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Paper Title Other Keywords Page
MO102 The European XFEL SC Linac Project linac, undulator, electron, radiation 6
  • R. Brinkmann
    DESY, Hamburg

The European XFEL project is entering the construction phase, based on the very successful experience of the TESLA linac technology and the SASE FEL concept, now serving the FLASH user facility at DESY. The EU-XFEL will be realized by a widespread international collaboration and it is also relevant for the ILC planning. A description of the overall layout of the facility, of the technical developments and industrialization efforts for the accelerator components, and of the international collaboration will be given.


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MOP110 Precise Control of Cooling Water System for Stabilization of 125 MeV Linac at LEBRA linac, electron, klystron, target 331
  • T. Sakai, M. Inagaki, T. Kuwada, I. Sato
    Nihon University, Advanced Research Institute for the Sciences and Humanities, Funabashi
  • K. Hayakawa, Y. Hayakawa, K. Nakao, K. Nogami, Y. Takahashi, T. Tanaka
    LEBRA, Funabashi

The 125 MeV linac at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University has been used for generation of the near-infrared FEL and the Parametric X-ray Radiation (PXR). Currently the FELs from 0.86 to 6 microns and the PXR X-rays from 5 to 20 keV are available at LEBRA. Precise experiments using the light sources require a high stability in both the wavelength and the intensity of the lights. Though the linac was operated with the cooling water stabilized at 30 plus or minus 0.2 deg C, periodical fluctuation of the electron beam energy and the beam orbit suggested that the stability of the cooling water temperature was not sufficient. With this condition a large fluctuation (plus or minus 15%) was observed for the PXR intensity. After the improvement of the fine cooling water system and the water flow path, fluctuation of the cooling water temperature at the supply head of the accelerating tubes and the electromagnets was suppressed to within plus or minus 0.01 deg C. As a result of the improvement the PXR intensity fluctuation at the X-ray output port has been suppressed to within plus or minus 2% for the operation over several hours.

TUP031 Normal Conducting Options for the UK's New Light Source Project linac, klystron, emittance, cavity 462
  • C. Christou, R. Bartolini, J.H. Han, H.C. Huang, J. Kay
    Diamond, Oxfordshire

A New Light Source project has been initiated to deliver a conceptual design for a next-generation light source facility in the UK. One option for such a light source is a free electron laser based on normal-conducting linac technology. This paper considers the different options available for waveband, gun and rf design of a normal-conducting linac FEL, and presents an overview of accelerating structure, modulator and klystron capability and availability. Particular attention is paid to the issue of the operation of a normal-conducting device at repetition rates of several hundred pulses per second. Overall capabilities and limitations of this approach are illustrated by reference to a start-to-end model of a suitable 3 GeV S-band linac design.

TUP038 MIR-FEL with 4.5-Cell Thermionic RF-Gun gun, electron, undulator, klystron 477
  • T. Kii, K. Higashimura, R. Kinjo, K. Masuda, H. Ohgaki, H. Zen
    Kyoto IAE, Kyoto

An MIR-FEL facility, Kyoto University FEL (KU-FEL), has been developed for applications in "sustainable energy science", such as fundamental studies on high-efficiency solar cells. The KU-FEL, consisting of an S-band thermionic rf gun, a 3 m accelerator tube and a planer undulator, aims to generate 4-13 μmeter tunable FEL. The first lasing was achieved on March, 2008 at 12.4 μmeters by using a beamloading compensation method both in the rf gun and in the accelerator tube. *Furthermore, we introduced detuning to the rf gun and succeeded to generate an electron beam with macropulse duration of 5.1 μseconds, average current of 100 mA and energy spread of 0.5% which led to power saturation in FEL. In the conference, the improvements of the electron beam properties and power saturation of the KU-FEL will be discussed.

*H. Ohgaki et al., 'First Lasing at 12 um Mid Infrared Free Electron Laser at Kyoto University', Japanese Journal of Applied Physics, accepted for publication. (2008).

TUP039 Status of the LINAC-800 Construction at JINR electron, linac, acceleration, gun 480
  • G.V. Trubnikov, N. Balalykin, A.G. Kobets, V. Kobets, I.N. Meshkov, V. Minashkin, G. Shirkov, G.I. Sidorov
    JINR, Dubna, Moscow Region
  • V. Shabratov
    JINR/LHE, Moscow

800 MeV electron linac (LINAC-800) is under construction at JINR. It will be used as a driver for Volume FEL and as a test bench for commissioning of elements of the ILC. Presently the electron injector is commissioned and the electron beam of 50 keV of the energy at current of about 15 mA was obtained. The results of the injector operation at nominal parameters (400 keV, 300 mA) and commissioning of the first accelerating section at 20 MeV are discussed.

TUP040 Linear Accelerator for the PSI-XFEL FEL3 Beamline linac, emittance, gun, laser 483
  • Y. Kim, A. Adelmann, B. Beutner, M.M. Dehler, R. Ganter, T. Garvey, R. Ischebeck, M. Pedrozzi, J.-Y. Raguin, S. Reiche, L. Rivkin, V. Schlott, A. Streun, A.F. Wrulich
    PSI, Villigen

In the planned PSI-XFEL facility, three FEL branches will supply coherent, ultra-bright, and ultra-short XFEL photons at wide wavelength range. FEL branch 1 will use a 6.0 GeV driving linac to generate hard X-rays from 0.1 nm to 0.3 nm, while FEL branch 2 is foreseen for X-rays from 0.3 nm to 1.0 nm. However, FEL branch 3 was designed to supply spatially as well as temporally coherent soft X-rays from 1.0 nm to 10 nm with the High-order Harmonic Generation based seeded HGHG scheme. To reach emittances of 0.2 mm.mrad and to squeeze consequently the whole facility within an 800 m long tunnel, PSI is presently developing an advanced low emittance gun (LEG) based on a 1 MV high gradient pulsed diode and field emission. The advanced LEG will be used to drive FEL branch 1 and 2, while an RF photoinjector will be used to drive the FEL branch 3. In this paper, we describe a CTF3 RF gun based injector, two bunch compressors, two diagnostic sections, and linacs for the PSI-XFEL FEL branch 3.

TUP041 Superconducting Options for the UK's New Light Source Project cryomodule, linac, SRF, cavity 486
  • P.A. McIntosh, R. Bate, C.D. Beard, D.M. Dykes, S.M. Pattalwar
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire

The UK's new light source project was officially launched on April 11th 2007, which will be based on advanced conventional and free electron lasers, with unique and world leading capabilities. User consulation exercises have already been initiated to determine the fundamental photon output requirements for such a machine. In order to match a nominal requirement for high repetition rates (extending up to 1 MHz), a series of superconducting rf (SRF) linac options have been investigated, reflecting varied beam loading conditions and subsequent high and low power rf solutions.

TUP044 The NPS-FEL Injector Upgrade cathode, laser, gun, injection 495
  • J.W. Lewellen, W.B. Colson, S.P. Niles
    NPS, Monterey, California
  • A.E. Bogle, T.L. Grimm
    Niowave, Inc., Lansing, Michigan
  • W. Graves
    MIT, Middleton, Massachusetts
  • T.I. Smith
    Stanford University, Stanford, Califormia

Funding: This research is supported by the Office of Naval Research and the Joint Technology Office.
The Naval Postgraduate School (NPS) has begun the design and assembly of the NPS Free-Electron Laser (NPS-FEL). As part of this effort, the original dc gun-based injector system is being refurbished and upgraded. As described in the accompanying paper 'Status of the NPS-FEL' (these Proceedings), the overall NPS-FEL design parameters are for 40 MeV beam energy, 1 nC bunch charge, and 1 mA average beam current, in an energy-recovery linac configuration. As we move towards this configuration, the injector system will be incrementally upgraded to add photocathode capability, have a higher final beam energy, and improve the beam brightness, to meet the demands of the overall experimental program. This paper describes the current status of the injector system, the initial set of experiments planned, and the projected upgrade path.

TUP046 Linac Design for an Array of Soft X-Ray Free Electron Lasers linac, electron, emittance, lattice 501
  • A. Zholents, G. Penn, J. Qiang, M. Venturini, R.P. Wells
    LBNL, Berkeley, California
  • E. Kur
    UCB, Berkeley, California

Funding: This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
The design of the linac delivering the electron bunches into ten independent soft x-ray free electron lasers (FELs) is presented. The bunch repetition rate in the linac is 1 MHz and the bunch repetition rate in each FEL beam line is 100 kHz. Various issues regarding machine layout and lattice, bunch compression, collimation, and the beam switch yard are discussed. Particular attention is given to collective effects. A demanding goal is to preserve both a low beam slice emittance and low slice energy spread during acceleration, bunch compression and distribution of the electron bunches into the array of FEL beamlines. Detailed studies of the effect of the electron beam microbunching resulting from longitudinal space-charge forces and coherent synchrotron radiation as the beam undergoes compression have been carried out and are presented.

TUP049 The Electron Bunch Initial Energy Profile on a Seeded Free Electron Laser Performance electron, undulator, free-electron-laser, laser 509
  • J. Wu, A. Chao
    SLAC, Menlo Park, California
  • J. Bisognano
    UW-Madison/SRC, Madison, Wisconsin

Funding: The work of AWC and JW was supported by the US Department of Energy under contract DE-AC02-76SF00515. The work of JB was supported by National Science Foundation Award No. DMR-0537588.
A single-pass high-gain X-ray free electron laser (FEL) calls for a high quality electron bunch. In particular, for a seeded FEL, and for a cascaded harmonic generation (HG) FEL, the electron bunch initial energy profile uniformity is crucial to preserve an FEL narrow bandwidth. After the acceleration, compression, and transport, the electron bunch energy profile entering the undulator can acquire temporal non-uniformity. During the cascading stages, the electron bunch energy profile is also not uniform temporally entering the next stage. We study the effects of the electron bunch initial energy profile on the FEL performance, cascaded HG FEL or single stage FEL amplifier. Concrete examples are discussed for seeded FEL projects being studied.

TUP052 Status of the NPS Free-Electron Laser electron, booster, undulator, laser 518
  • J.W. Lewellen, W.B. Colson, S.P. Niles
    NPS, Monterey, California
  • T.I. Smith
    Stanford University, Stanford, Califormia

Funding: This research is supported by the Office of Naval Research and the Joint Technology Office.
The Naval Postgraduate School (NPS) has begun the design and assembly of the NPS Free-Electron Laser (NPS-FEL). The basic NPS-FEL design parameters are for 40 MeV beam energy, 1 nC bunch charge, and 1 mA average beam current, in an energy-recovery linac configuration. The NPS-FEL will make use of portions of the Stanford Superconducting Accelerator (decommissioned in 2007), in particular the injector system, Stanford/Rossendorf-style cryomodules and rf system. The injector will be gradually upgraded to improve beam properties and increase the injection voltage. Each cryomodule contains two, 9-cell TESLA-type 1.3 GHz cavities, each cavity powered by an individual 10 kW cw klystron. NPS has committed to refurbishing a building for the FEL, with approximate interior vault dimensions of 7 m x 20 m x 2.5 m. The building has overall dimensions of 12 m x 49 m and will house the vault, control room, and support equipment. This paper describes the overall goals of the program, initial experimental plans, and progress to date.

TUP069 Low Energy Photoemission Electron Source for Applications in THz Radiation Production and Time-Resolved Electron Microscopy electron, laser, cathode, radiation 554
  • N. Vinogradov, P. Piot, C.R. Prokop
    Northern Illinois University, DeKalb, Illinois
  • J.W. Lewellen, J. Noonan
    ANL, Argonne

Funding: Work supported by the Department of Education under contract P116Z010035 with Northern Illinois University.
A simple, inexpensive, and compact low-energy (~20 KeV) photoemission electron source was designed, built and recently commissioned. It uses a commercial ultraviolet photocathode drive laser producing 3 ns RMS pulse. The source will eventually be used to drive a table-top THz radiation source, based on the Smith-Purcell free-electron laser scheme, and could also have potential application to time-resolved electron microcopy. We present experimental measurements of the photoemitted electron beam and numerical simulations of the anticipated parameters. We also discuss the generation of flat beams required to efficiently drive the THz radiation source.

TUP089 Electron Beam Timing Jitter and Energy Modulation Measurements at the JLab ERL electron, wiggler, instrumentation, cavity 606
  • P. Evtushenko, S.V. Benson, D. Douglas, D.W. Sexton
    JLAB, Newport News, Virginia

When operating JLab high current ERL a strong reduction of the FEL efficiency was observed when increasing the average electron beam current. Investigating the FEL efficiency drop-off with the electron beam average current we also have measured the electron beam phase noise and the fast energy modulations. The so-called phase noise is essentially a variation of the time arrival of the electron bunches to the wiggler. That could be a very effective way of reducing the FEL efficiency if one takes in to account that the accelerator is routinely operated with the RMS bunch length of about 150 fs. Under a fast energy modulation we mean a modulation which can not be followed by the FEL due to its time constant, defined by the net gain. Such a modulation also could be a possible cause of the efficiency drop-off. Having the measurements made we could rule out the FEL efficiency drop-off due to either the fast energy modulation or the phase modulation. We also have learned a lot about instrumentation and techniques necessary for this kind of beam study. In this contribution we describe the used instrumentation and present results of the measurements.

TUP093 Activities on High Brightness Photo-injectors at the Frascati Laboratories, Italy linac, emittance, laser, radiation 618
  • R. Boni, D. Alesini, M. Bellaveglia, C. Biscari, M. Boscolo, M. Castellano, E. Chiadroni, A. Clozza, L. Cultrera, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, L. Ficcadenti, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, A. Ghigo, B. Marchetti, A. Marinelli, C. Marrelli, M. Migliorati, A. Mostacci, E. Pace, L. Palumbo, L. Pellegrino, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, F. Tazzioli, S. Tomassini, C. Vaccarezza, M. Vescovi, C. Vicario
    INFN/LNF, Frascati (Roma)
  • A. Bacci, I. Boscolo, F. Broggi, F. Castelli, S. Cialdi, C. De Martinis, D. Giove, C. Maroli, V. Petrillo, A.R. Rossi, L. Serafini
    Istituto Nazionale di Fisica Nucleare, Milano
  • M. Bougeard, B. Carré, D. Garzella, M. Labat, G. Lambert, H. Merdji, P. Salières, O. Tchebakoff
    CEA, Gif-sur-Yvette
  • L. Catani, A. Cianchi
    INFN-Roma II, Roma
  • F. Ciocci, G. Dattoli, M. Del Franco, A. Dipace, A. Doria, G.P. Gallerano, L. Giannessi, E. Giovenale, A. Lo Bue, G.L. Orlandi, S. Pagnutti, A. Petralia, M. Quattromini, C. Ronsivalle, P. Rossi, E. Sabia, I.P. Spassovsky, V. Surrenti
    ENEA C.R. Frascati, Frascati (Roma)
  • M.-E. Couprie
    SOLEIL, Gif-sur-Yvette
  • M. Mattioli, M. Petrarca, M. Serluca
    INFN-Roma, Roma
  • J.B. Rosenzweig
    UCLA, Los Angeles, California
  • J. Roßbach
    DESY, Hamburg

Funding: Work partially supported by the EU Commission in the sixth framework program. Contract No. 011935 EUROFEL and MIUR(Research Department of Italian Government).
An intense activity on high brilliance photo-injectors for SASE-FEL experiments and facilities, is being carried out, since 2003, in the research site of the INFN Frascati Laboratory, Rome, in collaboration with CNR and ENEA. The SPARC project, a 150 MeV photo-injector, is currently in advanced phase of commissioning. The electron beam, which drives a 530 nm FEL experiment, is being characterized in terms of emittance, energy spread, peak current. The matching with the linac confirmed the theoretical prediction of emittance compensation based on the invariant-envelope matching. The demonstration of the velocity-bunching technique is in progress too. The SPARC photo-injector is the test facility for the soft-X FEL project named SPARX, that is based on the generation of ultra high peak brightness electron beams at the energies of 1.2 and 2.4 GeV generating radiation in the 1.5-13 nm range. SPARX will be realized in the Tor-Vergata University campus. In this paper we report the experimental results obtained so far with SPARC and the design status of the SPARX project.


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TUP105 Simulation of the Upgraded Photoinjector for the 10 kW JLAB IR-FEL laser, emittance, simulation, cavity 649
  • D. Mihalcea, P. Piot
    Northern Illinois University, DeKalb, Illinois
  • C. Hernandez-Garcia, S. Zhang
    JLAB, Newport News, Virginia

Funding: Work supported by the Department of Defense under contract N00014-06-1-0587 with Northern Illinois University
The photoinjector of the JLab 10 kW IR FEL was recently upgraded: a new photocathode drive laser was commissioned and the booster section was replaced with 7-cell cavities. In this paper we present numerical simulation and optimization of the photoinjector perform with ASTRA, IMPACT-T and IMPACT-Z beam dynamics codes. We perform these calculations for two operating voltage of the dc gun: the nominal 350 keV and the planned 500 keV operating points.

TUP106 Simulation of Field-Emission Cathodes for High Current Electron Injectors cathode, electron, simulation, gun 652
  • D. Mihalcea, P. Piot
    Northern Illinois University, DeKalb, Illinois

Funding: Work supported by the Department of Defense under contract N00014-06-1-0587 with Northern Illinois University
From the prospect of the high average current electron injectors, the most important advantage of the field-emission cathodes is their capability to generate very large current densities. Simulation of field-emission cathodes is complicated by the large range of spatial dimensions: from sub-micron scale, for a single field-emission tip, to millimeter scale, for a field-emitter array. To overcome this simulation challenge our numerical model is split in two steps. In the first step, only electrons emitted by a single tip are considered. In the second step, the beams originating from many single emitting tips are merged together to mimic the field-emitter array configuration. We present simulation results of injector based on field array emitters cathodes.

TUP108 Initial RF Measurements of the CW Normal-Conducting RF Injector cavity, coupling, vacuum, cathode 656
  • D.C. Nguyen, G.O. Bolme, F.L. Krawczyk, F.A. Martinez, N.A. Moody, K.A. Young
    LANL, Los Alamos, New Mexico
  • L.M. Young
    AES, Medford, NY

Funding: This work is supported by ONR and HEL-JTO.
The LANL/AES 2.5-cell, normal-conducting radio-frequency (NCRF) injector has been fabricated. This room-temperature injector can be used to generate cw electron beams with average current greater than 100 mA and beam energy up to 2.5 MeV prior to injection into an energy-recovery linac. PARMELA simulations show the effectiveness of emittance compensation in generating high-brightness electron beams at relatively low accelerating gradients. We present the initial measurement results of the rf, accelerator and vacuum properties of the NCRF injector and the associated ridge-loaded waveguides. The impact of these rf measurement results on the planned thermal and electron beam tests will also be discussed.

TUP110 Modeling of a Low Frequency SRF Electron Gun for the Wisconsin FEL emittance, gun, cavity, cathode 658
  • R.A. Legg
    UW-Madison/SRC, Madison, Wisconsin

Funding: This work is supported by the University of Wisconsin-Madison and MIT, and by the US NSF under award No. DMR-0537588
The Wisconsin FEL project is a 2.2 GeV, HHG seeded, FEL designed to provide six individual beamlines with photons from 5 to 900 eV. The FEL requires electron bunches with 1 kA peak bunch current and less than 1 mm*mrad transverse slice emittance. To meet those requirements a low frequency, SRF electron gun is proposed which uses "blow-out" mode bunches*. Blow-out mode produces ellipsoidal bunches which are easily emittance compensated**. They also have a very smooth density and energy distribution. Results of the modeling of the injector and a diagnostic beamline will be presented.

* O.J. Luiten, et al., Phys. Rev. Lett., 93, 094802-1 (2004)
** C. Limborg-Deprey, P. Bolton, NIM-A, 557 (2006) 106-116

FR101 8-GeV C-Band Accelerator Construction for XFEL/SPring-8 klystron, high-voltage, cavity, electron 1090
  • T. Inagaki
    RIKEN/SPring-8, Hyogo

The 8 GeV C-band electron linear accelerator is under construction at the SPring-8 site aiming at generating an FEL X-ray beam in 2010. C-band accelerator technology has been developed initially at KEK for the e+e- linear collider project, and employed at the XFEL project in Japan. Since C-band generates a high gradient acceleration field as high as 35 MV/m, the total length of the accelerator fits within 400 m, including the injector and three bunch compressors. C-band uses normal conducting rf technology, thus it runs in pulse mode at 60 Hz, which is well suited to XFEL operation and is less expensive. The talk will cover the current status of the XFEL project and hardware production.


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FR102 Commissioning of the LCLS Linac emittance, laser, linac, electron 1095
  • H. Loos, R. Akre, A. Brachmann, F.-J. Decker, Y.T. Ding, D. Dowell, P. Emma, J.C. Frisch, A. Gilevich, G.R. Hays, P. Hering, Z. Huang, R.H. Iverson, C. Limborg-Deprey, A. Miahnahri, S. Molloy, H.-D. Nuhn, J.L. Turner, J.J. Welch, W.E. White, J. Wu
    SLAC, Menlo Park, California
  • D.F. Ratner
    Stanford University, Stanford, Califormia

Funding: This work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC02-76SF00515
Construction of the Linac Coherent Light Source (LCLS) X-ray free electron laser at the Stanford Linear Accelerator Center (SLAC) is nearing completion. A new injector and upgrades to the existing accelerator were installed in two phases in 2006 and 2007. We report on the commissioning of the injector, the two new bunch compressors at 250 MeV and 4.3 GeV, and transverse and longitudinal beam diagnostics up to the end of the existing linac at 13.6 GeV. The commissioning of the new transfer line from the end of the linac through the undulator beam line to the main dump is scheduled to start in January 2009 and for the undulator magnets in March 2009 with first light to be expected by May 2009.


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FR103 Operation of FLASH as an FEL User Facility electron, radiation, photon, gun 1100
  • K. Honkavaara
    DESY, Hamburg

FLASH, the FEL user facility at DESY, is operated with an electron beam energy up to 1 GeV corresponding to a photon wavelength down to 6.5 nm. The full year 2008 is dedicated to beam operation: about half of the time is scheduled for FEL users, and the rest for accelerator and FEL physics studies. Operational experience gathered at FLASH is very important not only for further improvements of the FLASH facility itself, but also for the European XFEL and for the ILC R&D effort. This talk reports our experience operating FLASH as a user facility. Failure statistics are included as well.


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FR105 Billion Particle Linac Simulations for Future Light Sources linac, electron, simulation, space-charge 1110
  • J. Qiang, R.D. Ryne, M. Venturini, A. Zholents
    LBNL, Berkeley, California

Funding: This work was supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC03-76SF00098.
In this paper, we will report on a billion macroparticle simulation of beam transport in a free electron laser (FEL) linac for future light source applications. The simulation includes a self-consistent calculation of 3D space-charge effects, short-range geometry wakefields, longitudinal coherent synchrotron radiation (CSR) wakefields, and detailed modeling of rf acceleration and focusing. We will discuss the needs and the challenges for such large-scale simulation. Application to the study of microbunching instability in the FEL linac will also be presented.


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