Rossi, L. Serafini
INFN-Milano, Milano
- L. Catani, E. Chiadroni, A. Cianchi, S. Tazzari
INFN-Roma II, Roma
- L. Giannessi, M. Quattromini, A. Renieri, C. Ronsivalle
ENEA C. R. Frascati, Frascati (Roma)
- M. Mattioli, P. Musumeci, M. Petrarca
INFN-Roma, Roma
- A. Perrone
INFN-Lecce, Lecce
- J. B. Rosenzweig
UCLA, Los Angeles, California
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The SPARC project is born to perform R&D activity headed to realize SASE-FEL experiments at 500nm and higher harmonic generation. The project foresees the realization of a high brightness photo-injector able to produce a 150-200MeV electron beam to drive FEL process inside a dedicated 14m long undulator. The machine is going to be assembled at LNF and its final configuration is made up of an RF gun, driven by a Ti:Sa laser, injecting into three SLAC type accelerating sections. Nowadays we are working in a photo-injector test phase, aiming to characterize the main hardware components and to investigate the behavior of the e-beam dynamics in the first meters of drift. To do this we utilize the emittance-meter, a home designed diagnostic device placed just after the RF gun, able to move 1.2 meters along the longitudinal axis to measure beam parameters. In this paper we report a more accurate description of the project, the status of the single systems constituting the machine and the most important results we obtained in the e-meter phase.
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| THCAU03 |
Operational Experience with the Emittance-Meter at SPARC
|
777 |
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- L. Catani, E. Chiadroni, A. Cianchi
INFN-Roma II, Roma
- M. Bellaveglia, R. Boni, M. Boscolo, M. Castellano, L. Cultrera, G. Di Pirro, A. Drago, M. Ferrario, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, F. Tazzioli, C. Vaccarezza, M. Vescovi, C. Vicario
INFN/LNF, Frascati (Roma)
- M. Migliorati, L. Palumbo
Rome University La Sapienza, Roma
- P. Musumeci, M. Petrarca
INFN-Roma, Roma
- C. Ronsivalle
ENEA C. R. Frascati, Frascati (Roma)
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We report the operational experience of the movable emittance meter at SPARC. This device is based on the well-known technique of pepper pot (1-D slits in our case) but it allows moving the measuring device along the beam line from about 840 mm to 2200 mm from the cathode, following the emittance oscillations. More than a simple improvement over conventional, though non-trivial, beam diagnostic tools this device defines a new strategy for the characterization of high performance photoinjectors, providing a tool for detailed analysis of the beam dynamics, over a section of the accelerator where emittance compensation take place. With this device we performed detailed and systematic studies on beam dynamics with particular attention to the transverse parameters as well as longitudinal. We report also the operating experience at the PITZ facility.
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