MOP —  Poster I   (21-Aug-17   15:30—18:30)
Paper Title Page
MOP001 Diamond Double-Crystal System for a Forward Bragg Diffraction X-Ray Monochromator of the Self-Seeded PAL XFEL 1
  • Yu. Shvyd'ko, J.W.J. Anton, S.P. Kearney, K.-J. Kim, T. Kolodziej, D. Shu
    ANL, Argonne, Illinois, USA
  • V.D. Blank, S. Terentiev
    TISNCM, Troitsk, Russia
  • H.-S. Kang, C.-K. Min, B.G. Oh
    PAL, Pohang, Kyungbuk, Republic of Korea
  • P. Vodnala
    Northern Illinois University, DeKalb, Illinois, USA
  An x-ray monochromator for a hard x-ray self-seeding system is planned at PAL XFEL to be used in a 3-keV to 10-keV photon spectral range. The monochromatization in a 5 keV to 7 keV range will be achieved by forward Bragg diffraction (FBD) from a 30-micron-thin diamond crystal in the [110] orientation employing the (220) symmetric Bragg reflection. FBD from the same crystal using the (111) asymmetric Bragg reflection will provide monochromatization in a 3 keV to 5 keV spectral range. In the 7-keV to 10-keV spectral range, a 100-micron crystal in the [100] orientation will be used employing FBD with the (400) symmetric Bragg reflection. Two almost defect-free diamond crystals in the required orientations and thicknesses are mounted in a strain-free mechanically-stable fashion on a common CVD diamond substrate using all-diamond components, ensuring radiation-safe XFEL operations with improved heat transport. We will present results of the optical and engineering designs, manufacturing, and x-ray diffraction topography characterization of the diamond double-crystal system.  
Design Study of FEL-2 for Dalian Coherent Light Source  
  • G.L. Wang
    DICP, Dalian, People's Republic of China
  • S. Chen
    SINAP, Shanghai, People's Republic of China
  Dalian Coherent Light Source (DCLS) is a free electron laser (FEL) user facility working at 50-150 nm, and is now in user operation with its first FEL line, FEL-1. In this paper, we present a design study of the second FEL line, FEL-2, a polarization controllable and femtosecond FEL. The main components including the switchyard and undulator system are considered and a possible schematic of the switchyard is presented to divert the beam and guarantee the beam properties will not be spoiled. The FEL-2 will be based on the principle of High-Gain Harmonic Generation (HGHG), and the radiator system is composed of 2 planer undulators and 3 helical afterburners. With the help of 3D simulation codes, we show the detailed performance of FEL-2 with the realistic parameters of DCLS.  
MOP003 Concept for a Seeded FEL at FLASH2 1
  • C. Lechner, R.W. Aßmann, J. Bödewadt, M. Dohlus, N. Ekanayake, G. Feng, I. Hartl, T. Laarmann, T. Lang, L. Winkelmann, I. Zagorodnov
    DESY, Hamburg, Germany
  • A. Azima, M. Drescher, Th. Maltezopoulos, T. Plathpresenter, J. Roßbach, W. Wurth
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • S. Khan, T. Plathpresenter
    DELTA, Dortmund, Germany
  The free-electron laser (FEL) FLASH is a user facility delivering photon pulses down to 4 nm wavelength. Recently, the second FEL undulator beamline 'FLASH2' was added to the facility. Operating in self-amplified spontaneous emission (SASE) mode, the exponential amplification process is initiated by shot noise of the electron bunch resulting in photon pulses of limited temporal coherence. In seeded FELs, the FEL process is initiated by coherent seed radiation, improving the longitudinal coherence of the generated photon pulses. The conceptual design of a possible seeding option for the FLASH2 beamline envisages the installation of the hardware needed for high-gain harmonic generation (HGHG) seeding upstream of the already existing undulator system. In this contribution, we present the beamline design and numerical simulations of the seeded FEL.  
Towards the Demonstration of Soft X-Ray Echo-Enabled Harmonic Generation at Fermi  
  • E. Allaria, R. Bracco, D. Castronovo, I. Cudin, M.B. Danailov, G. De Ninno, S. Di Mitri, B. Diviacco, W.M. Fawley, M. Ferianis, L. Giannessi, M. Lonza, G. Penco, P. Rebernik Ribič, E. Roussel, S. Spampinati, C. Spezzani, L. Sturari, M. Svandrlik, M. Veronese, R. Visintini, M. Zaccaria, D. Zangrando
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • H.-H. Braun, E. Prat, S. Reiche
    PSI, Villigen PSI, Switzerland
  • G. De Ninno
    University of Nova Gorica, Nova Gorica, Slovenia
  • B.W. Garcia, J.B. Hastings, E. Hemsing, T.O. Raubenheimer, G. Stupakov, J.J. Welch
    SLAC, Menlo Park, California, USA
  • G. Penn
    LBNL, Berkeley, California, USA
  • E. Roussel
    SOLEIL, Gif-sur-Yvette, France
  • A. Zholents
    ANL, Argonne, Illinois, USA
  The echo-enabled harmonic generation seeding scheme is based on an echo mechanism that develops in the electron beam phase-space interacting with two seed lasers before and after a strong dispersive region. It has been proposed for extending the capabilities of externally seeded free electron lasers to reach short wavelengths. After the original proposal, a few experiments have confirmed the capabilities of efficient bunching generation at very high harmonics. However, up to now none of the experiments demonstrated FEL amplification from high harmonic bunching produced at 10 nm wavelengths or shorter. In this work, we report about our plans for performing an EEHG experiment at FERMI. The experiment will be done at the FEL-2 line normally operated in the double stage high-gain harmonic generation configuration in the wavelength range 20-4 nm. After the modification of a few hardware components planned for the first semester of 2018, the FEL-2 layout will be suitable for EEHG at wavelengths down to approximately 6 nm.  
MOP005 FEL Pulse Shortening by Superradiance at FERMI 1
  • N.S. Mirian, L. Giannessipresenter
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • S. Spampinati
    Private Address, warrigton, United Kingdom
  Explorations of saturated superradiant regime is one of the methods that could be used to reduce the duration of the pulses delivered by FERMI. Here we present simulation studies that show the possible application of a superradiant cascade leading to a minimum pulse duration below 8 fs and to a peak power exceeding the GW level in both FEL lines FEL-1 and FEL-2.  
Characterization of the Polarization of the First and Second Stage of FERMI FEL-2  
  • E. Roussel, E. Allaria, C. Callegari, M. Coreno, R. Cucini, S. Di Mitri, B. Diviacco, E. Ferrari, P. Finetti, D. Gauthier, L. Giannessi, G. Penco, L. Raimondi, C. Svetina, M. Zangrando
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • A. Beckmann
    XFEL. EU, Hamburg, Germany
  • L. Giannessi
    ENEA C.R. Frascati, Frascati (Roma), Italy
  • L. Glaser, G. Hartmann, F. Scholz, J. Seltmann, I. Shevchuk, J. Viefhaus
    DESY, Hamburg, Germany
  • M. Zangrando
    IOM-CNR, Trieste, Italy
  The FERMI free-electron laser (FEL) is nowadays the only user facility equipped with Apple-II type undulators that permit to produce either elliptical, circular or linearly polarized light within the extreme ultraviolet and soft x-ray wavelength range. The FERMI FEL-2 line is based on a two-stage "fresh-bunch" high-gain harmonic generation (HGHG) scheme, where the light emitted by a first HGHG stage seeds a fresh portion of the electron bunch in a second FEL stage. Both FEL lights, from the first and second stages, can be tuned separately to linear horizontal, vertical or circular left and right polarization. We report on a systematic characterization of the polarization state of the two stages of FERMI FEL-2 by using an electron Time-Of-Flight based polarimeter. Our results show a good independent control of the polarization of the two stages, with a high degree of polarization typically higher than 95%*
* E. Roussel et al., Polarization Characterization of Soft X-Ray Radiation at FERMI FEL-2. Photonics 2017, 4, 29.
Study of an External Laser Seeding at the European XFEL  
  • T. Tanikawa, G. Geloni, S. Karabekyan, S. Serkez, S.I. Tomin
    XFEL. EU, Schenefeld, Germany
  Several XFEL facilities are currently in the commissioning or operation phase and have opened new exciting scientific opportunities. In May 2017, the European XFEL successfully achieved a first lasing. Recently, most of the FEL facilities are going to invest (or have already invested) in advanced schemes to increase the longitudinal coherence properties of radiation compared to SASE. As one of the techniques, an external laser seeding is currently applicable at soft X-ray facilities, in a frequency range where external seed pulses are powerful enough to overcome the SASE shot noise. However, these techniques are now also being considered at several hard X-ray FEL facilities and aim for the production of nearly Fourier-limited pulses up to the keV range. At the European XFEL, the challenge of HGHG and EEHG options is the usage of very high electron beam energy. In this presentation, we will report the preliminary simulation results of the external laser seeding feasibility at the European XFEL.  
MOP008 Status of the Hard X-Ray Self-Seeding Project at the European XFEL 1
  • G. Geloni, S. Karabekyan, L. Samoylova, S. Serkez, H. Sinn
    XFEL. EU, Hamburg, Germany
  • V.D. Blank, S. Terentiev
    TISNCM, Troitsk, Russia
  • W. Decking, C. Engling, N. Golubeva, V. Kocharyan, B. Krause, S. Lederer, S. Liupresenter, A. Petrov, E. Saldin, T. Wohlenberg
    DESY, Hamburg, Germany
  • X. Dong
    European X-Ray Free-Electron Laser Facility GmbH, Schelefeld, Germany
  • D. Shu
    ANL, Argonne, Illinois, USA
  A Hard X-ray Self-Seeding setup is currently under realization at the European XFEL, and will be ready for installation in 2018. The setup consists of two single-crystal monochromators that will be installed at the SASE2 undulator line. In this contribution, after a short summary of the physical principles and of the design, we will discuss the present status of the project including both electron beam and X-ray optics hardware. We will also briefly discuss the expected performance of the setup, which is expected to produce nearly Fourier-limited pulses of X-ray radiation with increased brightness compared to the baseline of the European XFEL, as well as possible complementary uses of the two electron chicanes.  
poster icon Poster MOP008 [2.440 MB]  
MOP010 Constraints on Pulse Duration Produced by Echo-Enabled Harmonic Generation 1
  • G. Penn
    LBNL, Berkeley, California, USA
  • B.W. Garcia, E. Hemsing, G. Marcus
    SLAC, Menlo Park, California, USA
  Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract Nos. DE-AC02-05CH11231 and DE-AC02-76SF00515.
Echo-enabled harmonic generation (EEHG) is well-suited for producing long, coherent pulses at high harmonics of seeding lasers. There have also been schemes proposed to adapt EEHG to output extremely short, sub-fs pulses by beam manipulations or through extremely short seed lasers, but the photon flux is generally lower than that produced by other schemes. For the standard EEHG layout, it is still interesting to consider different parameter regimes and evaluate how short a pulse can be generated. EEHG at high harmonics uses a large dispersive chicane which can change the relative distance of electrons by substantial distances, even longer than a typical FEL coherence length. We evaluate the ability to produce short pulses (in the femtosecond to 10-fs range) using a combination of theory and simulations.
poster icon Poster MOP010 [0.446 MB]  
MOP011 Strongly Tapered Undulator Design for High Efficiency and High Gain Amplification at 266 nm 1
  • Y. Park, P. Musumeci, N.S. Sudar
    UCLA, Los Angeles, USA
  • D.L. Bruhwiler, C.C. Hall, S.D. Webb
    RadiaSoft LLC, Boulder, Colorado, USA
  • A.Y. Murokh
    RadiaBeam, Santa Monica, California, USA
  • Y. Sun, A. Zholents
    ANL, Argonne, Illinois, USA
  Tapering Enhanced Stimulated Superradiant Amplification (TESSA) is a scheme developed at UCLA to increase efficiency of Free Electron Laser (FEL) light from less than 0.1% to above 10% using strongly tapered undulators and prebunched electron beams. Initial results validating this method have already been obtained at 10-um wavelength at Brookhaven National Laboratory. In this paper we will discuss the design of an experiment to demonstrate the TESSA scheme at high gain and shorter wavelength (266 nm) using the Linac Extension Area (LEA) beamline at the Advanced Photon Source of Argonne National Laboratory (ANL) to obtain conversion efficiencies around 10% depending on the length of the tapered undulator (up to 4m).  
MOP013 Hundred-Gigawatt X-Ray Self-Seeded High-Gain Harmonic Generation 1
  • L. Zeng, S. Huang, K.X. Liu, W. Qin, G. Zhao
    PKU, Beijing, People's Republic of China
  • Y. Ding, Z. Huang
    SLAC, Menlo Park, California, USA
  Self-seeded high-gain harmonic generation is a possible way to extend the wavelength of a soft x-ray free-electron laser (FEL). We have carried out simulation study on harmonic generation within the photon energy range from 2 keV to 4.5 keV, which is difficult to achieve due to a lack of monochromator materials. In this work, we demonstrate the third harmonic FEL with the fundamental wavelength at 1.52 nm. Our results shows that, by using undulator tapering technique, sub-terawatt narrow-bandwidth FEL output can be obtained.  
MOP014 Harmonic Lasing Towards Shorter Wavelengths in Soft X-Ray Self-Seeding FELs 1
  • L. Zeng, S. Huang, K.X. Liu, W. Qin, G. Zhao
    PKU, Beijing, People's Republic of China
  • Y. Ding, Z. Huang
    SLAC, Menlo Park, California, USA
  In this paper, we study a simple harmonic lasing scheme to extend the wavelength of X-ray self-seeding FELs. The self-seeding amplifier is comprised of two stages. In the first stage, the fundamental radiation is amplified but well restricted below saturation, and simultaneously harmonic radiation is generated. In the second stage, the fundamental radiation is suppressed while the harmonic radiation is amplified to saturation. We performed a start-to-end simulation to demonstrate third harmonic lasing in a soft x-ray self-seeding FEL at the fundamental wavelength of 1.52 nm. Our simulations show that a stable narrow-band FEL at GW levels can be obtained.  
Demonstration of Harmonic Lasing Self-Seeded Mode for Soft X-Rays Down to 1nm at PAL-XFEL  
  • I.H. Nam, H. Heo, H.-S. Kang, C. Kim, G. Kim, C.-K. Min, H. Yang
    PAL, Pohang, Republic of Korea
  Harmonic lasing is a promising way to provide the beams that can be brilliant, stable and narrow-band. We demonstrate the 3rd harmonic lasing operation in the current configuration with gap-tunable planar hybrid type undulators at soft X-ray beam line at PAL-XFEL. In order to suppress the fundamental resonant radiation, we used a set of phase shifters for optimal condition. This new operation mode can improve the spectral brightness compare to Self-Amplified Spontaneous emission (SASE) mode. In this paper, we report the results of these studies of the harmonic lasing mode for soft X-ray in the wavelength down to 1 nm with the electron beam energy of 3 GeV at PAL-XFEL.  
MOP016 Comparing FEL Codes for Advanced Configurations 1
  • B.W. Garcia, G. Marcus
    SLAC, Menlo Park, California, USA
  • L.T. Campbell
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • B.W.J. MᶜNeil
    USTRAT/SUPA, Glasgow, United Kingdom
  • S. Reiche
    PSI, Villigen PSI, Switzerland
  Various FEL codes employ different approximations and strategies to model the FEL radiation generation process. Many codes perform averaging procedures over various length scales in order to simplify the underlying dynamics. As FELs are developed in more advanced configurations beyond simple SASE, the assumptions of some codes may be called into question. We compare the unaveraged code Puffin to averaged FEL codes including a new version of GENESIS in a variety of situations. In particular, we study a harmonic lasing setup, a High-Gain Harmonic Generation (HGHG) configuration modeled after the FERMI setup, and a potential Echo-Enabled Harmonic Generation (EEHG) configuration also at FERMI. We find the codes are in good agreement, although small discrepancies do exist.  
MOP017 Echo-Enabled Harmonic Generation Results with Energy Chirp 1
  • B.W. Garcia, M.P. Dunning, C. Hast, E. Hemsing, T.O. Raubenheimer, G. Stupakov
    SLAC, Menlo Park, California, USA
  • D. Xiang
    Shanghai Jiao Tong University, Shanghai, People's Republic of China
  We report here on several experimental results from the NLCTA at SLAC involving chirped Echo-Enabled Harmonic Generation (EEHG) beams. We directly observe the sensitivity of the different n EEHG modes to a linear beam chirp. This differential sensitivity results in a multi-color EEHG signal which can be fine tuned through the EEHG parameters and beam chirp. We also generate a beam which, due to a timing delay between the two seed lasers, contains both regions of EEHG and High-Gain Harmonic Generation (HGHG) bunching. The two regions are clearly separated on the resulting radiation spectrum due to a linear energy chirp, and one can simultaneously monitor their sensitivities.  
MOP018 Distributed Self-Seeding Scheme for LCLS-II 1
  • C. Yang, Y. Feng, T.O. Raubenheimer, C.-Y. Tsai, J. Wupresenter, M. Yoon, G. Zhou
    SLAC, Menlo Park, California, USA
  • B. Yang
    University of Texas at Arlington, Arlington, USA
  Funding: The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
Self-seeding is a successful approach for generating high-brightness x-ray free electron laser (XFEL). A single-crystal monochromator in-between the undulator sections to generate a coherent seed is adopted in LCLS. However, for a high-repetition rate machine like LCLS-II, the crystal monochromator in current setup cannot sustain the high average power; hence a distributed self-seeding scheme utilizing multi-stages is necessary. Based on the criteria set on the crystal, the maximum allowed x-ray energy deposited in the crystal will determine the machine configuration for such a distributed self-seeding scheme. In this paper, a distributed self-seeding configuration is optimized for LCLS-II type projects in the hard x-ray FEL energy regime. The study is carried out based on numerical simulation.
MOP019 Transient Thermal Stress Wave Analysis of a Thin Diamond Crystal Under Laser Heat Load 1
  • J. Wu
    SLAC, Menlo Park, California, USA
  • B. Yang
    University of Texas at Arlington, Arlington, USA
  Funding: The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
When a laser pulse impinges on a thin crystal, energy is deposited resulting in an instantaneous temperature surge in the local volume and emission of stress waves. In the present work, we perform a transient thermal stress wave analysis of a diamond layer 200 μm thick in the low energy deposition per pulse regime. The layer thickness and laser spot size are comparable. The analysis reveals the characteristic non-planar stress wave propagation. The stress wave emission lasts by hundreds of nanoseconds, at a time scale relevant to the high-repetition-rate FELs at the megahertz range. The kinetic energy converted from the thermal strain energy is calculated, which may be important to estimate the vibrational amplitude of the thin crystal when excited under repeated heat loads. The transient heat transfer plays an important role in draining the mechanical energy during the dynamic wave emission process.
MOP020 Sideband Instability in a Tapered Free Electron Laser 1
  • C.-Y. Tsai
    Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
  • J. Wupresenter, C. Yang
    SLAC, Menlo Park, California, USA
  • M. Yoon
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • G. Zhou
    IHEP, Beijing, People's Republic of China
  Funding: The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
For a high-gain tapered free electron laser (FEL), it is known that there is a so-called second saturation point where the FEL power growth stops. Sideband instability is one of the major reasons leading to this second-saturation and thus prevents reaching terawatt-level power output in an X-ray FEL. It is believed that a strong taper can effectively suppress the sideband instability and further improve the efficiency and peak power. In this paper, we give quantitative analysis on the necessary taper gradient to minimize the sideband growth. We also discuss the transverse effects of induced electron de-trapping which is yet another major reason for the occurrence of the second-saturation point even with a strong enough taper. The study is carried out analytically together with numerical simulation. The numerical parameters are taken from LCLS-II type electron bunch and undulator system.
MOP021 Sideband Suppression in Tapered Free Electron Lasers 1
  • C.-Y. Tsai
    Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
  • J. Wupresenter, C. Yang
    SLAC, Menlo Park, California, USA
  • M. Yoon
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • G. Zhou
    IHEP, Beijing, People's Republic of China
  Funding: The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
It is known that in a high-gain tapered free electron laser, there is the so-called second saturation point where the FEL power ceases to grow. Sideband instability is one of the major reasons causing this second saturation. Electron synchrotron oscillation coupling to the wideband SASE radiation leads to the appearance of sidebands in the FEL spectrum, and is believed to prevent a self-seeding tapered FEL from reaching very high peak power. A strong seed together with a fresh electron bunch or a fresh slice in conjunction with strong tapering of undulators can effectively suppress the sideband instability. In this paper, we give quantitative analysis on the necessary seed power as well as undulator tapering to minimize the sideband effects. The study is carried out semi-analytically together with numerical simulation. The machine and electron bunch parameters are chosen as those of PAL-XFEL and LCLS-II.
Design Study and Preparations for the Echo-30 Experiment at SXFEL  
  • C. Feng, S. Chen, H.X. Deng, B. Liu, D. Wang, X.T. Wang, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  • D. Xiang
    Shanghai Jiao Tong University, Shanghai, People's Republic of China
  In this work, design study and hardware preparations for the echo-30 experiment at the SXFEL test facility are presented. With the realistic parameters of the SXFEL, start-to-end simulations considering various three-dimensional effects have been carried out, and the simulation results demonstrate that a single-stage EEHG can generate high-power soft x-ray radiation pulses with narrow bandwidth directly from UV seed lasers. We also show the preparations of the seed lasers, undulators and photon beam diagnostics for the echo-30 experiment at the SXFEL.  
MOP023 Two-Color Soft X-Ray Generation at the SXFEL User Facility Based on the EEHG Scheme 1
  • Z. Qi, C. Feng, B. Liu, W.Y. Zhang, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  We study the two-color soft x-ray generation at the Shanghai soft X-ray Free Electron Laser (SXFEL) user facility based on the echo-enabled harmonic generation (EEHG) scheme. Using the twin-pulse seed laser with different central wavelengths, an preliminary simulation result indicates that two-color soft x-ray FEL radiation with wavelengths at 8.890 nm and 8.917 nm can be obtained from the ultraviolet seed laser. The radiation power is about 600 MW and the time delay is adjustable.  
MOP024 Simulation and Optimization for Soft X-Ray Self-Seeding at SXFEL User Facility 1
  • K.Q. Zhang, C. Feng, D. Wang, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  The simulation and optimization studies for the soft x-ray self-seeding experiment at SXFEL have been presented in this paper. Some critical physical problems have been intensively studied to help us obtain a more stable output and a clearer spectrum. The monochromator is optimized considering various unideal conditions such as the reflection rate, diffraction rate and the roughness of the grating and the mirrors. An integrated self-seeding simulation is also presented. The calculation and simulation results show that the properties of the self-seeding can be significantly improved by using the optimized design of the whole system and the evaluation of grating monochromator shows that the presented design is reliable for soft x-ray self-seeding experiment at SXFEL.  
Extending the Photon Energy Coverage of an X-Ray Self-Seeding FEL via the Reverse Taper Enhanced Harmonic Generation Technique  
  • K.Q. Zhang, C. Feng, D. Wang
    SINAP, Shanghai, People's Republic of China
  In this paper, we propose a novel method that combines the reverse undulator taper and harmonic generation techniques to extend the photon energy coverage of a self-seeding FEL. The proposed scheme utilizes a baseline configuration of a self-seeding FEL and does not require the installation of any additional hardware in the undulator system. The proposed technique can be easily implemented at already existing or planned x-ray FEL facilities to generate x-ray radiation pulses with consecutively tuning wavelength from soft x-ray to hard x-ray regions. Theory and simulation is carried out in this paper. The proposed scheme will be a reliable method to extend the wavelength range of the soft x-ray self-seeding scheme.  
MOP026 Study of an Echo-Enabled Harmonic Generation Scheme for the French FEL Project LUNEX5 1
  • E. Roussel, M.-E. Couprie, A.M. Ghaith, A. Loulergue
    SOLEIL, Gif-sur-Yvette, France
  • C. Evain
    PhLAM/CERLA, Villeneuve d'Ascq, France
  • D. Garzella
    CEA, Gif-sur-Yvette, France
  In the French LUNEX5 project (Laser à électrons libres Utilisant un Nouvel accélérateur pour l'exploitation du rayonnement X de 5ème génération), a compact advanced free-electron laser (FEL) is driven by either a superconducting linac or a laser-plasma accelerator that can deliver a 400-MeV electron beam. LUNEX5 aims to produce FEL radiation in the ultraviolet and extreme ultraviolet (EUV) range. To improve the longitudinal coherence of the FEL pulses and reduce the gain length, it will operate in Echo-Enabled Harmonic Generation (EEHG) seeding configuration. EEHG is a strongly nonlinear harmonic up-conversion process based on a two-seed laser interaction that enables to reach very high harmonics of the seed laser. Recent experimental demonstration of ECHO-75, starting from an infrared seed laser, was recently achieved at SLAC and is opened the way for EEHG scheme in the EUV and soft x-ray range. Furthermore, FELs are promising candidates for the next generation of lithography technology using EUV light. In this work, we report a preliminary study of EEHG scheme for LUNEX5 in order to reach the target wavelength of 13.5 nm, currently expected for application to lithography.  
MOP027 Seeding of Electron Bunches in Storage Rings 1
  • S. Khan, B. Büsing, N.M. Lockmann, C. Mai, A. Meyer auf der Heide, R. Niemczyk, B. Riemann, B. Sawadski, M. Suski, P. Ungelenk
    DELTA, Dortmund, Germany
  Funding: Funded by BMBF (05K16PEA), MERCUR (Pr-2014-0047), DFG (INST 212/236-1 FUGG) and the Land NRW.
Seeding schemes for free-electron lasers (FELs) can be adopted to generate ultrashort radiation pulses in storage rings by creating laser-induced microbunches within a short slice of a long electron bunch giving rise to coherent emission at harmonics of the seed wavelength. In addition, terahertz (THz) radiation is produced over many turns. Even without FEL gain, a storage ring is an excellent testbed to study many aspects of seeding schemes and short-pulse diagnostics, given the high repetition rate and stability of the electron bunches. At DELTA, a storage ring operated by the TU Dortmund University in Germany, coherent harmonic generation (CHG) with single and double 40-fs pulses is performed at seed wavelengths of 800 nm or 400 nm. Seeding with intensity-modulated 10-ps pulses is also studied generating tunable narrowband THz radiation. As a preparation for echo-enabled harmonic generation (EEHG), simultaneous seeding with 800/400-nm pulses in two different undulators is performed and several techniques are employed to ensure optimum timing between the seed pulses. The paper describes these experiments and gives an outlook of future applications of seeding at storage rings.
MOP028 Extraction of the Longitudinal Profile of the Transverse Emittance From Single-Shot RF Deflector Measurements at sFLASH 1
  • T. Plath, Ph. Amstutz, L.L. Lazzarino, Th. Maltezopoulos, V. Miltchev, J. Roßbach
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • J. Bödewadt, N. Ekanayake, T. Laarmann, C. Lechner
    DESY, Hamburg, Germany
  • S. Khan
    DELTA, Dortmund, Germany
  The gain length of the free-electron laser (FEL) process strongly depends on the slice energy spread, slice emittance, and current of the electron bunch. At an FEL with only moderately compressed electron bunches, the slice energy spread is mainly determined by the compression process. In this regime, single-shot measurements using a transverse deflecting rf cavity enable the extraction of the longitudinal profile of the transverse emittance. At the free-electron laser FLASH at DESY, this technique was used to determine the slice properties of the electron bunch set up for seeded operation in the sFLASH experiment. Thereby, the performance of the seeded FEL process as a function of laser-electron timing can be predicted from these slice properties with the semi-analytical Ming-Xie model where only confined fractions of the electron bunch are stimulated to lase. The prediction is well in line with the FEL peak power observed during an experimental laser-electron timing scan. The power profiles of the FEL pulses were reconstructed from the longitudinal phase-space measurements of the seeded electron bunch that was measured with the rf deflector.  
Study of the Next Major Flash Upgrade: FLASH2020  
  • B. Faatz
    DESY, Hamburg, Germany
  The FLASH facility has delivered beam to two experiments simultaneously since Spring 2016. Both users can request a large variety of parameters independently, without interfering with the other experiment and the setup for both users can take place in parallel. For several years, a study has started to plan for the next major upgrade, referred to as FLASH2020. The ultimate goal is a CW version of FLASH with up to 1 million bunches per second which should be able to go down in wavelength to cover the complete water window. In this presentation we will present the different upgrade scenarios that are under discussion. Also we present tests already performed and planned for the near future to optimize the design and maximize the flexibility of the new facility.  
MOP031 First Operation of a Harmonic Lasing Self-Seeded FEL 1
  • E. Schneidmiller, B. Faatz, M. Kuhlmann, J. Rönsch-Schulenburg, S. Schreiber, M. Tischer, M.V. Yurkov
    DESY, Hamburg, Germany
  Harmonic lasing is a perspective mode of operation of X-ray FEL user facilities that allows it to provide brilliant beams of higher-energy photons for user experiments. Another useful application of harmonic lasing is so called Harmonic Lasing Self-Seeded Free Electron Laser (HLSS FEL), that allows it to improve spectral brightness of these facilities. In the past, harmonic lasing has been demonstrated in the FEL oscillators in infrared and visible wavelength ranges, but not in high-gain FELs and not at short wavelengths. In this paper, we report on the first evidence of the harmonic lasing and the first operation of the HLSS FEL at the soft X-ray FEL user facility FLASH in the wavelength range between 4.5 nm and 15 nm. Spectral brightness was improved in comparison with Self-Amplified Spontaneous emission (SASE) FEL by a factor of six in the exponential gain regime. A better performance of HLSS FEL with respect to SASE FEL in the post-saturation regime with a tapered undulator was observed as well. The first demonstration of harmonic lasing in a high-gain FEL and at a short wavelength paves the way for a variety of applications of this new operation mode in X-ray FELs.  
MOP032 Reverse Undulator Tapering for Polarization Control and Background-Free Harmonic Production in XFELs: Results from FLASH 1
  • E. Schneidmiller, M.V. Yurkov
    DESY, Hamburg, Germany
  Baseline design of a typical X-ray FEL undulator assumes a planar configuration which results in a linear polarization of the FEL radiation. However, many experiments at X-ray FEL user facilities would profit from using a circularly polarized radiation. As a cheap upgrade, one can consider an installation of a short helical afterburner, but then one should have an efficient method to suppress powerful linearly polarized background from the main undulator. There is an efficient method for such a suppression: an application of the reverse taper in the main undulator.* In this contribution, we present the results of experiments with reverse taper at FLASH2 where a high contrast between FEL intensities from the afterburner and from the reverse-tapered main undulator was demonstrated. Another important application of the reverse taper is a possibility to produce FEL harmonics in the afterburner (or in the last part of baseline gap-tunable undulator). We present recent results from FLASH2 where the second and the third harmonics were efficiently generated with a low background at the fundamental.
* E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST Accel. Beams 13-080702 (2013).
MOP033 Baseline Parameters of the European XFEL 1
  • E. Schneidmiller, M.V. Yurkovpresenter
    DESY, Hamburg, Germany
  We present the latest update of the baseline parameters of the European XFEL. It is planned that the electron linac will operate at four fixed electron energies of 8.5, 12, 14, and 17.5 GeV. Tunable gap undulators provide the possibility to change the radiation wavelength in a wide range. Operation with different bunch charges (0.02, 0.1, 0.25, 0.5 and 1 nC) provides the possibility to operate XFEL with different radiation pulse duration. We also discuss potential extension of the parameter space which does not require new hardware and can be realized at a very early stage of the European XFEL operation.  
XFEL Photon Pulses Database (XPD) at the European XFEL  
  • M. Manetti, L. Samoylova, H. Sinn, J. Szuba, K. Wrona
    XFEL. EU, Schenefeld, Germany
  • E. Schneidmiller, M.V. Yurkovpresenter
    DESY, Hamburg, Germany
  The best way to plan user experiments would be performing start-to-end simulations tracing a radiation pulse from its origin (undulator) through a beamline (mirrors, monochromators, etc.) to a target, simulations of physical processes of the radiation interaction with a sample, and simulations of detection processes of related debris (photon, electrons, ions, etc.) by detectors. Modern FEL simulation codes allow prediction of all details of the output radiation pulses from x-ray FEL (3D maps of radiation fields for the fundamental and higher frequency harmonics). We present an XFEL photon pulses simulation database accessible through public web-server that allows access to the data produced by the time-dependent FEL simulation code FAST. A web application allows pick-up of selected photon pulse data in the hdf5 format for any given XFEL operation mode (electron energy, charge/photon pulse duration, active undulator range, etc.) suitable for statistical analysis, including propagation through the optical system, interaction with the sample, etc. The pulse post-processing data, including the gain curve, time structure, source size and far-field angular divergence are also provided.  
Optimum Undulator Tapering of SASE FEL: Theory and Experimental Results From FLASH2  
  • E. Schneidmiller, M.V. Yurkovpresenter
    DESY, Hamburg, Germany
  Optimization of the amplification process in FEL amplifier with diffraction effects taken into account results in a specific law of the undulator tapering.* It is a smooth function with quadratic behavior in the beginning of the tapering section which transforms to a linear behavior for a long undulator. In practice, an undulator consists of a sequence of modules of fixed length separated with intersections. Two modes of undulator tapering can be implemented: step tapering and smooth tapering. Step tapering uses a step change of the undulator gap from module to module, while smooth tapering assumes additional linear change of the gap along each module. In this report, we simulate the performance of both experimental options and compare with theoretical limit.
* E.A. Schneidmiller and M.V. Yurkov, Optimization of a high efficiency free electron laser amplifier, Phys. Rev. ST Accel. Beams 18-030705 (2015).
MOP036 Frequency Doubling Mode of Operation of Free Electron Laser FLASH2 1
  • M. Kuhlmann, E. Schneidmiller, M.V. Yurkovpresenter
    DESY, Hamburg, Germany
  We report on the results of the first operation of a frequency doubler at free electron laser FLASH2. The scheme uses the feature of the variable-gap undulator. The undulator is divided into two parts. The second part of the undulator is tuned to the double frequency of the first part. The amplification process in the first undulator part is stopped at the onset of the nonlinear regime, such that nonlinear higher-harmonic bunching in the electron beam density becomes pronouncing, but the radiation level is still small to disturb the electron beam significantly. The modulated electron beam enters the second part of the undulator and generates radiation at the second harmonic. A frequency doubler allows operation in a two-color mode and operation at shorter wavelengths with respect to standard SASE scheme. Tuning of the electron beam trajectory, phase shifters and compression allows tuning of intensities of the first and the second harmonic. The shortest wavelength of 3.1 nm (photon energy 400 eV) has been achieved with a frequency doubler scheme, which is significantly below the design value for the standard SASE option.  
MOP037 Opportunities for Two-Color Experiments at the SASE3 Undulator Line of the European XFEL 1
  • S. Serkez, G. Geloni, T. Mazza, M. Meyer
    XFEL. EU, Schenefeld, Germany
  • V. Kocharyan, E. Saldin
    DESY, Hamburg, Germany
  As is well known, the installation of a simple magnetic chicane in the baseline undulator of an XFEL allows for producing two-color FEL pulses. In this work we discuss the possibility of applying this simple and cost-effective method at the SASE3 soft X-ray beamline of the European XFEL. We consider upgrades of this method that include the further installation of a mirror chicane. We also discuss the scientific interest of this upgrade for the Small Quantum Systems (SQS) instrument, in connection with the high-repetition rate of the European XFEL, and we provide start-to-end simulations up to the radiation focus on the sample, proving the feasibility of our concept. Our proposed setup has been recently funded by the Finnish Research Infrastructure (FIRI) and will be built at SASE3 in 2020-2021.  
poster icon Poster MOP037 [1.844 MB]  
MOP038 Overview of the Soft X-Ray Line Athos at SwissFEL 1
  • R. Ganter, S. Bettoni, H.-H. Braun, M. Calvi, P. Craievich, R. Follath, C.H. Gough, F. Löhl, M. Paraliev, L. Patthey, M. Pedrozzi, E. Prat, S. Reiche, T. Schmidt, A.C. Zandonella
    PSI, Villigen PSI, Switzerland
  The Athos line will cover the photon energy range from 250 to 1900 eV and will operate parallel to the hard x-ray line Aramis of SwissFEL. Athos consists of fast kicker magnets, a dog-leg transfer line, a small linac and 16 APPLE undulators. The Athos undulators follow a new design: the so-called APPLE X design where the 4 magnet arrays can be moved radially in a symmetric way. Besides mechanical advantages of such a symmetric distribution of forces, this design allows for easy photon energy scans at a constant polarization or for the generation of transverse magnetic gradients. Another particularity of the Athos FEL line is the inclusion of a short magnetic chicane between every undulator segment. These chicanes will allow the FEL to operate in optical klystron mode, high-brightness SASE mode, or superradiance mode. A larger delay chicane will split the Athos line into two sections such that two colors can be produced with adjustable delay. Finally a post undulator transverse deflecting cavity will be the key tool for the commissioning of the FEL modes. The paper will present the current status of this four years project started in 2017.  
MOP039 Possible Method for the Control of SASE Fluctuations 1
  • N. Thompson
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  It is well known that because the SASE FEL starts up from the intrinsic electron beam shot noise, there are corresponding fluctuations in the useful properties of the output pulses which restrict their usability for many applications. In this paper, we discuss possible new methods for controlling the level of fluctuations in the output pulses.  
MOP041 Commissioning of FEL-Based Coherent Electron Cooling System 1
  • V. Litvinenko, Z. Altinbas, R. Anderson, S.A. Belomestnykh, K.A. Brown, J.C.B. Brutus, A.J. Curcio, A. Di Lieto, C. Folz, D.M. Gassner, T. Hayes, R.L. Hulsart, P. Inacker, J.P. Jamilkowski, Y.C. Jing, D. Kayran, R. Kellermann, R.F. Lambiase, G.J. Mahler, M. Mapes, A. Marusic, W. Meng, K. Mernick, R.J. Michnoff, T.A. Miller, M.G. Minty, G. Narayan, P. Orfin, D. Phillips, I. Pinayev, T. Rao, D. Ravikumar, J. Reich, G. Robert-Demolaize, T. Roser, S.K. Seberg, F. Severino, B. Sheehy, J. Skaritka, L. Smart, K.S. Smith, L. Snydstrup, V. Soria, R. Than, C. Theisen, J.E. Tuozzolo, J. Walsh, E. Wang, G. Wang, D. Weiss, B. P. Xiao, T. Xin, A. Zaltsman, Z. Zhao
    BNL, Upton, Long Island, New York, USA
  • C.H. Boulware, T.L. Grimm
    Niowave, Inc., Lansing, Michigan, USA
  • K. Mihara
    Stony Brook University, Stony Brook, USA
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • K. Shih
    SBU, Stony Brook, New York, USA
  • W. Xu
    PKU, Beijing, People's Republic of China
  Funding: DoE NP office, grant DE-FOA-0000632, NSF grant PHY-1415252
In this talk we are presenting the most recent results from the commissioning of unique Coherent Electron Cooling system, which is using an FEL amplifier to facilitate cooling of hadrons by an electron beam. We present achieved results as well as changes we encountered in the process.
MOP042 Status of Seeding Development at sFLASH 1
  • V. Grattoni, R.W. Aßmann, J. Bödewadt, I. Hartl, T. Laarmann, C. Lechner, M.M. Mohammad Kazemi, A. Przystawik
    DESY, Hamburg, Germany
  • A. Azima, M. Drescher, W. Hillert, L.L. Lazzarino, V. Miltchev, J. Roßbach
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • S. Khan, N.M. Lockmann, T. Plath
    DELTA, Dortmund, Germany
  The experimental seeding setup at FLASH has operated now for two years in high-gain harmonic generation mode. Using a transverse deflecting structure downstream of the seeding section allows a temporal characterization of seeded electron bunches. In addition, temporal characterization of the seeded FEL beam can be performed in a dedicated diagnostic hutch. In this contribution, we give an overview of the latest achievements and present an outlook of the planned studies.  
poster icon Poster MOP042 [1.713 MB]  
MOP043 Plasma Wakefield Accelerated Beams for Demonstration of FEL Gain at FLASHForward 1
  • P. Niknejadi, A. Aschikhin, C. Behrens, S. Bohlen, R.T.P. D'Arcy, J. Dale, L. Di Lucchio, M. Felber, B. Foster, L. Goldberg, J.-N. Gruse, Z. Hu, S. Karstensen, A. Knetsch, O. S. Kononenko, V. Libov, K. Ludwig, A. Martinez de la Ossa, F. Marutzky, T.J. Mehrling, J. Osterhoff, C.A.J. Palmer, K. Poder, P. Pourmoussavi, M. Quast, J.-H. Röckemann, J. Schaffran, L. Schaper, H. Schlarb, B. Schmidt, S. Schreiber, S. Schröder, J.-P. Schwinkendorf, B. Sheeran, M.J.V. Streeter, G.E. Tauscher, V. Wacker, S. Weichert, S. Wesch, P. Winkler, S. Wunderlich, J. Zemella
    DESY, Hamburg, Germany
  • A.R. Maier
    CFEL, Hamburg, Germany
  • A.R. Maier, A. Martinez de la Ossa, M. Meisel, J.-H. Röckemann
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • C.B. Schroeder
    LBNL, Berkeley, California, USA
  • V. Wacker
    University of Hamburg, Hamburg, Germany
  Funding: Work supported by Helmholtz ARD program and VH-VI-503
FLASHForward is the Future-ORiented Wakefield Accelerator Research and Development project at the DESY free-electron laser (FEL) facility FLASH. It aims to produce high-quality, GeV-energy electron beams over a plasma cell of a few centimeters. The plasma is created by means of a 25 TW Ti:Sapphire laser system. The plasma wakefield will be driven by high-current-density electron beams extracted from the FLASH accelerator. The project focuses on the advancement of plasma-based particle acceleration technology through the exploration of both external and internal witness-beam injection schemes. Multiple conventional and cutting-edge diagnostic tools, suitable for diagnosis of short electron beams, are under development. The design of the post-plasma beamline sections will be finalized based on the result of these aforementioned diagnostics. In this paper, the status of the project, as well as the progress towards achieving its overarching goal of demonstrating FEL gain via plasma wakefield acceleration, is discussed.
MOP044 Commissioning Status of the European XFEL Photon Beam System 1
  • F. Le Pimpec
    XFEL. EU, Hamburg, Germany
  The European XFEL located in the Hamburg region in Germany has finished its construction phase and is currently being commissioned. The European XFEL facility aims at producing X-rays in the range from 260~eV up to 24~keV out of three undulators that can be operated simultaneously with up to 27000~pulses/second. The FEL is driven by a 17.5~GeV linear accelerator based on TESLA-type superconducting accelerator modules. The accelerator has finished its first commissioning phase and is currently delivering photon beam to the experimental areas for commissioning in view to the user operation. This paper presents the status of the photon beam system from the undulators to the 3 experimental areas as well as the status of each instruments.  
MOP046 Progress of Delhi Light Source at IUAC, New Delhi 1
  • S. Ghosh, S. R. Abhilash, R.K. Bhandari, G.K. Chaudhari, V.J. Joshi, D. Kabiraj, D. Kanjilal, B. Karmakar, J. Karmakar, N. Kumar, S. Kumar, A. Pandey, P. Patra, G.O. Rodrigues, B.K. Sahu, A. Sharma, S. Tripathi
    IUAC, New Delhi, India
  • A. Aryshev, M.K. Fukuda, S. Fukuda, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  • U. Lehnertpresenter, P. Michel
    HZDR, Dresden, Germany
  • V. Naik, A. Roy
    VECC, Kolkata, India
  • T. Rao
    BNL, Upton, Long Island, New York, USA
  • M. Tischer
    DESY, Hamburg, Germany
  Funding: This project is jointly supported by Inter University Accelerator Center and Board of Research in Nuclear Science.
The first phase of the pre-bunched FEL based on the Photoinjector RF electron gun, known as Delhi Light Source (DLS),* has been planned at Inter University Accelerator Centre (IUAC), New Delhi. The electron gun made from OFHC copper had already been fabricated and tested with low power RF at KEK, Japan. The beam optics calculation by using ASTRA, GPT codes has been performed and radiation produced from the pre-bunched electron bunches are being calculated.** The high power RF systems will be commissioned at IUAC by the beginning of 2018. The design of the laser system is being finalized and assembly/testing of the complete laser system will be started soon at KEK. The initial design of the photocathode deposition mechanism has also been completed and its procurement/development process will start shortly. The first version of the undulator magnet design has been completed and further improvements are underway.*** The initial arrangements of the DLS beam line have been worked out and various beam diagnostics components are being finalised. The production of the electron beam and THz radiation is expected by 2018 and 2019, respectively.
* S. Ghosh et al., NIM-B, (2017) in press.
** V. Joshi et al., Proc. of this conference.
*** S. Tripathi et al., Proc. of this conference.
poster icon Poster MOP046 [1.594 MB]  
MOP047 Design Calculation on Beam Dynamics and THz Radiation of Delhi Light Source 1
  • V.J. Joshi, R.K. Bhandari, S. Ghosh, D. Kanjilal, B. Karmakar, J. Karmakar, N. Kumar, S. Tripathi
    IUAC, New Delhi, India
  • A. Aryshev
    KEK, Ibaraki, Japan
  • U. Lehnertpresenter
    HZDR, Dresden, Germany
  Funding: This project is jointly supported by Inter University Accelerator Center and Board of Research in Nuclear Science.
The development of a compact light source facility, Delhi Light Source (DLS), based on a pre-bunched free electron laser, has been initiated at Inter University Accelerator Centre (IUAC).* A photocathode-based normal conducting RF gun will generate a low-emittance 'comb' electron beam with a maximum energy of ~8 MeV which when injected into ~ 1.5 metre compact undulator magnet (~0.4 < Krms < ~2) will produce intense THz radiation in the frequency range of 0.15 THz to 3.0 THz.** Each microbunch of the electron beam is expected to emit super-radiant radiation, and an enhancement in the overall spectral power can be achieved if the frequency (inverse of the spatial separation) of the electron microbunches coincides with that of the THz radiation being emitted. There will be provisions to vary the spatial separation between the successive microbunches of the 'comb' beam so that by varying the undulator magnetic field and/or electron energy, the THz frequency range can be tuned. The results of the beam optics for the entire range of frequencies mentioned above along with the detailed information of the radiation to be generated from the facility will be presented in the paper.
* S. Ghosh et al., NIMB-2017, in press.
** S.Tripathi et al., Proc. of this conference.
poster icon Poster MOP047 [0.954 MB]  
MOP048 A Compact THz FEL at KAERI: the Project and the Status 1
  • S.V. Miginsky, S. Bae, B.A. Gudkov, K.H. Jang, Y.U. Jeong, K. Lee, J. Mun, S. Setiniyaz
    KAERI, Daejon, Republic of Korea
  • S. H. Park
    Korea University Sejong Campus, Sejong, Republic of Korea
  A new compact THz free electron laser driven by a microtron is being recently developed at KAERI. It uses a hybrid electromagnetic undulator. A novel scheme of injection/extraction/outcoupling is developed. The machine is partially assembled and commissioned. Characteristic features and current state are described in the paper.  
MOP049 Development of Compact THz Coherent Undulator Radiation Source at Kyoto University 1
  • S. Krainara, T. Kii, H. Ohgaki, H. Zen
    Kyoto University, Kyoto, Japan
  • S. Suphakul
    Chiang Mai University, Chiang Mai, Thailand
  A new THz Coherent Undulator Radiation (THz-CUR) source has been developed to generate intense quasi-monochromatic THz radiation at the Institute of Advanced Energy, Kyoto University. The system consists of a photocathode RF gun, bunch compression chicane, quadrupole magnets, and short planar undulator. The total length of this system is around 5 meters. At present, this compact accelerator has successfully started giving the THz-CUR in the frequency range of 0.16 - 0.65 THz. To investigate the performance of the source, the relationship between the total radiation energy, peak power and power spectrum as a function of bunch charge at the different undulator gaps were measured. The results are reported in the paper.  
MOP050 Present Status of Infrared FEL Facility at Kyoto University 1
  • H. Zen, T. Kii, S. Krainara, K. Masuda, H. Ohgaki, J. Okumura, S. Suphakul, S. Tagiri, K. Torgasin
    Kyoto University, Kyoto, Japan
  A mid-infrared free electron laser (FEL) named KU-FEL has been developed for promoting energy-related research at the Institute of Advanced Energy, Kyoto University.* KU-FEL can cover the wavelength range from 3.6 to 23 micrometers and is routinely operated for internal and external user experiments. Recently a THz Coherent Undulator Radiation (CUR) source using a photocathode RF gun has been developed as an extension of the facility.* As the result of commissioning the experiment, it was confirmed that the CUR source can cover the frequency range from 160 to 550 GHz. Present status of these infrared light sources will be presented.
* H. Zen et al., Physics Procedia 84, pp.47-53 (2016).
MOP051 Polish In-Kind Contribution to European XFEL: Status in Summer 2017 1
  • J.A. Lorkiewicz, K. Chmielewski, Z. Gołębiewski, W.C. Grabowski, K. Kosinski, K. Kostrzewa, P. Krawczyk, I.M. Kudla, P. Markowski, K. Meissner, E.P. Plawski, M. Sitek, J. Szewiński, M. Wojciechowski, Z. Wojciechowski, G. Wrochna
    NCBJ, Świerk/Otwock, Poland
  • J. Świerbleski, M. Duda, M. Jezabek, K. Kasprzak, A. Kotarba, K. Krzysik, M. Stodulski, M. Wiencek
    IFJ-PAN, Kraków, Poland
  • P.B. Borowiec
    Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland
  • M. Chorowski, P. Duda, A. Iluk, K. Malcher, J. Polinski, E. Rusinski
    WRUT, Wrocław, Poland
  • J. Fydrych
    ESS, Lund, Sweden
  • J. Glowinkowski, M. Winkowski, P. Wlk
    Wroclaw Technology Park, Wroclaw, Poland
  • P. Grzegory, G. Michalski
    Kriosystem, Wroclaw, Poland
  • J.K. Sekutowicz
    DESY, Hamburg, Germany
  In the years 2010-2017, some of the Polish research institutes took responsibility of production and delivery of certain components or test procedures for the EU-XFEL sc linear electron accelerator and elements of slow control systems for the first six XFEL experimental instruments. The presentation summarizes the output of the work on design and manufacturing of cryogenic transfer lines for supercritical helium transport and two vertical cryostats for low-power acceptance tests of sc cavities. The cryogenic installations were prepared by Wroclaw University of Science and Technology and its subcontractors. A team of Institute of Nuclear Physics in Cracow was in charge of preparation and performance of acceptance tests for XFEL sc cavities, accelerator modules and sc magnets. Two teams of National Centre for Nuclear Research (NCBJ)in Świerk were involved in the project. One of them was responsible for design, manufacturing, testing and delivery of 1648 high-order mode couplers, 824 pick-up antennae and 108 beam-line absobers. The other NCBJ group was obliged to deliver 200 modules containing programmable logic controller terminals to be used at the ends of SASE x-ray beam lines.  
MOP052 First Observation of Coherent THz Undulator Radiation Driven by NSRRC High Brightness Photo-Injector 1
  • M.C. Chou, K.T. Hsu, S.Y. Hsu, N.Y. Huang, C.-S. Hwang, J.-Y. Hwang, J.C. Jan, C.K. Kuan, W.K. Lau, A.P. Lee, C.C. Liang, G.-H. Luo, I.C. Sheng
    NSRRC, Hsinchu, Taiwan
  • Y.H. Wen
    NTHU, Hsinchu, Taiwan
  Generation and characterization of coherent undulator radiation in the THz region using the NSRRC S-band photo-injector linac system is achieved. The system consists of a laser photocathode RF gun and one 5.2-m long S-band accelerating linac. Electron bunches in the linac can be accelerated and compressed simultaneously by velocity bunching. In this work, narrow-band tunable fully-coherent THz radiation can be produced from a U100 planar undulator when it is driven by a 100 pC electron bunch with effective bunch length of 90 fs. The experimental setup and the measurement of the power and the frequency spectrum of the coherent THz undulator radiation are reported.  
poster icon Poster MOP052 [2.111 MB]  
MOP053 High Spectral Density Compton Back-Scattered Gamma-Ray Sources at Fermilab 1
  • D. Mihalcea, A. Khizhanok, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • B.T. Jacobson, A.Y. Murokh
    RadiaBeam, Santa Monica, California, USA
  • P. Piot, J. Ruan
    Fermilab, Batavia, Illinois, USA
  A ~1 MeV gamma-ray source is planned to be built at Fermilab following the completion of the ~300 MeV superconducting linac. The high-energy photons are back-scattered from the interactions between electrons and high-intensity IR laser pulses. In this contribution, we discuss some of the experiment design challenges and evaluate the performances of the gamma-ray source. We expect the peak brilliance to be of the order of 1022 photons/s-(mm-mrad)2-0.1\% BW and the spectral density of the radiation in excess of 3x105 photons/s/eV.  
MOP054 CLARA Facility Layout and FEL Schemes 1
  • D.J. Dunning
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  CLARA is a new FEL test facility being developed at STFC Daresbury Laboratory in the UK. Commissioning has started on the front-end (photo-injector and linac) while the design of the later stages is still being finalised. We present the latest design work, focusing on the layout and specification of components in and around the undulator sections. We give an overview of the design and modelling of the FEL schemes planned to be tested.  
MOP055 SCLF: An 8-GeV CW SCRF Linac-Based X-Ray FEL Facility in Shanghai 1
  • Z.T. Zhao, D. Wang, L. Yin
    SINAP, Shanghai, People's Republic of China
  • Z.H. Yang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  The Shanghai Coherent Light Facility (SCLF) is a newly proposed high repetition-rate X-ray FEL facility, based on an 8-GeV CW superconducting RF linac. It will be located at Zhangjiang High-tech Park, close to the SSRF campus in Shanghai, at the depth of ~38m underground and with a total length of 3.1 km. Using 3 phase-I undulators, the SCLF aims at generating X-rays between 0.4 and 25 keV at rates up to 1MHz. This paper describes the design concepts of this hard X-ray user facility.  
MOP056 Design of Apparatus for a High-Power-Density Diamond Irradiation Endurance Experiment for XFELO Applications 1
  • S.P. Kearney, K.-J. Kim, T. Kolodziej, R.R. Lindberg, D. Shu, Yu. Shvyd'ko, D. Walko, J. Wang
    ANL, Argonne, Illinois, USA
  • S. Stoupin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
We have designed a diamond irradiation setup capable of achieving multiple kW/mm2 power density. The setup was installed at the 7-ID-B beamline at the Advanced Photon Source (APS) for a successful irradiation experiment, testing the capability of diamond to endure x-ray free electron laser oscillator (XFELO) levels of irradiation (≥ 10 kW/mm2) without degradation of Bragg reflectivity.* Focused white-beam irradiation (50 μm x 20 μm spot size at 12.5 kW/mm2 power density) of a diamond single crystal was conducted in a vacuum environment of 1x10-8 Torr for varying durations of time at different spots on the diamond, and also included one irradiation spot during a spoiled vacuum environment of 4x10-6 Torr. Here we present the apparatus used to irradiate the diamond consisting of multiple subassemblies: the fixed masks, focusing optics, gold-coated UHV irradiation chamber, water-cooled diamond holder, chamber positioning stages (with sub-micron resolution) and detector.
* T. Kolodziej et al., Free Electron Laser Conf. 2017.
Diamond Endurance to Irradiation with X-ray Beams of Multi kW/mm2 Power Densities for XFELO Application  
  • T. Kolodziej, T. Gog, S.P. Kearney, K.-J. Kim, W. Liu, A. Said, D. Shu, Yu. Shvyd'ko, D. Walko, J. Wang
    ANL, Argonne, Illinois, USA
  • M. Baldini, W. Yang
    High Pressure Synergic Consortium, Advanced Photon Source, Lemont, USA
  • V.D. Blank, S. Terentiev
    TISNCM, Troitsk, Russia
  • P. Rigg
    Dynamic Compression Sector, Washington State University, Lemont, USA
  • S. Stoupin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  Funding: Work at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357
X-ray science has recently been considerably shaped by the advent of modern bright and powerful x-ray sources: 3rd generation synchrotron radiation storage rings and XFELs. XFELs in the oscillator configuration (XFELO) are possible future new sources, in which x-ray beams generated by the undulator circulate in an optical x-ray cavity comprised of high-reflectance (close to 100%) diamond crystal mirrors working in Bragg backscattering. XFELOs will produce stable, fully coherent hard x-rays of ultra-high (meV) spectral purity. The average power density of the x-ray beams in the XFELO cavity is however predicted to be unprecedentedly high, about ≈15 kW/mm2. Therefore, the XFELO feasibility relies on the ability of diamond to withstand such a high radiation load and preserve its high reflectivity. We are reporting on endurance studies of the highest-quality, practically flawless synthetic diamond crystals to irradiation with power density close to that expected on the XFELO crystals. Most importantly, we are studying whether the extremely high Bragg reflectivity of meV-monochromatic x-rays from the diamond crystals in backscattering is conserved after the irradiation.
High Precision Polarization Diagnostic System for Free-Electron Laser  
  • J. Yan, H. Hao, S.F. Mikhailov, V. Popov, G. Swift, Y.K. Wu
    FEL/Duke University, Durham, North Carolina, USA
  In the Duke storage ring FEL facility, an upgrade of the undulator system has created research opportunities to explore novel modes of storage ring FEL operation using as many as four helical undulators simultaneously. Recently, the generation of a linearly polarized FEL beam with the rotatable polarization direction has been realized using two sets of helical undulators of opposite helicities. To study and optimize this new FEL, high-precision polarization diagnostics are being developed to cover a wide range of wavelength from infrared (IR) to visible (VIS) to vacuum ultraviolet (VUV). In this work, we report the development of the first IR-VIS-UV polarization diagnostic system for Duke FEL operations from 1 micron to about 350 nm. This system is capable of measuring the FEL beam Stokes parameters using the extracted FEL beam. High precision measurements of FEL beam polarization have been demonstrated using a set of carefully calibrated optics.  
MOP059 Synchronized Mid-Infrared Pulses at the Fritz Haber Institute IR-FEL 1
  • R. Kiessling, S. Gewinner, A. Paarmann, W. Schöllkopf, M. Wolf
    FHI, Berlin, Germany
  The combined application of FEL radiation and femtosecond table-top lasers for two-color spectroscopy demands an accurate pulse synchronization. In order to employ the Infared FEL at the Fritz Haber Institute for non-linear and time-resolved experiments, an RF-over-fiber-based timing system has been established. Using a balanced optical cross-correlation scheme, we determined an FEL micro-pulse timing jitter of 100-200 fs (rms). The long-term timing drift was found to be well correlated to the energy fluctuations of the accelerated electron bunches. By means of the jitter-corrected cross-correlation signal, we directly measure the FEL pulse shape at different cavity detunings. For large cavity detuning, narrowband IR radiation (~ 0.3 % FWHM) can be generated and utilized for high-resolution non-linear spectroscopy. On the other hand, sub-picosecond pulses are provided at small detuning, which are well-suited for time-resolved measurements. At intermediate detuning values, we observe the build-up and dynamics of multipulses that result in the well-known limit-cycle power oscillations.  
poster icon Poster MOP059 [1.531 MB]  
Broadband THz FEL Oscillator via Resonant Coherent Diffraction Radiation at ERL Test Accelerator in KEK  
  • Y. Honda, A. Aryshev, R. Kato, T. Miyajima, T. Obina, M. Shimada, R. Takai, N. Yamamoto
    KEK, Ibaraki, Japan
  An Energy Recovery Linac can produce a low emittance and short bunch beam at a high-repetition rate. A test accelerator, compact-ERL, has been operating in KEK for development works of technologies related to ERL and CW-Superconducting accelerators. One of the promising applications of such a short bunch beam is a high-power THz radiation source produced by a coherent radiation. When a charged particle beam passes close to a conductive target, a radiation called diffraction radiation is produced. If the target mirrors form an optical cavity whose fundamental frequency matches the repetition frequency of the beam, the radiation resonates in the cavity, resulting in extracting a huge radiation power determined by the loss of the cavity. When the cavity is designed to be zero carrier envelope offset, all the longitudinal modes excite at the same time. This situation can be understood as an undulatory-less broadband FEL oscillator. We plan to perform an experiment of the resonant coherent diffraction mechanism in the return-loop of the compact-ERL. We report the design of the experimental setup to be installed in the summer of 2017.  
MOP061 X-ray Regenerative Amplifier Free-Electron Laser Concepts for LCLS-II 1
  • G. Marcus, Y. Ding, J.P. Duris, Y. Feng, Z. Huang, J. Krzywinski, T.J. Maxwell, D.F. Ratner, T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
  • K.-J. Kim, R.R. Lindberg, Yu. Shvyd'ko
    ANL, Argonne, Illinois, USA
  • D.C. Nguyen
    LANL, Los Alamos, New Mexico, USA
  High-brightness electron beams that will drive the next generation of high-repetition rate X-ray FELs allow for the possibility of optical cavity-based feedback. One such cavity-based FEL concept is the Regenerative Amplifier Free-Electron Laser (RAFEL). This paper examines the design and performance of possible RAFEL configurations for LCLS-II. The results are primarily based on high-fidelity numerical particle simulations that show the production of high brightness, high average power, fully coherent, and stable X-ray pulses at LCLS-II using both the fundamental and harmonic FEL interactions.  
MOP062 X-ray FEL Oscillator Seeded Harmonic Amplifier for High Energy Photons 1
  • W. Qin, J. Wu
    SLAC, Menlo Park, California, USA
  • K.-J. Kim, R.R. Lindberg
    ANL, Argonne, Illinois, USA
  High-power, high-energy X-ray pulses in the range of several tens of keV have important applications for material sciences.* The unique feature of an X-ray FEL Oscillator (XFELO) makes it possible to seed a harmonic amplifier to produce such high energy photons.** In this contribution, we present simulation studies using 14.4-keV output pulses from an XFELO to generate harmonics around 40 keV (3rd harmonic) and 60 keV (4th harmonic). Techniques such as undulator tapering and fresh bunch lasing are considered to improve the amplifier performance.
* MaRIE project:
** K.-J. Kim, XFELO-Seeded Amplifier, talk on MaRIE workshop, 2016.
Considerations on X-ray FEL Oscillator Operation for the Shanghai Coherent Light Facility  
  • K. Li, H.X. Dengpresenter
    SINAP, Shanghai, People's Republic of China
  Shanghai Coherent Light Facility (SCLF) is a quasi-CW hard X-ray free electron laser user facility which is recently proposed. Due to the high repetition rate and high quality electron beams, it is straightforward to consider an X-ray free electron laser oscillator (XFELO) operation for SCLF. The main parameters required for the undulator, X-ray cavity and electron beam for XFELO operation are discussed, and the performances of the expected fully coherent X-ray pulses are investigated and optimized by the combination of theoretical analysis and numerical simulation.  
MOP064 An Experimental Setup for Probing the Thermal Properties of Diamond Regarding Its Use in an XFELO 1
  • C.P. Maag, I. Bahns, J. Roßbach, P. Thiessenpresenter
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • H. Sinn
    XFEL. EU, Hamburg, Germany
  • J. Zemella
    DESY, Hamburg, Germany
  Funding: Work supported by BMBF (FKZ 05K13GU4 + FKZ 05K16GU4)
This work presents an pump-probe setup for measuring the thermal evolution of diamond crystals at cryogenic temperatures under the heat load conditions of an X-ray free electron laser oscillator (XFELO). As the diamond Bragg reflectors of an XFELO are subjected to intense heat loads during operation, the correct understanding of the thermal evolution in diamond plays a major role in the correct modeling of an XFELO. Stoupin et al.* did a room temperature x-ray diffraction measurement on the nanosecond transient thermal response of diamond to an optical pulse. The measurements presented in this paper for the first time incorporate effects due to the very short penetration depth of only a few μm of an XFELO pulse in combination with the high mean free path in diamond at cryogenic temperatures. While at room temperature the heat equation based on Fourier's law accurately fits the measured results, this vastly changes due to the onset of ballistic processes at cryogenic temperatures. These changes, which are hard to predict theoretically, show the necessity of measurements of the thermal evolution in diamond with special regard to a correct mimicking of the heat load in an XFELO.
*S. Stoupin et al., Phys. Rev. B, vol. 86, p. 054301, 2012.
poster icon Poster MOP064 [2.234 MB]  
MOP066 Free Electron Lasers in 2017 1
  • P.J. Neyman
    Compass Scientific Engineering, Compass Manufacturing Services, Fremont, USA
  • J. Blau, K. R. Cohn, W.B. Colsonpresenter
    NPS, Monterey, California, USA
  • S.C. Gottschalk
    STI Optronics, Inc., Redmond, USA
  • A.M.M. Todd
    AES, Medford, New York, USA
  Forty-one years after the first operation of the short wavelength free electron laser (FEL) at Stanford University, there continue to be many important experiments, proposed experiments, and user facilities around the world. Properties of FELs in the infrared, visible, UV, and x-ray wavelength regimes are tabulated and briefly discussed.