| Paper |
Title |
Page |
| MOPCH025 |
Laser Comb: Simulations of Pre-modulated E- Beams at the Photocathode of a High Brightness RF Photoinjector
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98 |
| |
- M. Boscolo, M. Ferrario, C. Vaccarezza
INFN/LNF, Frascati (Roma)
- I. Boscolo, F. Castelli, S. Cialdi
INFN-Milano, Milano
- P. Musumeci
INFN-Roma, Roma
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A density modulated beam at the photocathode though the proper modulation of the laser beam pulse does not change substantially emittance and energy spread, properties directly related to FEL. It has been found that bunch density modulation is transformed into energy modulation along the propagation through the injector*. There are some physical arguments that suggest a possibility to use this modulation for the enhancement of the FEL process, or for the production of plasma wakes. Preliminary beam dynamics studies have been carried on to explore the use of electron beam pre-modulation at the cathode to adjust their longitudinal structure at the end of the beamline. Energy modulation at the end of the beamline could eventually be turned into current modulation through a magnetic compressor with R56<0. The feasibility of this experiment has to be investigated carefully, preliminary studies are discussed here. This paper focuses on simulations that explore the properties of the energy modulation at the end of the beamline correlated to the initial characteristics of the train of electron pulses.
*M. Biagini et al. “Beam Dynamics Studies for the SPARC Project”, Proc. of PAC03.
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| MOPCH030 |
Production of Coherent X-rays with a Free Electron Laser Based on an Optical Wiggler
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113 |
| |
- V. Petrillo, A. Colzato
Universita' degli Studi di Milano, Milano
- A. Bacci, C. Maroli, L. Serafini
INFN-Milano, Milano
- M. Ferrario
INFN/LNF, Frascati (Roma)
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The interaction between high-brightness electron beams and counter-propagating laser pulses produces X rays via Thomson scattering. If the laser source is long enough, the electrons bunch on the scale of the emitted X-ray wavelength and a regime of collective effects establishes. In this case, the FEL instability develops and the system behaves like a FEL based on an optical undulator. Coherent X-rays are irradiated, with a bandwidth thinner than that of the incoherent emission. The emittance of the beam and gradients or irregularities in the laser energy distribution are the principal factors that limit the growth of the X-ray signal. We analyse with a 3-D code the transverse effects in the emission produced by a relativistic electron beam when it is under the action of an optical laser pulse and the X-ray spectra obtained. The scalings typical of the optical wiggler, with very short gain lengths and overall time durations of the process 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.
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| MOPCH024 |
Future Seeding Experiments at SPARC
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95 |
| |
- 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, P. Musumeci, M. Petrarca
Università di Roma I La Sapienza, Roma
- M. Nisoli, G. Sansone, S. Stagira, S. de Silvestri
Politecnico/Milano, Milano
- 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 gases (HHG) 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 nm wavelength scale. This communication describes the 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 crystals (400 nm and 266 nm) and in gases (266 nm, 160 nm, 114 nm). The SPARC FEL can be configured to test several cascaded FEL layouts that will be analysed in this contribution.
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| MOPCH028 |
Status of the SPARX FEL Project
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107 |
| |
- C. Vaccarezza, D. Alesini, M. Bellaveglia, S. Bertolucci, M.E. 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.A. Preger, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stella, F. Tazzioli, M. Vescovi, C. Vicario
INFN/LNF, Frascati (Roma)
- F. Alessandria, A. Bacci, F. Broggi, C. De Martinis, D. Giove, M. Mauri
INFN/LASA, Segrate (MI)
- L. Catani, E. Chiadroni, A. Cianchi, C. Schaerf
INFN-Roma II, Roma
- S. Cialdi, C. Maroli, V. Petrillo, M. Rome, L. Serafini
INFN-Milano, Milano
- F. Ciocci, G. Dattoli, A. Doria, F. Flora, G.P. Gallerano, L. Giannessi, E. Giovenale, G. Messina, P.L. Ottaviani, G. Parisi, L. Picardi, M. Quattromini, A. Renieri, C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma)
- P. Emma
SLAC, Menlo Park, California
- L. Ficcadenti, A. Mostacci
Rome University La Sapienza, Roma
- M. Mattioli
Università di Roma I La Sapienza, Roma
- P. Musumeci
INFN-Roma, Roma
- S. Reiche, J.B. Rosenzweig
UCLA, Los Angeles, California
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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 INFN-LNF 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.
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| MOPCH029 |
Status of the SPARC Project
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110 |
| |
- P. Musumeci, D. Levi, M. Mattioli, G. Medici, D. Pelliccia, M. Petrarca
Università di Roma I La Sapienza, Roma
- D. Alesini, M. Bellaveglia, S. Bertolucci, 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, M. Incurvati, C. Ligi, F. Marcellini, M. Migliorati, A. Mostacci, L. Palumbo, L. Pellegrino, M.A. Preger, R. Ricci, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, F. Tazzioli, C. Vaccarezza, M. Vescovi, C. Vicario
INFN/LNF, Frascati (Roma)
- F. Alessandria, A. Bacci, I. Boscolo, F. Broggi, S. Cialdi, C. De Martinis, D. Giove, C. Maroli, M. Mauri, V. Petrillo, M. Rome, A.R. Rossi, L. Serafini
INFN-Milano, Milano
- L. Catani, E. Chiadroni, A. Cianchi, E. Gabrielli, S. Tazzari
INFN-Roma II, Roma
- F. Ciocci, G. Dattoli, A. Dipace, A. Doria, G.P. Gallerano, L. Giannessi, E. Giovenale, G. Messina, P.L. Ottaviani, S. Pagnutti, L. Picardi, M. Quattromini, A. Renieri, G. Ronci, C. Ronsivalle, M. Rosetti, E. Sabia, M. Sassi, A. Torre, A. Zucchini
ENEA C.R. Frascati, Frascati (Roma)
- A. Perrone
INFN-Lecce, Lecce
- S. Reiche, J.B. Rosenzweig, G. Travish
UCLA, Los Angeles, California
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The SPARC Project is starting the commissioning of its photo-injector. RF gun, RF sources, RF network and control, power supplies, emittance meter, beam diagnostics and control to measure the RF gun beam are installed. The photocathode drive laser has been characterized in terms of pulse shape and quality. We expect to conduct beam measurements at RF gun exit in the next future and consequently to start the installation of accelerating sections. The design of the 12 m undulator for the FEL experiment has been completed and the first undulator section out of 6 is under construction: we expect to characterize it at Frascati ENEA laboratory within the next months. SPARC as a facility will host FEL experiments using SASE, seeding and non-linear resonant harmonics. Additional R&D on X-band and S-band structures for velocity bunching are in progress, as well as studies on new photocathode materials and exotic undulator designs. We also present studies on solenoid field defects, beam based alignments, exotic electron bunch production (blow-out of short laser pulses or intensity modulated laser pulses). The possible use of segmented superconducting micro-undulators will be discussed too.
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| WEPCH022 |
Study of the Effect of Multipolar Components in the SPARC Emittance Compensation Gun Solenoid
|
1969 |
| |
- C. Ronsivalle, G. Dattoli, L. Picardi, M. Quattromini
ENEA C.R. Frascati, Frascati (Roma)
- G. Bazzano
CNAO Foundation, Milan
- M. Ferrario, M. Migliorati, L. Palumbo, M.A. Preger, C. Sanelli
INFN/LNF, Frascati (Roma)
- P. Musumeci
INFN-Roma, Roma
- J.B. Rosenzweig
UCLA, Los Angeles, California
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The SPARC photoinjector rf gun requires a solenoid immediately downstream for emittance compensation. The analysis of the measured solenoid magnetic maps shows the existence of multipolar components added to the pure solenoid field. The effect of these added fields on beam dynamics and possible correction schemes have been studied from the theoretical point of view and by numerical calculations based on PARMELA/TREDI codes. An accurate 3D numerical modelization by using CST EM Studio has been done, in order to investigate the source of these multipolar components and to suggest some design modifications aimed to reduce their magnitude. The results of this study are presented here.
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| WEPCH127 |
Analysis of Radiative Effects in the Electron Emission from the Photocathode and in the Acceleration inside the RF Cavity of a Photoinjector using the 3D Numerical Code RETAR
|
2221 |
| |
- V. Petrillo, C. Maroli
Universita' degli Studi di Milano, Milano
- G. Alberti
Università degli Studi di Milano, Milano
- A. Bacci, A.R. Rossi, L. Serafini
INFN-Milano, Milano
- M. Ferrario
INFN/LNF, Frascati (Roma)
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The three-dimensional fully relativistic and self-consistent code RETAR has been developed to model the dynamics of high-brightness electron beams and in particular to assess the importance of the retarded radiative part of the emitted electromagnetic fields in all conditions where the electrons experience strong accelerations. In this analysis we evaluate the radiative energy losses in the electron emission process from the photocathode of an injector, during the successive acceleration of the electron beam in the RF cavity and the focalization due to the magnetic field of the solenoid, taking also into account the e.m. field of the laser illuminating the cathode. The analysis is specifically carried out with parameters of importance in the framework of the SPARC and PLASMONX projects.
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| WEPLS049 |
The Design of a Hybrid Photoinjector for High Brightness Beam Applications
|
2487 |
| |
- D. Alesini, M. Ferrario, V. Fusco, B. Spataro
INFN/LNF, Frascati (Roma)
- L. Ficcadenti, A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma
- B. O'Shea, J.B. Rosenzweig, G. Travish
UCLA, Los Angeles, California
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In this paper, we illustrate the electromagnetic and beam dynamics design procedure of a new class of photoinjector, a hybrid standing/traveling wave structure. In this device a standing wave RF gun section is integrated with a downstream traveling wave structure through a coupling cell that feeds simultaneously the two sections. We discuss the advantages in RF and beam performance of the hybrid photoinjector compared to conventional systems. The electromagnetic design has been performed using the 2D and 3D electromagnetic codes Superfish and HFSS. Results of beam dynamics simulations in different operating conditions are also discussed.
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| THYPA01 |
Overview of FEL Injectors
|
2733 |
| |
- M. Ferrario
INFN/LNF, Frascati (Roma)
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Future light sources based on high gain free electron lasers, require the production, acceleration and transport up to the undulator entrance of high brightness (low emittance, high peak current) electron bunches. Wake fields effects in accelerating sections and in magnetic bunch compressors typically contribute to emittance degradation, hence the photo-injector design and its operation is the leading edge for high quality beam production and for the success of the future light sources. RF guns, photo-cathode materials, laser pulse shaping and synchronization systems are evolving towards a mature technology to produce high quality and stable beams. Nevertheless reduction of thermal emittance, damping of emittance oscillations and bunch compression are still the main issues and challenges for injector designs. With the advent of Energy Recovery Linacs, superconducting RF guns have been also considered in many new projects as a possible electron source operating in CW mode. An overview of recent advancements and future perspectives in FEL injectors will be illustrated in this talk, including a comparison of merits and issues of RF compression versus magnetic compression techniques.
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Transparencies
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| THPCH010 |
Electron Beam-laser Interaction near the Cathode in a High Brightness Photoinjector
|
2805 |
| |
- M. Ferrario, G. Gatti
INFN/LNF, Frascati (Roma)
- J.B. Rosenzweig
UCLA, Los Angeles, California
- L. Serafini
INFN-Milano, Milano
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The production of high charge short bunches in a high brightness photoinjector requires laser pulses driving the cathode with GW range peak power on a mm spot size. The resulting transverse electric field experienced by the electron beam near the cathode is of the order of 200-500 MV/m, well in excess of a typical RF accelerating field of 50-100 MV/m. We present here an analytical and computational study of the resultant beam dynamics. Simulations including the electron beam-laser interaction have been performed with the code HOMDYN taking into account the superposition of incident and reflected laser pulses as well as space charge fields. Under this conditions the emittance degradation is negligible, as predicted by analytical methods, but a longitudinal charge modulation occurs on the scale of the laser wavelength, in case of oblique incidence, driven by the longitudinal component of the laser field. Preliminary simulations up to the photoinjector exit show that charge modulation is transformed into energy modulation via the space charge field, which may produce enhanced microbunching effects when the beam is further compressed in a magnetic chicane.
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| WEPLS021 |
The PLASMONX Project for Advanced Beam Physics Experiments
|
2439 |
| |
- L. Serafini, A. Bacci, R. Bonifacio, M. Cola, C. Maroli, V. Petrillo, N. Piovella, R. Pozzoli, M. Rome, A.R. Rossi, L. Volpe
INFN-Milano, Milano
- D. Alesini, M. Bellaveglia, S. Bertolucci, R. Boni, M. Boscolo, M. Castellano, A. Clozza, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, L. Ficcadenti, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, A. Ghigo, M. Incurvati, C. Ligi, F. Marcellini, M. Migliorati, A. Mostacci, L. Palumbo, L. Pellegrino, M.A. Preger, R. Ricci, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, F. Tazzioli, C. Vaccarezza, M. Vescovi, C. Vicario
INFN/LNF, Frascati (Roma)
- F. Alessandria, F. Broggi, C. De Martinis, D. Giove, M. Mauri
INFN/LASA, Segrate (MI)
- W. Baldeschi, A. Barbini, M. Galimberti, A. Giulietti, A. Gizzi, P. Koester, L. Labate, S. Laville, A. Rossi, P. Tomassini
CNR/IPP, Pisa
- U. Bottigli, B. Golosio, P.N. Oliva, A. Poggiu, S. Stumbo
INFN-Cagliari, Monserrato (Cagliari)
- C.A. Cecchetti, D. Giulietti
UNIPI, Pisa
- D. Levi, M. Mattioli, G. Medici, D. Pelliccia, M. Petrarca
Università di Roma I La Sapienza, Roma
- P. Musumeci
INFN-Roma, Roma
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The Project PLASMONX is well progressing into its design phase and has entered as well its second phase of procurements for main components. The project foresees the installation at LNF of a Ti:Sa laser system (peak power > 170 TW), synchronized to the high brightness electron beam produced by the SPARC photo-injector. The advancement of the procurement of such a laser system is reported, as well as the construction plans of a new building at LNF to host a dedicated laboratory for high intensity photon beam experiments (High Intensity Laser Laboratory). Several experiments are foreseen using this complex facility, mainly in the high gradient plasma acceleration field and in the field of mono-chromatic ultra-fast X-ray pulse generation via Thomson back-scattering. We present an innovative scheme of external injection of the SPARC beam into laser wake-field driven plasma waves. Detailed numerical simulations have been carried out to study the generation of short electron bunches, to be injected into plasma waves driven with adiabatically variable density in order to compress the bunch at injection and further accelerate it by preserving a small energy spread and good beam quality.
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| THPLS092 |
Nb-Pb Superconducting RF-Gun
|
3493 |
| |
- J.S. Sekutowicz, J.I. Iversen, D. Klinke, D. Kostin, W.-D. Möller
DESY, Hamburg
- I. Ben-Zvi, A. Burrill, T. Rao, J. Smedley
BNL, Upton, Long Island, New York
- M. Ferrario
INFN/LNF, Frascati (Roma)
- P. Kneisel
Jefferson Lab, Newport News, Virginia
- K. Ko, L. Xiao
SLAC, Menlo Park, California
- J. Langner, P. Strzyzewski
The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
- R.S. Lefferts, A.R. Lipski
SBUNSL, Stony Brook, New York
- J.B. Rosenzweig
UCLA, Los Angeles, California
- K. Szalowski
University of Lodz, Lodz
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We report on the status of an electron RF-gun made of two superconductors: niobium and lead. The presented design combines the advantages of the RF performance of bulk niobium superconducting cavities and the reasonably high quantum efficiency of lead, as compared to other superconducting metals. The concept, mentioned in a previous paper, follows the attractive approach of all niobium superconducting RF-gun as it has been proposed by the BNL group. Measured values of quantum efficiency for lead at various photon energies, analysis of recombination time of photon-broken Cooper pairs for lead and niobium, and preliminary cold test results are discussed in this paper.
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| THPLS098 |
Optimum Beam Creation in Photoinjectors Using Space-charge Expansion
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0 |
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- J.B. Rosenzweig, A.M. Cook, M.P. Dunning, C. Pellegrini
UCLA, Los Angeles, California
- M. Boscolo, M. Ferrario, D. Filippetto, L. Palumbo, C. Vicario
INFN/LNF, Frascati (Roma)
- P. Musumeci
INFN-Roma, Roma
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It has recently been shown by Luiten* 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 an experiment at the SPARC injector at Frascati in 2006. We review preparations for this experiment, and discuss the measurable quantities and their appropriate diagnosis, including the time-resolved observation of ellipsoidal beam shape at low energy. A scheme based on gating of Cerenkov radiation produced at an Aerogel for time-resolved measurements is proposed. Future measurements at high energy based on fs resolution RF sweepers are discussed. The prospects for using the very low longitudinal emittance beam in a future bunch compressor for producing 10 micron long beams are evaluated.
*O. J. Luiten et al. Physical Review Letters, 93, 094802-1 (2004).
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| THPLS105 |
Characterization of the SPARC Photo-injector with the Movable Emittance Meter
|
3523 |
| |
- A. Cianchi, L. Catani, E. Chiadroni
INFN-Roma II, Roma
- M. Boscolo, M. Castellano, G. Di Pirro, M. Ferrario, D. Filippetto, V. Fusco, L. Palumbo, C. Vaccarezza
INFN/LNF, Frascati (Roma)
- P. Musumeci
INFN-Roma, Roma
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As a first stage of the commissioning of SPARC accelerator a complete characterization of the photo-injector is planned. The objective is the optimization of the RF-gun setting that best matches the design working point and, generally, a detailed study of the emittance compensation process providing the optimal value of emittance at the end of the linac. For this purpose a novel beam diagnostic, the emittance-meter, consisting of a movable emittance measurement system, was conceived and built. This paper presents the results of the first measurements with the emittance-meter showing the characteristics and the performance at the SPARC photo-injector.
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