EPAC08 - Classification:02 Synchrotron Light Sources and FELs/A06 Free Electron Lasers

02 Synchrotron Light Sources and FELs

A06 Free Electron Lasers

Paper	Title	Page
MOYAGM01	Review of DESY FEL Activities	7
	J. Rossbach Uni HH, Hamburg J. Rossbach DESY, Hamburg
	A general overview will be given of DESY FEL activities. Overview of the technological upgrades and results of beam commissioning of the FLASH FEL. The talk will cover the latest results from FLASH at the shortest wavelengths. A description will be given of critical systems and performance. The status of the XFEL will be given, including integration of FLASH technology.
	Slides
MOPC001	The Status of TAC Infrared Free Electron Laser (IR-FEL) Facility	61
	A. Aksoy, Ö. Karsli, B. Ketenoglu, O. Yavas Ankara University, Faculty of Engineering, Tandogan, Ankara A. K. Ciftci, Z. Nergiz Ankara University, Faculty of Sciences, Tandogan/Ankara E. Kasap Gazi University, Faculty of Science and Arts, Ankara
	Turkish Accelerator Complex (TAC) Infrared Free Electron Laser (IR-FEL) project was approved by State Planning Organization (DPT) as a first step of the national project. The facility will consist of 15 40 MeV superconducting electron linac and two different optical cavity systems with different undulator period length to obtain FEL in 2 185 microns wavelengths range. In this study, the results of optimization and current status of TAC IR FEL facility is presented. The facility will give opportunity to search applications in material science, biotechnology, nonlinear optics, semiconductors, medicine and chemistry using IR-FEL in Turkey and our region.
MOPC002	Extension of the FERMI FEL1 to Shorter Wavelengths	64
	E. Allaria ELETTRA, Basovizza, Trieste G. De Ninno University of Nova Gorica, Nova Gorica
	We propose a modification of the first stage (FEL-1) of the FERMI@Elettra project in order to extend the wavelength from the original limit of 40 nm down to 20 nm. The modified setup takes advantage of a shorter radiator undulator period. We present the numerical studies that have been carried out to compare the expected performance of the new FEL-1 with that of the original FERMI setup. Results show that the modified configuration represents a good alternative to the second stage of the project (FEL-2) in the wavelength range between 40 nm and 20 nm. C. J. Bocchetta et al. 'FERMI@Elettra Conceptual Design Report' ST/F-TN-07/12 (2007)
MOPC003	Estimation of Undulator Requirements for Coherent Harmonic Generation on FERMI@Elettra	67
	E. Allaria, G. De Ninno, B. Diviacco ELETTRA, Basovizza, Trieste
	The FERMI project is devoted to the realization of a FEL user facility based on the principle of coherent harmonic generation (CHG). The advantages of such a method (with respect, e.g., to self amplified spontaneous emission) is that the output properties of the light are strongly determined by the interaction of the seed laser with the electron beam within the modulator undulator. In CHG FELs therefore, in addition to the requirements for the radiator where FEL radiation is produced, it is important to understand and satisfy the requirements for the modulator. In this work, we present a study focused on the first stage (FEL-1) of the FERMI@Elettra setup. The study aims at providing an estimation of the undulator requirements in terms of magnetic field accuracy for both the modulator and the radiator. The work is based on numerical simulations of the FEL-1 using the numerical code GINGERH [1]. The required undulator tolerances have been obtained by means of a large number of simulation runs taking into account different sets of undulator parameters. [1] W. Fawley, “A User Manual for GINGER-H and its Post-Processor XPLOTGINH” LCLS-TN-07-YY Technical note, Lawrence Berkeley National Laboratory (2007)
MOPC004	First Results from the Upgraded PITZ Facility	70
	J. W. Baehr, S. Lederer DESY, Hamburg G. Asova INRNE, Sofia C. H. Boulware, H.-J. Grabosch, M. Hänel, Ye. Ivanisenko, S. Khodyachykh, S. A. Korepanov, M. Krasilnikov, B. Petrosyan, S. Rimjaem, T. A. Scholz, R. Spesyvtsev, L. Staykov, F. Stephan DESY Zeuthen, Zeuthen L. Hakobyan YerPhI, Yerevan R. Richter BESSY GmbH, Berlin J. Roensch Uni HH, Hamburg K. Rosbach Humboldt University Berlin, Institut für Physik, Berlin A. Shapovalov MEPhI, Moscow
	During autumn and winter 2007 a general reconstruction of the PITZ facility was performed. A new spectrometer based on a dipole magnet with 180 degree deflection angle was inserted in the facility. The new spectrometer contains two screen stations for the measuring of the longitudinal phase space and the slice emittance. A new "Conditioning Test Stand" (CTS) was added to the facility. Using this CTS a new electron gun having an improved cooling system is under conditioning. A new photocathode laser system (developed by MBI) was installed and commissioned. The goal is to reach rise and fall times of the laser pulses of 2 ps. The system of laser diagnostic was upgraded. The results reached using this upgraded facility are reported. This concerns the conditioning results of the new gun. Furthermore, a gun will be characterised using the new diagnostics beamline and the new photocathode laser. Results of the commissioning and first measurements of the new diagnostics components will be reported.
MOPC005	The ARC-EN-CIEL Radiation Sources	73
	M.-E. Couprie, M. Labat CEA, Gif-sur-Yvette C. Benabderrahmane, O. V. Chubar, G. Lambert, A. Loulergue, O. Marcouillé SOLEIL, Gif-sur-Yvette C. Bruni LAL, Orsay L. Giannessi ENEA C. R. Frascati, Frascati (Roma)
	The ARC-EN-CIEL project proposes a panoply of light sources for the scientific community on a 1 GeV superconducting LINAC (phase 2) on which two ERL loops (1 and 2 GeV) are added in phase 3. LEL1 (200-1.5 nm), LEL2 (10-0.5 nm) and LEL4 (2-0.2 nm) are three kHz High Gain Harmonic Generation Free Electron Laser sources seeded with the High order Harmonics generated in Gas, with 100-30 FWHM pulses. A collaboration, which has been set-up with the SCSS Prototype Accelerator in Japan for test this key concept of ARC-EN-CIEL, has led to the experimental demonstration of the seeding with HHG and the observation up the 7th non linear harmonic with a seed at 160 nm. Besides. LEL3 (40-8 nm) installed on the 1 GeV loop is a MHz FEL oscillator providing higher average power and brilliance. In addition, in vacuum undulator spontaneous emission source extend the spectral range above 10 keV and intense THz radiation is generated by edge radiation of bending magnets. Optimisations and light sources characteristics are described.
MOPC006	Seeding of the Test FEL at MAX-lab	76
	N. Cutic, F. Curbis, F. Lindau, S. Thorin, S. Werin MAX-lab, Lund
	The test FEL at MAX-lab has recently been completed. The system will be seeded at 263 nm by a tripled Ti:sapphire laser synchronized to the RF system and the gun laser. Issues important for the seeding will be presented, ranging from the laser system via the layout of photon and electron optics to timing/synchronization and the theoretical approach. Experimental results on the seeding operation will also be presented.
MOPC007	Status and Upgrade Program of the FERMI@ELETTRA Linac	79
	G. D'Auria, A. O. Borga, S. Di Mitri, O. Ferrando, G. C. Pappas, A. Rohlev, A. Rubino, C. Serpico, M. Trovo, A. Turchet, D. Wang ELETTRA, Basovizza, Trieste
	FERMI@ELETTRA is a seeded FEL user facility under construction at Sincrotrone Trieste, Italy. It will use the existing normal conducting S-band linac and with the installation of seven accelerating sections received from CERN after the LIL decommissioning, will be operated at 1.2 GeV. After the successful commissioning of the new injector system of ELETTRA, the linac has been disconnected from the storage ring and now is being revised and upgraded with the installation of new important subsystems, i.e., a new photoinjector, bunch compressors, laser heater, additional accelerating structures, etc. Here a description of the upgrade program as well as the ongoing activities on the main parts of the machine are reported and discussed.
MOPC008	The Impact of PSK Timing on Energy Stability of e-Beam at FERMI@ELETTRA	82
	G. D'Auria, P. Delgiusto, M. M. Milloch, C. Serpico, D. Wang ELETTRA, Basovizza, Trieste
	The existing linac sections S1-S7 at ELETTRA will be upgraded for the FERMI@ELETTRA FEL project. These seven sections are 3/4 π-mode backward traveling wave (BTW) constant-impedance structures, powered by 45-MW klystrons (Thales TH 2132A) and with a SLED system to increase the RF peak power. Because of the strict requirement on the pulse-to-pulse beam energy stability (<0.1%) of the FERMI@ELETTRA project, the impact of phase shift keying (PSK), the timing of phase flipping, on beam energy needs to be revisited and evaluated. Here the results obtained with a simulation model built up by use of MATLAB simulink are present and discussed.
MOPC010	Injector System for X-ray FEL at SPring-8	85
	H. Hanaki, T. Asaka, H. Ego, H. Kimura, T. Kobayashi, S. Suzuki JASRI/SPring-8, Hyogo-ken T. Hara, A. Higashiya, T. Inagaki, N. Kumagai, H. Maesaka, Y. Otake, T. Shintake, H. Tanaka, K. Togawa RIKEN/SPring-8, Hyogo
	The SPring-8 X-FEL based on the SASE process has been developed to generate X-rays of 0.1 nm by the combination of an 8 GeV high gradient linac (400 m) and a mini-gap undulator of in-vacuum type (90 m). The design goals of the slice beam emittance and peak current at the end of the linac are 1 π mm mrad and 3 kA, respectively. The injector of the linac generates an electron beam of 1 nC, accelerates it up to 30 MeV, and compresses its bunch length down to 20 ps step by step. The injector has been designed on the basis of the SCSS test accelerator. We adopted the following keys to toward the goals: A 500 kV thermionic gun (CeB6) without a control grid ejecting a beam holding the low rms emittance of 1.1 π mm mrad, a beam deflector downstream gating the beam to form a bunch of a 1 ns length, multi-stage RF structures (238, 476 and 1428 MHz) bunching and accelerating the beam gradually to maintain the initial emittance, and extra RF cavities of 1428 and 5712 MHz linearizing the energy chirp of the beam bunch to achieve the bunch compression resulting the required peak current.
MOPC011	Improvement and Recent Results of the DELTA Storage Ring FEL	88
	H. Huck, R. Burek, G. Schmidt, K. Wille DELTA, Dortmund
	Several modifications to the storage ring FEL at DELTA have been conducted, in order to enhance speed and reproducability of mirror alignment as well as flexibility of electron beam settings. We present the new hardware design and experimental results at a laser wavelength of 470 nm. Lasing was achieved with different filling patterns, and the output power of the FEL was measured. By modulating the accelerating RF the laser macropulses can be forced into a Q-switch mode, varying between roughly 10 and 250 Hz without significant loss of outcoupled average power. A special input optics setup for a streak camera enables simultaneous measurement of electron beam and laser pulse dynamics, to study the correlations between them. Recent measurements will be presented.
MOPC012	PSI XFEL Simulations with SIMPLEX and GENESIS	91
	V. G. Khachatryan, V. M. Tsakanov CANDLE, Yerevan R. J. Bakker PSI, Villigen V. V. Sahakyan, A. Tarloyan YSU, Yerevan
	The numerical simulation results of the SASE FEL process for PSI XFEL project are presented. The main purpose of the investigations using FEL simulation codes SIMPLEX and GENESIS is the reliable definition of the undulators design parameters (K value, period, segment length, number of segments) that provide desirable radiation characteristics such as wavelength, bandwidth, saturation length, peak power and the brightness.
MOPC013	Effect of Jitter and Quadrupole Alignment Errors on SASE FEL Performance	94
	V. G. Khachatryan, A. Tarloyan, V. M. Tsakanov CANDLE, Yerevan W. Decking DESY, Hamburg
	Numerical simulations of the radiation process at the European XFEL project are presented. The impact of quadrupole misalignments on the saturation length and saturation power is investigated using the simulation codes SIMPLEX and GENESIS. The influence of trajectory steering in the presence of BPM misalignments on the FEL performance is analyzed. The study is performed for the SASE 1 undulator designed for 0.1nm radiation wavelength.
MOPC014	Optimization of the Focusing Lattice for European XFEL	97
	V. G. Khachatryan, A. Tarloyan, V. M. Tsakanov CANDLE, Yerevan W. Decking DESY, Hamburg V. V. Sahakyan YSU, Yerevan
	Detailed knowledge of the impact of the undulator section focusing lattice on the FEL performance is an important issue to ensure the stable operation of the facility with reliable tolerances. In this paper the results of numerical simulation studies for the European XFEL project are presented. The saturation length, saturation power and the spectral brightness of the SASE FEL are calculated for various focusing lattice arrangements. A focusing optics option with reduced number of FODO cells is discussed to reach the design goals with relaxed quadrupole magnet tolerances. The numerical simulations are performed using the SIMPLEX and GENESIS codes.
MOPC015	Start-to-End Simulations of the PSI 250 MeV Injector Test Facility	100
	Y. Kim, A. Adelmann, R. J. Bakker, M. Dehler, R. Ganter, T. Garvey, A. Oppelt, M. Pedrozzi, J.-Y. Raguin, L. Rivkin, A. Streun, F. Stulle, A. F. Wrulich PSI, Villigen
	From 2003, PSI has been investigating the advanced Low Emittance Gun (LEG) based 6 GeV PSI XFEL facility to supply coherent, ultra-bright, and ultra-fast XFEL photon beams covering from 0.1 nm to 10 nm. To build whole facility within a 800 m space, required beam parameters in front of undulators are challenging. For the first two FEL beamlines (FEL 1 and FEL 2), the required normalized slice emittance, slice energy spread, and peak current are about 0.2 mm.mrd, 0.6 MeV, and 1.5 kA, respectively. However, the required beam parameters for the third FEL beamline (FEL 3) covering 1 nm to 10 nm are somewhat flexible. Therefore PSI has been developing two different gun technologies. The 1 MV high gradient pulsed diode and field emission based advanced LEG will be used for first two FEL beamlines, while the CTF3 gun type V based conventional RF photoinjector will be used for the third FEL beamline. To test those two injector technologies, a dedicated 250 MeV injector test facility will be constructed at PSI from 2008. In this paper, we describe beam dynamics in two accelerator optimizations of the CTF3 RF gun based 250 MeV injector test facility for the PSI XFEL project.
MOPC016	Status of the CUTE-FEL Project	103
	S. Krishnagopal, B. Biswas, S. K. Gupta, U. Kale, A. Kumar, V. Kumar, S. Lal, P. Nerpagar, K. K. Pant, A. Patel RRCAT, Indore (M. P.)
	We are building a Compact Ultrafast TErahertz Free-Electron Laser (CUTE-FEL), designed to lase around 80 microns, driven by a 10 MeV electron beam, and using a 5 cm period, 2.5 m long undulator. We present the latest status of the project, including acceleration and commissioning trials.
MOPC017	Operation of the UVSOR-II CHG-FEL in Helical Configuration	106
	M. Labat CEA, Gif-sur-Yvette M.-E. Couprie, G. Khalili SOLEIL, Gif-sur-Yvette M. Hosaka, N. Yamamoto Nagoya University, Nagoya M. Katoh, M. Shimada UVSOR, Okazaki A. Mochihashi JASRI/SPring-8, Hyogo-ken
	In the Coherent Harmonic Generation Free Electron Laser (CHG-FEL) configuration, an external laser source injected inside a first undulator modulates in energy, and consequently in phase, an electron bunch, allowing coherent radiation in a second undulator. The CHG-FEL implemented on UVSOR-II storage ring (Okazaki, Japan) consists of a 600 MeV electron beam, and of a 2.5 mJ Ti:Sa seeding laser at 800 nm wavelength, 1 kHz repetition rate, and 100 fs up to 2 ps pulse duration. Operation in planar configuration of the undulators is being characterized since 2005. Recent experiments enabled a step forward using helical configuration of the undulators. A description of the experimental setup is given, and the main results are presented: influence of seeding laser parameters (polarisation, average power, focusing) on the intensity and beam profile of the second and third coherent harmonics. Those investigations provide attractive insights for the future HGHG FEL sources, about to deliver sub-nm and sub-ps pulses.
MOPC018	Seeding the FEL of the SCSS Test Accelerator with the 5th Harmonic of a Ti: Sa Laser Produced in Gases	109
	G. Lambert, O. V. Chubar, M.-E. Couprie SOLEIL, Gif-sur-Yvette M. Bougeard, B. Carré, D. Garzella, O. B. Gobert, M. Labat, H. Merdji, P. Salieres CEA, Gif-sur-Yvette T. Hara, T. Ishikawa, H. Kitamura, T. Shintake, M. Yabashi RIKEN/SPring-8, Hyogo K. Tahara, Y. T. Tanaka, T. Tanikawa RIKEN Spring-8 Harima, Hyogo
	We present the strong amplification of the 5th harmonic of a Ti: Sa laser (10 Hz, 100 fs) generated in a Xe gas cell, i.e. 160 nm, and the generation of intense and coherent odd and even Non Linear Harmonics (NLH) from 80 nm to 23 nm. The experiment has been carried out on the SCSS (SPring-8 Compact SASE Source, Japan) Test Accelerator FEL. This facility is mainly based on a thermionic cathode electron gun, a C-band LINAC (5712 MHz, 35 MV/m) and an in-vacuum undulator (15 mm of period, 2 sections of 4.5 m length). The external source is properly focused in the first undulator section in order to efficiently interact with the electron beam (150 MeV, 10 Hz, 0.5-3 ps). In case of high peak current mode, the 160 nm seed light is amplified by a factor of 7000 in the first undulator section. Moreover, the amplification can be observed even for very low HHG seed level. This result opens new perspectives for seeding at short wavelengths in the XUV to soft X-Ray region. Association with NLH, HGHG (High Gain Harmonic Generation) and/or cascade schemes would allow the generation of fully coherent X-ray radiations from the “water window” spectral range to the Angstrom region.
MOPC019	Velocity Bunching at FLASH	112
	T. Limberg, B. Beutner, W. Decking, M. Huening, M. Krasilnikov, M. Vogt DESY, Hamburg O. Grimm Uni HH, Hamburg
	The vacuum-ultra-violet free electron laser in Hamburg (FLASH) is a linac driven SASE-FEL. High peak currents are, in routine operation, produced using magnetic bunch compression chicanes. Longitudinal dispersion in these chicanes allow bunch length changes of relativistic electron beams. For low energy electron beams (~5 MeV), the velocity dependence on electron energy can be utilized for bunch compression. Since strong bunch compression at low beam energies gives rise to strong space charge interactions which has an impact on, for instance, beam emittance and is therefore not suitable for full compression to the kA peak currents needed for SASE operation. Moderate velocity bunching, however, might be used to optimize the total bunch compression system of FLASH or the European XFEL. Experiments on the velocity bunching process at FLASH are presented here. Results on bunch length and transverse emittance measurements are discussed and compared with numerical tracking calculations.
MOPC023	ARC-EN-CIEL Beam Dynamics	115
	A. Loulergue, M.-E. Couprie SOLEIL, Gif-sur-Yvette C. Bruni LAL, Orsay
	ARC-EN-CIEL project is based on a CW 1.3 GHz superconducting linac accelerator delivering high charge, subpicosecond and low emittance electron bunches at high repetition rate. According to the electron energy, it provides tunable light source of high brightness in the VUV to soft X-ray wavelength domain. The project will evolve into three phases: first and second phases are based on high brightness single pass SC linac configuration with a low average current (few μA), while third phase comports recirculation loops to increase the average current (up to 100 mA). This paper deals with electron beam dynamics issues for the single pass configuration in the two first phases from the RF gun to undulators including magnetic compression stages. In the ERL configuration of the third phase, the accelerator scheme and focusing are investigated in order to take into account collective effects as Beam Break Up instability.
MOPC024	Calculation of Coherent Synchrotron Radiation in General Particle Tracer	118
	I. V. Bazarov Cornell University, Department of Physics, Ithaca, New York T. Miyajima KEK, Ibaraki
	General Particle Tracer (GPT) is a particle tracking code, which includes 3D space charge effect based on nonequidistant multigrid Poisson solver or point-to-point method. It is used to investigate beam dynamics in ERL and FEL injectors. We have developed a new routine to simulate coherent synchrotron radiation (CSR) in GPT based on the formalism of Sagan. The routine can calculate 1D-wake functions for arbitrary beam trajectories as well as CSR shielding effect. In particular, the CSR routine does not assume ultrarelativistic electron beam and is therefore applicable at low beam energies in the injector. Energy loss and energy spread caused by CSR effect were checked for a simple circular orbit, and compared with analytic formulas. In addition, we enhanced the 3D space charge routine in GPT to obtain more accurate results in bending magnets. D. Sagan, EPAC06, pp. 2829-2831.
MOPC026	Status of SPARX Project	121
	L. Palumbo Rome University La Sapienza, Roma
	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 1.2 and 2.4 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 1.2 GeV and 2.4 GeV respectively, both in SASE and Seeded FEL configurations.
MOPC027	A Fast Switching Mirror Chamber for FLASH	124
	S. Pauliuk, U. Gensch, R. Heller, M. Sachwitz, H. Thom, D. Thürmann DESY Zeuthen, Zeuthen U. Hahn, S. Karstensen, H. Schulte-Schrepping, K. I. Tiedtke DESY, Hamburg
	Switching mirrors are used to provide several beamlines with FEL or synchrotron radiation from one source. Since most users do not need the nominal pulse density, this is a method to supply many experimental groups. So far, the switching process has a duration of several minutes. A study at DESY Zeuthen analyzes the possibility and accuracy of permanent switching, e.g. at half the FEL's pulse frequency of 1 to 10 Hz. A prototype satisfying highest demands on repetition accuracy of the position (below 1 μm) and yawing (about 1 arcsec) is being tested. In the course of the work many technical concepts from industry like PLC or Position-Velocity Streaming found their way into beamline technology, allowing fast proceedings in development.
MOPC028	Experimental Layout of 30 nm High Harmonic Laser Seeding at FLASH	127
	H. Schlarb, S. Düsterer, J. Feldhaus, T. Laarmann DESY, Hamburg A. Azima, J. Boedewadt, H. Delsim-Hashemi, M. Drescher, S. Khan, Th. Maltezopoulos, V. Miltchev, M. Mittenzwey, J. Rossbach, R. Tarkeshian, M. Wieland Uni HH, Hamburg
	Since 2004, the free-electron laser FLASH at DESY has operated in the Self-Amplified Stimulated Emission mode, delivering to users photon beams with wavelengths between 6.5 nm and 40 nm. In 2009, DESY plans to install a 3.9 GHz RF acceleration section for the production of electron bunches with high peak currents (~kA), but ten times larger pulse durations (~250 fs) compared to the present configuration. The relaxed timing requirements of the new configuration make it possible to externally seed FLASH with high harmonics of an optical laser (sFLASH). The aim of the project is to study the technical feasibility of seeding an FEL at 30 nm with a stability suited for user operation. sFLASH will use 10 m of gap-tunable undulators installed in front of the fixed gap SASE-undulator. A chicane behind the seeding undulators will allow to extract the output radiation for a careful characterisation and for first pump-probe experiments with a resolution in the 10 fs range by combining FEL and seed laser pulses.
MOPC029	Longitudinal Structure of Electron Bunches at the Micrometer Scale from Spectroscopy of Coherent Transition Radiation	130
	B. Schmidt, C. Behrens, S. Wesch DESY, Hamburg H. Delsim-Hashemi, J. Rossbach, P. Schmüser Uni HH, Hamburg
	At the free electron laser FLASH in Hamburg, a longitudinal bunch compression scheme is used resulting in a longitudinal current profile with a narrow leading spike. Part of this spike is responsible for producing high-intensity short FEL pulses via the SASE process. The width and the structure of the current spike, which are key parameters for the efficiency of the SASE process, are barely accessible to direct measurements in the time domain. Using an infrared multi-stage grating spectrometer, we have studied the spectral composition of coherent transition radiation from single electron bunches. The data show that the 'fundamental width' of the current spike is about 40 fs (fwhm) with prominent substructures down to the 10 fs scale. The intensity fluctuations of coherent radiation in the corresponding wavelength range are strongly correlated to the fluctuations of the FEL pulse energy. Extension of the method to the near infrared regime have revealed micro-structures with characteristic lengths from a few micrometers down to fractions of a micrometer. Their interrelation with the parameters of the electron beam and the compression system have been studied.
MOPC030	Operation of FLASH at 6.5 nm Wavelength	133
	S. Schreiber, B. Faatz, K. Honkavaara DESY, Hamburg
	FLASH, the Free-Electron-Laser at DESY, Germany has been upgraded in 2007. A 6th accelerating module with eight 9-cell superconducting cavities of the TESLA type has been installed. In addition, another module has been replaced and the tuners of a third module have been repaired. In September 2007, a beam energy of 1 GeV has been achieved for the first time, followed by lasing at 6.5 nm shortly after. With this remarkable achievement, the initial design goals of the FEL in terms of beam energy and wavelength have been reached.
MOPC031	Status of X-ray FEL/SPring-8 Machine Construction	136
	T. Shintake RIKEN/SPring-8, Hyogo
	XFEL/SPring-8: the X-ray Free Electron Laser Project is under construction at SPring-8 site, which is aiming at generating 0.1 nm coherent radiation using 8 GeV electron beam. After the ground breaking in 2007, concrete piling has been completed. Construction of the accelerator tunnel will be completed in end of the FY2008, then machine installation will be started. The first electron beam acceleration is scheduled in FY2010. XFEL/SPring-8 based on SASE-FEL, and unique design, thermionic CeB6 gun, adiabatic bunching, C-band high gradient accelerator and in vacuum undulator. To reach 8 GeV within 400 m available tunnel length, we use 64 C-band klystron, which drives 128 accelerating tube at 37 MV/m.
MOPC032	Progress of the Commissioning of the Test FEL at MAX-lab	139
	S. Thorin, F. Curbis, N. Cutic, F. Lindau, S. Werin MAX-lab, Lund M. Abo-Bakr, J. Bahrdt, K. Holldack BESSY GmbH, Berlin
	In a collaboration between MAX-lab and BESSY a seeded Harmonic Generation Free Electron Laser is being constructed at MAX-lab. The setup uses the existing MAX-lab facility together with a Ti:Sa 266 nm lasersytem used for both the gun and seeding and an optical klystron consisting of a modulator, a chicane and a radiator. The different parts of the system has been installed and commissioning with electrons of the full setup started during the fall of 2007. In this paper the progress of the commissioning of the Test FEL and our initial results are presented.
MOPC033	Sapphire - A High Peak Brightness X-Ray Source as a Possible Option for a Next Generation UK Light Source	142
	R. P. Walker, C. Christou, J. H. Han, J. Kay Diamond, Oxfordshire R. Bartolini JAI, Oxford
	In the UK there is increasing interest in a radiation source which would provide ultra-fast (from 100 fs down to a few fs and potentially below) multi-keV X-ray pulses with high peak brightness, in order to study rapid dynamical processes in electronic and molecular systems, complementary to the newly operational Diamond Light Source which has been designed principally for high time-averaged X-ray brightness. In this paper we present the results of our initial studies for one option for a cost-effective, staged, linac based source suitable as a national facility which can act additionally as a portal to larger X-ray free-electron laser facilities in Europe, the US and Japan.
MOPC034	Collective Effects in a Short-Pulse FEL Driver	145
	P. H. Williams, H. L. Owen STFC/DL/ASTeC, Daresbury, Warrington, Cheshire G. Bassi Cockcroft Institute, Warrington, Cheshire S. Thorin MAX-lab, Lund
	There is much interest in the provision of coherent, tunable VUV and soft X-ray pulses of duration less than 10fs. A 1.3 GHz linac driver concept has been developed, and in this paper we address collective effects in the short electron bunches using start-to-end modelling. In particular, we examine the limitations from coherent radiation and induced microbunching, and their impact on the design of the accelerator system.
MOPC035	PULSE - A High-Repetition-Rate Linac Driver for X-ray FELs	148
	P. H. Williams, B. L. Militsyn, H. L. Owen, M. W. Poole, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire B. W.J. McNeil USTRAT/SUPA, Glasgow
	We describe a staged concept for a linac-based free-electron laser providing coherent tunable VUV and soft X-ray output with pulse lengths less than 10 fs. Use of recent developments in high brightness injectors and 1.3 GHz cryomodules gives stable, reliable output with very good electron beam quality and flexible pulse pattern. Options for achieving repetition rates up to 1 MHz are examined. We also consider the development and demonstration of novel FEL concepts that access photon pulses in the attosecond regime. The combination of these parameters would open up new areas in femtosecond and attosecond science.
MOPC036	Pancakes versus Beer-cans in Terms of 6D Phase-space Density	151
	S. B. van der Geer, O. J. Luiten, M. J. de Loos TUE, Eindhoven S. B. van der Geer Pulsar Physics, Eindhoven
	Uniformly filled ellipsoidal (waterbag) electron bunches can be created in practice by space charge blow out of transversely tailored ‘pancake’ bunches. Ellipsoidal bunches have linear self fields in all dimensions, and will not deteriorate in quality under linear transport and acceleration. There is a discussion if such a bunch is better than a conventional beer-can shape. This paper compares the two approaches in terms of usable phase-space density. Detailed GPT simulations of a simplified setup show that although the pancakes approach requires less charge, it is the application that is decisive. O. J. Luiten et al. Phys. Rev. Lett. Vol 93, 094802 (2004).
MOPC037	Single Spike Operation in SPARC SASE-FEL	154
	V. Petrillo, I. Boscolo Universita' degli Studi di Milano, Milano A. Bacci, S. Cialdi, L. Serafini INFN-Milano, Milano R. Bonifacio, M. Boscolo, M. Ferrario, C. Vaccarezza INFN/LNF, Frascati (Roma) F. Castelli Università degli Studi di Milano, Milano L. Giannessi, C. Ronsivalle ENEA C. R. Frascati, Frascati (Roma) L. Palumbo Rome University La Sapienza, Roma S. Reiche, J. B. Rosenzweig UCLA, Los Angeles, California M. Serluca INFN-Roma, Roma
	We describe in this paper a possible experiment with the existing SPARC photoinjector to test the generation of sub-picosecond high brightness electron bunches able to produce single spike radiation pulses at 500 nm in the SPARC self-amplified spontaneous emission free-electron laser (SASE-FEL). The main purpose of the experiment will be the production of short electron bunches as long as few SASE cooperation lengths and to validate scaling laws to foresee operation at shorter wavelength in the future operation with SPARX. The basic physics, the experimental parameters and 3-D simulations are discussed. Complete start-to-end simulations with realistic SPARC parameters are presented, in view of an experiment for tests on superradiant theory with the existing hardware.
MOPD012	Half Wave Injector Design for WiFEL	469
	R. A. Legg UW-Madison/SRC, Madison, Wisconsin W. Graves MIT, Cambridge, Massachusetts T. L. Grimm Niowave, Inc., Lansing, Michigan P. Piot Fermilab, Batavia, Illinois
	Seeded FELs will require exceptional beam quality. The Wisconsin FEL (WiFEL) requires peak currents of greater than 1 kA with less than 1 mm-mrad transverse slice emittance and 1·10^-4 δp/p at the undulator. To perform the obligatory bunch compression after the injector without allowing micro-bunching will require very smooth bunch energy and density profiles and relatively low compression ratios. An injector which uses a low frequency, superconducting, half wave resonator gun combined with self-inflating, ellipsoidal bunches* to meet those requirements is described. The superconducting radio frequency TEM-class cavities have been in use for more than 25 years and because of their potential for flat field profiles, are desirable as electron gun structures. A Superfish model and field map of the specific gun cavity is presented. ASTRA** simulations from the cathode to 120MeV are provided. A description is given of the technique used to emittance compensate the space charge induced energy chirp while maintaining the peak bunch current. * O. J.Luiten, et al., Phys. Rev. Lett. Vol 93, 094802 (2004) ** K. Floetmann, ASTRA, www.desy.de/~mpyflo
WEXM01	Overview of VUV and Soft X-Ray FELs Worldwide	1938
	R. J. Bakker PSI, Villigen
	A comprehensive overview of the status of FEL projects worldwide providing photons in the VUV to soft X-ray region. The paper should give an update of projects, the technolgies proposed and methods for stable high brilliance user beams. Seeding schemes should be discussed along with critical issues for reaching the shorter wavelengths. 1st priority
	Slides
WEXM02	Status of the Linac Coherent Light Source	1939
	J. N. Galayda SLAC, Menlo Park, California
	The Linac Coherent Light Source (LCLS) is a free-electron laser facility in construction at Stanford Linear Accelerator Center. It is designed to operate in the wavelength range 0.15-1.5 nanometers. At the time of this conference, civil construction of new tunnels and buildings is complete, the necessary modifications to the SLAC linac are complete, and the undulator system and x-ray optics/diagnostics are being installed. The electron gun, 135 MeV injector linac and 250 MeV bunch compressor were commissioned in 2007. Accelerator commissioning activities are presently devoted to the achievement of performance goals for the completed linac. R. Akre, et al., "Commissioning the LCLS Injector", submitted to PRSTAB, 2007
	Slides
WEOAM01	Operation Status of the SCSS Test Accelerator: Continuous Saturation of SASE FEL at the Wavelength Range from ~50 to 60 nanometers	1944
	H. Tanaka, T. Fukui, T. Hara, A. Higashiya, N. Hosoda, T. Inagaki, S. I. Inoue, T. Ishikawa, H. Kitamura, M. K. Kitamura, H. Maesaka, M. Nagasono, T. Ohshima, Y. Otake, T. Sakurai, T. Shintake, K. Shirasawa, T. Tanaka, K. Togawa, M. Yabashi RIKEN/SPring-8, Hyogo T. Asaka, T. Hasegawa, H. Ohashi, S. Takahashi, S. Tanaka JASRI/SPring-8, Hyogo-ken T. Tanikawa RIKEN Spring-8 Harima, Hyogo
	The SPring-8 compact SASE source (SCSS) test accelerator for XFEL/SPring-8 was constructed in 2005. The first lasing at 49 nm, though not reached saturation, was observed with the 250-MeV electron beam in June 2006. Towards the saturation, we started stabilizing the RF system in the injector section, which dramatically stabilized the lasing condition. The stable operation enables us to tune each of the machine parameter precisely by using the lasing response. The second undulator, which did not sufficiently contribute to the first lasing because of large multipole field errors, was replaced by new one. These improvements led us to the successful observation of SASE saturation at the wavelength ranging from ~50 to 60 nm in September 2007. A pulse-energy of 30 uJ is routinely obtained at 60 nm. Analysis of the obtained SASE saturation data with a 3D-FEL simulation code, SIMPLEX, suggests that the electron beam emittance is almost unchanged through the bunch compression process. The stable and intense EUV SASE FEL has been offered for user experiments since October 2007. The achieved electron beam performance, lasing property as well as the latest analysis result will be presented.
	Slides
WEOAM02	A Scheme for Stabilization of Output Power of an X-ray SASE FEL	1947
	E. Schneidmiller, G. Geloni, E. Saldin, M. V. Yurkov DESY, Hamburg
	Stability of XFEL radiation is naturally linked to stability of the linac RF system through bunch compression, leading to very tight requirements on RF amplitude and phase. We propose a new scheme that allows to relax these requirements by a large factor.
	Slides