FEL 2006 - List of Keywords (undulator)

A B C D E F G H I K L M O P Q R S T U V W

undulator

Paper	Title	Other Keywords	Page
MOAAU01	FEL Prize Lecture: Coherent Electron-Beam Radiation Sources and FELs: A Theoretical Overview	radiation, electron, bunching, laser	1
	A. Gover, E. Dyunin University of Tel-Aviv, Faculty of Engineering, Tel-Aviv
	The theory of Coherent electron beam radiation devices in general, and FEL in particular, is reviewed in terms of a general simple formulation based on modal expansion of the radiation field. A variety of e-beam radiation mechanisms (FEL, TWT, Cerenkov Radiation) have common features. All these radiation mechanisms can emit coherent or partially coherent radiation by means of three basic kinds of radiation processes: Spontaneous emission (shot-noise radiation), Superradiance (bunched-beam coherent radiation) and Stimulated emission. The common radiation processes and their relations are explained, in both frequency and time domains, in terms of the radiation modes expansion formulation. It is shown that the coherence properties of the emitted radiation, in each radiation process, depend on the phase relations between the radiation wave-packets, emitted by the individual electrons and their entrance distribution statistics. In the high gain linear regime all these radiation mechanisms satisfy the Pierce dispersion equation, and all radiation characteristics are derived from the Pierce transfer functions. I employ the formulation to delineate limits of coherence of electron beam radiation sources, and particularly examine possible schemes for turning SASE FELs to operate as coherent radiation sources.
	Slides
	Talk

MOAAU04	First Lasing at SCSS	emittance, radiation, focusing, gun	16
	T. Shintake RIKEN Spring-8 Harima, Hyogo
	On 20 June, the SCSS prototype accelerator firstly generated pulses at VUV 49 nm FEL radiation, using ultra-low emittance beam provided by a newly developed single-crystal CeB6 thermionic cathode. SCSS prototype accelerator has been recently constructed in 2004-2005 at SPring-8 site in Japan, and comissioned recently. Its major purpose is to test hardware components developed at RIKEN/SPring-8 in SCSS R&D required to realize X-ray FEL at 1 Angstrom wavelength. One of the most challenging ideas in SCSS is to use CeB6 single crystal cathode to generate ultra-low emittance beam. We start from a lower beam current of 1 A from 500 kV e-gun, then we compress the bunch length more than a few 100 times to generate a few 100 A beam without deteliorating the emittance in the injector. Careful design was made on rf-cavities and magnetic lenses to perform velocity bunching in the injector system, which has been installed in the prototype accelerator. After four C-band accelerators, beam energy reaches 250 MeV. On 15 June, evening 4 pm, we firstly closed the upstream undulator, after one hour tuning, we observed narrow spectrum peaked at 49 nm in the intense VUV radiation, which was totally different from the natural undulator radiation (spontanenous mode). We performed careful measurements on various aspects, and announced "the first lasing" on 20 June.
	Slides
	Talk

MOAAU05	The First Lasing of 193 nm SASE, 4th Harmonic HGHG and ESASE at the NSLS SDL	laser, electron, diagnostics, linac	18
	X. J. Wang, J. B. Murphy, J. Rose, Y. Shen, T. Tsang, T. Watanabe BNL, Upton, Long Island, New York
	After successfully achieving SASE lasing at 198 nm on April 20, 2006, we have also observed the first 4th harmonic High Gain Harmonic Generation (HGHG) with a 795 nm seed laser. We will report the progress and experimental characterization of the 198 nm SASE and 4th harmonic HGHG.
	Slides
	Talk

MOBAU03	The European XFEL Project	linac, electron, radiation, photon	24
	R. Brinkmann DESY, Hamburg
	The European X-ray Free Electron Laser XFEL is a 4th generation synchrotron radiation facility based on the SASE FEL concept and the superconducting TESLA technology for the linear accelerator. This multi-user facility will provide photon beams in a wavelength regime from 0.1nm to 5nm in three FEL beam lines and hard X-rays in two spontaneous radiation beam lines, serving in total 10 experimental stations in the first stage. The project is in an advanced planning and technical preparation stage and its construction as a European/International facility near DESY in Hamburg will start in 2007. This talk gives an overview of the overall layout and parameters of the facility, with emphasis on the accelerator design, technology and physics.
	Slides
	Talk

MOBAU04	Optical Klystron Enhancement to SASE X-Ray FELs	klystron, electron, radiation, simulation	29
	Y. T. Ding, P. Emma, Z. Huang SLAC, Menlo Park, California V. Kumar RRCAT, Indore (M. P.)
	The optical klystron enhancement to self-amplified spontaneous emission (SASE) free electron lasers (FELs) is studied in theory and in simulations. In contrast to a seeded FEL, the optical klystron gain in a SASE FEL is not sensitive to any phase mismatch between the radiation and the microbunched electron beam. The FEL performance with the addition of four optical klystrons located at the undulator long breaks in the Linac Coherent Light Source (LCLS) shows significant improvement if the uncorrelated energy spread at the undulator entrance can be controlled to a very small level. In addition, FEL saturation at shorter x-ray wavelengths (around 1.0 angstrom) within the LCLS undulator length becomes possible. We also discuss the application of the optical klystron in a compact x-ray FEL design that employs relatively low electron beam energy together with a shorter-period undulator.
	Slides
	Talk

MOBAU05	Status of Japanese XFEL Project and SCSS Test Accelerator	emittance, electron, cathode, radiation	33
	T. Shintake RIKEN Spring-8 Harima, Hyogo
	Japanese XFEL based on SASE, aming at generating 1 A X-ray with 8 GeV e-beam, has been funded. Construction 2006-2010, beam comissioning is scheduled in 2010. In order to estabilish technology for XFEL, SCSS test accelerator, e-beam 250 MeV, 60 nm minimum wavelength, has been constructed, now under beam comissioning. We hope to be able to report the first lasing.
	Slides
	Talk

MOPPH001	Coherent Harmonic Generation on UVSOR-II Storage Ring	laser, electron, storage-ring, radiation	37
	M. Labat, G. Lambert 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 D. Nutarelli LAC, Orsay Y. Takashima Nagoya University, Nagoya
	In the Coherent Harmonic Generation Free Electron Laser configuration, an external seed signal, a commercial laser source, is focused inside the first undulator. The interaction between the electron beam and this seed leads to a more coherent light emission. Such devices are very promising for short wavelength operation with a rather compact facility. Experiments have been performed on the UVSOR-II Storage Ring (Okazaki, Japan) with electrons stored at 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, allowing emission at 266 nm. This third harmonic has been characterised versus various parameters. Optimizations have been realized on the electron beam and laser synchronisation, seed characteristics (focussing point, energy, and pulse duration). The dependency of the harmonic signal on the gain (undulator gap, magnetic functions) has also been studied. Theory is compared to experiment using both analytical models and simulation. These encouraging results make UVSOR-II storage ring an active test facility for Coherent Harmonic Generation scheme, as well as a potential VUV source for users experiments.

MOPPH011	FELO: A One-Dimensional Time-Dependent FEL Oscillator Code	simulation, electron, radiation, emittance	59
	B. W.J. McNeil, G. R.M. Robb USTRAT/SUPA, Glasgow D. J. Dunning, N. Thompson CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
	A one-dimensional, SDDS compliant time-dependent FEL oscillator code has been developed in Fortran 90. The code, FELO, solves universally-scaled FEL equations to simulate oscillator FELs operating from the low to high gain regime. The code can simulate start-up from shot noise, different electron pulse current distributions, the effects of cavity length detuning and temporal jitter between electron bunches. Cavity detuning curves for both the low-gain IR-FEL and the regenerative amplifier VUV-FEL of the 4th Generation Light Source (4GLS) proposal at Daresbury Laboratory are modelled. The code predictions for the VUV-FEL output are compared with simulations performed with the parallel implementation of Genesis 1.3 and are found to be in good agreement.

MOPPH012	The Conceptual Design of the 4GLS XUV-FEL	electron, photon, lattice, simulation	63
	B. W.J. McNeil USTRAT/SUPA, Glasgow B. Sheehy Sheehy Scientific Consulting, Wading River, New York N. Thompson CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
	The Conceptual Design Report for the 4th Generation Light Source (4GLS) at Daresbury Laboratory in the UK was published in Spring 2006. A key component of the proposal is an XUV-FEL amplifier directly seeded by a High Harmonic source and operating in the photon energy range 8-100eV. Numerical modelling shows the FEL may generate ~50fs (FWHM) pulses of variably-polarised, temporally-coherent radiation with peak powers in the range 2-8 GW.

MOPPH015	Analysis of Smith-Purcell BWO with End Reflections	electron, simulation, damping, interaction-region	71
	V. Kumar RRCAT, Indore (M. P.) K.-J. Kim ANL, Argonne, Illinois
	All the previous analyses of Smith-Purcell Backward Wave Oscillator (SP-BWO) have assumed that there is no reflection at the end of the grating. We present an analysis of SP-BWO taking the reflection at the end of the grating into account. We study the dependence of start current on end reflection, taking the attenuation due to finite conductivity into account.

MOPPH026	Overview of Perseo, a System for Simulating FEL Dynamics in Mathcad	simulation, coupling, electron, resonance	91
	L. Giannessi ENEA C. R. Frascati, Frascati (Roma)
	The computing performances of today's personal computers are sufficient for executing interactively one dimensional FEL simulations. Mathcad is a versatile tool for implementing math expressions, plotting data and analysing results with the main prerogative of the simplicity of the user-interface. This suggested to develope a set of functions devoted to the simulation of FEL dynamics that can be accessed from the Mathcad environment. The result is Perseo, a flexible tool that can be simply programmed to set up FEL simulations in a wide variety of practical configurations. Perseo allows the time dependent simulation of SASE and seeded FEL configurations, oscillator configurations and exhotic configurations like master oscillator power amplifier or multiple stages cascaded FELs. The model include higher order harmonics and startup from shot-noise. Perseo is freely available at http://www.perseo.enea.it

MOPPH028	Future Seeding Experiments at SPARC	laser, radiation, resonance, electron	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 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
	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.

MOPPH031	The Saturated Regime of a Seeded Single-Pass Free Electron Laser: a Theoretical Investigation through the Statistical Mechanics of the Vlasov Equation	electron, bunching, laser, radiation	103
	F. Curbis, F. Curbis Università degli Studi di Trieste, Trieste A. Antoniazzi, D. Fanelli Università di Firenze, Florence G. De Ninno ELETTRA, Basovizza, Trieste
	The quasi-stationary state characterizing the saturation of a single-pass free-electron laser is governed by the Vlasov equation obtained by performing the continuum limit of the Colson-Bonifacio model. By means of a statistical treatment, this approach allows to predict analytically the saturated laser intensity as well as the final electron-beam energy distribution. In this paper we consider the case of coherent harmonic generation obtained from a seeded free-electron laser and present predictions for the first stage of the project FERMI at Elettra project at Sincrotrone Trieste.

MOPPH032	Analysis of FEL Oscillations in a Perfectly Synchronized Optical Cavity	electron, laser, radiation, linac	107
	N. Nishimori JAEA/FEL, Ibaraki-ken
	We analyze free electron laser (FEL) oscillations in a perfectly synchronized optical cavity by solving the one dimensional FEL equations. The radiation stored in the cavity is shown to finally evolve into an intense few-cycle optical pulse in the high gain and low loss regime. The evolution of the leading slope of the optical pulse, which is defined from the front edge toward the primary peak, is found to play an important role in generating the intense few-cycle pulse. The phase space evolution of electrons on the second pass which interact with the leading slope of a SASE output pulse is obtained in a perturbation method similar to that used in our previous study for a SASE FEL. The resulting analytical solution of the leading slope in the 2nd pass is shown to be approximated by that of a SASE FEL with FEL parameter greater than rho. The same perturbation method can thus be used to the subsequent passes. The peak amplitude and the pulse length at saturation are found to scale with the electron beam density and optical cavity loss. Those scalings accounts for the intense few-cycle FEL pulses observed in a high power FEL. N. Nishimori, Phys. Rev. ST-AB 8, 100701 (2005).

MOPPH040	Transverse Coherence Properties of the LCLS X-Ray Beam	radiation, electron, simulation, laser	126
	S. Reiche UCLA, Los Angeles, California H.-D. Nuhn SLAC, Menlo Park, California
	Self-amplifying spontaneous radiation free-electron lasers, such as the LCLS or the European XFEL, rely on the incoherent, spontaneous radiation as the seed for the amplifying process. Though this method overcomes the need for an external seed source one drawback is the incoherence of the effective seed signal. The FEL process allows for a natural growth of the coherence because the radiation phase information is spread out within the bunch due to slippage and diffraction of the radiation field. However, at short wavelengths this spreading is not sufficient to achieve complete coherence. In this presentation we report on the results of numerical simulations of the LCLS X-ray FEL. From the obtained radiation field distribution the coherence properties are extracted to help to characterize the FEL as a light source.

MOPPH042	An Analysis of Shot Noise Propagation and Amplification in Harmonic Cascade FELs	electron, laser, bunching, radiation	130
	Z. Huang SLAC, Menlo Park, California
	The harmonic generation process in a harmonic cascade (HC) FEL is subject to noise degradation which is proportional to the square of the total harmonic order. In this paper, we study the shot noise evolution in the first-stage modulator and radiator of a HC FEL that produces the dominant noise contributions. We derive the effective input noise for a modulator operating in the low-gain regime, and analyze the radiator noise for a density-modulated beam. The significance of these noise sources in different harmonic cascade designs is also discussed. E. Saldin, E. Schneidmiller, M. Yurkov, Opt. Commun. 202, 169 (2002).

MOPPH046	Seeding the FEL of the SCSS Prototype Accelerator with Harmonics of a Ti:Sa Laser Produced in Gas.	laser, focusing, radiation, simulation	138
	G. Lambert, M. Bougeard, W. Boutu, B. Carré, D. Garzella, M. Labat 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
	A particular seeded configuration 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), 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 external source, obtained by the High order Harmonic Generation (HHG) process, can be tuned from the 3th (260 nm) to the 13th harmonic (60 nm) of a Ti: Sa laser generated in a gas cell. The experiment contains a first chamber, dedicated to harmonic generation and a second one for harmonic beam diagnostics and adaptation of the harmonic waist in the modulator. The tests have been performed in Saclay (15 mJ, 10 Hz, 50 fs). An energy of 2e-6J with a high stability for the 3th harmonic and a good transversal shape with an optimized energy level and a high stability for the 13th harmonic have been obtained at the modulator center place. The performances using PERSEO, GENESIS and SRW will be updated. The chambers will be installed on the SCSS test facility in the beginning of July for seeding tests during summer.

MOPPH047	Seeding SPARC Facility with Harmonic Generation in Gases: Preliminary Tests of the Harmonic Generation in Gas Chamber	laser, electron, photon, focusing	142
	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)
	A coherent short wavelength source can be realised with a Free Electron Laser by using High Gain Harmonic Generation configuration. The injection of an external light source in the first part of an undulator results in a coherent light emission in its second part. The SPARC FEL (Frascati, Italy), delivering an electron beam at 200 MeV passing through an undulator of 6 sections, can be configured to test such schemes. We propose to use High order Harmonic Generation (HHG) in gases process as the seed. HHG produces a coherent XUV source by focusing an intense laser pulse into a gas medium. This beam, composed of odd harmonics of the fundamental laser, is then shaped using a telescope of two spherical mirrors, allowing the focusing at a given position, in the SPARC undulator. Appropriate tuning of the undulator gaps will amplify the 3rd and 5th harmonics seeded, and non-linear harmonics of those wavelengths, allowing the perspective of producing VUV coherent radiation. The chambers for harmonic generation and shaping have been realised and tested at the CEA (Saclay, France). We present these tests as well as simulations of the expected performances of the SPARC FEL with this seed.

MOPPH048	The ARC-EN-CIEL FEL Proposal	laser, emittance, radiation, electron	146
	C. Bruni, O. V. Chubar, J.-M. Filhol, A. Loulergue, L. Nahon SOLEIL, Gif-sur-Yvette P. Bosland, B. Carré, M.-E. Couprie, G. Devanz, D. Garzella, O. Gobert, Ph. Hollander, M. Jablonka, M. Labat, G. Lambert, M. Luong, F. Meot, P. Monot, A. Mosnier, G. Petite, O. Tcherbakoff, B. Visentin CEA, Gif-sur-Yvette J.-R. Marquès LULI, Palaiseaux H. Monard, J.-M. Ortega CLIO/ELYSE/LCP, Orsay A. Rousse LOA, Palaiseau
	ARC-EN-CIEL (Accelerator-Radiation for Enhanced Coherent Intense Extended Light aims at providing the user community with coherent femtosecond light pulses covering from UV to soft X ray in France. Phase 1 aims at exploiting the different sources of seeding, in particular Harmonic generation in Gas (HHG), to improve the longitudinal coherence and shortening the output radiation wavelength in a rather compact device. Phase 2 uses a CW 10 KHz 1 GeV superconducting linear accelerator delivering high charge, subpicosecond, low emittance electron bunches for HHG seeded High Gain harmonic Generation extending to 1 nm. In phase 3, fs undulator sources in the IR, VUV and X ray and a FEL oscillator in the 10 nm range will be implemented on ERL beam loops for beam current or energy enhancement. Electron plasma acceleration and fs hard X ray produced by Thomson Scattering are also foreseen. Preliminary studies are carried out in the frame of the EUROFEL collaboration, concerning the electro-optical measurement at ELYSE, carbon nanotubes, synchronisation and beam shaping for the gun, seeding with high harmonics produced in gas on SPARC and compensation of microphonics for the Linac.

MOPPH050	The Properties of the FEL Output for Different Seeding Schemes	radiation, simulation, optics, electron	150
	J. Bahrdt BESSY GmbH, Berlin B. Faatz, R. Treusch DESY, Hamburg V. Miltchev Uni HH, Hamburg R. Reininger New Affiliation Request Pending, -TBS-
	Several seeding schemes, like self seeding for FLASH or seeded HGHG cascades for BESSY soft X-ray FEL, are proposed for existing or planned free electron laser facilities. The simulation of these schemes requires the detailed knowledge of the properties of the seeding radiation and the implementation of these properties in the Codes. Time dependent simulations with the 3D code GENESIS calculate the electric field distribution in and at the end of the undulator. The physical optics code PHASE permits the propagation of wave fronts across grazing incidence optics. Using the combination GENESIS PHASE GENESIS, the properties of the FEL output for different seeding schemes can be obtained. For example, the radiation quality of a SASE FEL can be improved in a self seeding scheme. Here, the radiation is monochromatized after a first undulator section and reflected back to the second Undulator modules. We present simulation studies for the self seeding option of FLASH.

MOPPH053	Simulation Studies on the Self-Seeding Option at FLASH	electron, radiation, simulation, optics	162
	V. Miltchev, J. Rossbach Uni HH, Hamburg B. Faatz, R. Treusch DESY, Hamburg
	In order to improve the temporal coherence of the radiation generated by FLASH, a two-stage seeding scheme* is presently being realized. It consists of two undulator stages and a magnetic chicane and a monochromator located between them. In this contribution we investigate various configurations of the electron optics of the seeding set-up. The optimization of the lattice in the first seeding stage and the parameters of the magnetic chicane will be discussed. Simulation results for the performance of the seeded FEL at different resonant wavelengths will be presented. * J. Feldhaus et. al. "Possible application of X-ray optical elements for reducing the spectral bandwidth of an X-ray SASE FEL". Optics Communications, Volume 140, Pages 341-352

MOPPH054	FERMI @ Elettra: A Seeded FEL Facility for EUV and Soft X-Rays	electron, linac, laser, radiation	166
	J. N. Corlett, L. R. Doolittle, W. M. Fawley, S. M. Lidia, G. Penn, I. V. Pogorelov, J. Qiang, A. Ratti, J. W. Staples, R. B. Wilcox, A. Zholents LBNL, Berkeley, California E. Allaria, C. J. Bocchetta, D. Bulfone, F. C. Cargnello, D. Cocco, P. Craievich, G. D'Auria, M. B. Danailov, G. De Ninno, S. Di Mitri, B. Diviacco, M. Ferianis, A. Galimberti, A. Gambitta, M. Giannini, F. Iazzourene, E. Karantzoulis, M. Lonza, F. M. Mazzolini, G. Penco, L. Rumiz, S. Spampinati, G. Tromba, M. Trovo, A. Vascotto, M. Veronese, M. Zangrando ELETTRA, Basovizza, Trieste M. Cornacchia, P. Emma, Z. Huang, J. Wu SLAC, Menlo Park, California W. Graves, F. X. Kaertner, D. Wang MIT, Middleton, Massachusetts
	We describe the conceptual design and major performance parameters for the FERMI FEL project funded for construction at the Sincrotrone Trieste, Italy. This user facility complements the existing storage ring light source at Sincrotrone Trieste, and will be the first facility to be based on seeded harmonic cascade FELs. Seeded FELs provide high peak-power pulses, with controlled temporal duration of the coherent output allowing tailored x-ray output for time-domain explorations with short pulses of 100 fs or less, and high resolution with output bandwidths of the order of meV. The facility uses the existing 1.2 GeV S-band linac, driven by electron beam from a new high-brightness rf photocathode gun, and will provide tunable output over a range from ~100 nm to ~10 nm, and APPLE undulator radiators allow control of x-ray polarization. Initially, two FEL cascades are planned, a single-stage harmonic generation to operate over ~100 nm to ~40 nm, and a two-stage cascade operating from ~40 nm to ~10 nm or shorter wavelengh, each with spatially and temporally coherent output, and peak power in the GW range.

MOPPH055	Coherent Harmonic Emission of the Elettra Storage-Ring Free-Electron Laser in Single-Pass Configuration: a Numerical Study for Different Undulator Polarizations	simulation, laser, electron, storage-ring	170
	F. Curbis, F. Curbis Università degli Studi di Trieste, Trieste G. De Ninno ELETTRA, Basovizza, Trieste H. Freund SAIC, McLean
	The optical klystron installed on the Elettra storage-ring is normally used as interaction region for an oscillator free-electron laser, but, removing the optical cavity and using an external seed laser, one obtains an effective scheme for the single-pass harmonic generation. In this configuration, which is presently under development, the high-power external laser is synchronized with the electron beam entering the first undulator of the optical klystron. The laser-electron beam interaction produces a spatial partition of electrons in micro-bunches separated by the seed wavelength. The micro-bunching is then exploited in the second undulator (radiator) to produce coherent light at the harmonics of the seed wavelength. The Elettra radiator is an APPLE type undulator and this allows to explore different configurations of polarization. We present here numerical results obtained using the code Medusa for both planar and helical configurations. We also draw a comparison with predictions of the numerical code Genesis.

MOPPH057	Design and Performance of the FERMI at Elettra FEL	electron, simulation, photon, laser	174
	G. De Ninno, E. Allaria ELETTRA, Basovizza, Trieste W. M. Fawley, G. Penn LBNL, Berkeley, California
	The FERMI project* at Sincrotrone Trieste is the first user facility based on seeded, harmonic cascade FELs. The second stage FEL will produce tunable output in the 10-40nm wavelength range and will rely upon two stages of harmonic up-conversion. A major goal for this FEL is good longitudinal output coherence (i.e., small spectral bandwidth). At present, we are examining the performance characteristics of two possible configurations. The first "fresh bunch" option is a classic harmonic cascade, where the output radiation from the first radiator is used to seed a fresh part of the electron bunch in the second-stage modulator. The second "whole bunch" scheme seeds the entire e-beam pulse, uses a much shorter first radiator and completely eliminates the second modulator, with the second radiator involving many e-folds of gain. Relying both upon time-steady input parameter sensitivity studies and full start-to-end time-dependent simulations*, we examine the predicted performance of the two configurations and compare with users requirements. C. Bocchetta et al., this meeting ** S. Di Mitri et al., this meeting

MOPPH061	The Test Facility for Harmonic Generation at the MAX-lab Injector Linac	laser, electron, gun, linac	182
	S. Werin, M. Brandin, T. Hansen, S. Thorin MAX-lab, Lund M. Abo-Bakr, J. Bahrdt, K. Goldammer BESSY GmbH, Berlin A. L'Huillier, J. Larsson, A. Persson, C.-G. Wahlstrom New Affiliation Request Pending, -TBS-
	The MAX-lab injector linac system will be used in a test set-up for developing and testing techniques important for the designs of the BESSY FEL and the MAX IV FEL proposals. The first goal is using a 400 MeV electron beam to generate third harmonic photons at 90 nm from a 266 nm seed laser. The installations at MAX-lab are being improved by a new photo cathode RF gun (to improve emittance and peak current), an optical klystron (2 undulators + chicane, supplied by BESSY) and a combined synchronised laser system for both the RF-gun and the seeding system. The injector optics and transport system are also being retuned to allow the necessary electron beam compression. The project is a part of the EUROFEL collaboration.

MOPPH063	Coherent X-Ray Production by Cascading Stages of High Gain Harmonic Generation Free Electron Lasers Seeded by IR Laser Driven High-Order Harmonic Generation	radiation, electron, laser, emittance	186
	J. Wu, P. R. Bolton SLAC, Menlo Park, California
	Coherent x-ray production achieved by seeded free electron lasing with cascaded high gain harmonic generation (HGHG) is important for next generation development of synchrotron light sources. We examine the feasibility and some features of FEL emission seeded by a high order harmonic of an intense infrared conventional laser source (HHG). In addition to the intrinsic FEL chirp phenomenon, the longitudinal profile and spectral bandwidth of the HHG seed are modified significantly by the FEL interaction well before saturation occurs. This smears out the original attosecond pulselet structure. As an example, we describe a cascaded HGHG scheme for coherent x-ray FEL generation that is seeded by the twenty-seventh harmonic of an ultrashort 800 nm laser pulse with 10 fs rms duration. Given the multiple order HHG spectrum, proof-of-principle experiments using lower order harmonics can also be considered.

MOPPH066	Chirped Pulse Amplification Experiment at 800 nm	electron, laser, linac, dipole	194
	L.-H. Yu, D. F.L. Liu, J. Rose, T. V. Shaftan, T. Tsang, X. J. Wang, T. Watanabe BNL, Upton, Long Island, New York
	We report the chirped pulse amplification (CPA) experiment carried out using 800 nm direct seed and NISUS undulator as free electron laser amplifier at SDL of BNL. The experiment indicated that due to saturation in the center part of the chirped electron bunch the output pulse shape has a dip in the middle, as result the edge of the bunch has higher power than the center. Hence the output spectrum also showed a dip in the center, resulting a larger FWHM bandwidth than the seed. An interesting result is that the output of the 800 nm chirped FEL pulse was compressed and generated a pulse length shorter than what the seed itself can be compressed to.

MOPPH068	Attosecond Pulses from X-Ray FEL with an Energy-Chirped Electron Beam and a Tapered Undulator	electron, laser, simulation, radiation	202
	E. Saldin, E. Schneidmiller, M. V. Yurkov DESY, Hamburg
	We present a new scheme for generation of attosecond pulses in X-ray SASE FEL. A short slice in the electron beam is strongly modulated in energy by a few-cycle laser pulse in a short undulator, placed in front of the main undulator. Gain degradation within this slice is compensated by an appropriate undulator taper while the rest of the bunch suffers from this taper and does not lase. Three-dimensional simulations with the code FAST predict that short (200 attoseconds) high-power (up to 100 GW) pulses can be produced in Angstrom wavelength range with a high degree of contrast. A possibility to reduce pulse duration to sub-100 attosecond scale is discussed.

MOPPH069	Transverse and Longitudinal Coherence Properties of the Radiation from X-Ray SASE FELs	radiation, electron, simulation, emittance	206
	E. Saldin, E. Schneidmiller, M. V. Yurkov DESY, Hamburg
	We present the results of comprehensive numerical studies on transverse and longitudinal coherence of SASE FEL radiation. Development of coherence in exponential gain regime and saturation is studied with the help of similarity techniques. Expected coherence properties of X-ray sourses at the European XFEL, LCLS and SCSS are compared. The simulations were performed with the three-dimensional time-dependent code FAST using a real number of particles in the electron bunch.

MOPPH071	Design Status of PAL-XFEL	radiation, linac, electron, space-charge	210
	T.-Y. Lee, Y. S. Bae, J. Choi, J. Y. Huang, H.-S. Kang, C. Kim, D. E. Kim, M. Kim, I. S. Ko, J.-S. Oh, Y. W. Parc PAL, Pohang, Kyungbuk Y. Kim FEL/Duke University, Durham, North Carolina J. H. Park POSTECH, Pohang, Kyungbuk
	Pohang Accelerator Laboratory has a plan to build an X-ray FEL machine. This new machine will utilize the existing 2.5 GeV injection linac to the storage ring by upgrading its energy up to 3.7 GeV or more. The target wavelength will be 3-4.5 Angstrom and its third harmonic 1-1.5 Angstrom will also be used. The project will proceed in two stages: In the first stage, a VUV SASE machine with 385 MeV will be constructed and tested for the proof-of-principle. The full X-ray machine will be constructed in the next stage.

MOPPH073	An Enhanced GINGER Simulation Code with Harmonic Emission and HDF5 IO Capabilities	radiation, simulation, vacuum, diagnostics	218
	W. M. Fawley LBNL, Berkeley, California
	GINGER* is an axisymmetric, polychromatic (r-z-t) FEL simulation code originally developed in the mid-1980's to model the performance of single-pass amplifiers. Over the past 15 years GINGER's capabilities have been extended to include more complicated configurations such as undulators with drift spaces, dispersive sections, and vacuum chamber wakefield effects; multi-pass oscillators; and multi-stage harmonic cascades. Its coding base has been tuned to permit running effectively on platforms ranging from desktop PC's to massively parallel processors such as the IBM-SP. Recently, we have made significant changes to GINGER by replacing the original predictor-corrector field solver with a new direct implicit algorithm, adding harmonic emission capability, and switching to the HDF5 IO library** for output diagnostics. In this paper, we discuss some details regarding these changes and also present simulation results for a number of test cases ranging from LCLS SASE emission to performance of the FERMI@ELETTRA two-stage, harmonic cascade. * http://www-ssrl.slac.stanford.edu/lcls/technotes/LCLS-TN-04-3.pdf (also LBNL-49625-Rev. 1) ** http://hdf.ncsa.uiuc.edu/HDF5/

MOPPH075	Simulations of High Power-FEL Amplifiers	electron, simulation, extraction, laser	222
	J. Blau, D. T. Burggraff, W. B. Colson, T. Voughs NPS, Monterey, California
	FEL amplifier simulations have been updated and parallelized, and system vibration effects have been added. The simulations are used to study proposed high-power amplifier FELs at LANL and BNL. We look at the single-pass gain and output power, including the effects of wiggler tapering, electron beam pinching, and shifting and tilting of the electron beam.

MOCAU01	The BESSY Soft X-Ray FEL: A Seeded HGHG FEL	electron, radiation, laser, bunching	226
	A. Meseck BESSY GmbH, Berlin
	Reproducibility, high power and short pulse length combined with variable polarization and tunable wavelength are the requirements to open new frontiers for the soft X-ray users. To provide radiation with such extraordinary properties, BESSY has been designing a seeded FEL based on high-gain harmonic-generation (HGHG) concept. The seeding with an external tunable laser ensures the reproducibility of the full-coherent radiation. The combination of so-called HGHG stages, used to down-convert the seed wavelength, and a final amplifier provides for the high power and superior spectral properties. Furthermore, the HGHG concept and the fresh bunch techniques planned for BESSY FEL mitigate the effects of parameter variation along the bunch which are expected from realistic assumptions of the Gun and LINAC structure. The design concept of the BESSY soft X-ray FEL will be presented and the stabilizing effect of HGHG stages and the benefits from the fresh bunch techniques and final amplifier will be discussed.
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MOCAU03	The Use of HHG at 4GLS	radiation, electron, photon, simulation	234
	B. W.J. McNeil USTRAT/SUPA, Glasgow D. J. Dunning, N. Thompson CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire B. Sheehy Sheehy Scientific Consulting, Wading River, New York
	4GLS is a facility proposed for the Daresbury Laboratory in the UK* which will offer users a suite of high brightness synchronised sources from THz frequencies into the XUV. In the current design, photon energies from 8-100eV will be generated in a variable polarisation FEL amplifier directly seeded by a High Harmonic Gain system. The reasoning behind this choice will be discussed and characterisation of the sources based on the present design presented. *http://www.4gls.ac.uk/documents.htm#CDR
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MOCAU05	Analysis of the Process of Amplification in a Single Pass FEL of High Order Harmonics Generated in a Gas Jet	electron, laser, simulation, radiation	248
	L. Giannessi, M. Quattromini ENEA C. R. Frascati, Frascati (Roma) P. Musumeci INFN-Roma, Roma M. Nisoli, G. Sansone, S. Stagira, S. de Silvestri Politecnico/Milano, Milano
	We have studied the amplification of high harmonics generated by a short infrared pulse in a gas jet, injected in a free electron laser amplifier. The high-order harmonic spectra have been simulated using a 3D non-adiabatic model that includes both the single atom response and the effect of the propagation of the XUV field inside the gas jet. The response of a single atom to the IR field is calculated in the framework of the Strong Field Approximation (SFA); The nonlinear polarization associated to this process is evaluated as the acceleration of the nonlinear dipole moment. This term is used as source term in the propagation of the harmonic field inside the gas jet. The propagation effect are extremely relevant for the temporal structure of the XUV field as the coherent interference of the dipole emission of the different atoms leads to the selection of only one XUV pulse for each semi-cycle of the driving IR field. The amplification in the free electron laser has been simulated both in 1D and 3D with Perseo and GENESIS 1.3 respectively. The effects of filtering the seed spectrum have been analyzed and the coherence properties of the light are considered.
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TUAAU02	Future Light Sources: Integration of Lasers, FELs and Accelerators at 4GLS	electron, linac, radiation, laser	257
	J. A. Clarke CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
	4GLS is a novel next generation proposal for a UK national light source to be sited at Daresbury Laboratory, based on a superconducting energy recovery linac (ERL) with both high average current photon sources (undulators and bending magnets) and three high peak current free electron lasers. Key features are a high gain, seeded FEL amplifier to generate XUV radiation and the prospect of advanced research arising from unique combinations of sources with femtosecond pulse structure. The conceptual design is now completed and a CDR recently published. The 4GLS concept will be summarised, highlighting how the significant design challenges have been addressed, and the project status and plans explained.
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TUAAU03	FEL Oscillation with a High Extraction Efficiency at JAEA ERL FEL	electron, quadrupole, laser, linac	265
	N. Nishimori JAEA/FEL, Ibaraki-ken R. Hajima, H. Iijima, N. Kikuzawa, E. J. Minehara, R. Nagai, T. Nishitani, M. Sawamura JAEA/ERL, Ibaraki
	One of challenges that high power FEL oscillators with energy recovery linac (ERL) are facing is to increase the extraction FEL efficiency as high as possible. The high efficiency oscillation relaxes the total beam current needed for high power lasing and makes the FEL optical pulse length shorter, which is useful for various applications. A Bates type recovery loop with energy acceptance well in excess of 10% allows an ERL FEL at Jefferson Lab to operate with a high FEL efficiency. A triple bend achromat loop with energy acceptance of 7% has been used in an ERL FEL at Japan Atomic Energy Agency (JAEA). Recently we have achieved the efficiency exceeding 2%, which accompanies large energy spread beyond the energy acceptance of the loop, by doubling the electron bunch repetition rate*. The optical pulse can now interact with a fresh electron bunch every round trip, while it overlapped with an injected electron every two round trips before the doubling of the bunch repetition. This talk will summarize our recent development of a high power FEL with a high extraction efficiency at JAEA ERL FEL. S. Benson et al., in proceedings of the FEL2004, (2004) 229. R. Hajima et al., Nucl. Instr. and Meth. A445 (2000) 384. * R. Nagai et al., in these proceedings.
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TUAAU05	Optical Design of the Energy Recovery Linac FEL at Peking University	linac, emittance, simulation, space-charge	277
	Z. C. Liu, J.-E. Chen, J. K. Hao, K. X. Liu, X. Y. Lu, S. W. Quan, B. C. Zhang, K. Zhao, G. M. wang PKU/IHIP, Beijing
	Peking University is currently building an Energy Recovery Linac FEL (PERFEL). The system is consisted of the DC-SC photocathode injector, the superconducting main linac which is composed of two nine cell TESLA-type cavities and the beam transport system. The objective of the PERFEL is to build a testbed for the study of beam dynamics and accelerator technology for energy recovery except to provide infrared FEL. In this paper the main parameters of the PERFEL are described and the optical design for the beam transport of PERFEL is presented. The simulation is carried out using the typical particle tracking codes such as elegant. *Corresponding author. Tel: +86-10-6275-8528; Fax: +86-10-6275-1875. Email address: kxliu@pku.edu.cn
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TUBAU01	Prospects of Cascaded Harmonic Generation FELs	laser, electron, bunching, radiation	281
	G. Penn LBNL, Berkeley, California
	Harmonic generation in Free Electron Lasers (FELs) encompasses many techniques for using an input seed laser to produce FEL radiation at a frequency that is multiples above that of the seed laser itself. This allows for the advantages of seeded FELs to be preserved, while extending the reach of these FELs to photon energies far above those produced by conventional laser sources. Many new projects are underway to make use of these methods, including the FERMI@Elettra* facility which envisions the use of two harmonic generation stages to reach photon energies above 100 eV. Different methods of harmonic generation are discussed, as well as the technical challenges to overcome in attempting to chain together multiple harmonic stages in an FEL. * C. Bocchetta et al., Proceedings of the 2005 FEL Conference, (2005) 682.
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TUBAU04	Inverse Free Electron Lasers for Advanced Light Sources	laser, electron, radiation, simulation	292
	P. Musumeci, F. Germoni, M. Mattioli, M. Serluca INFN-Roma, Roma
	Laser accelerators hold the promise for high gradient acceleration and production of ultra short electron bunches. Among these, the inverse free-electron laser has recently demonstrated to be a mature and reliable scheme ready to step up from successful proof-of-principle experiments to cutting-edge applications. The very high gradient and the multi kAmp peak current of the output beam make it an attractive option in the hundreds of MeV to few GeV energy region. We examine the feasibility of using an IFEL driven by an high power Ti:Sa laser source to generate soft x-rays by FEL interaction in an undulator. A control of the slippage of the radiation over the ultrashort spikes of the IFEL-microbunched beam current is implemented to increase the gain and maintain the 200as-long pulse structure in the radiation profile.
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	Talk

TUBAU05	Technical Aspects of the Integration of the Optical Replica Synthesizer for the Diagnostics of Ultra-short Bunches into FLASH at DESY	laser, electron, diagnostics, vacuum	296
	P. van der Meulen, N. X. Javahiraly, M. Larsson FYSIKUM, AlbaNova, Stockholm University, Stockholm E. Saldin, H. Schlarb, E. Schneidmiller, A. Winter, M. V. Yurkov DESY, Hamburg V. G. Ziemann UU/ISV, Uppsala
	Recently, Saldin et al.* introduced a novel scheme to characterise ultra-short electron bunches in a FEL. The method is based on producing an 'optical copy' of the electron bunch, which can then be easily analysed using well-known non-linear optical techniques. To this end, a near-IR laser beam is overlapped with the electron beam in the first undulator of an optical klystron. In the following dispersive section the laser-induced energy modulation is transformed into a density modulation . The modulated electron bunch then produces a strong optical pulse in the second undulator. Analysis of this near-IR pulse (the optical copy) then provides information about the length, the slice emittance and the slice energy spread of the original electron bunch. We discuss the implementation of such a measurement set-up at the VUV-FEL at DESY and investigate the influence of various parameters on the performance of the device. Topics we address include the electron beam optics of the undulators, quadrupoles and the dispersive chicane, as well as the requirements for the seed laser pulses. The detection and analysis of the near-IR pulse and an extension to the XUV-FEL are also covered. * E. Saldin, et al. "A simple method for the determination of the structure of ultrashort relativistic electron bunches," Nucl. Inst. and Methods A 539 (2005) 499.
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	Talk

TUPPH001	A 3D Model of the 4GLS VUV-FEL Conceptual Design Including Improved Modelling of the Optical Cavity	simulation, radiation, electron, optics	304
	N. Thompson, D. J. Dunning CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire K.-J. Boller, J. G. Karssenberg, P. J.M. van der Slot Twente University, Laser Physics and Non-Linear Optics Group, Enschede B. W.J. McNeil USTRAT/SUPA, Glasgow
	The Conceptual Design Report for the 4th Generation Light Source (4GLS) at Daresbury Laboratory in the UK was published in Spring 2006. The proposal includes a low-Q cavity (also called a regenerative amplifier) FEL to generate variably-polarised, temporally-coherent radiation in the photon energy range 3-10eV. A new simulation code has been developed that incorporates the 3D FEL code Genesis 1.3 and which simulates in 3D the optical components and radiation propagation within the non-amplifying sections of an optical cavity. This code is used to estimate the optimum low-Q cavity design and characterise the output from the 4GLS VUV-FEL. J. G. Karstenberg, P. J.M. van der Slot, J. W.J. Verschuur, I. V. Volohkin, K.-J. Boller (ibid)

TUPPH014	Laser Gain and Intra-Cavity Losses of the ELBE Mid-IR FEL	laser, electron, radiation, optics	339
	U. Lehnert, P. Michel, W. Seidel, J. Teichert, R. Wuensch FZR, Dresden
	The the U27-FEL of the ELBE radiation source allows to choose between five mirrors with different outcoupling holes. This allows to adapt the optical resonator to the required wavelength range to ensure the needed laser gain and to optimize the outcoupled laser power. Another parameter which influences the achievable laser gain and output power is the detuning length of the optical cavity. While for CW operation often the minimum detuning point is choosen which maximizes the outcoupled power, for pulsed-mode operation about one wavelength of cavity detuning maximizes the laser gain and yields best stability of the laser. To gain some insight into the behavior of the optical resonator we have measured the round-trip losses and the net laser gain and compare both to calulations. For the measurements we have used a fast-readout MCT detector to measure the decay and rise-time of the outcoupled infrared beam caused by a 10μs break in the electron beam micro-pulse train. We show gain and loss for 5, 10 and 20μm wavelength with the typical detuning curves of an FEL.

TUPPH016	The Partial-Waveguide Resonator of the U100-FEL at FZ Rossendorf	vacuum, laser, alignment, electron	345
	R. Wuensch, M. Freitag, R. Schlenk, W. Seidel, U. Willkommen, D. Wohlfarth, B. Wustmann FZR, Dresden
	The U100-FEL, which is under construction at the Forschungszentrum Rossendorf, will be equipped with a parallel-plate waveguide which is 10 mm high (inside), almost 8 m long and covers more than two third of the total resonator length. Its horizontal width varies from 70 mm within the undulator up to 130 mm at the downstream resonator mirror. A special diagnostics had to be developed to align the electron and the IR beam within this waveguide. A drive system has been designed for the cylindrical downstream resonator mirror. It allows to shift and tilt the mirror, which is completely embedded in the waveguide. The size and the curvature of the bifocal upstream resonator mirror has been fitted to minimize the optical loss in the resonator. To adjust the outcoupling to the varying beam size on the mirror surface a set of three collocated, relocatable mirrors with different outcoupling hole sizes will be applied. We present various sophisticated design concepts which comply with the large wavelength range and the special requirements caused by the bulky waveguide construction and its small free space in vertical direction.

TUPPH026	Dispersion Effects in Short Pulse Waveguide FEL	electron, radiation, simulation, free-electron-laser	378
	N. S. Ginzburg, A. Sergeev IAP/RAS, Nizhny Novgorod E. R. Kocharovskaya New Affiliation Request Pending, -TBS-
	The influence of waveguide dispersion on the FEL operation driven by short electron bunches is studied. Under the assumption of a high quality resonator a parabolic equation for the evolution of electromagnetic pulse profile is derived. Based on an analytical theory describing the linear stage of generation a starting condition is determined. A structure of supermodes representing the sum of resonator eigenmodes with locked phases is found as well. It is demonstrated that due to waveguide dispersion FEL is able to generate not only for positive but also for negative cavity detuning. The computer simulation of a nonlinear regime taking into account electromagnetic pulse dispersion defines a stationary profile of electromagnetic pulse in good agreement with experimental results,. It is shown that regimes with periodic and chaotic self-modulation of the pulse profile are realized for considerable exceeding of the length of interaction region over the threshold. A superradiant (transient) regime of short pulse generation is found for small cavity detuning. Jeong Y. U., et al. Proc. of the 2004 FEL Conference, Trieste, Italy, 2004, P.667. ** Doria A., Bartolini R., Feinstein J. IEEE J. Quantum Electron., 1993, V.29, P.1428.

TUPPH033	A FEL Amplifier Based on Planar Bragg Waveguides	coupling, electron, resonance, lattice	393
	N. S. Ginzburg, K. E. Dorfman, A. Malkin, R. M. Rozental IAP/RAS, Nizhny Novgorod
	A planar periodic Bragg structure can be used for wave guiding in the direction transverse to the lattice vector. Open Bragg waveguide can provide high selectivity over the transverse coordinate when its size essentially exceeds wavelength. We study several new schemes of FEL amplifiers based on these structures. In a transverse current amplifier scheme it is beneficial to use a grating with a step of corrugation, that results in the existence of a single low dissipative mode located near defect. The sheet electron beam moves across the waveguide to be resonant to one of partial waves forming the operating mode. Another way is a traditional traveling wave amplifier scheme where electron beam moves along waveguide axis. To increase effective size of operating mode is suggested a structure with regular longitudinal corrugation that couples two partial waves propagating at some angle to the axis to the wave propagating directly along the axis. This wave, which in moving reference frame is transformed into a cut off mode, is excited by the electrons. Analysis shows rather high gain and efficiency of the novel application schemes with simultaneous discrimination of parasitic modes. 1. N.S. Ginzburg, A. M.Malkin, N. Yu. Peskov et. al. Improving selectivity of free electron maser with 1D Bragg resonator using coupling of propagating and trapped waves, PR ST-AB 8,040705(2005)

TUPPH034	Generation of Narrow Band Short mm Wave Superradiance Pulses in a Non-uniform Planar Waveguide	electron, radiation, simulation, cyclotron	397
	N. S. Ginzburg, R. M. Rozental, A. Sergeev, I. V. Zotova IAP/RAS, Nizhny Novgorod
	Recently significant progress was achieved in production of ultrashort pulses in millimeter wave band based on intense electron bunch supperradiance,,*. One of the problems for advance similar mechanisms in shorter wave bands is spectrum broadening caused by the simultaneous bunch interaction with several waveguide modes. To suppress spurious interaction we suggest to use the non-uniform planar waveguide. In such a waveguide the phase velocities of the different modes varied over longitudinal coordinate, with the exception of the fundamental TEM mode. As a result it is possible to suppress interaction of the short electron bunch with higher-orders modes responsible for lower frequencies radiation including cut-off modes. We studied 200-500 GHz superradiance of a 2 MV, 100 A, 100-300 ps electron bunch in a planar regular wiggler. It is shown that narrow band superradiance pulses could be produced in the 2 m long planar waveguide with the gap between plates linear increasing from 1-2 to 5-8 wavelength. The peak power of the pulses amounted 3 MW and hundreds of kW for the 200 GHz and 500 GHz bands correspondingly. Ginzburg N. S, et al. // Nucl. Instr. Meth. Phys. Res., 1999, A429 (1), 94 N. S.Ginzburg, et al. // Opt. Comm., 2000, 175 (1-3), 139 *A. G.Reutova, et al. // JETP Lett., 2005, 82(5), 263

TUPPH037	FEL-Oscillator Simulations with Genesis 1.3	simulation, radiation, laser, optics	407
	J. G. Karssenberg, K.-J. Boller, J. W.J. Verschuur, P. J.M. van der Slot Twente University, Laser Physics and Non-Linear Optics Group, Enschede I. Volokhine Philips Research, Eindhoven
	We present a paraxial optical propagation code (OPC) as an extension to Genesis 1.3* for the theoretical description of FELs with an optical resonator. The OPC receives the optical output from a Genesis simulation, propagates it once through the resonator, and applies the result as the optical input pulse for a next run of Genesis. The OPC allows both the description of time dependent and steady state FEL operation. The propagation algorithms available are the Spectral algorithm, the Fresnel algorithm and a modified Fresnel algorithm. The latter enables a fast modelling of feedback via complex resonator designs that may include hard-edge elements (apertures) or hole-coupled mirrors with arbitrary shapes. The code enables to predict the output at each of the various optical elements which is of advantage for beam diagnostics and for designing suitable optics for a further propagation of the output beam. Finally, the OPC can be used to determine the far field output in connection with any Genesis 1.3 simulation, be it an oscillator or an amplifier FEL. As a test of the combined OPC and Genesis 1.3 codes we found good agreement with experimental data available for FELIX*. http://pbpl.physics.ucla.edu/~reiche/index.html** B. Faatz, Ph. D. Thesis, Nieuwegein, The Netherlands 1992.

TUPPH052	Future FEL Studies at the VISA Experiment in the SASE and Seeded Modes	radiation, electron, laser, simulation	443
	G. Andonian, M. P. Dunning, A. Y. Murokh, C. Pellegrini, S. Reiche, J. B. Rosenzweig UCLA, Los Angeles, California M. Babzien, I. Ben-Zvi, V. Yakimenko BNL, Upton, Long Island, New York
	The VISA (Visible to Infrared SASE Amplifier) experiment at BNL (Brookhaven National Laboratory) has previously demonstrated saturation at 840 nm in 2001. Further SASE studies, in 2003, have demonstrated an anomalously large bandwidth spread of the FEL spectrum due to off-angle emissions. This paper disseminates the current and future program of the VISA program at BNL. This includes a study of a seeded FEL, using a 1 micron YAG laser as a seed, and the accompanying diagnostics to characterize the radiation. Diagnostics include the double differential spectrometer, a mode converter to investigate the orbital angular momentum of light in the FEL, and an optical pepper-pot for coherence measurements. As usual, start-to-end simulations are presented.

TUPPH055	A Design for an XUV FEL Driven by the Laser-Plasma Accelerator at the LBNL LOASIS Facility	electron, laser, radiation, plasma	455
	W. M. Fawley, E. Esarey, W. Leemans, C. B. Schroeder LBNL, Berkeley, California
	We present a design for a compact FEL source of ultra-fast, high-peak flux, soft x-ray pulses employing a high-current, GeV-energy electron beam from the existing laser-plasma accelerator at LBNL's LOASIS facility. The proposed ultra-fast source would be intrinsically temporally synchronized to the drive laser pulse, enabling pump-probe studies in ultra-fast science with pulse lengths of ~10–25 fs. Owing both to the high current (>10 kA) and reasonable charge/pulse (~0.1-0.5 nC) of the laser-plasma-accelerated electron beams, saturated output fluxes are potentially on the order of 10¹⁴ photons/pulse. We examine devices based both on SASE and high-harmonic generated input seeds to give improved coherence and reduced undulator length, presenting both analytic scalings and numerical simulation results for expected FEL performance. A successful source would result in a new class of compact laser-driven FELs in which a conventional RF accelerator is replaced by a GeV-class laser-plasma accelerator whose active acceleration region is only several cm in length.

TUPPH057	First Tolerance Studies for the 4GLS FEL Sources	electron, simulation, radiation, photon	462
	D. J. Dunning, J. A. Clarke, D. J. Scott, N. Thompson CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire B. W.J. McNeil USTRAT/SUPA, Glasgow
	The Conceptual Design Report for the 4th Generation Light Source (4GLS) at Daresbury Laboratory in the UK was published in Spring 2006. 4GLS features three distinct FEL designs, each operating in a different wavelength range: an externally seeded amplifier operating in the photon energy range 8-100eV (XUV-FEL); a low-Q cavity (regenerative amplifier) FEL operating over 3-10eV (VUV-FEL); a high-Q cavity FEL operating from 2.5-200μm (IR-FEL). Preliminary results of tolerance studies for the FELs designs are presented. In particular, the effects of the relative timing offset between the seed pulse of the XUV-FEL and the electron bunch, as well as the effects of electron bunch timing jitter in the VUV-FEL, are presented.

TUCAU02	The Rossendorf IR-FEL ELBE	electron, laser, radiation, linac	488
	P. Michel, H. Buettig, F. G. Gabriel, M. Helm, U. Lehnert, Ch. Schneider, R. Schurig, W. Seidel, D. Stehr, J. Teichert, S. Winnerl, R. Wuensch FZR, Dresden
	The radiation source ELBE is the central research facility in the Forschungszentrum Rossendorf. The machine is based on a 40 MeV superconducting RF Linac wich can be operated up to 1 mA in cw mode. After commissioning the Bremsstrahlung and the X-ray facilities in 2002, and 2003 respectively, and the first lasing of the mid-IR FEL (4-22 um) in 2004 about 7000 hours user beam-time have been provided. At present a second FEL for long IR waves (15-150 um) using a partial waveguide is under commissioning. Besides in-house users especially the IR beam is available to external users in the FELBE (FEL@ELBE) program witch is a part of the integrated activity on synchrotron and free electron laser science in the EU. In this talk the fundamental features of the ELBE IR FEL's and the parameters demanded by users are displayed. In addition, an overview about user experimental work and important machine date like availability are shown. Future projects like the combination of the new High Magnetic Field lab with the ELBE-IR beams will be described.
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TUCAU03	Status of the Novosibirsk High Power Terahertz FEL	radiation, electron, laser, linac	492
	N. Vinokurov, N. Gavrilov, B. A. Knyazev, E. I. Kolobanov, V. V. Kotenkov, V. V. Kubarev, G. Kulipanov, A. N. Matveenko, L. E. Medvedev, S. V. Miginsky, L. A. Mironenko, A. D. Oreshkov, A. V. Ovchar, V. Ovchar, V. M. Popik, T. V. Salikova, M. A. Scheglov, S. S. Serednyakov, O. A. Shevchenko, A. N. Skrinsky, V. G. Tcheskidov BINP SB RAS, Novosibirsk
	The first stage of Novosibirsk high power free electron laser (FEL) was commissioned in 2003. It is based on the normal conducting CW energy recovery linac (ERL). Now the FEL provides electromagnetic radiation in the wavelength range 120 - 230 micron. The maximum average power is 400 W. The minimum measured linewidth is 0.3%, which is close to the Fourier-transform limit. Four user stations are in operation now. Manufacturing of the second stage of the FEL (based on the four-turn ERL) is in progress.
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TUCAU04	FEL Activities in India	gun, electron, linac, plasma	496
	S. Krishnagopal, B. Biswas, S. Chouksey, S. K. Gupta, U. Kale, A. Kumar, V. Kumar, S. Lal, P. Mehta, P. Nerpagar, K. K. Pant RRCAT, Indore (M. P.)
	We are building a Compact Ultrafast Terahertz Free-Electron Laser (CUTE- FEL), designed to lase between 50 - 100 microns. It will be driven by a 15 MeV electron beam from a Plane-Wave Transformer linac. The undulator is a 5 cm period, 2.5 m long, PPM planar undulator. We present details of the FEL design and the present status of activities. We also present very preliminary plans for a short-wavelength SASE FEL in India.
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THAAU02	Fourier Optics Treatment of Classical Relativistic Electrodynamics	radiation, electron, optics, laser	501
	G. Geloni, E. Saldin, E. Schneidmiller, M. V. Yurkov DESY, Hamburg
	In this paper we present a critical re-examination of Transition Undulator radiation, that has been first investigated a decade ago. We study a realistic undulator setup, which includes an undulator, two straight sections and two bends, before and after the undulator. This allows us to underline an important physical fact: it does not make sense to study the intensity distribution of transition radiation from an undulator without a detailed knowledge of the complete setup. The present paper also helps to point out several misconceptions present in literature regarding Coherent Transition Undulator Radiation.
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THAAU06	Parametric Optimization of a X-Ray FEL Based on a Thomson Source	laser, electron, radiation, simulation	517
	L. Serafini, A. Bacci, C. Maroli, V. Petrillo, A. R. Rossi INFN-Milano, Milano M. Ferrario INFN/LNF, Frascati (Roma)
	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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THBAU01	APPLE Undulators for HGHG-FELs	electron, controls, radiation, vacuum	521
	J. Bahrdt BESSY GmbH, Berlin
	Cascaded HGHG-FEL facilities have been proposed by several groups. In these machines the beam characteristics of the initial seeding laser like short pulses and a small bandwidth are transformed to shorter wavelengths where lasers are not available. The first stages are equipped with planar devices. For full polarization control the last amplifier and the final radiator can be realized as APPLE devices. The specific demands on the polarizing devices as compared to planar hybrid devices are discussed for the example of the proposed BESSY HE-FEL to be operated at 1nm: the small good field region implies tight geometrical tolerances. Gap and phase dependent focussing effects have to be compensated. The field optimization procedure requires specific strategies. An improvement of the magnetic material is helpful in this context. Other important issues are the radiation protection system and the complexity of the control system.
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THBAU02	Electron Beam Alignment Strategy in the LCLS Undulators	alignment, quadrupole, electron, controls	529
	H.-D. Nuhn, P. Emma, G. L. Gassner, C. M. LeCocq, F. Peters, R. E. Ruland SLAC, Menlo Park, California
	The x-ray FEL process puts very tight tolerances on the straightness of the electron beam trajectory (2 μm rms) through the LCLS undulator system. Tight but less stringent tolerances of 80 μm rms vertical and 140 μm rms horizontally are to be met for the placement of the individual undulator segments with respect to the beam axis. The tolerances for electron beam straightness can only be met through beam-based alignment (BBA) based on electron energy variations. Conventional alignment will set the start conditions for BBA. Precision-fiducialization of components mounted on remotely adjustable girders and the use of beam-finder wires (BFW) will enable to satisfy placement tolerances. Girder movement due to ground motion and temperature changes will be monitored continuously by an alignment monitoring system (ADS) and remotely corrected. This stabilization of components as well as the monitoring and correction of the electron beam trajectory based on BPMs and correctors will increase the time between BBA applications. Undulator segments will be periodically removed from the undulator Hall and measured to monitor radiation damage and other effects that might degrade undulator tuning.
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THBAU05	Precision Measurement of the Undulator K Parameter using Spontaneous Radiation	photon, electron, radiation, alignment	548
	J. J. Welch, J. Arthur, P. Emma, J. B. Hastings, Z. Huang, H.-D. Nuhn, P. Stefan SLAC, Menlo Park, California R. M. Bionta LLNL, Livermore, California R. J. Dejus, B. X. Yang ANL, Argonne, Illinois
	Obtaining a precise and uniform value of the undulator parameter, K, over the full undulator length is critical for producing high-gain FEL radiation, especially in a hard x-ray source such as the LCLS. At an FEL wavelength of 1.5-Å the relative variation of K over the full undulator must be (dK/K)rms < 0.015%. Transverse misalignments, construction errors, radiation damage, and temperature variations all contribute to a different K value in each few-meter-long undulator segment. It is therefore important to measure relative K precisely, after installation and alignment, using beam-based techniques, if possible. We propose a fairly simple method using the angle-integrated spontaneous radiation spectrum of two interfering undulators, and the natural shot-to-shot energy centroid jitter of the electron beam, to measure the relative K error between two segments using both ideal and measured undulator fields. By 'leap-frogging' to different pairs of undulators with extended separations we hope to confirm or correct the value of K, including proper tapering, over the entire 130-m long FEL undulator.
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THPPH016	First Experience with the Machine Protections System of FLASH	linac, beam-losses, radiation, laser	587
	L. Fröhlich Uni HH, Hamburg M. Görler, P. Göttlicher, D. Noelle, D. Pugachov, H. Schlarb, S. Schreiber, M. Staack, M. Werner DESY, Hamburg A. Hamdi, M. Luong, J. Novo CEA, Gif-sur-Yvette
	Superconducting LINACs provide high brightness beams with substantial beam power. The design of the TTF2 machine is 70 kW beam power at the dump, XFEL will run 2 dump systems with 600 kW each. From this numbers is becomes very clear, that protections systems are required. This paper will present the design and implementation of the machine protection system of the FLASH facility, and will report on the first operational experience.

THPPH025	Design of the Cavity BPM for FERMI@ELETTRA	dipole, coupling, simulation, electron	613
	P. Craievich, D. Castronovo, M. Ferianis ELETTRA, Basovizza, Trieste M. Poggi INFN/LNL, Legnaro, Padova
	The Beam Position Monitors (BPM) are fundamental diagnostics for a seeded FEL, like FERMI@ELETTRA, as they allow to measure the electron beam trajectory non destructively and on a shot-by shot basis. A cavity BPM provides sub-micrometer resolution relying on excitation of the TM110 dipoles modes by beam when it passes through the cavity off axis. Therefore for the seeded FEL FERMI, we adopted a set of cavity BPMs to be located upstream the modulating undulator to correct the electron beam trajectory to the micrometer level. In this paper we first discuss the requirements for this cavity BPM including that for beam based alignment. The scaling from an X-band design to the final C-band design is presented. The resolution to stay below one micrometer has been cross-checked both analytically and numerically, The losses of the common mode TM010 have been checked for too, leading to the final dimensions preserving the losses of the X-band cavity BPM.

THPPH035	Design Study on High-Tc Superconducting Micro-Undulator	electron, dipole, superconductivity, radiation	653
	T. Kii, K. Masuda, M. Nakano, H. Ohgaki, N. Okawachi, T. Yamazaki, K. Yoshikawa, H. Zen Kyoto IAE, Kyoto
	A micro-undulator will be essential for compact and economical FEL systems. In this work, we introduce staggered array type micro-undulator using high Tc superconducting material. The high Tc superconducting material works as antiferromagnet pieces with pinning effect. Because a transverse magnetic field is potentially high, a micro-undulator with high K-value will be possible. Results of the field measurement with test pieces and estimated performance will be discussed in this conference.

THPPH037	Magnetic Field Measurement of the Undulator in KU-FEL	electron, laser, radiation, gun	660
	M. Nakano, T. Kii, K. Masuda, H. Ohgaki, N. Okawachi, T. Yamazaki, K. Yoshikawa, H. Zen Kyoto IAE, Kyoto
	We have constructed an infrared FEL facility for advanced energy researches. In the last FEL conference, numerical studies on the undulator in KU-FEL by optimizing both for electron beam and for the optical cavity have been presented. On the other hand, since the undulator had been used in FELI, demagnetization has been anticipated. So we have measured the magnetic field of the undulator. In this conference, we will show the FEL gain and the spectrum of spontaneous emission by using the measurement data. T. Fukui, et al., Proc. of the 2005 FEL conference (2005) 195-198. ** E. Nishimura, et al., Nucl. Instr. and Methods, A341 (1994) 39-42.

THPPH054	Linac Coherent Light Source Undulator RF BPM System	dipole, coupling, linac, vacuum	706
	R. M. Lill, L. H. Morrison, G. J. Waldschmidt, D. R. Walters ANL, Argonne, Illinois R. Johnson, Z. Li, S. Smith, T. Straumann SLAC, Menlo Park, California
	The LCLS will be the world's first x-ray free electron laser when it becomes operational in 2009. LCLS is currently in the construction phase. The beam position monitor (BPM) system planned for the LCLS undulator will incorporate a high resolution X-band cavity BPM system described in this paper. The X-band cavity BPM system will provide high-resolution measurements of the electron beam trajectory on a pulse-to-pulse basis and over many shots. The X-band cavity BPM size, simple fabrication and high resolution make it an ideal choice for the LCLS beam position detection. We will discuss the system specifications, design, and prototype test results.

THPPH057	Modeling and Measurement of Mu-Metal Shielding Effect on the Magnetic Performance of an LCLS Undulator*	shielding, linac, simulation, dipole	718
	S. Sasaki, E. Trakhtenberg, I. Vasserman ANL, Argonne, Illinois
	In a previous paper (FEL05), we presented results showing that the Earth's field might give a significant effect on the LCLS undulator performance due to a large concentration of the field by the undulator poles. Based on the result of model calculation, we decided to shield the Earth's field by surrounding the undulator backing structure with a 1-mm-thick mu-metal sheet. First, the effect of the shield was modeled using the code RADIA. According to the calculation, the shielding factor of a C-shape mu-metal shield was better than a factor of 8. Second, we measured the Earth's field shielding effect without an undulator. In our measurement laboratory, the vertical component of the Earth's field was 0.5 gauss. It was suppressed to smaller than 0.1 gauss with the shield. After these background measurements, we examined the effect of the shield with an undulator in place. The measurement results show very good agreement with the model calculation.

THPPH071	Free Electron Lasers in 2006	electron, laser, free-electron-laser, storage-ring	756
	W. B. Colson, J. Blau, A. Kampouridis NPS, Monterey, California
	Twenty-nine years after the first operation of the short wavelength free electron laser (FEL) at Stanford University, there continue to be many important experiments, proposed experiments, and user facilities around the world. Properties of FELs in the infrared, visible, UV, and x-ray wavelength regimes are listed and discussed.

THCAU02	Low Emittance Injector at SCSS	emittance, electron, gun, acceleration	769
	T. Shintake, T. Hara, A. Higashiya, T. Inagaki, H. Maesaka, Y. Otake, K. Shirasawa, T. Tanaka, K. Togawa, M. Yabashi RIKEN Spring-8 Harima, Hyogo H. Baba, K. Onoe, H. Tanaka JASRI/SPring-8, Hyogo-ken H. Matsumoto KEK, Ibaraki T. Tanikawa University of Hyogo, Hyogo
	In order to realize X-ray FEL at 1 A wavelength, it is required to generate low emittance beam with high peak power. Typically 1 π-mm-mrad, and 2~4 kA beam has to obtained at undulator line. In SCSS: SPring-8 Compact SASE Source, we decided to use thermionic cathode and velocity bunching process rather than the rf-gun with photo-cathode. To verify our principle and hardwares, we constructed a test accelerator, 250 MeV, 60 nm FEL. The author reports experimental results of the test accelerator.
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FRAAU01	Photon Optics at SCSS	radiation, photon, optics, diagnostics	785
	M. Yabashi, T. Ishikawa RIKEN Spring-8 Harima, Hyogo S. Goto, T. Hirono, H. Kimura, H. Ohashi, S. Takahashi, K. Tamasaku JASRI/SPring-8, Hyogo-ken
	Developments of x-ray optics for the SCSS project are summarized. The optics has two important roles: beam handling (conditioning) and diagnostics. For the former issue, our R&D program for improving qualities of optical components (diamond monochromator, total-reflection mirror, beryllium windows, etc.) are presented. For the latter, a new spectrometer will be introduced. M. Yabashi et al., PRL (in press)
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