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FEL

       
Paper Title Other Keywords Page
MOZBPA01 Results from the VUV-FEL radiation, electron, undulator, laser 34
 
  • J. Rossbach
    DESY, Hamburg
  The talk will provide the latest results from the VUV-FEL. It will cover the general performance of the machine and comparison to theory. A status will be given of the performance of key systems: the gun, accelerating modules and RF systems, electron and photon beam diagnostics, timing and synchronization and undulator performance. Future developments and implementations will also be discussed (and implications to the XFEL).  
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MOZBPA02 A Review of ERL Prototype Experience and Light Source Design Challenges ERL, linac, gun, superconducting-RF 39
 
  • S.L. Smith
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  The presentation will review the status of commissioning of ERL light source prototype projects drawing on experience from the JLab IR FEL, UK's ERL prototype ring and the Cornell injector project. State of the art design for future light source based on ERLs and FELs will be illustrated using the concept for the UK's 4GLS project.  
slides icon Transparencies
 
MOPCH002 Seeding the FEL of the SCSS Phase 1 Facility with the 13th Laser Harmonic of a Ti: Sa Laser Produced in Gas laser, undulator, radiation, SASE 44
 
  • G. Lambert, M. Bougeard, W. Boutu, P. Breger, B. Carré, D. Garzella, M. Labat, H. Merdji, P. Monchicourt, P. Salieres
    CEA, Gif-sur-Yvette
  • O.V. Chubar, M.-E. Couprie
    SOLEIL, Gif-sur-Yvette
  • T. Hara, H. Kitamura, T. Shintake
    RIKEN Spring-8 Harima, Hyogo
  • D. Nutarelli
    LAC, Orsay
  A seeding configuration, in which the 13th harmonic (60 nm) of a Ti: Sa laser (50 mJ, 10 Hz, 130 fs) generated in a gas cell is used as the external source, will be tested in 2006 on the SCSS test facility (SPring-8 Compact Sase Source, Japan). This facility is based on a thermionic cathode electron gun (1 nC of bunch charge), a C-band LINAC (5712 MHz, 35 MV/m) and two in-vacuum undulators (15 mm of period). The maximum electron beam energy is 250 MeV and the SASE emission from visible to 60 nm can be obtained. The High order Harmonic Generation (HHG) experiment was mounted off-line at the end of last December. A first chamber is dedicated to harmonic generation. A second one is used for spectral selection and adaptation of the harmonic waist in the modulator. The tests are performed in Saclay with the LUCA (Laser Ultra Court Accordable) laser (15 mJ, 10 Hz, 50 fs) from January to March at 266 nm, 160 nm and 60 nm and its results are presented here. Also, before performing the real tests in SPring-8 FEL presence, final theoretical estimations of the performances relying on 1D simulations using PERSEO code and 3D simulations using GENESIS and SRW codes are given.  
 
MOPCH003 Seeding SPARC Facility with Harmonic Generation in Gases: Preliminary Tests of the Harmonic Generation in Gas Chamber laser, undulator, electron, radiation 47
 
  • O. Tcherbakoff, M. Bougeard, P. Breger, B. Carré, D. Garzella, M. Labat, G. Lambert, H. Merdji, P. Monchicourt, P. Salieres
    CEA, Gif-sur-Yvette
  • M.-E. Couprie
    SOLEIL, Gif-sur-Yvette
  • A. Doria, L. Giannessi
    ENEA C.R. Frascati, Frascati (Roma)
  In High Gain Harmonic Generation Free Electron Laser configuration, an external light source is injected in the first part of an undulator. The electron-photon interaction leads to a coherent light emission in the second part of the undulator. We propose to use the High Order Harmonic Generation in gases process as the seed for SPARC project (Frascati, Italy). With this facility, the electron beam is accelerated to 200 MeV and passes through an undulator of 6 sections. The preliminary tests on the seeding chambers presented in this paper have been realised at the CEA (Saclay, France). The experiment is based on three vacuum chambers. In the first one, a Ti: Sa laser (800 nm, 2.5 mJ, 50 fs, 10 Hz) is focussed in a 10 Hz pulsed gas jet (Argon or Xenon), producing harmonics of the fundamental. Filters in the second chamber enable the selection of the harmonic (3rd or 5th). Finally, a telescope focuses the harmonic beam at a given position. The whole module is to be moved to the SPARC facility. Appropriate tuning of the undulator gaps will amplify the 3rd and 5th harmonics seeded, as well as non-linear harmonics of those wavelengths, allowing the perspective of producing a FEL at 53 nm  
 
MOPCH005 The ARC-EN-CIEL FEL Proposal emittance, laser, radiation, undulator 53
 
  • M.-E. Couprie, C. Bruni, O.V. Chubar, A. Loulergue, L. Nahon
    SOLEIL, Gif-sur-Yvette
  • B. Carré, D. Garzella, M. Jablonka, M. Labat, G. Lambert, F. Meot, P. Monot, A. Mosnier
    CEA, Gif-sur-Yvette
  • J.-R. Marquès
    LULI, Palaiseaux
  • D. Nutarelli
    LAC, Orsay
  • J.-M. Ortega
    CLIO/ELYSE/LCP, Orsay
  ARC-EN-CIEL (Accelerator-Radiation Complex for Enhanced Coherent Intense Extended Light), the French project of a fourth generation light source aims at providing the user community with coherent femtosecond light pulses covering from UV to soft X ray. It is based on a CW 1 GeV superconducting linear accelerator delivering high charge, subpicosecond, low emittance electron bunches with a high repetition rate (1 kHz). Electron beam calculations will be presented. The FEL is based on the injection of High Harmonics Generated in Gases (HHG) in a High Gain Harmonic Generation scheme, leading to a rather compact solution. The produced radiation extending down to 0.8 nm with the Non Linear Harmonics reproduces the good longitudinal and transverse coherence of the harmonics in gas. Calculations are preformed with PERSEO, taking into account the proper transverse overlap between HHG and the electron beam, and with SRW. Optional beam loops are foreseen to increase the beam current or the energy. They will accommodate fs synchrotron infrared Coherent Synchrotron Radiation sources, VUV and X ray ranges and a FEL oscillator in the 10 nm range. An important synergy is expected between accelerat  
 
MOPCH006 Beam Adaptation at the Infrared FEL, CLIO undulator, electron, simulation, quadrupole 56
 
  • J.P. Berthet, F. Glotin, J.-M. Ortega
    CLIO/ELYSE/LCP, Orsay
  • W. Salah
    The Hashemite University, Zarka
  The infrared free-electron laser CLIO is tunable from 3 to 150 5m by operating its driver RF linear accelerator between 50 and 12 MeV. This is the largest spectral range ever obtained with a single optical cavity. We have studied the electron beam transverse adaptation in the FEL undulator throughout the spectral and energy range. Each beam dimension is measured by a moving wire whose temperature dependant resistivity is monitored. The results are compared with simulations computed with the TRANSPORT code.  
 
MOPCH007 Undulators for a Seeded HGHG-FEL Test Bench at MAX-lab undulator, electron, radiation, laser 59
 
  • J. Bahrdt, H.-J. Baecker, W.F. Frentrup, A. Gaupp, K. Goldammer, A. Meseck, M. Scheer
    BESSY GmbH, Berlin
  • S. Werin
    MAX-lab, Lund
  Undulators for a Seeded HGHG-FEL at MAX-lab Within the European FEL Design Study a seeded HGHG-FEL will be set up at MAX-lab. In the modulator, a planar pure permanent magnet undulator, the 3rd harmonic of a Ti:Sapphire laser (267nm) interacts with the electron beam. In the following dispersive section the energy modulation is converted into a spatial modulation. The radiator emits at the third harmonic (89nm). The radiator has an APPLE II type magnetic structure providing full polarization control. The undulators and the dispersive section are currently built at BESSY. The electron beam height at MAX-lab of 400mm requires a specific design of the undulator carriages. The magnetic and mechanical design of the HGHG stage will be presented.  
 
MOPCH008 Considerations for Double Pulse Lasing from the BESSY-FEL electron, simulation, bunching, laser 62
 
  • K. Goldammer, B.C. Kuske, A. Meseck
    BESSY GmbH, Berlin
  BESSY proposes a linac-based High-Gain Harmonic-Generation (HGHG) free electron laser (FEL) facility with three independent FEL lines. Two to four HGHG stages downconvert the initial seed wavelength (230nm to 460nm) to the desired radiation range (1.24nm to 51nm). High FEL gain is ensured as the seed radiation interacts only with unperturbed parts of the electron bunch in every HGHG-stage. This so-called fresh-bunch-technique relies on dipole chicanes that delay the electron bunches relative to the radiation. Fresh-bunch chicanes are incorporated prior to each modulator in the BESSY-FEL allowing the bunch to completely travel through all undulators. However, simulations show that bunch parts that have previously lased generate a noticeable radiation power level in the final amplifiers. This motivated simulation studies on the significance and applicability of such inherent additional pulses. It is revealed that the BESSY-FEL provides the opportunity to deliver double pulses at the FEL exit being of high interest to the user community. Temporal seperation and intensity levels can be controlled by carefully optimising the properties of the magnetic chicanes.  
 
MOPCH009 The BESSY 2nd Generation Soft X-ray FEL User Facility radiation, undulator, laser, controls 65
 
  • J. Knobloch
    BESSY GmbH, Berlin
  Future VUV-to-soft-X-ray FEL facilities promise to open fundamentally new frontiers for the synchrotron user community. So-called 2nd generation FELs, which use seeded schemes rather than SASE, can deliver reproducible ultra-short photon pulses at an energy level of mJ/pulse. BESSY has been designing a High-Gain-Harmonic-Generation (HGHG) based FEL with a 2.3 GeV superconducting driver linac that covers photon energies from 24 eV to 1 keV. The design provides full tuneability of photon energy, variable beam polarization and complete synchronization to external lasers—all essential for future femtosecond, time-resolved pump-probe experiments. Also, the CW linac offers great flexibility for the repetition rates and pulse patterns. BESSY-organized User Workshops helped identify the user requirements for such an FEL. This information provided the basis for the Technical Design Report that was submitted to the German Wissenschaftsrat in 2004, which then held an on-site review in 2005. Meanwhile, preparatory studies continue at BESSY. They include start-to-end simulations, tolerance studies, and the development of superconducting RF technology in the HoBiCaT test facility.  
 
MOPCH010 High Power Tests of a High Duty Cycle, High Repetition Rate RF Photoinjector Gun for the BESSY FEL gun, DESY, PITZ, klystron 68
 
  • F. Marhauser
    BESSY GmbH, Berlin
  The proposed BESSY Soft X-ray FEL uses a normal conducting 1.3 GHz photoinjector RF gun cavity at comissioning phase. Due to the challenging RF pulse pattern the cavity has to cope with an average power of 75 kW. A 1.5-cell RF gun prototype has been built with a dedicated cooling layout. Results of the first high power RF tests are detailed in this paper.  
 
MOPCH011 Jitter Measurement by Spatial Electro-optical Sampling at the Flash Free Electron Laser laser, electron, diagnostics, polarization 71
 
  • A. Azima, S. Düsterer, J. Feldhaus, H. Schlarb
    DESY, Hamburg
  • A.L. Cavalieri
    MPQ, Garching, Munich
  • D. Fritz
    Michigan University, Ann Arbor, Michigan
  • K. Sengstock
    Uni HH, Hamburg
  For pump-probe experiments carried out at the VUV-FEL at DESY, FEL laser pulses with 32 nm wavelength have to be synchronized with high precision to optical laser pulses generated by a TiSa oscillator. To measure the relative timing variations between the FEL and the optical laser, an electro-optical experiment to determine the electron beam arrival time at the undulator has been installed. Here, the electron beam profile is encoded spatially into the laser pulse and readout by an intensified camera. A similar experimental setup has been successfully used at the sub-picosecond pulsed source (SPPS) at higher charge and shorter rms bunch length. In this paper, we report about the achievements and difficulties of the Timing Electro-Optical (TEO) setup, that allows to post-order experimental user data with a precision of 100 fs rms and better.  
 
MOPCH014 Energy-time Correlation Measurements Using a Vertically Deflecting RF Structure acceleration, CSR, emittance, DESY 80
 
  • M. Roehrs, C. Gerth, M. Huening, H. Schlarb
    DESY, Hamburg
  To initiate the lasing process in SASE-based Free Electron Lasers, electron bunches with high peak currents are necessary. At the VUV-FEL at DESY, high peak currents are produced by bunch shortening in magnetic chicanes induced by a linear energy-time gradient. The residual uncorrelated time-sliced energy width after compression is a crucial parameter for the lasing process. The final energy-time correlation provides important information about the compression process. This paper presents a measurement of slice energy spread and energy-time correlation using a vertically deflecting rf-structure (LOLA). The structure allows to map the time delay of bunch slices to the vertical axis of a screen. After dispersing the bunches horizontally with a dipole, the energy-time correlation can be directly obtained in a single shot measurement. Results for different bunch compression schemes are presented. The measured bunch length in case of a non-compressed beam is compared to streak camera measurements.  
 
MOPCH015 Impact of Undulator Wakefileds and Tapering on European X-ray FEL Performance undulator, radiation, simulation, SASE 83
 
  • I. Zagorodnov, M. Dohlus, T. Limberg
    DESY, Hamburg
  The European X-ray Free-Electron Laser (XFEL) based on self-amplified spontaneous emission (SASE) requires an electron beam with a few kA peak current and a small-gap undulator system up to 250 m in length. The interaction between the high-current electron bunch and the undulator vacuum chamber affects the FEL performance. In this paper we estimate the induced wakefields in elliptical pipe geometry, taking into account the main geometrical variations of the chamber. To study the expected performance in the presence of the calculated wakefields, we are doing start-to-end simulations with the tracking codes ASTRA, CSRtrack and GENESIS. To compensate the wakefield impact on the FEL performance, an adiabatic change of undulator parameters is considered.  
 
MOPCH016 Bunch Compression Monitor radiation, electron, SASE, acceleration 86
 
  • H. Delsim-Hashemi, J. Rossbach, P. Schmüser
    Uni HH, Hamburg
  • O. Grimm, H. Schlarb, B. Schmidt
    DESY, Hamburg
  • A.F.G. van der Meer
    FOM Rijnhuizen, Nieuwegein
  An accelerated bunch of electrons radiates coherently at wavelengths longer than or comparable to the bunch length. The first generation Bunch Compression Monitor (BCM) that is installed at the VUV-FEL applies this principle by measuring the total radiation intensity. For a better control on the degree of the compression, the radiated intensity in different bandwidth can be used. Dependent on the changes in the structure of the bunch, its radiation spectrum changes correspondingly. A new generation BCM uses wavelength dependent diffracting devices and multi-channel sensors to measure the signal in different wavelength channels simultaneously. This paper describes the construction of the first prototypes and experimental results in different short wavelength bands measured at the linac of the VUV-FEL at DESY, Hamburg.  
 
MOPCH018 Macro-Pulse Generation in a Storage-Ring Free-Electron Laser: A Single-Particle Plus FEL Numerical Approach electron, simulation, storage-ring, ELETTRA 89
 
  • F. Curbis, E. Allaria, G. De Ninno
    ELETTRA, Basovizza, Trieste
  In a storage-ring free-electron laser (FEL), the onset and growth of intra-cavity power at the fundamental resonant wavelength is naturally accompanied by coherent emission at higher harmonics. Contrary to what happens in single-pass linac-based devices, the electron beam is re-circulated in the storage ring and the microbunching becomes thermalized. As a consequence, a correct theoretical understanding of the process requires a proper modelling of the turn-by-turn evolution of the electron-beam phase space, both inside the undulators (where the FEL interaction takes place) and along the ring. To simulate this process we have coupled an ad hoc modified version of the 3D numerical code Ginger (which models the FEL interaction) together with a linear one-turn map (which propagates the electron beam along the ring). We present our results and draw a comparison with previous simplified approaches. We also present the first benchmarking of experiments carried out with the ELETTRA storage-ring FEL.  
 
MOPCH019 Baseline Design of the Linac Upgrade for Fermi linac, controls, laser, ELETTRA 92
 
  • G. D'Auria, P. Craievich, P. Delgiusto, S. Di Mitri, M. Ferianis, M.M. Milloch, G.C. Pappas, G. Penco, M. Trovo
    ELETTRA, Basovizza, Trieste
  • L.R. Doolittle, A. Ratti
    LBNL, Berkeley, California
  The FERMI FEL requires a major upgrade of the existing linac, which needs to be transformed from being the injector for the ELETTRA light source, to becoming the source for the FERMI FEL. In this work, we present the baseline design, including the integration of the 7 additional systems from the LIL linac, and one X-band station as linearizers. We will present the new layout with the required modifications and additions to the existing infrastructure to meet the more demanding needs of the system. Such modifications include a new RF controller, improvements in the modulator stability and an upgrade to the average power capabilities of the system to operate at 50 Hz. Test results from the characterization of the existing systems will be included, as well as plans for future development.  
 
MOPCH024 Future Seeding Experiments at SPARC undulator, laser, radiation, resonance 95
 
  • L. Giannessi, S. Ambrogio, F. Ciocci, G. Dattoli, A. Doria, G.P. Gallerano, E. Giovenale, M. Quattromini, A. Renieri, C. Ronsivalle, I.P. Spassovsky
    ENEA C.R. Frascati, Frascati (Roma)
  • D. Alesini, M.E. Biagini, R. Boni, M. Castellano, A. Clozza, A. Drago, M. Ferrario, V. Fusco, A. Gallo, A. Ghigo, M. Migliorati, L. Palumbo, C. Sanelli, F. Sgamma, B. Spataro, S. Tomassini, C. Vaccarezza, C. Vicario
    INFN/LNF, Frascati (Roma)
  • M. Bougeard, B. Carré, D. Garzella, M. Labat, G. Lambert, H. Merdji, P. Salieres, O. Tcherbakoff
    CEA, Gif-sur-Yvette
  • M.-E. Couprie
    SOLEIL, Gif-sur-Yvette
  • A. Dipace, E. Sabia
    ENEA Portici, Portici (Napoli)
  • M. Mattioli, P. Musumeci, M. Petrarca
    Università di Roma I La Sapienza, Roma
  • M. Nisoli, G. Sansone, S. Stagira, S. de Silvestri
    Politecnico/Milano, Milano
  • L. P. Poletto, G. T. Tondello
    Univ. degli Studi di Padova, Padova
  • L. Serafini
    INFN-Milano, Milano
  Sources based on High order Harmonics Generated in gases (HHG) with high power Ti:Sa lasers pulses represent promising candidates as seed for FEL amplifiers for several reasons, as spatial and temporal coherence, wavelength tunability and spectral range, which extends down to the nm wavelength scale. This communication describes the research work plan that is under implementation at the SPARC FEL facility in the framework of the EUROFEL programme. The main goal of the collaboration is to study and test the amplification and the FEL harmonic generation process of an input seed signal obtained as higher order harmonics generated both in crystals (400 nm and 266 nm) and in gases (266 nm, 160 nm, 114 nm). The SPARC FEL can be configured to test several cascaded FEL layouts that will be analysed in this contribution.  
 
MOPCH030 Production of Coherent X-rays with a Free Electron Laser Based on an Optical Wiggler laser, radiation, electron, emittance 113
 
  • V. Petrillo, A. Colzato
    Universita' degli Studi di Milano, Milano
  • A. Bacci, C. Maroli, L. Serafini
    INFN-Milano, Milano
  • M. Ferrario
    INFN/LNF, Frascati (Roma)
  The interaction between high-brightness electron beams and counter-propagating laser pulses produces X rays via Thomson scattering. If the laser source is long enough, the electrons bunch on the scale of the emitted X-ray wavelength and a regime of collective effects establishes. In this case, the FEL instability develops and the system behaves like a FEL based on an optical undulator. Coherent X-rays are irradiated, with a bandwidth thinner than that of the incoherent emission. The emittance of the beam and gradients or irregularities in the laser energy distribution are the principal factors that limit the growth of the X-ray signal. We analyse with a 3-D code the transverse effects in the emission produced by a relativistic electron beam when it is under the action of an optical laser pulse and the X-ray spectra obtained. The scalings typical of the optical wiggler, with very short gain lengths and overall time durations of the process make possible considerable emission also in violation of the Pellegrini criterion for static wigglers. A generalized form of this criterion is validated on the basis of the numerical evidence.  
 
MOPCH036 Photocathode Roughness Impact on Photogun Beam Characteristics emittance, cathode, electron, gun 121
 
  • T.V. Gorlov
    MEPhI, Moscow
  • A.M. Tron
    LPI, Moscow
  Photocathode surface roughness has an impact on photoelectron yield, bunch duration, beam emittance at the exit of femtosecond photogun with an accelerating field that is considered in assumption of quasi-stationary one in the paper. The main problem in investigating the impact is determination of the field near the surface, statistical properties of which are defined through rms values of deviation and slope in profile line of the surface roughness. Developed and created code allows determining the field with relative rms error not worse than 0.001%. The results of the investigation for rms values of roughness and its slope within respectively 500…0 nm and 20…0 degrees are presented and discussed.  
 
MOPCH038 Predicted Parameters of the Second Stage of High Power Novosibirsk FEL undulator, electron, simulation, ERL 124
 
  • A.V. Kuzmin, O.A. Shevchenko, N. Vinokurov
    BINP SB RAS, Novosibirsk
  The first stage of Novosibirsk high power terahertz FEL was successfully put into operation in 2003*. The measured parameters of the FEL turned out to be in a good agreement with calculations [2]. The second and the third stages of the FEL are under construction now. The beam energy at the second stage will be about 20 MeV and the wavelength will change in the range 40-80 μm. In this paper we present the design parameters for the second stage FEL. The simulations were carried out with the help of 1-D code based on macroparticles. This code was previously used for the first stage simulations**.

*E. A. Antokhin et al. NIM A528 (2004) p.15-18.**A. V. Kuzmin et al. NIM A543 (2005) p.114-117.

 
 
MOPCH040 Simulations for the FEL Test Facility at MAX-lab within EUROFEL undulator, electron, simulation, gun 127
 
  • S. Thorin, M. Brandin, S. Werin
    MAX-lab, Lund
  • M. Abo-Bakr, J. Bahrdt, K. Goldammer
    BESSY GmbH, Berlin
  Within the EUROFEL project a High Gain Harmonic Generation Free Electron Laser will be constructed at MAX-lab in collaboration with BESSY. The electron bunches will be created in the existing MAX-lab injector and transported to the inside of the MAX II ring where the FEL undulators will be located. To predict FEL performance and stability, simulations of the photo injector, linac, recirculator, transport and undulator sections as well as start to end simulations have been carried out.  
 
MOPCH043 An Optimization Study for an FEL Oscillator at TAC Test Facility electron, radiation, undulator, laser 136
 
  • Ö.M. Mete, Ö. Karsli, O. Yavas
    Ankara University, Faculty of Engineering, Tandogan, Ankara
  Recently, conceptual design of the Turkic Accelerator Center (TAC) proposal was completed. The main goal of this proposal is a charm factory that consists of a linac-ring type electron-positron collider. In addition, synchrotron radiation from the positron ring and free electron laser from the electron linac are proposed. The project related with this proposal has been accepted by the Turkish government. It is planned that the Technical Design Report of TAC will have been written in the next three years. In this period, an infrared oscillator free electron laser (IR FEL) will be constructed as a test facility for TAC. 20 and 50 MeV electron energies will be used to obtain infrared FEL. The main parameters of the electron linacs, the optical cavities and the FEL were determined. The possible use of obtained laser beam in basic and applied research areas such as biotechnology, nanotechnology, semiconductors and photo chemistry were discussed.  
 
MOPCH045 A Source of Coherent Soft X-ray Radiation Based on High-order Harmonic Generation and Free Electron Lasers laser, undulator, electron, simulation 142
 
  • M. Gullans, J.S. Wurtele
    UCB, Berkeley, California
  • G. Penn, A. Zholents
    LBNL, Berkeley, California
  We examine a scheme for a Free Electron Laser (FEL) harmonic amplifier seeded by a ~30-nm wavelength signal produced using a process of High-order Harmonic Generation (HHG). The seed is first amplified in an optical klystron from ~100 kW to ~30 MW using a 1 GeV electron beam and then is used for an energy modulation of electrons in the downstream undulator. Subsequently, a 100-MW level of radiation at shorter wavelengths down to 4 nm is obtained by bunching the energy modulated electrons and passing the bunched beam through an undulator tuned to the desired harmonic of 30 nm. We also compare this scheme to a more familiar harmonic cascade FEL by replacing the HHG with an additional stage of harmonic generation.  
 
MOPCH064 The Specification, Design and Measurement of Magnets for the Energy Recovery Linac Prototype (ERLP) at Daresbury Laboratory dipole, quadrupole, ERLP, linac 175
 
  • F. Bødker
    Danfysik A/S, Jyllinge
  • N. Marks, N. Thompson
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  The Energy Recovery Linac Prototype (ERLP) is currently under construction at Daresbury Laboratory in the UK and will serve as a test bed for the investigation of technologies and beam physics issues necessary for the development of Daresbury Laboratory's Fourth Generation Light Source (4GLS) proposal. A number of new ERLP beam transport system magnets have been procured for the project. The magnets have been designed, manufactured and measured by Danfysik following a stringent magnetic field specification produced by Daresbury Laboratory. In this paper we summarise the magnet specification. We then present details of the magnetic and mechanical design of the magnets and finally discuss the measurement techniques used to demonstrate that the field quality of the magnets satisfied the specification.  
 
MOPCH066 The Conceptual Design of 4GLS at Daresbury Laboratory linac, radiation, electron, undulator 181
 
  • 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 is summarised, highlighting how the significant design challenges have been addressed, and the project status and plans explained.  
 
MOPCH069 Lattice Design for the Fourth Generation Light Source at Daresbury Laboratory linac, laser, undulator, electron 184
 
  • B.D. Muratori, M.A. Bowler, H.L. Owen, S.L. Smith
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • S.V. Miginsky
    BINP SB RAS, Novosibirsk
  The proposed Fourth Generation Light Source (4GLS) has three electron transport paths, an energy recovery loop containing the main linac, IDs and a VUV-FEL, a separate branch after the main linac for an XUV-FEL and a transport path for an IR-FEL. The first two present major challenges in lattice design. The energy recovery loop will be fed by a high average current gun, with bunches of charge of about 80 pC. High charge (1nC) bunches from a high brightness gun will be accelerated prior to the main linac and split into the XUV-FEL branch using energy separation after the main linac. We present a lattice design and results from numerical modelling of the electron bunch transport. The requirements of the machine are short bunches, a small emittance for both branches and an overall topology which gives a reasonable dimension for the building. Different transport and compression schemes were assessed to meet these requirements whilst balancing the disruptive effects of longitudinal and transverse space charge, CSR, wakefields and BBU. Investigations into all of these instabilities are summarized together with other transport issues and the resulting requirements on all IDs.  
 
MOPCH073 A Project of a High-power FEL Driven by an SC ERL at KAERI sextupole, ERL, emittance, dipole 196
 
  • A.V. Bondarenko, S.V. Miginsky
    BINP SB RAS, Novosibirsk
  • Y.H. Han, Y.U. Jeong, B.C. Lee, S. H. Park
    KAERI, Daejon
  A project of a high-power FEL at Korea Atomic Energy Research Institute is described. The FEL is driven by a superconducting energy recovery linac. The future ERL will be connected to the existing machine without any modification. It consists of two 180-degree bents and two straight sections: one is for the FEL, another for a Compton X-rays source. One can choose the regime controlling the lenses. The total ERL is isochronous to avoid any problems with longitudinal beam instability. The total relative emittance degradation through the whole machine is ? 1.5. The FEL will be based on a 2 m helical in-vacuum undulator made of permanent magnets. One mirror of the optical cavity is blind and made of copper; the other one, the outcoupler, is semi-transparent and made of CVD diamond. The expected average power is a few kW and the tuning range 35…70 ?m.  
 
MOPCH150 Characterization of a Piezo-based Microphonics Compensation System at HoBiCaT resonance, controls, TESLA, linac 408
 
  • A. Neumann, W. Anders, S. Klauke, J. Knobloch, O. Kugeler, M. Schuster
    BESSY GmbH, Berlin
  In the superconducting driver linac for the BESSY FEL, piezo actuators will be utilized to rapidly counteract the detuning of the cavity resonance caused by nm mechanical oscillations (microphonics). This is of importance to guarantee field stability and lower the power consumption of the RF system for the superconducting cavities. To design a suitable compensator, mechanical and electro-mechanical transfer functions, as well as the tuning range of the system under operating conditions have been measured and will be presented.  
 
MOPCH182 The JLAB Ampere-class Cryomodule Conceptual Design damping, impedance, coupling, BBU 490
 
  • R.A. Rimmer, G. Ciovati, E. Daly, T. Elliott, J. Henry, W.R. Hicks, P. Kneisel, S. Manning, R. Manus, J.P. Preble, K. Smith, M. Stirbet, L. Turlington, L. Vogel, H. Wang, K. Wilson, G. Wu
    Jefferson Lab, Newport News, Virginia
  For the next generation of compact high-power FELs a new cryomodule is required that is capable of accelerating up to Ampere levels of beam current. Challenges include strong HOM damping, high HOM power and high fundamental-mode power (in operating scenarios without full energy recovery). For efficient use of space a high real-estate gradient is desirable and for economic operation good fundamental-mode efficiency is important. The technology must also be robust and should be based on well-proven and reliable technologies. For Ampere-class levels of beam current both halo interception and beam break-up (BBU) are important considerations. These factors tend to drive the designs to lower frequencies where the apertures are larger and the transverse impedances are lower. To achieve these goals we propose to use a compact waveguide-damped multi-cell cavity packaged in an SNS-style cryomodule.  
 
MOPCH187 Key Cryogenics Challenges in the Development of the 4GLS linac, cryogenics, TESLA, ERLP 499
 
  • R. Bate, R.K. Buckley, A.R. Goulden, C. Hodgkinson, S.M. Pattalwar
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  The fourth generation light source (4GLS) is a uniquely flexible source of ultra-high brightness continuous and pulsed radiation covering the IR to XUV range of the spectrum. It is the first light source in the world that is planned from the outset to be a multi-user, multi-source facility combining ERL (energy recovery LINAC) and FEL (free electron laser) technology. 4GLS will require six different sets of superconducting LINACs. Each of the LINAC modules consists of 2 to 7, 1.3 GHz superconducting RF cavities of the TESLA design operating at 1.8 K. The overall cooling power necessary to cool the cavities is estimated to be around 2.5KW demanding the superfluid liquid helium flow rates in excess of 200g/s. Even though the technology of the superconducting RF cavities is somewhat well understood, the design and subsequent operation of the cryogenic system / Cryo modules is an extremely complex task. In this paper we describe the key cryogenic challenges of the 4GLS project and our approach in identifying solutions to meet them.  
 
TUPCH024 Comparative Study of Bunch Length and Arrival Time Measurements at FLASH laser, electron, SASE, DESY 1049
 
  • H. Schlarb, A. Azima, S. Düsterer, M. Huening, E.-A. Knabbe, M. Roehrs, R. Rybnikov, B. Schmidt, B. Steffen
    DESY, Hamburg
  • M.C. Ross
    SLAC, Menlo Park, California
  • P. Schmüser, A. Winter
    Uni HH, Hamburg
  Diagnostic devices to precisely measure the longitudinal electron beam profile and the bunch arrival time require elaborate new instrumentation techniques. At the VUV-FEL, two entirely different methods are used. The bunch profile can be determined with high precision by a transverse deflecting RF structure. The method is disruptive and does not allow to monitor multiple bunches in a macro-pulse train. Therefore, it is augmented by two non-disruptive electro-optical devices, called EO and TEO. The EO setup uses a dedicated diagnostic laser synchronized to the machine RF. The longitudinal electron beam profile is encoded in the intensity profile of a chirped laser pulse and analyzed by looking at the spectral composition of the pulse. The second setup, TEO, utilizes the TiSa-based laser system used for pump-probe experiments. Here, the temporal electron shape is encoded into a spatial dimension of laser pulse by an intersection angle between the laser and the electron beam at the EO-crystal. In this paper, we present a comparative study of bunch length and arrival time measurements performed simultaneously with all three experimental techniques.  
 
TUPCH026 Single Shot Longitudinal Bunch Profile Measurements at FLASH using Electro-optic Techniques electron, laser, linac, SASE 1055
 
  • B. Steffen, E.-A. Knabbe, B. Schmidt
    DESY, Hamburg
  • G. Berden, A.F.G. van der Meer
    FOM Rijnhuizen, Nieuwegein
  • W.A. Gillespie, P.J. Phillips
    University of Dundee, Nethergate, Dundee, Scotland
  • S.P. Jamison, A. MacLeod
    UAD, Dundee
  • P. Schmüser
    Uni HH, Hamburg
  For the high-gain operation of a SASE FEL, extremly short electron bunches are essential to generate sufficiently high peak currents. At the superconducting linac of the VUV-FEL at DESY, we have installed an electro-optic experiment with temporal decoding and spectral decoding to probe the time structure of the electric field of single sub 200fs e-bunches. In this technique, the field-induced birefringence in an electro-optic crystal is encoded on a chirped ps laser pulse. The longitudinal electric field profile of the electron bunch is then obtained from the encoded optical pulse by a single-shot cross correlation with a 30 fs laser pulse using a second-harmonic crystal (temporal decoding) or by a single-shot measurement of its spectrum (spectral decoding). In the temporal decoding measurements an electro-optic signal of 230fs FWHM was observed, and is limited by the material properties of the particular electro-optic crystal used. Bunch profile and time jitter measurements were obtained simultaneously with VUV SASE operation.  
 
TUPCH027 Time Resolved Single-shot Measurements of Transition Radiation at the THz Beamline of FLASH using Electro-optic Spectral Decoding radiation, electron, laser, DESY 1058
 
  • B. Steffen, E.-A. Knabbe, B. Schmidt
    DESY, Hamburg
  • G. Berden, A.F.G. van der Meer
    FOM Rijnhuizen, Nieuwegein
  • W.A. Gillespie, P.J. Phillips
    University of Dundee, Nethergate, Dundee, Scotland
  • S.P. Jamison, A. MacLeod
    UAD, Dundee
  • P. Schmüser
    Uni HH, Hamburg
  Single-shot electro-optic detection was used to measure the temporal profile of coherent transition radiation (CTR) pulses at the VUV-FEL at DESY. The CTR was generated from single bunches kicked to an off-axis screen, with the radiation transported through a 20m long transfer line imaging the CTR from a radiation screen to an experimental station outside the accelerator tunnel. Bipolar pulses with a FWHM less than 1ps have been measured and are consistent with simulations of the propagation of radiation through the transfer line.  
 
TUPCH029 High-precision Laser Master Oscillators for Optical Timing Distribution Systems in Future Light Sources laser, feedback, linac, DESY 1064
 
  • A. Winter, P. Schmüser, A. Winter
    Uni HH, Hamburg
  • J. Chen, F.X. Kaertner
    MIT, Cambridge, Massachusetts
  • F.O. Ilday
    Bilkent University, Bilkent, Ankara
  • F. Ludwig, H. Schlarb
    DESY, Hamburg
  X-ray pulses with a pulse duration in the 10 fs regime or even less are needed for numerous experiments planned at next generation free electron lasers. A synchronization of probe laser pulses to the x-ray pulses with a stability on the order of the pulse width is highly desirable for these experiments. This requirement can be fulfilled by distributing an ultra-stable timing signal to various subsystems of the machine and to the experimental area to provide synchronization at the fs level over distances of several kilometers. Mode-locked fiber lasers serve as laser master oscillators (LMO), generating the frequencies required in the machine. The pulse train is distributed through length-stabilized fiber links. This paper focuses on the LMO, devoting special attention to the phase noise properties of the frequencies to be generated, its reliability to operate in an accelerator environment, and the residual timing jitter and drifts of the RF feedback for the fiber links. A prototype experimental system has been constructed and tested in an accelerator environment and its performance characteristics will be evaluated.  
 
TUPCH053 Bunch Length Characterization Downstream from the Second Bunch Compressor at FLASH DESY, Hamburg electron, radiation, CDR, SASE 1127
 
  • E. Chiadroni
    INFN-Roma II, Roma
  The characterization of the longitudinal density profile of picosecond and sub-picosecond relativistic particle bunches is a fundamental requirement in many particle accelerator facilities, since knowledge of the characteristics of the accelerated beams is of utmost importance for the successful development of the next generation light sources and linear colliders. The development of non-intercepting beam diagnostics is thus necessary to produce and control such beams. First experimental evidences of the non-intercepting nature of diffraction radiation diagnostics are given. The longitudinal bunch distribution downstream of the second bunch compressor of the DESY TTF VUV-FEL has been reconstructed using a frequency-domain technique based on the autocorrelation of coherent diffraction radiation. Due to the low and high frequency suppression, introduced by the experimental apparatus, only a portion of the CDR spectrum participates to the reconstruction of the longitudinal bunch profile. The knowledge of the system frequency response is then crucial in order to correct the results and extrapolate a bunch shape as close as possible to the real one.  
 
THXPA03 Laser Systems and Accelerators laser, electron, undulator, gun 2728
 
  • H. Schlarb
    DESY, Hamburg
  The presentation will cover the use of laser systems in accelerators. Topics covered will be the use of lasers for the production of electron beam from photocathodes, timing and diagnostics, laser heater systems to control space charge effects, as seed systems. Challenges in terms of stability, pulse shaping, power and pulse lengths, wavelength range and tuning will be covered for the various aspects.  
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THOPA03 An Integrated Femtosecond Timing Distribution System for XFELs laser, electron, free-electron-laser, controls 2744
 
  • J. Kim, J. Burnham, dc. Cheever, J. Chen, F.X. Kaertner
    MIT, Cambridge, Massachusetts
  • M. Ferianis
    ELETTRA, Basovizza, Trieste
  • F.O. Ilday
    Bilkent University, Bilkent, Ankara
  • F. Ludwig, H. Schlarb, A. Winter
    DESY, Hamburg
  Tightly synchronized lasers and rf-systems with timing jitter in the few femtoseconds range are an important component of future x-ray free electron laser facilities. In this paper, we present an optical-rf phase detector that is capable of extracting an rf-signal from an optical pulse stream without amplitude-to-phase conversion. Extraction of a microwave signal with less than 10 fs timing jitter (from 1 Hz to 10 MHz) from an optical pulse stream is demonstrated. Scaling of this component to sub-femtosecond resolution is discussed. Together with low noise mode-locked lasers, timing-stabilized optical fiber links and compact optical cross-correlators, a flexible femtosecond timing distribution system with potentially sub-10 fs precision over distances of a few kilometres can be constructed. Experimental results on both synchronized rf and laser sources will be presented.

*A. Winter et al. "Synchronization of Femtosecond Pulses", Proceedings of FEL 2005.**J. Kim et al. "Large-Scale Timing Distribution and RF-Synchronization for FEL Facilities", Proc. of FEL 2004.

 
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THPPA01 High-precision Laser Master Oscillators for Optical Timing Distribution Systems in Future Light Sources laser, feedback, electron, diagnostics 2747
 
  • A. Winter, P. Schmüser, A. Winter
    Uni HH, Hamburg
  • J. Chen, F.X. Kaertner
    MIT, Cambridge, Massachusetts
  • F.O. Ilday
    Bilkent University, Bilkent, Ankara
  • F. Ludwig, H. Schlarb
    DESY, Hamburg
  Abstract to be supplied  
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THOBFI01 A Sub 100 fs Electron Bunch Arrival-time Monitor System for FLASH laser, pick-up, electron, DESY 2781
 
  • F. Loehl, K.E. Hacker, F. Ludwig, H. Schlarb, B. Schmidt
    DESY, Hamburg
  • A. Winter
    Uni HH, Hamburg
  The stability of free-electron lasers and experiments carried out in pump-probe configurations depends sensitively on precise synchronization between the photo-injector laser, low-level RF-systems, probe lasers, and other components in the FEL. A measurement of the jitter in the arrival-time of the electron bunch with respect to the clock signal of a master oscillator is, therefore, of special importance. For this task, we propose an arrival-time monitor based on a beam pick-up with more than 10GHz bandwidth which permits measurements in the sub 100 fs regime. The RF-signal from the beam pick-up is sampled by an ultra-short laser pulse using a broad-band electro-optical modulator. The modulator converts the electron bunch arrival-time jitter into an amplitude modulation of the laser pulse. This modulation is detected by a photo detector and sampled by a fast ADC. By directly using the laser pulses from the master laser oscillator of the machine, any additional timing jitter is avoided. In this paper we present the layout of the system and first experimental results.  
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THPCH043 Jitter Studies for the FERMI@ELETTRA Linac linac, electron, ELETTRA, simulation 2880
 
  • P. Craievich, S. Di Mitri
    ELETTRA, Basovizza, Trieste
  • A. Zholents
    LBNL, Berkeley, California
  The FEL project FERMI@ELETTRA* will use the existing linac upgraded to 1.2GeV to produce photon pulses in the wavelength range between 100-10 nm by means of harmonic generation in a seeded scheme. FEL operations foresee stringent requirements for the stability of the global linac output parameters, such as the electron bunch arrival time, peak current, average energy and the slice electron bunch parameters, such as the slice peak current and slice average energy. In order to understand the sensitivity of these parameters to jitters of various error sources along the linac an elaborate study using tracking codes has been performed. As a result, we created a tolerance budget to be used as guidance in the design of the linac upgrade. In this paper we give a detailed description of the applied procedures and present the obtained results.

*C. Bocchetta et al. "FERMI@ELETTRA - Conceptual Design for a Seeded Harmonic Cascade FEL for EUV and Soft X-rays", this conference.

 
 
THPCH044 Beam Break-up Instability in the FERMI@ELETTRA Linac linac, emittance, BBU, simulation 2883
 
  • S. Di Mitri, P. Craievich
    ELETTRA, Basovizza, Trieste
  The beam break-up instability is studied for the 1.2 GeV linac of FERMI @ ELETTRA FEL*. This instability is driven by transverse wake fields acting on an electron beam travelling off-axis in the accelerating structures due to the launching errors in positions, angles, energy and misalignment of various lattice elements. Two operational scenarios are considered: one with a relatively long electron bunch of 1.5 ps and a moderate peak current of 500 A and one with a shorter bunch of 0.7 ps and a higher peak current of 800 A. Attention is given to the correction of the "banana" shape of the electron bunch caused by the instability. The simulation results are compared with the analytical predictions.

*C. Bocchetta et al. “FERMI@Elettra – Conceptual Design for a Seeded Harmonic Cascade FEL for EUV and Soft X-rays”, this conference.

 
 
THPCH073 Reflectivity Measurements for Copper and Aluminum in the Far Infrared and the Resistive Wall Impedance in the LCLS Undulator LCLS, undulator, impedance, SLAC 2955
 
  • K.L.F. Bane, G.V. Stupakov
    SLAC, Menlo Park, California
  • J. Tu
    City College of The City University of New York, New York
  Reflectivity measurements in the far infrared, performed on aluminum and copper samples, are presented and analyzed. Over a frequency range of interest for the LCLS bunch, the data is fit to the free-electron model, and to one including the anomalous skin effect. The models fit well, yielding parameters dc conductivity and relaxation times that are within 30-40\% of expected values. We show that the induced energy in the LCLS undulator region is relative insensitive to variations on this order, and thus we can have confidence that the wake effect will be close to what is expected.  
 
THPCH150 Double-pulse Generation with the FLASH Injector Laser for Pump/Probe Experiments laser, SASE, radiation, polarization 3143
 
  • O. Grimm, K. Klose, S. Schreiber
    DESY, Hamburg
  The injector laser of the VUV-FEL at DESY, Hamburg, was modified to allow the generation of double-pulses, separated by a few cycles of the 1.3 GHz radio-frequency. Such double pulses are needed for driving the planned infrared/VUV pump/probe facility. Construction constraints of the facility will result in an optical path length about 80 cm longer for the infrared. Although the VUV can be delayed using normal-incidence multilayer mirrors at selected wavelengths, a fully flexible scheme is achieved by accelerating two electron bunches separated by more than the path length difference and then combine the infrared radiation from the first with the VUV from the second. This paper explains schemes for the generation of double-pulses with the laser system. It summarizes experimental studies of the effect on the operation of diagnostic instrumentation and on the tunability of the machine. Of special concern is the effect of wakefields on the quality of the second bunch, critical for achieving lasing.  
 
THPCH159 Analysis of Microphonic Disturbances and Simulation for Feedback Compensation feedback, simulation, linac, resonance 3167
 
  • M. Luong, P. Bosland, G. Devanz, E. Jacques
    CEA, Gif-sur-Yvette
  For FEL projects based on a superconducting linac operating in CW mode, the RF power optimization finally comes up against the microphonics disturbances, which result in an unpredictable detuning of the cavities. A new piezoelectric tuner was developed and mounted on a TTF 9-cell cavity with an appropriate instrumentation. This system enables a full characterization of the disturbances and the tuner behavior. First measurements were made in a horizontal cryomodule at 4.2 K. They set a basis for simulations to assess the possibility of a feedback compensation, which is usually credited as impracticable. The outcome of such a compensation is also shown in terms of acceleration voltage amplitude and phase residual errors.  
 
THPLS040 Present Status of the UVSOR-II electron, laser, undulator, emittance 3374
 
  • M. Katoh, K. Hayashi, M. Hosaka, A. Mochihashi, J. Yamazaki
    UVSOR, Okazaki
  • T. Hara
    RIKEN Spring-8 Harima, Hyogo
  • M. Shimada
    KEK, Ibaraki
  UVSOR electron storage ring, which was a 2nd-generation synchrotron radiation (SR) light source for VUV and soft x-ray region, has been renewed as UVSOR-II at the beginning of 2003. Because of the improvement, the beam emittance has been reduced from 165nm-rad to 27nm-rad, and longer straight sections with smaller vertical betatron functions have been provided. In addition to a helical/linear undulator, two in-vacuum undulators have been installed in the long straight sections at the improvement. New variably polarized undulator will be also installed in summer 2006. Improvement of booster synchrotron will be also performed in summer 2006 with aiming to top-up operation in the future. Now UVSOR-II has been operated in 750MeV with the emittance of 27nm-rad in daily users runs. Not only the development of high quality SR beams but also basic investigations for new light source have been performed; development of storage ring FEL and investigation of intense THz burst SR. Bunch slicing experiment with a Ti:Sa laser (800nm) has also been started since 2005, and experiments for coherent harmonic generation and coherent SR generation with the laser-beam interaction have been performed.  
 
THPLS109 Measurements and Diagnostics on the MAX Recirculator electron, radiation, linac, injection 3532
 
  • M. Brandin, B. Nelander, S. Werin
    MAX-lab, Lund
  The MAX Recirculator is a unique accelerator, a two-pass linac at 500 MeV, that operates as injector for three storage rings. Here are presented some discussions on measurments of beam parameters such as emittance, energy spread, and bunch length. We describe what measurements are done, by wich methods, results, and how they can be improved. Also, we make an analysis of What methods and hardware are needed to perform the measurements that can't be done with the equipment in place today.  
 
THPLS117 In-vacuum and FEL Undulators at Danfysik undulator, SLS, insertion-device, insertion 3553
 
  • F. Bødker, H. Bach, E.B. Christensen, E. Juul, C.W.O. Ostenfeld, M. Pedersen, T.L. Svendsen
    Danfysik A/S, Jyllinge
  Danfysik has recently designed and produced two in-vacuum insertion devices. The first device is a 19 mm period device made for the Swiss Light Source and the second is a 20 mm period device for SOLEIL. Both are hybrid undulators with Samarium Cobalt magnets where the SLS device is made with steel poles while the SOLEIL undulator is optimized for high peak field using Vanadium Permendur poles and relative large magnet blocks. A quasi-periodic undulator has been built for FEL applications at the FOM-Institute for Plasma Physics. The device is based on a standard pure permanent undulator design but then converted into a quasi-periodic device. The magnetic performance of the device was in excellent agreement with theoretical calculations with high suppression of the 3. and 5. harmonics. A conventional undulator has also been built for FEL applications at FZR Rossendorf. A high degree of software assistance and automation has been developed for the magnet mounting, shimming and magnetic testing of the insertion devices. This technique reduces the shimming time significantly, reduces the need for highly trained personnel and results in superior magnetic performance.  
 
THPLS132 Physics Requirement of a PLS-XFEL Undulator undulator, radiation, SASE, XFEL 3592
 
  • D.E. Kim, C.W. Chung, I.S. Ko, J.-S. Oh, K.-H. Park
    PAL, Pohang, Kyungbuk
  Pohang Accelerator Laboratory(PAL)is planning a 0.3nm SASE (Self Amplification of Spontaneous Emission) XFEL based on a 3.7GeV linear accelerator. For short saturation length, application of the SPring8 type in the vacuum undulator is needed. This reflects the experiences from the Spring8 SCSS project. The end structures were designed to be asymmetric along the beam direction to ensure systematic zero 1st field integral. The thickness of the last magnets was adjusted to minimize the transition distance to the fully developed periodic field. This approach is more convenient to control than adjusting the strength of the end magnets. The final design features 4mm minimum pole gap, 15mm period, and peak effective field of 1.09 Tesla. In this article, the physical design of the undulator, the design of the end structure, and the physics requirements of the undulator system will be presented.  
 
FRYBPA01 Overview of Single Pass Free Electron Lasers electron, radiation, laser, undulator 3636
 
  • C. Pellegrini
    UCLA, Los Angeles, California
  The presentation will cover world wide status of single pass free electron lasers. A general status will be given of the projects. Common themes will be discussed, as will the challenges of these themes. Unique characteristics of individual projects will also be covered. Here the emphasis will be on a description of novel and challenging techniques: for example examples seeding of the FEL, different types of guns for high brightness electron beam production, very short or very long pulse production, etc.  
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