EPAC 2006 - Classification:02 Synchrotron Light Sources and FELs/A06 Free Electron Lasers

02 Synchrotron Light Sources and FELs

A06 Free Electron Lasers

Paper	Title	Page
MOZBPA01	Results from the VUV-FEL	34
	J. Rossbach DESY, Hamburg
	The talk will provide the latest results from the VUV-FEL. It will cover the general performance of the machine and comparison to theory. A status will be given of the performance of key systems: the gun, accelerating modules and RF systems, electron and photon beam diagnostics, timing and synchronization and undulator performance. Future developments and implementations will also be discussed (and implications to the XFEL).
	Transparencies
MOPCH001	Modeling Coherence Decay in Broad Band Triplet Interaction	0
	M. Frichembruder, R. Pakter, F.B. Rizzato IF-UFRGS, Porto Alegre
	In the present analysis we study the transition from coherent to incoherent dynamics in a nonlinear triplet of broad band combs of waves. We first reduce the original set of equations into a set where all submodes within a comb interact with all pairs of submodes in the remaining combs. We then develop a spectral formalism that in a self-contained way enables: (i) to determine the point of the transition; (ii) to obtain a convenient set of low dimensional equations modeling the full dynamics. As shall be discussed in connection with accelerator physics, the results can be applied to a variety of parametric or nonlinear wave devices like beat wave accelerators, FELs, etc. G. I. Oliveira et al. Physica D 164, 59 (2002).**M. Frichembruder et al. submitted to Physica. D (2005).
MOPCH002	Seeding the FEL of the SCSS Phase 1 Facility with the 13th Laser Harmonic of a Ti: Sa Laser Produced in Gas	44
	G. Lambert, M. Bougeard, W. Boutu, P. Breger, B. Carré, D. Garzella, M. Labat, H. Merdji, P. Monchicourt, P. Salieres CEA, Gif-sur-Yvette O.V. Chubar, M.-E. Couprie SOLEIL, Gif-sur-Yvette T. Hara, H. Kitamura, T. Shintake RIKEN Spring-8 Harima, Hyogo D. Nutarelli LAC, Orsay
	A seeding configuration, in which the 13th harmonic (60 nm) of a Ti: Sa laser (50 mJ, 10 Hz, 130 fs) generated in a gas cell is used as the external source, will be tested in 2006 on the SCSS test facility (SPring-8 Compact Sase Source, Japan). This facility is based on a thermionic cathode electron gun (1 nC of bunch charge), a C-band LINAC (5712 MHz, 35 MV/m) and two in-vacuum undulators (15 mm of period). The maximum electron beam energy is 250 MeV and the SASE emission from visible to 60 nm can be obtained. The High order Harmonic Generation (HHG) experiment was mounted off-line at the end of last December. A first chamber is dedicated to harmonic generation. A second one is used for spectral selection and adaptation of the harmonic waist in the modulator. The tests are performed in Saclay with the LUCA (Laser Ultra Court Accordable) laser (15 mJ, 10 Hz, 50 fs) from January to March at 266 nm, 160 nm and 60 nm and its results are presented here. Also, before performing the real tests in SPring-8 FEL presence, final theoretical estimations of the performances relying on 1D simulations using PERSEO code and 3D simulations using GENESIS and SRW codes are given.
MOPCH003	Seeding SPARC Facility with Harmonic Generation in Gases: Preliminary Tests of the Harmonic Generation in Gas Chamber	47
	O. Tcherbakoff, M. Bougeard, P. Breger, B. Carré, D. Garzella, M. Labat, G. Lambert, H. Merdji, P. Monchicourt, P. Salieres CEA, Gif-sur-Yvette M.-E. Couprie SOLEIL, Gif-sur-Yvette A. Doria, L. Giannessi ENEA C.R. Frascati, Frascati (Roma)
	In High Gain Harmonic Generation Free Electron Laser configuration, an external light source is injected in the first part of an undulator. The electron-photon interaction leads to a coherent light emission in the second part of the undulator. We propose to use the High Order Harmonic Generation in gases process as the seed for SPARC project (Frascati, Italy). With this facility, the electron beam is accelerated to 200 MeV and passes through an undulator of 6 sections. The preliminary tests on the seeding chambers presented in this paper have been realised at the CEA (Saclay, France). The experiment is based on three vacuum chambers. In the first one, a Ti: Sa laser (800 nm, 2.5 mJ, 50 fs, 10 Hz) is focussed in a 10 Hz pulsed gas jet (Argon or Xenon), producing harmonics of the fundamental. Filters in the second chamber enable the selection of the harmonic (3rd or 5th). Finally, a telescope focuses the harmonic beam at a given position. The whole module is to be moved to the SPARC facility. Appropriate tuning of the undulator gaps will amplify the 3rd and 5th harmonics seeded, as well as non-linear harmonics of those wavelengths, allowing the perspective of producing a FEL at 53 nm
MOPCH004	Coherent Harmonic Generation Experiment on UVSOR-II Storage Ring	50
	M. Labat CEA, Gif-sur-Yvette M.-E. Couprie SOLEIL, Gif-sur-Yvette T. Hara RIKEN Spring-8 Harima, Hyogo M. Hosaka, M. Katoh, A. Mochihashi, M. Shimada, J. Yamazaki UVSOR, Okazaki G. Lambert RIKEN Spring-8, Hyogo D. Nutarelli LAC, Orsay Y. Takashima Nagoya University, Nagoya
	Harmonic Generation schemes on Free Electron Laser devices are very promising. The injection of a traditional laser source inside the first undulator leads to an efficient energy modulation of the electron bunch, and therefore, its spatial modulation, resulting in a more coherent light emission along the second undulator. Experiments have been performed on the UVSOR-II Storage Ring at Okazaki (Japan) with electrons stored at an energy of 600 MeV, and using a 2.5 mJ Ti:Sa laser at 800 nm wavelength, 1 kHz repetition rate, and 100 fs up to 2 ps pulse duration. The experimental setup is presented, including the transport alignment and synchronisation between the laser and the electron beam. The third harmonic at 266 nm has been characterised versus various parameters: current, RF cavity voltage, undulator gap, magnetic functions of the storage ring, and laser pulse duration. Those results are compared with theory via analytical models and simulations.
MOPCH005	The ARC-EN-CIEL FEL Proposal	53
	M.-E. Couprie, C. Bruni, O.V. Chubar, A. Loulergue, L. Nahon SOLEIL, Gif-sur-Yvette B. Carré, D. Garzella, M. Jablonka, M. Labat, G. Lambert, F. Meot, P. Monot, A. Mosnier CEA, Gif-sur-Yvette J.-R. Marquès LULI, Palaiseaux D. Nutarelli LAC, Orsay J.-M. Ortega CLIO/ELYSE/LCP, Orsay
	ARC-EN-CIEL (Accelerator-Radiation Complex for Enhanced Coherent Intense Extended Light), the French project of a fourth generation light source aims at providing the user community with coherent femtosecond light pulses covering from UV to soft X ray. It is based on a CW 1 GeV superconducting linear accelerator delivering high charge, subpicosecond, low emittance electron bunches with a high repetition rate (1 kHz). Electron beam calculations will be presented. The FEL is based on the injection of High Harmonics Generated in Gases (HHG) in a High Gain Harmonic Generation scheme, leading to a rather compact solution. The produced radiation extending down to 0.8 nm with the Non Linear Harmonics reproduces the good longitudinal and transverse coherence of the harmonics in gas. Calculations are preformed with PERSEO, taking into account the proper transverse overlap between HHG and the electron beam, and with SRW. Optional beam loops are foreseen to increase the beam current or the energy. They will accommodate fs synchrotron infrared Coherent Synchrotron Radiation sources, VUV and X ray ranges and a FEL oscillator in the 10 nm range. An important synergy is expected between accelerat
MOPCH006	Beam Adaptation at the Infrared FEL, CLIO	56
	J.P. Berthet, F. Glotin, J.-M. Ortega CLIO/ELYSE/LCP, Orsay W. Salah The Hashemite University, Zarka
	The infrared free-electron laser CLIO is tunable from 3 to 150 5m by operating its driver RF linear accelerator between 50 and 12 MeV. This is the largest spectral range ever obtained with a single optical cavity. We have studied the electron beam transverse adaptation in the FEL undulator throughout the spectral and energy range. Each beam dimension is measured by a moving wire whose temperature dependant resistivity is monitored. The results are compared with simulations computed with the TRANSPORT code.
MOPCH007	Undulators for a Seeded HGHG-FEL Test Bench at MAX-lab	59
	J. Bahrdt, H.-J. Baecker, W.F. Frentrup, A. Gaupp, K. Goldammer, A. Meseck, M. Scheer BESSY GmbH, Berlin S. Werin MAX-lab, Lund
	Undulators for a Seeded HGHG-FEL at MAX-lab Within the European FEL Design Study a seeded HGHG-FEL will be set up at MAX-lab. In the modulator, a planar pure permanent magnet undulator, the 3rd harmonic of a Ti:Sapphire laser (267nm) interacts with the electron beam. In the following dispersive section the energy modulation is converted into a spatial modulation. The radiator emits at the third harmonic (89nm). The radiator has an APPLE II type magnetic structure providing full polarization control. The undulators and the dispersive section are currently built at BESSY. The electron beam height at MAX-lab of 400mm requires a specific design of the undulator carriages. The magnetic and mechanical design of the HGHG stage will be presented.
MOPCH008	Considerations for Double Pulse Lasing from the BESSY-FEL	62
	K. Goldammer, B.C. Kuske, A. Meseck BESSY GmbH, Berlin
	BESSY proposes a linac-based High-Gain Harmonic-Generation (HGHG) free electron laser (FEL) facility with three independent FEL lines. Two to four HGHG stages downconvert the initial seed wavelength (230nm to 460nm) to the desired radiation range (1.24nm to 51nm). High FEL gain is ensured as the seed radiation interacts only with unperturbed parts of the electron bunch in every HGHG-stage. This so-called fresh-bunch-technique relies on dipole chicanes that delay the electron bunches relative to the radiation. Fresh-bunch chicanes are incorporated prior to each modulator in the BESSY-FEL allowing the bunch to completely travel through all undulators. However, simulations show that bunch parts that have previously lased generate a noticeable radiation power level in the final amplifiers. This motivated simulation studies on the significance and applicability of such inherent additional pulses. It is revealed that the BESSY-FEL provides the opportunity to deliver double pulses at the FEL exit being of high interest to the user community. Temporal seperation and intensity levels can be controlled by carefully optimising the properties of the magnetic chicanes.
MOPCH009	The BESSY 2nd Generation Soft X-ray FEL User Facility	65
	J. Knobloch BESSY GmbH, Berlin
	Future VUV-to-soft-X-ray FEL facilities promise to open fundamentally new frontiers for the synchrotron user community. So-called 2nd generation FELs, which use seeded schemes rather than SASE, can deliver reproducible ultra-short photon pulses at an energy level of mJ/pulse. BESSY has been designing a High-Gain-Harmonic-Generation (HGHG) based FEL with a 2.3 GeV superconducting driver linac that covers photon energies from 24 eV to 1 keV. The design provides full tuneability of photon energy, variable beam polarization and complete synchronization to external lasers—all essential for future femtosecond, time-resolved pump-probe experiments. Also, the CW linac offers great flexibility for the repetition rates and pulse patterns. BESSY-organized User Workshops helped identify the user requirements for such an FEL. This information provided the basis for the Technical Design Report that was submitted to the German Wissenschaftsrat in 2004, which then held an on-site review in 2005. Meanwhile, preparatory studies continue at BESSY. They include start-to-end simulations, tolerance studies, and the development of superconducting RF technology in the HoBiCaT test facility.
MOPCH010	High Power Tests of a High Duty Cycle, High Repetition Rate RF Photoinjector Gun for the BESSY FEL	68
	F. Marhauser BESSY GmbH, Berlin
	The proposed BESSY Soft X-ray FEL uses a normal conducting 1.3 GHz photoinjector RF gun cavity at comissioning phase. Due to the challenging RF pulse pattern the cavity has to cope with an average power of 75 kW. A 1.5-cell RF gun prototype has been built with a dedicated cooling layout. Results of the first high power RF tests are detailed in this paper.
MOPCH011	Jitter Measurement by Spatial Electro-optical Sampling at the Flash Free Electron Laser	71
	A. Azima, S. Düsterer, J. Feldhaus, H. Schlarb DESY, Hamburg A.L. Cavalieri MPQ, Garching, Munich D. Fritz Michigan University, Ann Arbor, Michigan K. Sengstock Uni HH, Hamburg
	For pump-probe experiments carried out at the VUV-FEL at DESY, FEL laser pulses with 32 nm wavelength have to be synchronized with high precision to optical laser pulses generated by a TiSa oscillator. To measure the relative timing variations between the FEL and the optical laser, an electro-optical experiment to determine the electron beam arrival time at the undulator has been installed. Here, the electron beam profile is encoded spatially into the laser pulse and readout by an intensified camera. A similar experimental setup has been successfully used at the sub-picosecond pulsed source (SPPS) at higher charge and shorter rms bunch length. In this paper, we report about the achievements and difficulties of the Timing Electro-Optical (TEO) setup, that allows to post-order experimental user data with a precision of 100 fs rms and better.
MOPCH012	FEL Disturbance by Ambient Magnetic Field Changes	74
	H. Kapitza, P. Göttlicher, N. Heidbrook, H. Schlarb DESY, Hamburg
	The VUV-FEL at DESY in Hamburg (Germany) is mostly located inside the circular accelerator PETRA which serves as an injector for the electron proton collider HERA. SASE was regularly lost in the VUV-FEL when protons were ramped to the injection energy in PETRA. This effect was mediated by magnetic field changes in the order of 1 microtesla, caused by time-dependent uncompensated magnet currents of more than 800 A which made PETRA act like a large current loop. The resulting beam displacements of several hundred micrometers in the undulators proved to be enough to make SASE fail. This serious disturbance of user runs was eliminated by introducing an improved compensation scheme which further limits residual currents in PETRA during proton injection. The consequences of this observation for the design of the XFEL are briefly discussed.
MOPCH013	Slice Emittance Measurements at FLASH	77
	M. Roehrs, C. Gerth, M. Huening, H. Schlarb DESY, Hamburg
	The SASE process in Free Electron Lasers mainly depends on time-sliced parameters of charge density, energy spread and transverse emittance. At the VUV-FEL at DESY, electron bunches are compressed longitudinally in two magnetic chicanes in order to achieve high peak currents. The compression causes considerabe variations in slice emittance along the bunches. The vertically deflecting rf-structure LOLA, which is in operation at the VUV-FEL since early 2005, allows to resolve longitudinal variations in horizontal slice width for single bunches. The horizontal slice emittances can be determined by additionally varying the strengths of the quadrupoles upstream of LOLA. Results of slice emittance measurements using different bunch compression schemes are presented.
MOPCH014	Energy-time Correlation Measurements Using a Vertically Deflecting RF Structure	80
	M. Roehrs, C. Gerth, M. Huening, H. Schlarb DESY, Hamburg
	To initiate the lasing process in SASE-based Free Electron Lasers, electron bunches with high peak currents are necessary. At the VUV-FEL at DESY, high peak currents are produced by bunch shortening in magnetic chicanes induced by a linear energy-time gradient. The residual uncorrelated time-sliced energy width after compression is a crucial parameter for the lasing process. The final energy-time correlation provides important information about the compression process. This paper presents a measurement of slice energy spread and energy-time correlation using a vertically deflecting rf-structure (LOLA). The structure allows to map the time delay of bunch slices to the vertical axis of a screen. After dispersing the bunches horizontally with a dipole, the energy-time correlation can be directly obtained in a single shot measurement. Results for different bunch compression schemes are presented. The measured bunch length in case of a non-compressed beam is compared to streak camera measurements.
MOPCH015	Impact of Undulator Wakefileds and Tapering on European X-ray FEL Performance	83
	I. Zagorodnov, M. Dohlus, T. Limberg DESY, Hamburg
	The European X-ray Free-Electron Laser (XFEL) based on self-amplified spontaneous emission (SASE) requires an electron beam with a few kA peak current and a small-gap undulator system up to 250 m in length. The interaction between the high-current electron bunch and the undulator vacuum chamber affects the FEL performance. In this paper we estimate the induced wakefields in elliptical pipe geometry, taking into account the main geometrical variations of the chamber. To study the expected performance in the presence of the calculated wakefields, we are doing start-to-end simulations with the tracking codes ASTRA, CSRtrack and GENESIS. To compensate the wakefield impact on the FEL performance, an adiabatic change of undulator parameters is considered.
MOPCH016	Bunch Compression Monitor	86
	H. Delsim-Hashemi, J. Rossbach, P. Schmüser Uni HH, Hamburg O. Grimm, H. Schlarb, B. Schmidt DESY, Hamburg A.F.G. van der Meer FOM Rijnhuizen, Nieuwegein
	An accelerated bunch of electrons radiates coherently at wavelengths longer than or comparable to the bunch length. The first generation Bunch Compression Monitor (BCM) that is installed at the VUV-FEL applies this principle by measuring the total radiation intensity. For a better control on the degree of the compression, the radiated intensity in different bandwidth can be used. Dependent on the changes in the structure of the bunch, its radiation spectrum changes correspondingly. A new generation BCM uses wavelength dependent diffracting devices and multi-channel sensors to measure the signal in different wavelength channels simultaneously. This paper describes the construction of the first prototypes and experimental results in different short wavelength bands measured at the linac of the VUV-FEL at DESY, Hamburg.
MOPCH018	Macro-Pulse Generation in a Storage-Ring Free-Electron Laser: A Single-Particle Plus FEL Numerical Approach	89
	F. Curbis, E. Allaria, G. De Ninno ELETTRA, Basovizza, Trieste
	In a storage-ring free-electron laser (FEL), the onset and growth of intra-cavity power at the fundamental resonant wavelength is naturally accompanied by coherent emission at higher harmonics. Contrary to what happens in single-pass linac-based devices, the electron beam is re-circulated in the storage ring and the microbunching becomes thermalized. As a consequence, a correct theoretical understanding of the process requires a proper modelling of the turn-by-turn evolution of the electron-beam phase space, both inside the undulators (where the FEL interaction takes place) and along the ring. To simulate this process we have coupled an ad hoc modified version of the 3D numerical code Ginger (which models the FEL interaction) together with a linear one-turn map (which propagates the electron beam along the ring). We present our results and draw a comparison with previous simplified approaches. We also present the first benchmarking of experiments carried out with the ELETTRA storage-ring FEL.
MOPCH019	Baseline Design of the Linac Upgrade for Fermi	92
	G. D'Auria, P. Craievich, P. Delgiusto, S. Di Mitri, M. Ferianis, M.M. Milloch, G.C. Pappas, G. Penco, M. Trovo ELETTRA, Basovizza, Trieste L.R. Doolittle, A. Ratti LBNL, Berkeley, California
	The FERMI FEL requires a major upgrade of the existing linac, which needs to be transformed from being the injector for the ELETTRA light source, to becoming the source for the FERMI FEL. In this work, we present the baseline design, including the integration of the 7 additional systems from the LIL linac, and one X-band station as linearizers. We will present the new layout with the required modifications and additions to the existing infrastructure to meet the more demanding needs of the system. Such modifications include a new RF controller, improvements in the modulator stability and an upgrade to the average power capabilities of the system to operate at 50 Hz. Test results from the characterization of the existing systems will be included, as well as plans for future development.
MOPCH020	Design and Optimization of the FERMI @ Elettra FEL Layout	0
	G. De Ninno, E. Allaria, B. Diviacco ELETTRA, Basovizza, Trieste W.M. Fawley, G. Penn LBNL, Berkeley, California W. Graves MIT, Middleton, Massachusetts
	The FERMI @ ELETTRA project at Sincotrone Trieste will be comprised of two FEL's, each based on the principle of seeded harmonic generation. The first undulator line, FEL-1, will operate in the 40-100 nm wavelength range and will rely upon one stage of harmonic up-conversion. The second undulator line, FEL-2, extends the output spectral domain to the 10^-40 nm wavelength range and will use two harmonic stages operating as a cascade. We review the FEL studies that have led to the final design and present results of numerical simulations with GENESIS and GINGER codes including those examining the effects of undulator errors and shot-to-shot fluctuations in multiple input parameters.
MOPCH021	FERMI @ Elettra: Conceptual Design for a Seeded Harmonic Cascade FEL for EUV and Soft X-rays	0
	C.J. Bocchetta, E. Allaria, D. Bulfone, P. Craievich, G. D'Auria, M.B. Danailov, G. De Ninno, S. Di Mitri, B. Diviacco, M. Ferianis, A. Gambitta, A. Gomezel, E. Karantzoulis, G. Penco, M. Trovo ELETTRA, Basovizza, Trieste J.N. Corlett, W.M. Fawley, S.M. Lidia, G. Penn, A. Ratti, J.W. Staples, R.B. Wilcox, A. Zholents LBNL, Berkeley, California M. Cornacchia, P. Emma SLAC, Menlo Park, California W. Graves, F.O. Ilday, F.X. Kaertner, D. Wang MIT, Middleton, Massachusetts F. Parmigiani Università Cattolica-Brescia, Brescia
	We present a summary of the conceptual design for the FERMI FEL project funded for construction at the Sincrotrone Trieste, Italy. The project will be the first user facility based on seeded harmonic cascade FEL's, providing controlled, high peak-power pulses, and complementing the storage ring light source at Sincrotrone Trieste. The facility is to be driven by electron beam from a high-brightness rf photocathode gun, and using the existing 1.2 GeV S-band linac. Designed for an initial complement of two FEL's, providing tunable output over a range from ~100 nm to ~10 nm, FERMI will allow control of pulse duration from less than 100 fs to approximately1 ps, and with polarization control from APPLE undulator radiators. Seeded by tunable UV lasers, FEL-1 is a single-stage of harmonic generation to operate over ~100 nm to ~40 nm, and FEL-2 a two-stage cascade operating from ~40 nm to ~10 nm or shorter wavelength. Photon output is spatially and temporally coherent, with peak power in the 100’s MW to GW range. We have designed FEL-2 to minimize the output radiation spectral bandwidth. Major systems and overal facility layout are described, and key performance parameters summarized.
MOPCH022	Time-resolved "Start-to-end" FEL Simulation Results for the FERMI @ Elettra Project	0
	G. De Ninno, E. Allaria ELETTRA, Basovizza, Trieste W.M. Fawley, G. Penn LBNL, Berkeley, California W. Graves MIT, Middleton, Massachusetts
	The FERMI FEL project* is the first user facility based on seeded harmonic cascade FEL's, providing controlled, high peak-power pulses, and complementing the storage ring light source at Sincrotrone Trieste. FERMI will initial comprise two FEL's, providing tunable output over a wavelength range from ~100- to 40-nm (FEL-1) and ~40-to-10-nm (FEL-2) with control of both polarization and temporal pulse duration. We present results concerning the predicted FEL output based the expected 6D electron beam phase space at the undulator entrance as determined from detailed "start-to-end" simulations*. Both the GENESIS and GINGER codes were applied to this study. We discuss the expected transverse and longitudinal coherence, and also the predicted sensitivity to both undulator errors and accelerator jitter. C. J. Bocchetta et al. “FERMI @ Elettra – Conceptual Design for a Seeded Harmonic Cascade FEL for EUV and Soft X-rays”, this conference. **S. DiMitri et al. “Start to End Simulations of FERMI@ELETTRA”, this conference.
MOPCH024	Future Seeding Experiments at SPARC	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
	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.
MOPCH025	Laser Comb: Simulations of Pre-modulated E- Beams at the Photocathode of a High Brightness RF Photoinjector	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
	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.
MOPCH026	A Biperiodic X-band RF Cavity for SPARC	101
	L. Ficcadenti, M.E. Esposito, A. Mostacci, L. Palumbo Rome University La Sapienza, Roma D. Alesini, B. Spataro INFN/LNF, Frascati (Roma) A. Bacci INFN-Milano, Milano
	The Frascati photo-injector SPARC (Pulsed Self Amplified Coherent Radiation Source) will be equipped with an X-band RF cavity for linearizing emittance to enhance bunch compression and for reducing bunch longitudinal energy spread. A biperiodic cavity working on the pi/2-mode offers some advantages in comparison to a conventional (periodic) cavity despite the need of accurate machining. A copper prototype made of 17 separated cells has been built following numerical simulation. In this paper we report on preliminary measurements of its RF properties. The main characteristics of the cooling system for the final device are also addressed.
MOPCH027	Metal Film Photocathodes for High Brightness Electron Injectors	104
	G. Gatti, L. Cultrera, F. Tazzioli, C. Vicario INFN/LNF, Frascati (Roma) A. Fiori, S. Orlanducci Università di Roma II Tor Vergata, Roma J. Langner, M. S. Sadowski, P. Strzyzewski The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock A. Perrone INFN-Lecce, Lecce C. Ristoscu INFLPR, Bucharest - Magurele
	Advanced high brightness injectors require photocathodes with fast response,high quantum efficiency and good surface uniformity. Both Mg films deposited by laser ablation and Pb films deposited by vacuum arc could satisfy these requirements. Their emission and morphology are compared.
MOPCH028	Status of the SPARX FEL Project	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
	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.
MOPCH029	Status of the SPARC Project	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
	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.
MOPCH030	Production of Coherent X-rays with a Free Electron Laser Based on an Optical Wiggler	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)
	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.
MOPCH031	Progress on the Pi-mode X-band RF Cavity for SPARC	116
	L. Ficcadenti, M.E. Esposito, A. Mostacci, L. Palumbo Rome University La Sapienza, Roma D. Alesini, B. Spataro INFN/LNF, Frascati (Roma) A. Bacci INFN-Milano, Milano
	The Frascati photo-injector SPARC (Pulsed Self Amplified Coherent Radiation Source) will be equipped with an x-band RF cavity for linearizing emittance to enhance bunch compression and for reducing bunch longitudinal energy spread. The nine cell standing wave cavity prototype made of separated cells has been already built and measured. In this paper we report on characterization of the first brazed prototype. Heat load studies have been performed as well to design the cooling system for the final device. D. Alesini et al. Nucl. Instr. and Meth. A 554 (2005) 1.
MOPCH034	On a Skeleton CASSINI Ovals Current Undulator	119
	A.M. Mihalache, V.I.R. Niculescu INFLPR, Bucharest - Magurele V. Babin INOE, Bucharest M.R. Leonovici, C. Stancu Bucharest University, Faculty of Physics, Bucharest-Magurele F. Scarlat Valahia University, Faculty of Sciences, Targoviste
	A new undulator structure for free electron lasers was presented. Current skeleton CASSINI ovals produced magnetic fields which are spatially periodic. The current structure was in the shape of stacks of modified CASSINI ovals. The current has alternating directions. The magnetic field components for each wire present C2 symmetry. CASSINI undulator transverse cross-section* was approximated by polygons. In cartesian coordinates the Biot-Savart law was analytically evaluated. The magnetic field was mainly transversal and easily adjusted with the current. The versatility of this structure introduces a new type of two beams longitudinal undulator or wiggler design for transverse moments. *Cassini curve; C. Mihu, I.P. Iambor-1989.
MOPCH036	Photocathode Roughness Impact on Photogun Beam Characteristics	121
	T.V. Gorlov MEPhI, Moscow A.M. Tron LPI, Moscow
	Photocathode surface roughness has an impact on photoelectron yield, bunch duration, beam emittance at the exit of femtosecond photogun with an accelerating field that is considered in assumption of quasi-stationary one in the paper. The main problem in investigating the impact is determination of the field near the surface, statistical properties of which are defined through rms values of deviation and slope in profile line of the surface roughness. Developed and created code allows determining the field with relative rms error not worse than 0.001%. The results of the investigation for rms values of roughness and its slope within respectively 500…0 nm and 20…0 degrees are presented and discussed.
MOPCH038	Predicted Parameters of the Second Stage of High Power Novosibirsk FEL	124
	A.V. Kuzmin, O.A. Shevchenko, N. Vinokurov BINP SB RAS, Novosibirsk
	The first stage of Novosibirsk high power terahertz FEL was successfully put into operation in 2003. The measured parameters of the FEL turned out to be in a good agreement with calculations [2]. The second and the third stages of the FEL are under construction now. The beam energy at the second stage will be about 20 MeV and the wavelength will change in the range 40-80 μm. In this paper we present the design parameters for the second stage FEL. The simulations were carried out with the help of 1-D code based on macroparticles. This code was previously used for the first stage simulations. E. A. Antokhin et al. NIM A528 (2004) p.15-18.**A. V. Kuzmin et al. NIM A543 (2005) p.114-117.
MOPCH040	Simulations for the FEL Test Facility at MAX-lab within EUROFEL	127
	S. Thorin, M. Brandin, S. Werin MAX-lab, Lund M. Abo-Bakr, J. Bahrdt, K. Goldammer BESSY GmbH, Berlin
	Within the EUROFEL project a High Gain Harmonic Generation Free Electron Laser will be constructed at MAX-lab in collaboration with BESSY. The electron bunches will be created in the existing MAX-lab injector and transported to the inside of the MAX II ring where the FEL undulators will be located. To predict FEL performance and stability, simulations of the photo injector, linac, recirculator, transport and undulator sections as well as start to end simulations have been carried out.
MOPCH041	Design of a New Preinjector for the MAX Recirculator to be Used in EUROFEL	130
	S. Werin, M. Brandin, T. Hansen, D. Kumbaro, L. Malmgren, S. Thorin MAX-lab, Lund J. Bahrdt BESSY GmbH, Berlin
	The MAX-lab recirculator injector will be equipped with a new preinjector system. The aim is to reduce the emittance, increase the charge and achieve a proper timing between accelerator and laser systems. All is aimed at the MAX-lab test facility for HG built in collaboration with BESSY in the EUROFEL program. The preinjector system consists of a photo cathode RF-gun with an emittance compensating solenoid. Special issues regard the injection of the new beam into the beam path of the MAX recirculator and the conservation of beam parameters.
MOPCH042	Progress in the Design of a Two-Frequency RF Cavity for an Ultra-Low Emittance Pre-Accelerated Beam	133
	J.-Y. Raguin, A. Anghel, R.J. Bakker, M. Dehler, R. Ganter, C. Gough, S. Ivkovic, E. Kirk, F. Le Pimpec, S.C. Leemann, K.L. Li, M. Paraliev, M. Pedrozzi, L. Rivkin, V. Schlott, A.F. Wrulich PSI, Villigen
	Today most of the X-rays Free-Electron Laser projects are based on state of the art RF guns, which aim at a normalized electron beam emittance close to 1 mm$·$mrad. In this paper we report on the progress made at PSI towards a hybrid DC + RF Low Emittance Gun (LEG) capable of producing a beam with an emittance below 0.1 mm.mrad. To reduce the intrinsic thermal emittance at the LEG cathode the electrons are extracted from nano-structured field-emitters. A gun test facility is under construction wherein after emission the beam is accelerated up to 500 keV in a diode before being injected and accelerated in a two-frequency 1.5-cell RF cavity. The fast acceleration in the diode configuration allows to minimize the emittance dilution due to the strong space charge forces. The two-frequency RF structure is optimized to limit the emittance blow-up due to the non-linearity of the RF field.
MOPCH043	An Optimization Study for an FEL Oscillator at TAC Test Facility	136
	Ö.M. Mete, Ö. Karsli, O. Yavas Ankara University, Faculty of Engineering, Tandogan, Ankara
	Recently, conceptual design of the Turkic Accelerator Center (TAC) proposal was completed. The main goal of this proposal is a charm factory that consists of a linac-ring type electron-positron collider. In addition, synchrotron radiation from the positron ring and free electron laser from the electron linac are proposed. The project related with this proposal has been accepted by the Turkish government. It is planned that the Technical Design Report of TAC will have been written in the next three years. In this period, an infrared oscillator free electron laser (IR FEL) will be constructed as a test facility for TAC. 20 and 50 MeV electron energies will be used to obtain infrared FEL. The main parameters of the electron linacs, the optical cavities and the FEL were determined. The possible use of obtained laser beam in basic and applied research areas such as biotechnology, nanotechnology, semiconductors and photo chemistry were discussed.
MOPCH044	Peculiarities of the Doppler Effect for Moving Radiative Particles in Dispersive Medium at Extreme Conditions	139
	M.V. Vysotskyy, V.I. Vysotskii National Taras Shevchenko University of Kyiv, Radiophysical Faculty, Kiev
	The features of Doppler effect for fast moving radiating particles with discrete energy levels spectrum (e.g. radiation at channeling) at parameters close or equal to extreme condition of Cherenkov effect are studied. The formal usage of Cherenkov condition leads in this case to incorrect and unphysical results. The main task of this work was to find maximal radiation frequency and its dependence from the system parameters. This finite frequency was found. It was shown that at correct use of conservation laws the dependence of radiation and absorption frequencies on deviation from exact Cherenkov condition contains one discontinuity. The value of these frequencies on two sides of this discontinuity is different by 2.5 times. It was shown that the positions of these discontinuities depend on deviation value and corresponds to the condition of normal Doppler effect transformation into abnormal. Conditions that correspond to maximal radiation and absorption frequencies are different and are shifted in different directions form the exact Cherenkov condition (in relation to the velocity and dielectric permittivity).
MOPCH045	A Source of Coherent Soft X-ray Radiation Based on High-order Harmonic Generation and Free Electron Lasers	142
	M. Gullans, J.S. Wurtele UCB, Berkeley, California G. Penn, A. Zholents LBNL, Berkeley, California
	We examine a scheme for a Free Electron Laser (FEL) harmonic amplifier seeded by a ~30-nm wavelength signal produced using a process of High-order Harmonic Generation (HHG). The seed is first amplified in an optical klystron from ~100 kW to ~30 MW using a 1 GeV electron beam and then is used for an energy modulation of electrons in the downstream undulator. Subsequently, a 100-MW level of radiation at shorter wavelengths down to 4 nm is obtained by bunching the energy modulated electrons and passing the bunched beam through an undulator tuned to the desired harmonic of 30 nm. We also compare this scheme to a more familiar harmonic cascade FEL by replacing the HHG with an additional stage of harmonic generation.
MOPCH047	Study of the Electron Beam Dynamics in the FERMI @ ELETTRA Linac	145
	M. Cornacchia, P. Craievich, S. Di Mitri ELETTRA, Basovizza, Trieste I.V. Pogorelov, J. Qiang, M. Venturini, A. Zholents LBNL, Berkeley, California D. Wang MIT, Middleton, Massachusetts R.L. Warnock SLAC, Menlo Park, California
	A study of the electron beam dynamics in the linac is made within the framework of the design of a free electron laser (FEL) at the Syncrotrone Trieste. A scope of the work includes analysis of two operational scenarios, one with relatively long electron bunches of the order of 1.5 ps and a moderate peak current of 500 A and one with shorter bunches of the order of 0.7 ps and higher peak current of the order of 800 A. In both cases, care has been taken to preserve the slice and projected emittances formed in the photocathode gun injector and to minimize the slice energy spread. The latter goal is accomplished by balancing the onset of the microbunching instability driven by the longitudinal space charge forces and the emission of coherent synchrotron radiation using Landau damping produced by a so-called laser heater. Various analytical techniques and tracking codes have been employed to obtain the reported results. C. Bocchetta, et al., this conference.
MOPCH048	Linac Coherent Light Source Electron Beam Collimation	148
	J. Wu, D. Dowell, P. Emma, C. Limborg-Deprey, J.F. Schmerge SLAC, Menlo Park, California
	This paper describes the design and preliminary simulations of the electron beam collimation system in the Linac Coherent Light Source (LCLS) linac. Dark current is expected from the gun and some of the accelerating cavities. Particle tracking of the expected dark current through the entire LCLS linac, from L0-linac exit to FEL undulator entrance, is used to estimate final particle extent in the undulator as well as expected beam loss at each collimator or aperture restriction. A table of collimators and aperture restrictions is listed along with halo particle loss results, which includes an estimate of average continuous beam power lost on each individual collimator. In addition, the transverse wakefield alignment tolerances are calculated for each collimator.
MOPCH049	Trajectory Stability Modeling and Tolerances in the LCLS	151
	J. Wu, P. Emma SLAC, Menlo Park, California
	To maintain stable performance of the Linac Coherent Light Source X-ray Free-electron laser, one has to control undulator trajectory stability to a small fraction of the rms beam size. BPM based feedback loops running at 120 Hz will be effective in controlling jitter at low frequencies less than a few Hz. On the other hand, linac and injector stability tolerances must control jitter at higher frequencies. In this paper, we study the possible sources of such high frequency jitter, including: 1) steering coil current regulation; 2) quadrupole (and solenoid) transverse vibrations; 3) quadrupole (and solenoid) current regulation in presence of typical 200-micron misalignments; 4) charge jitter coupling to RF cavity transverse wakefield due to alignment errors; and 5) bunch length jitter coupling to Coherent Synchrotron Radiation in Chicane. Based on this study, we then set tolerances on each item.
THXPA03	Laser Systems and Accelerators	2728
	H. Schlarb DESY, Hamburg
	The presentation will cover the use of laser systems in accelerators. Topics covered will be the use of lasers for the production of electron beam from photocathodes, timing and diagnostics, laser heater systems to control space charge effects, as seed systems. Challenges in terms of stability, pulse shaping, power and pulse lengths, wavelength range and tuning will be covered for the various aspects.
	Transparencies
THYPA01	Overview of FEL Injectors	2733
	M. Ferrario INFN/LNF, Frascati (Roma)
	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.
	Transparencies
THOPA02	Status of the SCSS Test Accelerator and XFEL Project in Japan	2741
	T. Shintake RIKEN Spring-8 Harima, Hyogo
	Construction of the SCSS* 250 MeV test accelerator was completed in October 2005, and the beam commissioning was started in November 2005. The first light at visible wavelength, which is the spontaneous radiation from undulator, was observed right after machine commissioning. We expect the first SASE beam around 60 nm in 2006. The purpose of the test accelerator is to assemble all hardware components in a real machine, and check their performance, reliability and stability. It is also very important to build all control software and link to the main frame to see system performance. All experience will provide feedback to 8 GeV XFEL design, whose construction will start in April 2006. *http://www-xfel.spring8.or.jp
THOPA03	An Integrated Femtosecond Timing Distribution System for XFELs	2744
	J. Kim, J. Burnham, dc. Cheever, J. Chen, F.X. Kaertner MIT, Cambridge, Massachusetts M. Ferianis ELETTRA, Basovizza, Trieste F.O. Ilday Bilkent University, Bilkent, Ankara F. Ludwig, H. Schlarb, A. Winter DESY, Hamburg
	Tightly synchronized lasers and rf-systems with timing jitter in the few femtoseconds range are an important component of future x-ray free electron laser facilities. In this paper, we present an optical-rf phase detector that is capable of extracting an rf-signal from an optical pulse stream without amplitude-to-phase conversion. Extraction of a microwave signal with less than 10 fs timing jitter (from 1 Hz to 10 MHz) from an optical pulse stream is demonstrated. Scaling of this component to sub-femtosecond resolution is discussed. Together with low noise mode-locked lasers, timing-stabilized optical fiber links and compact optical cross-correlators, a flexible femtosecond timing distribution system with potentially sub-10 fs precision over distances of a few kilometres can be constructed. Experimental results on both synchronized rf and laser sources will be presented. A. Winter et al. "Synchronization of Femtosecond Pulses", Proceedings of FEL 2005.*J. Kim et al. "Large-Scale Timing Distribution and RF-Synchronization for FEL Facilities", Proc. of FEL 2004.
	Transparencies
FRYBPA01	Overview of Single Pass Free Electron Lasers	3636
	C. Pellegrini UCLA, Los Angeles, California
	The presentation will cover world wide status of single pass free electron lasers. A general status will be given of the projects. Common themes will be discussed, as will the challenges of these themes. Unique characteristics of individual projects will also be covered. Here the emphasis will be on a description of novel and challenging techniques: for example examples seeding of the FEL, different types of guns for high brightness electron beam production, very short or very long pulse production, etc.
	Transparencies