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Sample records for coherent sase fel

  1. A non-destructive electron beam diagnostic for a SASE FEL using coherent off-axis undulator radiation

    International Nuclear Information System (INIS)

    Neuman, C.P.; Ponds, M.L.; Barnett, G.A.; Madey, J.M.J.; O'Shea, P.G.

    1999-01-01

    We show that by observing coherent off-axis undulator radiation (COUR) from a short diagnostic wiggler, it may be possible to determine the length and structure of a short electron bunch. Typically the on-axis undulator radiation is incoherent, but at angles of a few degrees, the wavelength of the emitted radiation may be comparable to the length of a short electron bunch, and thus coherence effects emerge. Due to such coherence effects, the intensity of the emitted radiation may change by up to a factor of 10 9 as the angle of observation is increased. The radiation becomes coherent in a way which depends on the length and structure of the electron bunch. Observing COUR disturbs the electron bunch negligibly. Thus, COUR can be used as a non-destructive diagnostic which would allow for optimization of FEL performance while an FEL is operating. Such a diagnostic could be used for proposed SASE FELs, which use short electron bunches. We present two methods to describe the theory for COUR, and we use these methods to calculate the expected outcome of a COUR experiment. We propose an experiment to demonstrate COUR effects and their applications to SASE FELs

  2. Quantum SASE FEL with a Laser Wiggler

    CERN Document Server

    Bonifacio, R

    2005-01-01

    Quantum effects in high-gain FELs become relevant when ρ'=ρ(mcγ/ ћ k)<1. The quantum FEL parameter ρ' rules the maximum number of photons emitted per electrons. It has been shown that when ρ'<1 a "quantum purification" of the SASE regime occurs: in fact, the spectrum of the emitted radiation (randomly spiky in the usual classical SASE regime) shrinks to a very narrow single line, leading to a high degree of temporal coherence. From the definition of ρ it appears that in order to achieve the quantum regime, small values of ρ, beam energy and radiation wavelength are necessary. These requirements can be met only using a laser wiggler. In this work we state the scaling laws necessary to operate a SASE FEL in the Angstrom region. All physical quantities are expressed in terms of the normalized emittance and of two parameters: the ratio between laser and electron beam spot sizes and the ratio between Rayleigh range and electron ...

  3. Electron beam bunch length characterizations using incoherent and coherent transition radiation on the APS SASE FEL project

    CERN Document Server

    Lumpkin, Alex H; Berg, W J; Lewellen, J W; Sereno, N S; Happek, U

    2000-01-01

    The Advanced Photon Source (APS) injector linac has been reconfigured with a low-emittance RF thermionic gun and a photocathode (PC) RF gun to support self-amplified spontaneous emission (SASE) free-electron laser (FEL) experiments. One of the most critical parameters for optimizing SASE performance (gain length) is the electron beam peak current, which requires a charge measurement and a bunch length measurement capability. We report here initial measurements of the latter using both incoherent optical transition radiation (OTR) and coherent transition radiation (CTR). A visible light Hamamatsu C5680 synchroscan streak camera was used to measure the thermionic RF gun beam's bunch length (sigma approx 2-3 ps) via OTR generated by the beam at 220 MeV and 200 mA macropulse average current. In addition, a CTR monitor (Michelson Interferometer) based on a Golay cell as the far-infrared (FIR) detector has been installed at the 40-MeV station in the beamline. Initial observations of CTR signal strength variation wi...

  4. Status and initial commissioning of a high gain 800 nm SASE FEL

    CERN Document Server

    Tremaine, Aaron M; Murokh, A; Musumeci, P; Pellegrini, C; Rosenzweig, J; Babzien, M; Ben-Zvi, I; Johnson, E; Malone, R; Rakowsky, G; Skaritka, J; Wang, X J; Yu, L H; Van Bibber, K A; Hill, J M; Le Sage, G P; Carr, R; Cornacchia, M; Nuhn, H D; Ruland, R; Nguyen, D C

    2000-01-01

    We describe the status and initial commissioning of the Visible to Infrared SASE Amplifier (VISA) experiment. VISA uses a strong focusing 4 m undulator, the Brookhaven National Laboratory ATF linac with an energy of 72 MeV, and a photoinjector electron source. The VISA fundamental radiation wavelength is near 800 nm and the power expected at saturation is near 60 MW. Power, angular and spectral measurements are planned for the VISA radiation and these results will be analyzed and compared with SASE FEL theory and computer simulation. In addition, the induced electron beam micro-bunching will be measured using coherent transition radiation.

  5. Initial gain measurements of an 800 nm SASE FEL, VISA

    CERN Document Server

    Frigola, P; Ben-Zvi, I; Bertolini, L R; Carr, R; Cornacchia, M; Hill, J M; Johnson, E; Klaisner, L; Le Sage, G P; Libkind, M; Malone, R; Murokh, A; Musumeci, P; Nguyen, D C; Nuhn, H D; Pellegrini, C; Rakowsky, G; Reiche, S; Rosenzweig, J; Ruland, R; Skaritka, J; Toor, A; Tremaine, Aaron M; Van Bibber, K A; Wang, X J

    2001-01-01

    The Visible to Infrared SASE Amplifier (VISA) FEL is designed to obtain high gain at a radiation wavelength of 800 nm. The FEL uses the high brightness electron beam of the Accelerator Test Facility (ATF), with energy of 72 MeV. VISA uses a novel, 4 m long, strong focusing undulator with a gap of 6 mm and a period of 1.8 cm. To obtain large gain the beam and undulator axis have to be aligned to better than 5 mu m. Results from initial measurements on the alignment, gain, and spectrum will be presented and compared to theoretical calculations and simulations.

  6. Femtosecond X-ray Pulses from a Spatially Chirped Electron Bunch in a SASE FEL

    Energy Technology Data Exchange (ETDEWEB)

    Emma, P.

    2003-01-14

    We propose a simple method to produce short x-ray pulses using a spatially chirped electron bunch in a SASE FEL. The spatial chirp is generated using an rf deflector which produces a transverse offset (in y and/or y') correlated with the longitudinal bunch position. Since the FEL gain is very sensitive to an initial offset in the transverse phase space at the entrance of the undulator, only a small portion of the electron bunch with relatively small transverse offset will interact significantly with the radiation, resulting in an x-ray pulse length much shorter than the electron bunch length. The x-ray pulse is also naturally phase locked to the rf deflector and so allows high precision timing synchronization. We discuss the generation and transport of such a spatially chirped electron beam and show that tens of femtosecond long pulse can be generated for the linac coherent light source (LCLS).

  7. Start-to-end simulations of SASE FEL at the TESLA Test Facility

    International Nuclear Information System (INIS)

    Dohlus, M.; Floettmann, K.; Limberg, T.; Saldin, E.L; Schneidmiller, E.A.; Kozlov, O.S.; Yurkov, M.V.; Piot, Ph.

    2004-01-01

    VUV SASE FEL at the TESLA Test Facility (Phase 1) was successfully running and reached saturation in the wavelength range 80-120 nm. We present a posteriori start-to-end simulations of this machine. The codes Astra and elegant are used to track particle distribution from the cathode to the undulator entrance. An independent simulation of the beam dynamics in the bunch compressor is performed with the code CSRtrack. SASE FEL process is simulated with the code FAST. The simulation results are in good agreement with the measured properties of SASE FEL radiation. It is shown that the beam dynamics after the bunch compressor is mainly defined by space charge fields. FEL radiation is produced by the head of the electron bunch having a peak current of about 3 kA and a duration of 100 fs

  8. Recent Results from and Future Plans for the VISA II SASE FEL

    CERN Document Server

    Andonian, Gerard; Babzien, Marcus; Ben-Zvi, Ilan; Boscolo, Ilario; Cialdi, Simone; Ferrario, Massimo; Flacco, Alessandro Federico; Frigola, Pedro; Huang, Jung Y; Litvinenko, Vladimir N; Murokh, Alex; Palumbo, Luigi; Pellegrini, Claudio; Reiche, Sven; Rosenzweig, James E; Travish, Gil; Vicario, Carlo; Yakimenko, Vitaly

    2005-01-01

    As the promise of X-ray Free Electron Lasers (FEL) comes close to realization, the creation and diagnosis of ultra-short pulses is of great relevance in the SASE FEL (Self-Amplified Spontaneous Emission) community. The VISA II (Visible to Infrared SASE Amplifier) experiment entails the use of a chirped electron beam to drive a high gain SASE FEL at the Accelerator Test Facility (ATF) in Brookhaven National Labs (BNL). The resulting ultra-short pulses will be diagnosed using an advanced FROG (Frequency Resolved Optical Gating) technique, as well as a double differential spectrum (angle/wavelength) diagnostic. Implementation of sextupole corrections to the longitudinal aberrations affecting the high energy-spread chirped beam during transport to the VISA undulator is studied. Start-to-end simulations, including radiation diagnostics, are discussed. Initial experimental results involving a highly chirped beam transported without sextupole correction, the resulting high gain lasing, and computational analysis are...

  9. Generation of a comb electron beam to drive SASE FEL radiation spikes

    International Nuclear Information System (INIS)

    Boscolo, M.; Boscolo, I.; Castelli, F.; Cialdi, S.; Ferrario, M.; Petrillo, V.; Vaccarezza, C.

    2008-01-01

    A radiofrequency electron gun followed by a compressor can generate trains of subpicosecond electron pulses by illuminating the photocathode with a comb laser pulse. This kind of electron beams can generate trains of single radiation spikes in a SASE-FEL. The dynamics of different electron beam trains traveling in an accelerator is investigated by PARMELA simulations. A set of parameters relative to the SPARC machine are studied with the intent of generating a train of single radiation spikes in a 500 nm SASE-FEL

  10. Measurements of nonlinear harmonic generation at the Advanced Photon Source's SASE FEL

    CERN Document Server

    Biedron, S G; Borland, M; Dejus, Roger J; Den Hartog, P K; Erdmann, M; Fawley, W M; Freund, H P; Gluskin, E; Huang, Z; Kim, K J; Lewellen, J W; Li, Y; Lumpkin, Alex H; Milton, S V; Moog, E; Nassiri, A; Sajaev, Vadim; Wiemerslage, G; Yang, B X

    2002-01-01

    SASE saturation was recently achieved at the Advanced Photon Source's SASE FEL in the low-energy undulator test line at 530 nm and 385 nm. The electron beam microbunching becomes more and more prominent until saturation is achieved. This bunching causes nonlinear harmonic emission that extends the usefulness of a SASE system in achieving shorter FEL wavelengths for the same electron beam energy. We have investigated the intensity of the fundamental and second harmonic undulator radiation as a function of distance along the undulator line and present the experimental results and compare them to numerical simulations. In addition, we have measured the single-shot second harmonic spectra as well as the simultaneous fundamental and second harmonic spectra and present the experimental results.

  11. The SPARC project: a high-brightness electron beam source at LNF to drive a SASE-FEL experiment

    International Nuclear Information System (INIS)

    Alesini, D.; Bertolucci, S.; Biagini, M.E.; Biscari, C.; Boni, R.; Boscolo, M.; Castellano, M.; Clozza, A.; Di Pirro, G.; Drago, A.; Esposito, A.; Ferrario, M.; Fusco, V.; Gallo, A.; Ghigo, A.; Guiducci, S.; Incurvati, M.; Laurelli, P.; Ligi, C.; Marcellini, F.; Migliorati, M.; Milardi, C.; Palumbo, L.; Pellegrino, L.; Preger, M.; Raimondi, P.; Ricci, R.; Sanelli, C.; Sgamma, F.; Spataro, B.; Serio, M.; Stecchi, A.; Stella, A.; Tazzioli, F.; Vaccarezza, C.; Vescovi, M.; Vicario, C.; Zobov, M.; Acerbi, E.; Alessandria, F.; Barni, D.; Bellomo, G.; Boscolo, I.; Broggi, F.; Cialdi, S.; DeMartinis, C.; Giove, D.; Maroli, C.; Petrillo, V.; Rome', M.; Serafini, L.; Chiadroni, E.; Felici, G.; Levi, D.; Mastrucci, M.; Mattioli, M.; Medici, G.; Petrarca, G.S.; Catani, L.; Cianchi, A.; D'Angelo, A.; Di Salvo, R.; Fantini, A.; Moricciani, D.; Schaerf, C.; Bartolini, R.; Ciocci, F.; Dattoli, G.; Doria, A.; Flora, F.; Gallerano, G.P.; Giannessi, L.; Giovenale, E.; Messina, G.; Mezi, L.; Ottaviani, P.L.; Picardi, L.; Quattromini, M.; Renieri, A.; Ronsivalle, C.; Avaldi, L.; Carbone, C.; Cricenti, A.; Pifferi, A.; Perfetti, P.; Prosperi, T.; Albertini, V. Rossi; Quaresima, C.; Zema, N.

    2003-01-01

    The Project Sorgente Pulsata e Amplificata di Radiazione Coerente (SPARC), proposed by a collaboration among ENEA-INFN-CNR-Universita' di Tor Vergata-INFM-ST, was recently approved by the Italian Government and will be built at LNF. The aim of the project is to promote an R and D activity oriented to the development of a coherent ultra-brilliant X-ray source in Italy. This collaboration has identified a program founded on two main issues: the generation of ultra-high peak brightness electron beams and of resonant higher harmonics in the SASE-FEL process, as presented in this paper

  12. Comprehensive z-dependent measurements of electron-beam microbunching using COTR in a saturated SASE FEL

    CERN Document Server

    Lumpkin, Alex H; Lewellen, J W; Berg, W; Biedron, S G; Borland, M; Chae, Y; Erdmann, M; Huang, Z; Kim, K J; Li, Y; Milton, S V; Moog, E; Rule, D W; Sajaev, Vadim; Yang, B X

    2002-01-01

    We report the initial, comprehensive set of z-dependent measurements of electron-beam microbunching using coherent optical transition radiation (Cot) in a saturated self-amplified spontaneous emission (SASE) free-electron laser (FEL) experiment. In this case the FEL was operated near 530 nm using an enhanced facility including a bunch-compressed photocathode gun electron beam, linac, and 21.6 m of undulator length. The longitudinal microbunching was tracked by inserting a metal foil and mirror after each of the nine 2.4-m-long undulators and measuring the visible COTR spectra, intensity, angular, distribution, and spot size. We observed for the first time the z-dependent transition of the COTR spectra from simple lines to complex structure/sidebands near saturation. We also observed the change in the microbunching fraction after saturation, multiple fringes in the COTR interferogram that are consistent with involvement of a smaller core of the e-beam transverse distribution, and the second harmonic content of...

  13. Conceptual design of a high-brightness linac for soft X-ray SASE-FEL source

    International Nuclear Information System (INIS)

    Alesini, D.; Bertolucci, S.; Biagini, M.E.; Biscari, C.; Boni, R.; Boscolo, M.; Castellano, M.; Clozza, A.; Pirro, G.D.G. Di; Drago, A.; Esposito, A.; Ferrario, M.; Fusco, V.; Gallo, A.; Ghigo, A.; Guiducci, S.; Incurvati, M.; Laurelli, P.; Ligi, C.; Marcellini, F.; Migliorati, M.; Milardi, C.; Palumbo, L.; Pellegrino, L.; Preger, M.; Raimondi, P.; Ricci, R.; Sanelli, C.; Sgamma, F.; Spataro, B.; Serio, M.; Stecchi, A.; Stella, A.; Tazzioli, F.; Vaccarezza, C.; Vescovi, M.; Vicario, C.; Zobov, M.; Acerbi, E.; Alessandria, F.; Barni, D.; Bellomo, G.; Birattari, C.; Bonardi, M.; Boscolo, I.; Bosotti, A.; Broggi, F.; Cialdi, S.; DeMartinis, C.; Giove, D.; Maroli, C.; Michelato, P.; Monaco, L.; Pagani, C.; Petrillo, V.; Pierini, P.; Serafini, L.; Sertore, D.; Volpini, G.; Chiadroni, E.; Felici, G.; Levi, D.; Mastrucci, M.; Mattioli, M.; Medici, G.; Petrarca, G.S.; Catani, L.; Cianchi, A.; D'Angelo, A.; Salvo, R.D.R. Di; Fantini, A.; Moricciani, D.; Schaerf, C.; Bartolini, R.; Ciocci, F.; Dattoli, G.; Doria, A.; Flora, F.; Gallerano, G.P.; Giannessi, L.; Giovenale, E.; Messina, G.; Mezi, L.; Ottaviani, P.L.; Picardi, L.; Quattromini, M.; Renieri, A.; Ronsivalle, C.; Avaldi, L.; Carbone, C.; Cricenti, A.; Pifferi, A.; Perfetti, P.; Prosperi, T.; Albertini, V.R.V. Rossi; Quaresima, C.; Zema, N.

    2003-01-01

    FELs based on SASE are believed to be powerful tools to explore the frontiers of basic sciences, from physics to chemistry to biology. Intense R and D programs have started in the USA and Europe in order to understand the SASE physics and to prove the feasibility of these sources. The allocation of considerable resources in the Italian National Research Plan (PNR) brought about the formation of a CNR-ENEA-INFN-University of Roma 'Tor Vergata' study group. A conceptual design study has been developed and possible schemes for linac sources have been investigated, leading to the SPARX proposal. We report in this paper the results of a preliminary start to end simulation concerning one option we are considering based on an S-band normal conducting linac with high-brightness photoinjector integrated in an RF compressor

  14. Strong Focusing Wiggler for SASE and FEL in the Far-Infrared Region at ISIR, Osaka University

    CERN Document Server

    Kashiwagi, S; Kato, R; Noda, N

    2005-01-01

    We apply the edge-focusing scheme to the wiggler for FEL and SASE in the far-infrared region at ISIR, Osaka University in order to make the gain length of SASE shorter by keeping the beam size small along the wiggler. As the electron beam energy is 10-30 MeV and the magnetic field of the wiggler is up to 0.4 T, the natural focusing force in the vertical direction is strong in the wiggler and it is strongly dependent on the electron energy and the wiggler gap. The focusing forces should be compatible to or higher than the strong natural focusing force, equally in the horizontal and vertical directions over the wide range of the electron beam energy and the wiggler gap. In order to meet this requirement, we adopt the strong focusing scheme using the EF wiggler. The wiggler consists of 4 FODO cells in the 1.938 m long (32 periods, period length: 60mm). A focusing element and defocusing element are incorporate with single wiggler periods with edge angles of +5 and -5 degrees, respectively, and they are separated ...

  15. A compact FEL upconverter of coherent radiation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y.; Marshall, T.C. [Columbia Univ., New York, NY (United States)

    1995-12-31

    The objective is to generate a powerful millimeter-wave FEL signal in a single pass, using a coherent microwave source (24GHz) to prebunch the electron beam for a harmonically-related wave (72GHz). We use the Columbia FEL facility, operating the electron beam at 600kV, 100A; undulator period = 1.85cm and 250G (K = 0.25); electron beam diameter = 3mm inside a 8.5 mm ID drift tube; guiding field of 8800G. Under these conditions, both the microwave signal (5kW input) and the millimeter signal will show travelling-wave gain in the TE11 mode. We report initial experimental results for the millimeter wave spectrum and find an overall power gain of {approximately}20 for the 24GHz input wave. Also presented will be numerical solutions of the wave growth using the FEL equations with slippage. This device has the advantage of producing a high-power FEL output in a single-pass travelling-wave configuration, obtaining a millimeter wave which is phase-referenced to a coherent laboratory source.

  16. A simple method for controlling the line width of SASE X-ray FELs

    International Nuclear Information System (INIS)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2010-04-01

    chicane in the baseline undulator, it is possible to decrease the bandwidth of the radiation well beyond the XFEL design down to 10 -5 . The installation of the magnetic chicane does not perturb the undulator focusing system and does not interfere with the baseline mode of operation. We present feasibility study and exemplifications for the SASE2 line of the European XFEL. (orig.)

  17. Ultrafast Coherent Control and Characterization of Surface Reactions using FELs

    CERN Document Server

    Ogasawara, Hirohito; Nordlund, Dennis

    2005-01-01

    The microscopic understanding of surface chemistry requires a detailed understanding of the dynamics of elementary processes at surfaces. The ultrashort electron pulse obtained in the linear accelerator to feed the FEL can be used for generation of coherent synchrotron radiation in the low energy THz regime. With the current parameters for LCLS this corresponds to radiation with energy corresponding to excitations of low-energy vibrational modes of molecules on surfaces or phonons in substrates. The coherent radiation can coherently manipulate atoms or molecules on surfaces. In this respect a chemical reaction can be initiated by coherent atomic motion along a specific reaction coordinate. Since the THz radiation is generated from the same source as the FEL radiation full-time synchronization for pump-probe experiments will be possible. The possibility to perform time-resolved X-ray Emission Spectroscopy (XES) and X-ray Photoelectron Spectroscopy (XPS) measurements as a probe of chemical dynamics is an exciti...

  18. Ultrafast Coherent Control and Characterization of Surface Reactions using FELs

    International Nuclear Information System (INIS)

    Ogasawara, Hirohito

    2005-01-01

    The microscopic understanding of reactions at surfaces requires an in-depth knowledge of the dynamics of elementary processes on an ultrafast timescale. This can be accomplished using an ultrafast excitation to initiate a chemical reaction and then probe the progression of the reaction with an ultrashort x-ray pulse from the FEL. There is a great potential to use atom-specific spectroscopy involving core levels to probe the chemical nature, structure and bonding of species on surfaces. The ultrashort electron pulse obtained in the linear accelerator to feed the X-ray FEL can also be used for generation of coherent synchrotron radiation in the low energy THz regime to be used as a pump. This radiation has an energy close to the thermal excitations of low-energy vibrational modes of molecules on surfaces and phonons in substrates. The coherent THz radiation will be an electric field pulse with a certain direction that can collectively manipulate atoms or molecules on surfaces. In this respect a chemical reaction can be initiated by collective atomic motion along a specific reaction coordinate. If the coherent THz radiation is generated from the same source as the X-ray FEL radiation, full-time synchronization for pump-probe experiments will be possible. The combination of THz and X-ray spectroscopy could be a unique opportunity for FEL facilities to conduct ultrafast chemistry studies at surfaces

  19. Scheme for generation of fully-coherent, TW power level hard X-ray pulses from baseline undulators at the European X-ray FEL

    International Nuclear Information System (INIS)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2010-07-01

    The most promising way to increase the output power of an X-ray FEL (XFEL) is by tapering the magnetic field of the undulator. Also, significant increase in power is achievable by starting the FEL process from a monochromatic seed rather than from noise. This report proposes to make use of a cascade self-seeding scheme with wake monochromators in a tunable-gap baseline undulator at the European XFEL to create a source capable of delivering coherent radiation of unprecedented characteristics at hard X-ray wavelengths. Compared with SASE X-ray FEL parameters, the radiation from the new source has three truly unique aspects: complete longitudinal and transverse coherence, and a peak brightness three orders of magnitude higher than what is presently available at LCLS. Additionally, the new source will generate hard X-ray beam at extraordinary peak (TW) and average (kW) power level. The proposed source can thus revolutionize fields like single biomolecule imaging, inelastic scattering and nuclear resonant scattering. The self-seeding scheme with the wake monochromator is extremely compact, and takes almost no cost and time to be implemented. The upgrade proposed in this paper could take place during the commissioning stage of the European XFEL, opening a vast new range of applications from the very beginning of operations.We present feasibility study and examplifications for the SASE2 line of the European XFEL. (orig.)

  20. Undulators to FELs: Nanometers, Femtoseconds, Coherence and Applications

    Energy Technology Data Exchange (ETDEWEB)

    Attwood, David [University of California Berkeley

    2011-11-30

    For scientists in many fields, from material science to the life sciences and archeology, synchrotron radiation, and in particular undulator radiation, has provide an intense source of x-rays which are tunable to the absorption edges of particular elements of interest, often permitting studies at high spatial and spectral resolution. Now a close cousin to the undulator, the x-ray free electron laser (XFEL) has emerged with improved spatial coherence and, perhaps more importantly, femtosecond pulse durations which permit dynamical studies. In the future attosecond x-ray capabilities are anticipated. In this colloqium we will describe some state of the art undulator studies, how undulators work, the evolution to FELs, their pulse and coherence properties, and the types of experiments envisioned.

  1. FEL Simulations for the LCLS

    Energy Technology Data Exchange (ETDEWEB)

    Nuhn, Heinz-Dieter

    1998-10-06

    A first Design Study Report has recently been completed [1] for the Linac Coherent Light Source (LCLS), a proposal to build an x-ray Free Electron Laser (FEL) at the Stanford Linear Accelerator Center (SLAC) as a single pass SASE (Self-Amplified Spontaneous Emission) amplifier. The proposal includes the use of a very low emittance electron beam accelerated up to 15 GeV by the last third of the SLAC linac to produce sub-picosecond x-ray pulses with high brightness and full transverse coherence in a 112-meter long undulator. Many aspects of the FEL design have been analyzed with FEL simulation codes. The paper discusses some of the results of these aspects, i.e. temporal x-ray pulse structure and power sprectrum, trajectory errors and effects of undulator beam tube wakefields.

  2. Coherent harmonic production using a two-section undulator FEL

    Energy Technology Data Exchange (ETDEWEB)

    Jaroszynski, D.A. [Commissariat a l`Energie, Bruyeres-le-Chatel (France); Prazeres, R.; Glotin, F. [Centre Universitaire Paris-Sud (France)] [and others

    1995-12-31

    We present measurements and a theoretical analysis of a new method of generating harmonic radiation in a free-electron laser oscillator with a two section undulator in a single optical cavity. To produce coherent harmonic radiation the undulator is arranged so that the downstream undulator section resonance frequency matches a harmonic of the upstream undulator. Both the fundamental and the harmonic optical fields evolve in the same optical cavity and are coupled out with different extraction fractions using a hole in one of the cavity mirrors. We present measurements that show that the optical power at the second and third harmonic can be enhanced by more than an order of magnitude in this fundamental/harmonic configuration. We compare the production of harmonic radiation of a two sectioned fundamental/harmonic undulator with that produced from a FEL operating at its highest efficiency with a step-tapered undulator, where the bunching at the end of the first section is very large. We examine, the dependence of the harmonic power on the intracavity power by adjusting the optical cavity desynchronism, {delta}L. We also examine the evolution of the fundamental and harmonic powers as a function of cavity roundtrip number to evaluate the importance of the small signal gain at the harmonic. We compare our measurements with predictions of a multi-electron numerical model that follows the evolution of fundamental and harmonic power to saturation. This fundamental/harmonic mode, of operation of the FEL may have useful applications in the production of coherent X-ray and VUV radiation, a spectral range where high reflectivity optical cavity mirrors are difficult or impossible to manufacture.

  3. Coherent undulator radiation of electron beam, microbunched for the FEL power outcoupling

    Energy Technology Data Exchange (ETDEWEB)

    Kulipanov, G.N.; Sokolov, A.S.; Vinokurov, N.A. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation)

    1995-12-31

    The spectral intensity of the coherent undulator radiation of electron beam, preliminarily microbunched by the FEL oscillator for the FEL power outcoupling, is approximately calculated by simple analytic considerations, taking into account the transverse emittances and the energy spread of the microbunched electron beams.

  4. Current-enhanced SASE using an optical laser and its application to the LCLS

    International Nuclear Information System (INIS)

    Zholents, Alexander A.; Fawley, William M.; Emma, Paul; Huang, Zhirong; Reiche, Sven; Stupakov, Gennady

    2004-01-01

    We propose a significant enhancement of the electron peak current entering a SASE undulator by inducing an energy modulation in an upstream wiggler magnet via resonant interaction with an optical laser, followed by microbunching of the energy-modulated electrons at the accelerator exit. This current enhancement allows a reduction of the FEL gain length. The x-ray output consists of a series of uniformly spaced spikes, each spike being temporally coherent. The duration of this series is controlled by the laser pulse and in principle can be narrowed down to just a single, 200-attosecond spike. Given potentially absolute temporal synchronization of the x-ray spikes to the energy-modulating laser pulse, this scheme naturally makes pump-probe experiments available to SASE FEL's. We also study various detrimental effects related to the high electron peak current

  5. Study of coherence limits and chirp control in long pulse FEL oscillator

    International Nuclear Information System (INIS)

    Socol, Y.; Gover, A.; Eliran, A.; Volshonok, M.; Kapilevich, B.; Yahalom, A.; Lurie, Y.; Einat, M.; Pinhasi, Y.

    2004-01-01

    Full Text:We report experimental studies of the spectral line width and chirp characteristics of the mm-wave RF radiation of Israeli Electrostatic Accelerator FEL (EA-FEL), along with theory and numerical simulations. The simulations matching the experimental data were carried out using space-frequency model. EA-FELs have the capacity to generate long pulses of tens microseconds and more, that in principle can be elongated indefinitely (CW operation). Since a cold beam FEL is by nature a ''homogeneously broadened laser'', EA-FEL can operate, unlike other kinds of FELs, at a Angle longitudinal mode (single frequency). This allows the generation of very coherent radiation. The current status of the Israeli Tandem Electrostatic Accelerator FEL (EA-FEL), which is based on an electrostatic Van de Graaff accelerator, allows the generation of pulses of tens microseconds duration. It has been operated recently past saturation, and produced single mode coherent radiation of record narrow inherent relative line width Δ f/f = 10 -6 at frequencies near 100 GHz. A clear frequency chirp is observed during pulses of tens of microseconds (0.3 -0.5 MHz/μs). This is essentially a drifting frequency pulling effect associated with the accelerator voltage drop during the pulse. Additionally, aperiodic oscillation relaxation was experimentally measured and compared with theory both numerically, and analytically in general framework of non-harmonic oscillations. Possibilities of chirp applications and power boosting are also discussed

  6. The Harmonically Coupled 2-Beam FEL

    CERN Document Server

    McNeil, Brian W J

    2004-01-01

    A 1-D model of a 2-beam Free Electron Laser amplifier is presented. The two co-propagating electron beams have different energies, chosen so that the fundamental resonant FEL interaction of the higher energy beam is at an harmonic of the lower energy beam. In this way, a coupling between the FEL interactions of the two beams occurs via the harmonic components of the electron bunching and radiation emission of the lower energy interaction. Such resonantly coupled FEL interactions may offer potential benefits over existing single beam FEL schemes. A simple example is presented where the lower energy FEL interaction only is seeded with radiation at its fundamental resonant wavelength. It is predicted that the coherence properties of this seed field are transfered via the resonantly coupled FEL interaction to the un-seeded higher energy FEL interaction, thereby improving its coherence properties over that of a SASE interaction alone. This method may offer an alternative seeding scheme for FELs operating in the XU...

  7. Optics-free x-ray FEL oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko, V.N.; Hao, Y.; Kayran, D.; Trbojevic, D.

    2011-03-28

    There is a need for an Optics-Free FEL Oscillators (OFFELO) to further the advantages of free-electron lasers and turning them in fully coherent light sources. While SASE (Self-Amplified Spontaneous Emission) FELs demonstrated the capability of providing very high gain and short pulses of radiation and scalability to the X-ray range, the spectra of SASE FELs remains rather wide ({approx}0.5%-1%) compared with typical short wavelengths FEL-oscillators (0.01%-0.0003% in OK-4 FEL). Absence of good optics in VUV and X-ray ranges makes traditional oscillator schemes with very high average and peak spectral brightness either very complex or, strictly speaking, impossible. In this paper, we discuss lattice of the X-ray optics-free FEL oscillator and present results of initial computer simulations of the feedback process and the evolution of FEL spectrum in X-ray OFFELO. We also discuss main limiting factors and feasibility of X-ray OFFELO.

  8. Coherence and linewidth studies of a 4-nm high power FEL

    International Nuclear Information System (INIS)

    Fawley, W.M.; Sessler, A.M.; Scharlemann, E.T.

    1993-05-01

    Recently the SSRL/SLAC and its collaborators elsewhere have considered the merits of a 2 to 4-nm high power FEL utilizing the SLAC linac electron beam. The FEL would be a single pass amplifier excited by spontaneous emission rather than an oscillator, in order to eliminate the need for a soft X-ray resonant cavity. We have used GINGER, a multifrequency 2D FEL simulation code, to study the expected linewidth and coherence properties of the FEL, in both the exponential and saturated gain regimes. We present results concerning the effective shot noise input power and mode shape, the expected subpercent output line widths, photon flux, and the field temporal and spatial correlation functions. We also discuss the effects of tapering the wiggler upon the output power and line width

  9. Design and simulation of 3½-cell superconducting gun cavity and beam dynamics studies of the SASE-FEL System at the Institute of Accelerator Technologies at Ankara University

    International Nuclear Information System (INIS)

    Yildiz, H. Duran; Cakir, R.; Porsuk, D.

    2015-01-01

    Design and simulation of a superconducting gun cavity with 3½ cells have been studied in order to give the first push to the electron beam for the linear accelerating system at The Institute of Accelerator Technologies at Ankara University. Electrons are accelerated through the gun cavity with the help of the Radiofrequency power suppliers from cryogenic systems. Accelerating gradient should be as high as possible to accelerate electron beam inside the cavity. In this study, electron beam reaches to 9.17 MeV energy at the end of the gun cavity with the accelerating gradient; E c =19.21 MV/m. 1.3 GHz gun cavity consists of three TESLA-like shaped cells while the special designed gun-cell includes a cathode plug. Optimized important beam parameters inside the gun cavity, average beam current 3 mA, transverse emittance 2.5 mm mrad, repetition rate 30 MHz and other parameters are obtained for the SASE-FEL System. The Superfish/Poisson program is used to design each cell of the superconducting cavity. Superconducting gun cavity and Radiofrequency properties are studied by utilizing 2D Superfish/Poisson, 3D Computer Simulation Technology Microwave Studio, and 3D Computer Simulation Technology Particle Studio. Superfish/Poisson is also used to optimize the geometry of the cavity cells to get the highest accelerating gradient. The behavior of the particles along the beamline is included in this study. ASTRA Code is used to track the particles

  10. Development of intense terahertz coherent synchrotron radiation at KU-FEL

    International Nuclear Information System (INIS)

    Sei, Norihiro; Zen, Heishun; Ohgaki, Hideaki

    2016-01-01

    We produced intense coherent synchrotron radiation (CSR) in the terahertz (THz) region using an S-band linac at the Kyoto University Free Electron Laser (KU-FEL), which is a mid-infrared free-electron laser facility. The CSR beam was emitted from short-pulse electron bunches compressed by a 180° arc, and was transferred to air at a large solid angle of 0.10 rad. The measured CSR energy was 55 μJ per 7 μs macropulse, and KU-FEL was one of the most powerful CSR sources in normal conducting linear accelerator facilities. The CSR spectra were measured using an uncooled pyroelectric detector and a Michelson-type interferometer designed specifically for the KU-FEL electron beam, and had a maximum at a frequency of 0.11 THz. We found that adjusting the energy slit enhanced the CSR energy and shortened the electron beam bunch length in the CSR spectra measurements. Our results demonstrated that the efficient use of the energy slit can help improve the characteristics of CSR. - Highlights: • We have developed intense coherent synchrotron radiation (CSR) at KU-FEL. • The elevation angle of the CSR was correctly measured by a new technique. • The CSR power extracted to the air was 55 μJ per 7 μs macropulse. • It was demonstrated that an energy slit was effective to improve the CSR properties.

  11. Development of intense terahertz coherent synchrotron radiation at KU-FEL

    Energy Technology Data Exchange (ETDEWEB)

    Sei, Norihiro, E-mail: sei.n@aist.go.jp [Research Institute for Measurement and Analytical Instrumentation, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Zen, Heishun; Ohgaki, Hideaki [Institute for Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

    2016-10-01

    We produced intense coherent synchrotron radiation (CSR) in the terahertz (THz) region using an S-band linac at the Kyoto University Free Electron Laser (KU-FEL), which is a mid-infrared free-electron laser facility. The CSR beam was emitted from short-pulse electron bunches compressed by a 180° arc, and was transferred to air at a large solid angle of 0.10 rad. The measured CSR energy was 55 μJ per 7 μs macropulse, and KU-FEL was one of the most powerful CSR sources in normal conducting linear accelerator facilities. The CSR spectra were measured using an uncooled pyroelectric detector and a Michelson-type interferometer designed specifically for the KU-FEL electron beam, and had a maximum at a frequency of 0.11 THz. We found that adjusting the energy slit enhanced the CSR energy and shortened the electron beam bunch length in the CSR spectra measurements. Our results demonstrated that the efficient use of the energy slit can help improve the characteristics of CSR. - Highlights: • We have developed intense coherent synchrotron radiation (CSR) at KU-FEL. • The elevation angle of the CSR was correctly measured by a new technique. • The CSR power extracted to the air was 55 μJ per 7 μs macropulse. • It was demonstrated that an energy slit was effective to improve the CSR properties.

  12. Design considerations for the coherent radiator, FEL, in the MAX IV proposal

    CERN Document Server

    Werin, Sverker; Brandin, Mathias; Eriksson, Mikael; Hansen, T N; Larsson, Jörgen; Lindgren, L J; Tarawneh, Hamed

    2004-01-01

    The MAX IV proposal is a project for the next Swedish synchrotron radiation source. Currently a design study is produced with funding from the Swedish research council (VR). One half of the project will be a double storage ring (at 3 and 1.5 GeV respectively) but the other half will be a coherent radiator, FEL, based on the 3 GeV injector. The basic FEL solution will consist of a normal conducting linac at 3 GeV which feeds three seeded cascaded optical klystrons and a radiator undulator to produce radiation down to 1.5-3 nm at GW powers. To assure synchronisation the gun laser and the seed laser share initial laser and amplifier. This basic system can be enhanced in various ways which will be discussed .

  13. Estimates of SASE power in the short wavelength region

    International Nuclear Information System (INIS)

    Kim, Kwang-Je.

    1992-03-01

    Given a sufficiently bright electron beam, the self-amplified-spontaneous emission (SASE) can provide gigawatts of short wavelength coherent radiation. The advantages of SASE approach are that is requires neither optical cavity nor an imput seed laser. In this note, we estimate the peak power performance of SASE for wavelengths shorter than 1000 Angstrom. At each wavelength, we calculate the saturated power from a uniform parameter undulator and the enhanced power from a tapered undulator. The method described here is an adaptation of that discussed by L.H. Yu, who discussed the harmonic generation scheme with seeded laser, to the case of SASE

  14. Simulation of the short pulse effects in the start-up from noise in high-gain FELS

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, S.J. [Chung-Ang Univ., Seoul (Korea, Democratic People`s Republic of); Kim, K.J. [Lawrence Berkeley Lab., CA (United States)

    1995-12-31

    The spatio-temporal evolution of high-gain free electron lasers from noise is investigated by 1-D simulation calculation. To understand the discrepancy between the experimental result and theoretical prediction of the self-amplified spontaneous emission (SASE), the strong slippage effect in the short pulse electron beam and the coherent bunched beam effect are considered. When the length over which the electron density varies significantly is comparable or smaller than the FEL wavelength, the initial noise level would be increased due to the enhanced coherence between electrons. With a proper computer modeling of the start-up from noise including the energy spread, the overall performance and characteristics of SASE are studied. This work will be helpful to increase the credibility of the simulation calculation to predict the SASE performance in all wave-length regions.

  15. Study of Coherence Limits and Chirp Control in Long Pulse FEL Oscillator

    CERN Document Server

    Gover, Avraham; Socol, Yehoshua; Volshonok, Mark

    2004-01-01

    Electrostatic Accelerator FELs have the capacity to generate long pulses of tens microseconds and more, that in principle can be elongated indefinitely (CW operation). This allows the generation of very coherent radiation. The fundamental linewidth is extremely narrow [1], and in practice the spectral width is limited by the pulse duration (Fourier transform limit) and e-beam stability. Practical problems such as the accelerator terminal voltage drop due to a non-ideal electron beam transport may reduce the length of the radiation pulse and hence create a limiting factor for coherence measurement. The current status of the Israeli Tandem Electrostatic Accelerator FEL allows the generation of pulses of tens microseconds duration. It has been operated recently past saturation, and produces single mode coherent radiation of relative linewidth ~Δf/f=10-5 at frequencies near 100GHz. A clear frequency chirp is observed during pulses of tens of microseconds (0.1-1 MHz/mS), and is directly proportional to th...

  16. GINGER simulations of short-pulse effects in the LEUTL FEL

    International Nuclear Information System (INIS)

    Huang, Z.; Fawley, W.M.

    2001-01-01

    While the long-pulse, coasting beam model is often used in analysis and simulation of self-amplified spontaneous emission (SASE) free-electron lasers (FELs), many current SASE demonstration experiments employ relatively short electron bunches whose pulse length is on the order of the radiation slippage length. In particular, the low-energy undulator test line (LEUTL) FEL at the Advanced Photon Source has recently lased and nominally saturated in both visible and near-ultraviolet wavelength regions with a sub-ps pulse length that is somewhat shorter than the total slippage length in the 22-m undulator system. In this paper we explore several characteristics of the short pulse regime for SASE FELs with the multidimensional, time-dependent simulation code GINGER, concentrating on making a direct comparison with the experimental results from LEUTL. Items of interest include the radiation gain length, pulse energy, saturation position, and spectral bandwidth. We address the importance of short-pulse effects when scaling the LEUTL results to proposed x-ray FELs and also briefly discuss the possible importance of coherent spontaneous emission at startup

  17. A HIGH REPETITION RATE VUV-SOFT X-RAY FEL CONCEPT

    International Nuclear Information System (INIS)

    Corlett, J.; Byrd, J.; Fawley, W.M.; Gullans, M.; Li, D.; Lidia, S.M.; Padmore, H.; Penn, G.; Pogorelov, I.; Qiang, J.; Robin, D.; Sannibale, F.; Staples, J.W.; Steier, C.; Venturini, M.; Virostek, S.; Wan, W.; Wells, R.; Wilcox, R.; Wurtele, J.; Zholents, A.

    2007-01-01

    We report on design studies for a seeded FEL light source that is responsive to the scientific needs of the future. The FEL process increases radiation flux by several orders of magnitude above existing incoherent sources, and offers the additional enhancements attainable by optical manipulations of the electron beam: control of the temporal duration and bandwidth of the coherent output, reduced gain length in the FEL, utilization of harmonics to attain shorter wavelengths, and precise synchronization of the x-ray pulse with seed laser systems. We describe an FEL facility concept based on a high repetition rate RF photocathode gun, that would allow simultaneous operation of multiple independent FEL's, each producing high average brightness, tunable over the VUV-soft x-ray range, and each with individual performance characteristics determined by the configuration of the FEL. SASE, enhanced-SASE (ESASE), seeded, harmonic generation, and other configurations making use of optical manipulations of the electron beam may be employed, providing a wide range of photon beam properties to meet varied user demands

  18. Contributions to the FEL2005 conference

    International Nuclear Information System (INIS)

    Grimm, O.

    2005-01-01

    The following topics were dealt with: First lasing at 32 nm of the VUV-FEL at DESY, properties of the radiation from VUV-FEL at DESY, accelerator lay out and physics of X-ray free-electron lasers, bunch compression stability dependence on RF parameters, undulator systems and photon diagnostic for the European XFEL project, electron beam characterization at PITZ and the VUV-FEL at DESY, high precision optical synchronization systems for X-ray free electron lasers, optical laser synnchronized for the DESY VUV-FEL for two-color pump probe experiments, properties of the third harmonic of the SASE FEL radiation, detector response and beam line transmission measurements with far-infrared radiation, upgrades of the laser beam-line at PITZ, bunch length measurements using a Martin-Puplett interferometer at the VUV-FEL, next generation synchronization system for the VUV-FEL at DESY, transverse electron beam diagnostics at the VYV-FEL at DESY, the infrared undulator project at the VUV-FEL, misconceptions regarding second harmonic generation in X-ray free-electron lasers, influence of an energy chirp on SASE FEL operation, design considerations for the 4GLS XUV-FEL, broadband single shot spectrometer, commissioning of TTF2 bunch compressors for 20 fs SASE source, observation of femtosecond bunch length using a transverse deflecting structure, measurement of slice-emittance using a transverse deflecting structure, the injector of the VUV-FEL at DESY, spectral decoding electro-optic measurements for longitudinal bunch diagnostics at the DESY VUV-FEL, longitudinal phase space studies at PITZ, modelling the transverse phase space and core emittance studies at PITZ, measurements of thermal emittance for cesium telluride photocathodes at PITZ, status and first results from the upgraded PITZ facility, commissioning of the SPARC movable emittance meter and its first operation at PITZ. (HSI)

  19. Contributions to the FEL2005 conference

    Energy Technology Data Exchange (ETDEWEB)

    Grimm, O. (comp.)

    2005-07-01

    The following topics were dealt with: First lasing at 32 nm of the VUV-FEL at DESY, properties of the radiation from VUV-FEL at DESY, accelerator lay out and physics of X-ray free-electron lasers, bunch compression stability dependence on RF parameters, undulator systems and photon diagnostic for the European XFEL project, electron beam characterization at PITZ and the VUV-FEL at DESY, high precision optical synchronization systems for X-ray free electron lasers, optical laser synnchronized for the DESY VUV-FEL for two-color pump probe experiments, properties of the third harmonic of the SASE FEL radiation, detector response and beam line transmission measurements with far-infrared radiation, upgrades of the laser beam-line at PITZ, bunch length measurements using a Martin-Puplett interferometer at the VUV-FEL, next generation synchronization system for the VUV-FEL at DESY, transverse electron beam diagnostics at the VYV-FEL at DESY, the infrared undulator project at the VUV-FEL, misconceptions regarding second harmonic generation in X-ray free-electron lasers, influence of an energy chirp on SASE FEL operation, design considerations for the 4GLS XUV-FEL, broadband single shot spectrometer, commissioning of TTF2 bunch compressors for 20 fs SASE source, observation of femtosecond bunch length using a transverse deflecting structure, measurement of slice-emittance using a transverse deflecting structure, the injector of the VUV-FEL at DESY, spectral decoding electro-optic measurements for longitudinal bunch diagnostics at the DESY VUV-FEL, longitudinal phase space studies at PITZ, modelling the transverse phase space and core emittance studies at PITZ, measurements of thermal emittance for cesium telluride photocathodes at PITZ, status and first results from the upgraded PITZ facility, commissioning of the SPARC movable emittance meter and its first operation at PITZ. (HSI)

  20. The Israeli EA-FEL Upgrade Towards Long Pulse Operation for Ultra-High Resolution Single Pulse Coherent Spectroscopy

    CERN Document Server

    Gover, A; Kanter, M; Kapilevich, B; Litvak, B; Peleg, S; Socol, Y; Volshonok, M

    2005-01-01

    The Israeli Electrostatic Accelerator FEL (EA-FEL) is now being upgraded towards long pulse (1005s) operation and ultra-high resolution (10(-6)) single pulse coherent spectroscopy. We present quantitative estimations regarding the applications of controlled radiation chirp for spectroscopic applications with pulse-time Fourier Transform limited spectral resolution. Additionally, we describe a novel extraction-efficiency-improving scheme based on increase of accelerating voltage (boosting) after saturation is achieved. The efficiency of the proposed scheme is confirmed by theoretical and numerical calculations. The latter are performed using software, based on 3D space-frequency domain model. The presentation provides an overview of the upgrade status: the high-voltage terminal is being reconfigured to accept the accelerating voltage boost system; a new broad band low-loss resonator is being manufactured; multi-stage depressed collector is assembled.

  1. Influence of the partial temporal coherence of short FEL pulses on two-colour photoionization and photoinduced Auger decay of atoms

    International Nuclear Information System (INIS)

    Kazansky, A K; Sazhina, I P; Kabachnik, N M

    2013-01-01

    The influence of the partial temporal coherence of free electron laser (FEL) radiation on the sidebands arising in the electron spectra of laser-assisted photoionization and photoinduced Auger decay of atoms is theoretically analysed. A simple model is developed which describes the inner-shell photoionization by a short (femtosecond) FEL pulse and the following Auger decay in a strong field of an infrared laser. The model is based on the time-dependent approach and uses the strong field approximation for both photo- and Auger electrons. Particular calculations have been carried out for Ne 1s photoionization and KLL Auger emission. We demonstrate that the temporal coherence of FEL pulses influences the line widths in the photoelectron spectrum. For a small coherence time the sidebands in this spectrum cannot be resolved. On the other hand, our calculations show that in the Auger electron spectrum the sidebands are practically independent of the coherence time of the ionizing pulse.

  2. Coherent spontaneous radiation from highly bunched electron beams

    International Nuclear Information System (INIS)

    Berryman, K.W.; Crosson, E.R.; Ricci, K.N.

    1995-01-01

    Coherent spontaneous radiation has now been observed in several FELs, and is a subject of great importance to the design of self-amplified spontaneous emission (SASE) devices. We report observations of coherent spontaneous radiation in both FIREFLY and the mid-infrared FEL at the Stanford Picosecond FEL Center. Coherent emission has been observed at wavelengths as short as 5 microns, and enhancement over incoherent levels by as much as a factor of 4x10 4 has been observed at longer wavelengths. The latter behavior was observed at 45 microns in FIREFLY with short bunches produced by off-peak acceleration and dispersive compression. We present temporal measurements of the highly bunched electron distributions responsible for the large enhancements, using both transition radiation and energy-phase techniques

  3. Research on the Undulator Used for PKU-FEL

    CERN Document Server

    Lu, Huihua; Dai, Jianping; Li, Yanan; Shi, Caitu; Yang Yu Feng; Zhuang, Jiejia

    2004-01-01

    A 5m-long combined function undulator used for the Peking University Infrared SASE FEL facility (PKU-FEL) is currently under construction at IHEP, and a 10 period prototype has already been developed. This paper describes the design study of the undulator, which is a hybrid planar magnet structure with extra focusing. The results of magnetic measurements performed on the prototype are also reported and discussed, and it demonstrates that the proposed combined function magnet structure is very promising for the use in the SASE FEL at Peking University.

  4. The GALAXIE all-optical FEL project

    Energy Technology Data Exchange (ETDEWEB)

    Rosenzweig, J. B.; Arab, E.; Andonian, G.; Cahill, A.; Fitzmorris, K.; Fukusawa, A.; Hoang, P.; Jovanovic, I.; Marcus, G.; Marinelli, A.; Murokh, A.; Musumeci, P.; Naranjo, B.; O' Shea, B.; O' Shea, F.; Ovodenko, A.; Pogorelsky, I.; Putterman, S.; Roberts, K.; Shumail, M. [Dept. of Physics and Astronomy, University of California, Los Angeles, 405 Hilgard Ave., Los Angeles, CA 90034 (United States); Dept. of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Dept. of Physics and Astronomy, University of California, Los Angeles, 405 Hilgard Ave., Los Angeles, CA 90034 (United States); and others

    2012-12-21

    We describe a comprehensive project, funded under the DARPA AXiS program, to develop an all-optical table-top X-ray FEL based on dielectric acceleration and electromagnetic undulators, yielding a compact source of coherent X-rays for medical and related applications. The compactness of this source demands that high field (>GV/m) acceleration and undulation-inducing fields be employed, thus giving rise to the project's acronym: GV/m AcceLerator And X-ray Integrated Experiment (GALAXIE). There are numerous physics and technical hurdles to surmount in this ambitious scenario, and the integrated solutions include: a biharmonic photonic TW structure, 200 micron wavelength electromagnetic undulators, 5 {mu}m laser development, ultra-high brightness magnetized/asymmetric emittance electron beam generation, and SASE FEL operation. We describe the overall design philosophy of the project, the innovative approaches to addressing the challenges presented by the design, and the significant progress towards realization of these approaches in the nine months since project initialization.

  5. Second and third harmonic measurements at the linac coherent light source

    Directory of Open Access Journals (Sweden)

    D. Ratner

    2011-06-01

    Full Text Available The linac coherent light source (LCLS is a self-amplified spontaneous emission (SASE free-electron laser (FEL operating at fundamental photon energies from 0.5 to 10 keV. Characterization of the higher harmonics present in the FEL beam is important to users, for whom harder x rays can either extend the useful operating wavelength range or increase experimental backgrounds. We present measurements of the power in both the second and third harmonics, and compare the results to expectations from simulations. We also present studies of the transport of harmonics to the users, and the harmonic power as a function of electron beam quality.

  6. Diagnostics and Instrumentation for FEL

    CERN Document Server

    Couprie, M E

    2001-01-01

    Free Electron Laser are coherent sources of radiation based on the interaction of a relativistic electron beam in an undulator field. According to the energy of the accelerator, they presently cover a wide spectral range, from the infra-red to the VUV. FELs combine the diagnostics of typical laser systems (for the measurement of spectral and temporal characteristics, the transverse mode pattern, the polarisation) and the diagnostics of relativistic electron beams. The electron beam is characterised in order to evaluate and control the FEL performances, but also in order to measure the effect of the FEL on the electron beam. The FEL characteristics are monitored with various types of detectors, depending mainly on the spectral range. Diagnostics for Linac based Infra Red FELs and storage ring FELs in the UV-VUV will be described. Particular instrumentation, required for FEL operation, such as the optical resonator, possible diagnostics inside the undulator will also be analysed.

  7. Quasi-real-time photon pulse duration measurement by analysis of FEL radiation spectra

    Energy Technology Data Exchange (ETDEWEB)

    Engel, Robin, E-mail: robin.engel@uni-oldenburg.de [Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22603 Hamburg (Germany); Institut für Physik, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg (Germany); Institut für Laser und Optik, Hochschule Emden/Leer, University of Applied Sciences, Constantiaplatz 4, D-26723 Emden (Germany); Düsterer, Stefan; Brenner, Günter [Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22603 Hamburg (Germany); Teubner, Ulrich [Deutsches Elektronen-Synchrotron, Notkestrasse 85, D-22603 Hamburg (Germany); Institut für Physik, Carl von Ossietzky Universität Oldenburg, D-26111 Oldenburg (Germany); Institut für Laser und Optik, Hochschule Emden/Leer, University of Applied Sciences, Constantiaplatz 4, D-26723 Emden (Germany)

    2016-01-01

    Considering the second-order spectral correlation function of SASE-FEL radiation allows a real-time observation of the photon pulse duration during spectra acquisition. For photon diagnostics at free-electron lasers (FELs), the determination of the photon pulse duration is an important challenge and a complex task. This is especially true for SASE FELs with strongly fluctuating pulse parameters. However, most techniques require an extensive experimental setup, data acquisition and evaluation time, limiting the usability in all-day operation. In contrast, the presented work uses an existing approach based on the analysis of statistical properties of measured SASE FEL spectra and implements it as a software tool, integrated in FLASH’s data acquisition system. This allows the calculation of the average pulse durations from a set of measured spectral distributions with only seconds of delay, whenever high-resolution spectra are recorded.

  8. Coherent x-rays from PEP

    International Nuclear Information System (INIS)

    Baird, S.; Nuhn, H.-D.; Tatchyn, R.; Winick, H.; Fisher, A.S.; Gallardo, J.C.; Pellegrini, C.

    1991-01-01

    This paper explores the use of a large-circumference, high-energy, electron-positron collider such as PEP to drive a free-electron laser (FEL), producing high levels of coherent power at short wavelengths. The author consider Self-Amplified Spontaneous Emission (SASE), in which electron bunches with low emittance, high peak current and small energy spread radiate coherently in a single passthrough a long undulator. As the electron beam passes down the undulator, its interaction with the increasingly intense spontaneous radiation causes a bunch density modulation at the optical wavelength, resulting in stimulated emissional growth of coherent power in a single pass. The need for optical-cavity mirrors, which place a lower limit on the wavelength of a conventional FEL oscillator, is avoided. The authors explore various combinations of electron-beam and undulator parameters, as well as special undulator designs and optical klystrons (OK), to reach high average or peak coherent power at wavelengths around 40 angstrom by achieving significant exponential gain or full saturation. Examples are presented for devices that achieve high peak coherent power (up to about 400 MW) with lower average coherent power (about 20 mW) and other devices which produce a few watts of average coherent power

  9. The FEL development at the Advanced Photon Source

    International Nuclear Information System (INIS)

    Construction of a single-pass free-electron laser (FEL) based on the self-amplified spontaneous emission (SASE) mode of operation is nearing completion at the Advanced Photon Source (APS) with initial experiments imminent. The APS SASE FEL is a proof-of-principle fourth-generation light source. As of January 1999 the undulator hall, end-station building, necessary transfer lines, electron and optical diagnostics, injectors, and initial undulatory have been constructed and, with the exception of the undulatory, installed. All preliminary code development and simulations have also been completed. The undulator hall is now ready to accept first beam for characterization of the output radiation. It is the project goal to push towards fill FEL saturation, initially in the visible, but ultimately to W and VUV, wavelengths

  10. Magnetic design of an Apple-X afterburner for the SASE3 undulator of the European XFEL

    Science.gov (United States)

    Li, Peng; Wei, Tao; Li, Yuhui; Pflueger, Joachim

    2017-10-01

    In its startup configuration the SASE3 beamline of the European XFEL provides only soft X-ray radiation, linearly polarized in the horizontal plane. In order to enhance capabilities of this beamline an afterburner scheme is proposed. It will be used as a coherent radiator using the micro-bunched electron beam of the linear SASE3 system. Radiation with variable polarization, which covers the full SASE3 wavelength range can be generated. For the radiator a new type of undulator design called Apple-X will be used. In this paper the design is described and magnet parameters, which are compatible with the SASE3 afterburner are determined using RADIA simulations. The end structure of such a device is optimized for minimum 1st field integrals.

  11. Linac Coherent Light Source (LCLS) design study report

    International Nuclear Information System (INIS)

    1998-04-01

    The Stanford Linear Accelerator Center (SLAC), in collaboration with Los Alamos National Laboratory, Lawrence Livermore National Laboratory, and the University of California at Los Angeles, is proposing to build a Free-Electron-Laser (FEL) R and D facility operating in the self-amplified spontaneous emission (SASE) mode in the wavelength range 1.5--15 angstrom. This FEL, called Linac Coherent Light Source (LCLS), utilizes the SLAC linac and produces sub-picosecond pulses of short wavelength x-rays with very high peak brightness and full transverse coherence. In this report, the Design Team has established performance parameters for all the major components of the LCLS and developed a layout of the entire system. Chapter 1 is the Executive Summary. Chapter 2 (Overview) provides a brief description of each of the major sections of the LCLS, from the rf photocathode gun, through the experimental stations and electron beam dump. Chapter 3 describes the scientific case for the LCLS. Chapter 4 provides a review of the principles of the FEL physics that the LCLS is based on, and Chapter 5 discusses the choice of the system's physical parameters. Chapters 6 through 10 describe in detail each major element of the system. Chapters 11 through 13 respectively cover undulator controls, mechanical alignment, and radiation issues

  12. Linac Coherent Light Source (LCLS) design study report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-04-01

    The Stanford Linear Accelerator Center (SLAC), in collaboration with Los Alamos National Laboratory, Lawrence Livermore National Laboratory, and the University of California at Los Angeles, is proposing to build a Free-Electron-Laser (FEL) R and D facility operating in the self-amplified spontaneous emission (SASE) mode in the wavelength range 1.5--15 {angstrom}. This FEL, called Linac Coherent Light Source (LCLS), utilizes the SLAC linac and produces sub-picosecond pulses of short wavelength x-rays with very high peak brightness and full transverse coherence. In this report, the Design Team has established performance parameters for all the major components of the LCLS and developed a layout of the entire system. Chapter 1 is the Executive Summary. Chapter 2 (Overview) provides a brief description of each of the major sections of the LCLS, from the rf photocathode gun, through the experimental stations and electron beam dump. Chapter 3 describes the scientific case for the LCLS. Chapter 4 provides a review of the principles of the FEL physics that the LCLS is based on, and Chapter 5 discusses the choice of the system's physical parameters. Chapters 6 through 10 describe in detail each major element of the system. Chapters 11 through 13 respectively cover undulator controls, mechanical alignment, and radiation issues.

  13. Coherent radiation characteristics of modulated electron bunch formed in stack of two plates

    Science.gov (United States)

    Gevorgyan, H. L.; Gevorgian, L. A.

    2017-07-01

    The present article is devoted to the radiation from the electron bunch with modulated density passes through the stack consisting of two plates with different thicknesses and electrodynamic properties. The new elegant expression for the frequency-angular distribution of transition radiation is obtained. Using the existence of resonant frequency at which the longitudinal form-factor of bunch not suppresses radiation coherence and choosing parameters for the stack of plates, one can also avoid suppression of the radiation coherence by transverse form-factor of bunch. The radiation from a bunch with modulated density in the process SASE (self-amplified spontaneous emission) FEL can be partially coherent at a resonant frequency. Then the intense sub monochromatic beam of X-ray photons is formed. On the other hand one can define an important parameter of the bunch density modulation depth which is unknown to this day.

  14. Study on the Planar Undulator Scheme with Focusing Properties for PKU-FEL

    CERN Document Server

    Ding, Yuantao; Huang, Senlin; Wang, Yugang; Zhao, Kui; Zhuang, Jiejia

    2004-01-01

    An IR range SASE FEL test facility will be built at Peking University. The project is designed to get the SASE FEL at 7 micron driven by a superconducting accelerator. A hybrid planar Nd-Fe-B undulator is employed and the optimization of the external focus system for the undulator is studied. In the PKU-FEL facility, the electron energy is about 30-40 MeV. The combined function undulator with FODO lattice imposes quite stringent tolerances on the strength of the quads. To solve this problem, the weak natural focusing of the undulator in the vertical plane together with horizontally focusing quads, is proposed to supply the focusing in the facility. The combined function undulator of FOFO lattice and FF lattice in the horizontal plane are studied. Compared with the FODO lattice, the FOFO and FF lattice make the saturation a bit longer and the requirements of the field accuracy for the focusing system are much reduced.

  15. Short wavelength FELS

    International Nuclear Information System (INIS)

    Sheffield, R.L.

    1991-01-01

    The generation of coherent ultraviolet and shorter wavelength light is presently limited to synchrotron sources. The recent progress in the development of brighter electron beams enables the use of much lower energy electron rf linacs to reach short-wavelengths than previously considered possible. This paper will summarize the present results obtained with synchrotron sources, review proposed short- wavelength FEL designs and then present a new design which is capable of over an order of magnitude higher power to the extreme ultraviolet. 17 refs., 10 figs

  16. Short wavelength FELS

    Energy Technology Data Exchange (ETDEWEB)

    Sheffield, R.L.

    1991-01-01

    The generation of coherent ultraviolet and shorter wavelength light is presently limited to synchrotron sources. The recent progress in the development of brighter electron beams enables the use of much lower energy electron rf linacs to reach short-wavelengths than previously considered possible. This paper will summarize the present results obtained with synchrotron sources, review proposed short- wavelength FEL designs and then present a new design which is capable of over an order of magnitude higher power to the extreme ultraviolet. 17 refs., 10 figs.

  17. An Experimental Study of the Beam-Steering Effect on the FEL Gain at LEUTL's Segmented Undulators

    CERN Document Server

    Chae, Yong Chul; Lewellen, John W; Lumpkin, Alex H; Milton, Stephen

    2004-01-01

    The electron trajectories at the LEUTL, a SASE FEL facility at Argonne, were routinely corrected during the user run in order to deliver maximum radiation power to the user. Even though we knew from experience that SASE gain at the segmented undulators was dependent on the trajectory, the quantitative understanding of steering effects associated with the specific trajectory was lacking. Recently Tanaka et al. proposed an analytical model for the single-kick error (SKE) effect. Since LEUTL has eight segmented undulators, we performed the first measurement of SKE on the FEL gain. In the experiments we varied the corrector strength up to the critical angle, and the gain over the undulator was measured for each corrector setting. The results were compared with the analytical model and GENESIS simulations. We also measured the e-beam positions and SASE intensities over the undulators. The experimental data were analyzed and their results were reproduced by GENESIS simulation. The simulation condition, including th...

  18. FEL Design Studies at LBNL: Activities and Plans

    International Nuclear Information System (INIS)

    Corlett, John N.; Fawley, W.; Lidia, S.; Padmore, H.; Penn, G.; Pogorelov, I.; Qiang, J.; Sannibale, F.; Staples, J.; Steier, C.; Venturini, M.; Wan, W.; Wilcox, R.; Zholents, A.

    2007-01-01

    LBNL staff are currently pursuing R and D for future x-ray FELs, and participate in two FEL construction projects. Our strategy is to address the most fundamental challenges, which are the cost-drivers and performance limitations of FEL facilities. An internally funded R and D program is aimed at investigating accelerator physics and technologies in three key areas: (1) Theoretical study, modeling, and experimental development of low emittance, high quantum efficiency cathodes; (2) Design studies of electron beam delivery systems, including emittance manipulations, high-resolution modeling of 6-D phase space, and low-emittance beam transport; and (3) Design studies of optical manipulations of electron beams for seeded and SASE FELs, providing short x-ray pulses of variable duration, synchronous with the seed and pump laser sources, and also long transform-limited pulses with a narrow bandwidth. Design studies of means for production of attosecond x-ray pulses at various wavelengths. We are collaborators in the FERMI(at)Elettra seeded FEL facility under construction at Sincrotrone Trieste, Italy, participating in accelerator design and FEL physics studies, and mechanical and electrical engineering. We are participating in the LCLS project at SLAC, implementing our design of stabilized timing and synchronization systems. Here we outline our long-term objectives, and current activities

  19. FEL Design Studies at LBNL: Activities and Plans

    Energy Technology Data Exchange (ETDEWEB)

    Corlett, John N.; Fawley, W.; Lidia, S.; Padmore, H.; Penn, G.; Pogorelov, I.; Qiang, J.; Sannibale, F.; Staples, J.; Steier, C.; Venturini, M.; Wan, W.; Wilcox, R.; Zholents, A.

    2007-03-01

    LBNL staff are currently pursuing R&D for future x-ray FELs, and participate in two FEL construction projects. Our strategy is to address the most fundamental challenges, which are the cost-drivers and performance limitations of FEL facilities. An internally funded R&D program is aimed at investigating accelerator physics and technologies in three key areas: (1) Theoretical study, modeling, and experimental development of low emittance, high quantum efficiency cathodes; (2) Design studies of electron beam delivery systems, including emittance manipulations, high-resolution modeling of 6-D phase space, and low-emittance beam transport; and (3) Design studies of optical manipulations of electron beams for seeded and SASE FELs, providing short x-ray pulses of variable duration, synchronous with the seed and pump laser sources, and also long transform-limited pulses with a narrow bandwidth. Design studies of means for production of attosecond x-ray pulses at various wavelengths. We are collaborators in the FERMI{at}Elettra seeded FEL facility under construction at Sincrotrone Trieste, Italy, participating in accelerator design and FEL physics studies, and mechanical and electrical engineering. We are participating in the LCLS project at SLAC, implementing our design of stabilized timing and synchronization systems. Here we outline our long-term objectives, and current activities.

  20. Measurement and analysis of coherent synchrotron radiation effects at FLASH

    International Nuclear Information System (INIS)

    Beutner, B.

    2007-12-01

    The vacuum-ultra-violet Free Electron Laser in Hamburg (FLASH) is a linac driven SASE-FEL. High peak currents are produced using magnetic bunch compression chicanes. In these magnetic chicanes, the energy distribution along an electron bunch is changed by eff ects of Coherent Synchrotron Radiation (CSR). Energy changes in dispersive bunch compressor chicanes lead to transverse displacements along the bunch. These CSR induced displacements are studied using a transverse deflecting RF-structure. Experiments and simulations concerning the charge dependence of such transverse displacements are presented and analysed. In these experiments an over-compression scheme is used which reduces the peak current downstream the bunch compressor chicanes. Therefore other self interactions like space charge forces which might complicate the measurements are suppressed. Numerical simulations are used to analyse the beam dynamics under the influence of CSR forces. The results of these numerical simulations are compared with the data obtained in the over-compression experiments at FLASH. (orig.)

  1. Measurement and analysis of coherent synchrotron radiation effects at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Beutner, B.

    2007-12-15

    The vacuum-ultra-violet Free Electron Laser in Hamburg (FLASH) is a linac driven SASE-FEL. High peak currents are produced using magnetic bunch compression chicanes. In these magnetic chicanes, the energy distribution along an electron bunch is changed by eff ects of Coherent Synchrotron Radiation (CSR). Energy changes in dispersive bunch compressor chicanes lead to transverse displacements along the bunch. These CSR induced displacements are studied using a transverse deflecting RF-structure. Experiments and simulations concerning the charge dependence of such transverse displacements are presented and analysed. In these experiments an over-compression scheme is used which reduces the peak current downstream the bunch compressor chicanes. Therefore other self interactions like space charge forces which might complicate the measurements are suppressed. Numerical simulations are used to analyse the beam dynamics under the influence of CSR forces. The results of these numerical simulations are compared with the data obtained in the over-compression experiments at FLASH. (orig.)

  2. Comparison of beam bunching in amplifier and SASE modes at the CEA-CESTA free-electron laser

    CERN Document Server

    Donohue, J T; Lefèvre, T; Marchese, G; Padois, M; Rullier, J L

    1999-01-01

    In previous studies of bunching we operated our 2.2 MeV, 800 A single shot FEL in the amplifier mode, and observed output power and bunching not only at the injected frequency of 35 GHz but also at the second-FEL resonant frequency near 3 GHz. In order to study the mechanism of the low-frequency bunching we have performed a series of measurements in SASE mode. Here we compare and contrast results obtained in these two modes. For both modes a detailed study of the formation of the low-frequency bunches during the pulse has been performed using a streak camera, as a function of both position in the wiggler and time in the pulse. Analysis of the images shows that despite the great difference in output power, the strong bunching we see is quite similar. In the amplifier mode the coexistence of the bunching at high frequency masks some of the details of the low-frequency bunch formation, whereas in the SASE mode the temporal and spatial behavior of bunching at 3 GHz is clearly seen.

  3. Gain length dependence on phase shake in the VUV-FEL at the TESLA Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    Pflueger, J. [DESY/HASYLAB, Hamburg (Germany); Schneidmiller, E.A. [Automatic Systems Corporation, Samara (Russian Federation); Pierini, P. [INFN, Milano (Italy)

    1995-12-31

    The TTF VUV FEL, which is in its design stage at DESY, consists of a 30 m long SASE FEL which will radiate around 6 nm, driven by a superconducting linac with final energy of 1 GeV. One of the important issues in its design is the undulator performance, which is studied in this paper. The present setup, including FODO lattice, is discussed in this paper. Results of simulations, including the realistic wiggler field errors and beam stearing, are presented. Dependence of the performance, in particular the gain and saturation length as well as the saturation peak power, on the wiggler field errors is discussed.

  4. A French proposal for an innovative accelerators based coherent UV-X-ray source

    Energy Technology Data Exchange (ETDEWEB)

    Couprie, M.E. E-mail: marie-emmanuelle.couprie@lure.u-psud.fr; Belakhovsky, M.; Gilquin, B.; Garzella, D.; Jablonka, M.; Meot, F.; Monot, P.; Mosnier, A.; Nahon, L.; Rousse, A

    2004-08-01

    At the initiative of the CEA (Commissariat a l'Energie Atomique), discussions were conducted in France on fourth generation light sources. A new independent accelerator based radiation facility ARC-EN-CIEL (Accelerator Radiation Complex for ENhanced Coherent Intense Extended Light) is proposed, aiming at providing coherent femtosecond light pulses in the UV- to X-ray range for scientific applications. The project is based on a 700 MeV superconducting LINAC, providing low emittance 200 fs RMS electron bunches. They can be injected in undulators used in the Self Amplified Spontaneous Emission mode (SASE), or in the High Gain Harmonic Generation (HGHG), seeded with high harmonics in gases at 20 nm.The SASE source covers the 100-5 nm spectral range, the HGHG goes down to 0.8 nm.Two optional loops, for Energy Recovery or energy enhancement (1.4 GeV), will accommodate fs synchrotron radiation sources in the IR-, VUV- and X-ray ranges, together with a FEL oscillator providing radiation down to 10 nm, taking advantage of the optical development for lithography. The facility also proposes to test plasma acceleration and to provide a Thomson radiation source. Characteristics of the light source will be described.

  5. A French proposal for an innovative accelerators based coherent UV-X-ray source

    Science.gov (United States)

    Couprie, M. E.; Belakhovsky, M.; Gilquin, B.; Garzella, D.; Jablonka, M.; Méot, F.; Monot, P.; Mosnier, A.; Nahon, L.; Rousse, A.

    2004-08-01

    At the initiative of the CEA (Commissariat à l'Énergie Atomique), discussions were conducted in France on fourth generation light sources. A new independent accelerator based radiation facility ARC-EN-CIEL (Accelerator Radiation Complex for ENhanced Coherent Intense Extended Light) is proposed, aiming at providing coherent femtosecond light pulses in the UV- to X-ray range for scientific applications. The project is based on a 700 MeV superconducting LINAC, providing low emittance 200 fs RMS electron bunches. They can be injected in undulators used in the Self Amplified Spontaneous Emission mode (SASE), or in the High Gain Harmonic Generation (HGHG), seeded with high harmonics in gases at 20 nm.The SASE source covers the 100-5 nm spectral range, the HGHG goes down to 0.8 nm.Two optional loops, for Energy Recovery or energy enhancement (1.4 GeV), will accommodate fs synchrotron radiation sources in the IR-, VUV- and X-ray ranges, together with a FEL oscillator providing radiation down to 10 nm, taking advantage of the optical development for lithography. The facility also proposes to test plasma acceleration and to provide a Thomson radiation source. Characteristics of the light source will be described.

  6. A 2--4 nm Linac Coherent Light Source (LCLS) using the SLAC linac

    International Nuclear Information System (INIS)

    Winick, H.; Bane, K.; Boyce, R.

    1993-05-01

    We describe the use of the SLAC linac to drive a unique, powerful. short wavelength Linac Coherent Light Source (LCLS). Operating as an FEL, lasing would be achieved in a single pass of a high peak current electron beam through a long undulator by self-amplified spontaneous emission (SASE). The main components are a high-brightness rf photocathode electron gun; pulse compressors; about 1/5 of the SLAC linac; and a long undulator with a FODO quadrupole focussing system. Using electrons below 8 GeV, the system would operate at wavelengths down to about 3 nm, producing ≥10 GW peak power in sub-ps pulses. At a 120 Hz rate the average power is ∼ 1 W

  7. Research and development toward a 4.5-1.5{angstrom} linac coherent light source (LCLS) at SLAC

    Energy Technology Data Exchange (ETDEWEB)

    Tatchyn, R.; Arthur, J.; Baltay, M. [Stanford Univ., CA (United States)] [and others

    1995-12-31

    In recent years significant studies have been initiated on the theoretical and technical feasibility of utilizing a portion of the 3km S-band accelerator at the Stanford Linear Accelerator Center (SLAC) to drive a short wavelength (4.5-1.5 {Angstrom}) Linac Coherent Light Source (LCLS), a Free-Electron Laser (FEL) operating in the Self-Amplified Spontaneous Emission (SASE) regime. Electron beam requirements for single-pass saturation include: (1) a peak current in the 3-7 kA range, (2) a relative energy spread of <0.05%, ad (3) a transverse emittance, {epsilon}{le}{lambda}/4{pi}, where {lambda}[m] is the output wavelength. Requirements on the insertion device include field error levels of 0.1-0.2% for keeping the electron bunch centered on and in phase with the amplified photons, and a focusing beta of 4-8 m for inhibiting the dilution of its transverse density. Although much progress techniques necessary for LCLS operation down to {approximately}20 {angstrom}, a substantial amount of research and development is still required in a number of theoretical and experimental areas leading to the construction and operation of a 4.5-1.5 {angstrom} LCLS. In this paper we report on a research and development program underway and in planning at SLAC for addressing critical questions in these areas. These include the construction and operation of a linac test stand for developing laser-driven photocathode rf guns with normalized emittances approaching 1 mm-mr; development of advanced beam compression, stability, an emittance control techniques at multi-GeV energies; the construction and operation of a FEL Amplifier Test Experiment (FATE) for theoretical and experimental studies of SASE at IR wavelengths; an undulator development program to investigate superconducting, hybrid/permanent magnet (hybrid/PM), and pulsed-Cu technologies; theoretical and computational studies of high-gain FEL physics and LCLS component designs.

  8. Design features of a planar hybrid/permanent magnet strong-focusing undulator for Free Electron Laser (FEL) and Synchrotron Radiation (SR) applications

    Science.gov (United States)

    Tatchyn, Roman

    1997-05-01

    Insertion devices for Angstrom-wavelength Free Electron Laser (FEL) amplifiers driven by multi-GeV electron beams generally require distributed focusing substantially stronger than their natural focusing fields(C. Pellegrini, "A 4 to 0.1 nm FEL Based on the SLAC Linac," in Proc. Workshop on 4th Generation Light Sources, M.Cornacchia and H. Winick, eds., SSRL, Feb. 1992. p. 364 ff.)(R. Tatchyn, "Optimal Insertion Device Parameters for SASE FEL Operation," ibid., p. 605 ff.). Over the last several years a wide variety of focusing schemes and configurations have been proposed for undulators of this class, ranging from conventional current-driven quadrupoles external to the undulator magnets(R. Tatchyn, R. Boyce, K. Halbach, H.-D. Nuhn, J. Seeman, H. Winick, and C. Pellegrini, "Design Considerations for a 60 Meter Pure Permanent Magnet Undulator for the SLAC Linac Coherent Light Source (LCLS)," in Proceedings of the 1993 Particle Accelerator Conference, IEEE Catalog No. 93CH3279-7, 1608(1993).) to permanent magnet (PM) lattices inserted into the insertion device gap(R. Tatchyn, "Selected applications of planar permanent magnet multipoles in FEL insertion device design," NIM A341, 449(1994).)(A. A. Varfolomeev, A. H. Hairetdinov, "Advanced hybrid undulator schemes providing enhanced transverse e-beam focusing," ibid., p. 462.)(G. Travish, J. Rosenzweig, "Strong sextupole focussing in planar undulators," NIM A345, 585(1994).). In this paper we present design studies of a flexible hybrid/PM undulator with superimposed planar PM focusing proposed for a 1.5 Angstrom Linac Coherent Light Source (LCLS) undulator(S. Caspi, R. Schlueter, R. Tatchyn, "High-Field Strong-Focusing Undulator Designs for X-Ray Linac Coherent Light Source (LCLS) Applications," Proc. IEEE PAC95, Dallas, TX, May 1-5, 1995, SLAC-PUB-95-6885.)(R. Tatchyn, "Permanent Magnet Edge-Field Quadrupole," US Patent 5,596,304.) driven by an electron beam with a 1 mm-mr normalized emittance(R. Tatchyn et al, NIM A

  9. Comparison of the coherent radiation-induced microbunching instability in a free-electron laser and a magnetic chicane

    Directory of Open Access Journals (Sweden)

    S. Reiche

    2003-04-01

    Full Text Available A self-amplified spontaneous emission free-electron laser (SASE FEL is a device which is based on the creation of a very intense, relativistic electron beam which has very little temperature in all three phase planes. The beam in this system is described as having “high brightness,” and when it is bent repetitively in a magnetic undulator, undergoes a radiation-mediated microbunching instability. This instability can amplify the original radiation amplitude at a particular, resonant wavelength by many orders of magnitude. In order to obtain high brightness beams, it is necessary to compress them to obtain higher currents than available from the electron source. Compression is accomplished by the use of magnetic chicanes, which are quite similar to, if much longer than, a single period of the undulator. It should not be surprising that such chicanes also support a radiation-mediated microbunching interaction, which has recently been investigated, and has been termed coherent synchrotron radiation (CSR instability. The purpose of this paper is to compare and contrast the characteristics of the closely related FEL and CSR microbunching instabilities. We show that a high-gain regime of the CSR instability exists which is formally similar to the FEL instability.

  10. Bunch compression for an FEL at NLCTA

    International Nuclear Information System (INIS)

    Zimmermann, F.

    1997-04-01

    As part of the design effort for a free electron laser driven by the Next Linear Collider Test Accelerator (NLCTA), the author reports studies of bunch-length compression utilizing the existing infrastructure and hardware. In one possible version of the NLCTA FEL, bunches with 900-microm FWHM length, generated by an S-band photo-injector, would be compressed to an rms length of 60--120 microm before entering the FEL undulator. It is shown that, using the present magnetic chicane, the bunch compression is essentially straightforward, and that almost all emittance-diluting effects, e.g. wakefields, chromaticity, or space charge in the bending magnets, are small. The only exception to this finding is the predicted increase of the horizontal emittance due to coherent synchrotron radiation (CSR). Estimates based on existing theories of coherent synchrotron radiation suggest a tripling or quadrupling of the initial emittance, which seems to preclude bunch compression during regular FEL operation. Serendipitously, the magnitude of the predicted emittance growth would, on the other hand, make the NLCTA chicane an excellent tool for measuring the effects of coherent synchrotron radiation. This will be of considerable interest to many future projects, in particular to the Linac Coherent Light Source (LCLS). As an aside, it is shown that coherent synchrotron radiation in a bending magnet gives rise to a minimum possible bunch length, which is very reminiscent of the Oide limit on the vertical spot size at the interaction point of a linear collider

  11. Two FEL`s in one

    Energy Technology Data Exchange (ETDEWEB)

    Epp, V. [Tomsk Pedagogical Institute (Russian Federation); Nikitin, M. [Tomsk Polytechnical Univ. (Russian Federation)

    1995-12-31

    A new scheme for a FEL operation is proposed. The conventional principle of FEL operation is means that the electron bunch passes through the interaction area of FEL only in one direction. We suggest another possible layout which implies that the electron bunch makes a turn after leaving the wiggler and entries the wiggler at the same end. Actually the wiggler is a kind of a bridge between two storage rings. The electron bunches on the orbit are expected to be adjusted in the way that after one of them leaves the wiggler, another one enters in the opposite direction and in the proper phase with the wave pulse emitted by the previous bunch. So the electron bunch comes in interaction with the amplified electromagnetic wave in both directions i.e. twice per period. It is especially important for the short wavelength FELs, because each reflection from the mirror causes a significant losses of the wave magnitude. The proposed design gives one interaction per each reflection instead of one interaction per two reflections in the traditional scheme. Another way to realize the suggested principle of operating is to insert the wiggler in the electron-positron storage ring. But this layout can be less efficient because of low intensity of the positron beam. The comparison study of radiation from different types of described double wigglers is fulfilled. The synchronization problems are discussed in this paper.

  12. Longitudinal impedance and wake from XFEL undulators. Impact on current-enhanced SASE schemes

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, G.; Saldin, E.; Schneidmiller, E.; Yurkov, M.

    2007-06-15

    In this article we derive longitudinal impedance and wake function for an undulator setup with arbitrary undulator parameter, taking into account a finite transverse size of the electron bunch. Earlier studies considered a line density-distribution of electrons instead. We focus our attention on the long-wavelength asymptote (compared with resonance wavelength), at large distance of the electron bunch from the undulator entrance compared to the overtaking length, and for large vacuumchamber size compared to the typical transverse size of the field. These restrictions define a parameter region of interest for practical applications. We calculate a closed expression for impedance and wake function that may be evaluated numerically in the most general case. Such expression allows us to derive an analytical solution for a Gaussian transverse and longitudinal bunch shape. Finally, we study the feasibility of current-enhanced SASE schemes (ESASE) recently proposed for LCLS, that fall well-within our approximations. Numerical estimations presented in this paper indicate that impedance-induced energy spread is sufficient to seriously degrade the FEL performance. Our conclusion is in contrast with results in literature, where wake calculations for the LCLS case are given in free-space, as if the presence of the undulator were negligible. (orig.)

  13. An RF-gun-driven recirculated linac as injector and FEL driver

    CERN Document Server

    Andersson, A; Werin, S; Biedron, S G; Freund, H

    2000-01-01

    A new pre-injector for the MAX-Laboratory is under design and construction. A thermionic RF gun, designed to operate at medium currents with low back bombardment power, is under construction. The gun will, via a magnetic compressor and energy filter, feed a recirculated linac consisting of two SLED-equipped structures giving 125 MeV each. The first will be delivered in 1999. The system is aimed as a pre-injector for the existing storage rings at MAX-Lab, but will also open up possibilities for a SASE FEL in the UV reaching above 100 MW below 100 nm.

  14. Seeding the FEL of the SCSS Phase 1 Facility with the 13th Laser Harmonic of a Ti Sa Laser (61.5 nm) Produced in Xe Gas

    CERN Document Server

    Lambert, G; Boutu, W; Breger, P; Couprie, M E; Garzella, D; Merdji, H; Monchicourt, P; Salieres, P

    2005-01-01

    In order to reach very short wavelengths in FEL, and to have a more compact, fully coherent and tunable source, a particular seeding configuration is foreseen to be tested as a demonstration experiment in 2006 into the SCSS phase 1 facility (Spring-8 Compact Sase Source, Japan). The external source is the 13th harmonic (61.5 nm) of a Ti: Sa laser (25 mJ, 10 Hz, 100 fs) generated in 10 Hz pulsed Xe gas cell. The harmonic generation process provides us with a intense (1 μJ) and ultra-short (50 fs) VUV beam. The design of the experiment implantation is discussed, taken into account the performances of the generation process, the focusing of the selected harmonic into the modulator, and the resistance of the optical components. Besides one should consider the vacuum needs, the geometrical problems and the mechanics for the under UHV mirrors translation. One first chamber is dedicated to the harmonic generation. A second one is used for spectral selection and adaptation of the harmonic in the modulator. F...

  15. Feasibility Study of a Laser Beat-Wave Seeded THz FEL at the Neptune Laboratory

    CERN Document Server

    Reiche, Sven; Pellegrini, Claudio; Rosenzweig, James E; Shvets, Gennady; Tochitsky, Sergei Ya

    2005-01-01

    Free-Electron Laser in the THz range can be used to generate high output power radiation or to modulate the electron beam longitudinally on the radiation wavelength scale. Microbunching on the scale of 1-5 THz is of particular importance for potential phase-locking of a modulated electron beam to a laser-driven plasma accelerating structure. However the lack of a seeding source for the FEL at this spectral range limits operation to a SASE FEL only, which denies a subpicosecond synchronization of the current modulation or radiation with an external laser source. One possibility to overcome this problem is to seed the FEL with two external laser beams, which difference (beat-wave) frequency is matched to the resonant FEL frequency in the THz range. In this presentation we study feasibility of an experiment on laser beat-wave injection in the THz FEL considered at the UCLA Neptune Laboratory, where both a high brightness photoinjector and a two-wavelength, TW-class CO2 laser system exist. By incorporating the en...

  16. THz Imaging by a Wide-band Compact FEL

    CERN Document Server

    Uk Jeong Young; Cheol Lee Byung; Hee-Park, S

    2004-01-01

    We have developed a laboratory-scale users facility with a compact THz FEL. The FEL operates in the wide wavelength range of 100–1200 μm, which corresponds to 0.3-3 THz. THz radiation from the FEL shows well collimated Gaussian spatial distribution and narrow spectral width of 0.3 μm, which is Fourier transform limited by the estimated pulse duration of 20 ps. The main application of the FEL is THz imaging for bio-medical researches. We are developing THz imaging techniques by 2-D scanning, single pulse capturing with the electro-optic method, and 3-D holography. High power, coherent, and pulsed feature of the FEL radiation is expected to show much better performance in advanced THz imaging of 3-D tomography by comparing with incoherent and weak THz sources. By controlling the optical delay between reference beam and scattered light from an object, we can get its 3-D tomography by the holograms. The coherent and pulse length of the FEL beam is measured to be 3-6 mm. In this paper we will show a...

  17. FEL components and diagnostics

    International Nuclear Information System (INIS)

    Carr, R.

    1997-01-01

    FEL hardware includes undulators, alignment systems, electron beam diagnostics, and mechanical and vacuum systems. While most FEL close-quote s employ conventional undulators, there is some interest in novel types, particularly where conventional designs cannot be used, as at very short periods and high fields. For these areas, superconducting technology is indicated. The most serious issue facing long FEL undulators is that of alignment; mechanical techniques may not be accurate enough, and beam-based strategies must be considered. To maintain alignment and control the electron trajectory, beam position monitors with micron precision are required. Beam size monitors are also required to assure control of emittance. The talks given in the working group sessions touch on undulators, alignment, and electron beam diagnostics, and they are summarized here. copyright 1997 American Institute of Physics

  18. Electron Beam Diagnostic Based on a Short Seeded FEL

    CERN Document Server

    Graves, W; Kaertner, Franz X; Zwart, T

    2005-01-01

    The optical properties of an FEL amplifier are sensitively dependent on the electron beam current profile, energy spread, and transverse emittance. In this paper we consider using a short FEL amplifier operating on a low harmonic of a visible-IR input seed as a mildly destructive electron beam diagnostic able to measure these properties for sub-ps time slices. The optical methods are described as well as a planned implementation of the device for the FERMI@Elettra XUV FEL under construction at Sincrotrone Trieste, including its fiber-based seed laser closely coupled with the facility timing system, undulator parameters, and requirements on the electron and FEL pulses. This diagnostic is conveniently integrated with a "laser heater" designed to increase the very low electron beam energy spread produced by a photoinjector in order to avoid space charge and coherent synchrotron radiation instabilities.

  19. Performance of the KHI FEL device at FEL-SUT

    CERN Document Server

    Yokoyama, M; Nomaru, K; Koike, H; Sobajima, M; Miura, H; Kawai, M; Kuroda, H

    2002-01-01

    FEL lasing with the saturated power in the wavelength of 4-16 mu m was achieved by using the KHI (Kawasaki Heavy Industries, Ltd.) FEL device. The macro-pulse length of the electron beam was improved by using the LaB sub 6 cathode instead of the dispenser cathode as a cathode of the OCS RF-gun. The improvement yielded the saturated FEL power with the macro-pulse length of 0.5-1.5 mu s. The FEL energy was 2-40 mJ. The measured FEL output powers were in agreement with the values which were taken into account Piovella's theory.

  20. Detailed numerical studies of space charge effects in an FEL RF gun

    CERN Document Server

    Cee, R R; Setzer, S; Weiland, T; Novokhatski, A

    2002-01-01

    The production of short bunches with low emittance is a key issue for the successful operation of an SASE-FEL as proposed by the TESLA collaboration (TESLA Technical design report, DESY 2001-011, Hamburg, 2001). In this paper we present the results of detailed MAFIA TS-2 (CST GmbH, Buedinger Strasse 2a, D-64289 Darmstadt) simulations for the FEL RF-gun revealing the main physical effects leading to emittance growth. The simulations prove that the transverse emittance growth can mainly be observed close to the cathode area. This is caused by the non-linear space charge forces acting inside the bunch during the injection process. For the application of an emittance compensation scheme (Nucl. Instr. and Meth. 285 (1989) 313) the slice emittance is of significant importance. Therefore, a wide range of parameters for the photo cathode laser has been investigated in order to find an appropriate operation point.

  1. FEL options for power beaming

    International Nuclear Information System (INIS)

    Kim, K.J.; Zholents, A.A.; Zolotorev, M.S.; Vinokurov, N.A.

    1997-10-01

    The demand for the output power of communication satellites has been increasing exponentially. The satellite power is generated from solar panels which collect the sunlight and convert it to electrical power. The power per satellite is limited due to the limit in the practical size of the solar panel. One way to meet the power demand is to employ multiple satellites (up to 10) per the internationally agreed-upon ''slot'' in the geosynchronous earth orbit (GEO). However, this approach is very expensive due to the high cost of sending a satellite into a GEO orbit. An alternative approach is power beaming, i.e., to illuminate the solar panels with high power, highly-directed laser beams from earth. The power beaming generates more power per satellite for the same area of the solar panel. The minimum optical beam power, interesting for power beaming application, is P L = 200kW. The wavelength is chosen to be λ 0.84 microm, so that it is within one of the transmission windows of the air, and at the same time near the peak of the photo-voltaic conversion efficiency of Si, which is the commonly used material for the solar panels. Free electron lasers (FELs) are well suited for the power beaming application because they can provide high power with coherent wavefront, but without high energy density in media. In this article the authors discuss some principal issues, such as the choice of accelerator and electron gun, the choice of beam parameters, radiation hazards, technological availability, and overall efficiency and reliability of the installation. They also attempt to highlight the compromise between the cost of the primary installation, the operation cost, and the choice of technology, and its maturity. They then present several schemes for the accelerator-FEL systems based on RF accelerators. The initial electron beam accelerator up to the energy of a few MeV is more or less common for all these schemes

  2. PARMELA-B A new version of PARMELA with coherent synchrotron radiation effects and a finite difference space charge routine

    CERN Document Server

    Koltenbah, B E C; Greegor, R B; Dowell, D H

    2002-01-01

    Recent interest in advanced laser light sources has stimulated development of accelerator systems of intermediate beam energy, 100-200 MeV, and high charge, 1-10 nC, for high power FEL applications and high energy, 1-2 GeV, high charge, SASE-FEL applications. The current generation of beam transport codes which were developed for high-energy, low-charge beams with low self-fields are inadequate to address this energy and charge regime, and better computational tools are required to accurately calculate self-fields. To that end, we have developed a new version of PARMELA, named PARMELA_B and written in Fortran 95, which includes a coherent synchrotron radiation (CSR) routine and an improved, generalized space charge (SC) routine. An electron bunch is simulated by a collection of macro-particles, which traverses a series of beam line elements. At each time step through the calculation, the momentum of each particle is updated due to the presence of external and self- fields. The self-fields are due to CSR and S...

  3. The ARC-EN-CIEL FEL Proposal

    CERN Document Server

    Couprie, M E

    2005-01-01

    ARC-EN-CIEL (Accelerator-Radiation for Enhanced Coherent Intense Extended Light), the French project of a fourth generation light source aims at providing the user community with coherent femtosecond light pulses covering from UV to soft X ray. It is based on a CW 1 GeV superconducting linear accelerator delivering high charge, subpicosecond, low emittance electron bunches with a high repetition rate. The FEL is based on in the injection of High Harmonics in Gases in a High Gain Harmonic Generation scheme, leading to a rather compact solution. The produced radiation extending down to 0.8 nm with the Non Linear Harmonic reproduces the good longitudinal and transverse coherence of the harmonics in gas. Optional beam loops are foreseen to increase the beam current or the energy. They will accommodate fs synchrotron radiation sources in the IR, VUV and X ray ranges and a FEL oscillator in the 10 nm range. An important synergy is expected between accelerator and laser communities. Indeed, electron plasma accelerat...

  4. Saturation and pulsed FEL dynamics

    International Nuclear Information System (INIS)

    Giannessi, L.; Mezi, L.

    1995-01-01

    The behavior of a FEL operating in the saturated pulsed regime, may be reproduced by the linear FEL integral equation, suitably modified to include saturation effects through a gain depression coefficient depending on the laser intensity. This simple method allows to evaluate several FEL parameters like gain, efficiency, band-width and optical pulse duration as functions of the optical cavity length, only with a numerical integration. The predictions have been compared with available experimental and numerical data, and the method has been applied to estimate the operating characteristics of some planned FEL experiments

  5. Prospects for high power Linac Coherent Light Source (LCLS) development in the 1000 angstrom - 1 angstrom wavelength range

    International Nuclear Information System (INIS)

    Tatchyn, R.; Bane, K.; Boyce, R.

    1994-03-01

    Electron bunch requirements for single-pass saturation of a Free-Electron Laser (FEL) operating at full transverse coherence in the Self-Amplified Spontaneous Emission (SASE) mode include: (1) a high peak current, (2) a sufficiently low relative energy spread, and (3) a transverse emittance var-epsilon[r-m] satisfying the condition var-epsilon ≤ λA/4π, where λ[m] is the output wavelength of the FEL. In the insertion device that induces the coherent amplification, the prepared electron bunch must be kept on a trajectory sufficiently collinear with the amplified photons without significant dilution of its transverse density. In this paper we discuss a Linac Coherent Light Source (LCLS) based on a high energy accelerator such as, e.g., the 3km S-band structure at the Stanford Linear Accelerator Center (SLAC), followed by a long high-precision undulator with superimposed quadrupole (FODO) focusing, to fulfill the given requirements for SASE operation in the 1000 Angstrom--1 Angstrom range. The electron source for the linac, an RF gun with a laser-excited photocathode featuring a normalized emittance in the 1--3 mm-mrad range, a longitudinal bunch duration of the order of 3 ps, and approximately 10 -9 C/bunch, is a primary determinant of the required low transverse and longitudinal emittances. Acceleration of the injected bunch to energies in the 5--25 GeV range is used to reduce the relative longitudinal energy spread in the bunch, as well as to reduce the transverse emittance to values consistent with the cited wavelength regime. Two longitudinal compression stages are employed to increase the peak bunch current to the 2--5 kA levels required for sufficiently rapid saturation. The output radiation is delivered, via a grazing-incidence mirror bank, to optical instrumentation and a multi-user beam line system. Technological requirements for LCLS operation at 40 Angstrom, 4.5 Angstrom, and 1.5 Angstrom are examined

  6. Seeded quantum FEL at 478 keV

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, Marc [Max-Planck-Institut fuer Quantenoptik, Garching (Germany); Thirolf, Peter; Seggebrock, Thorben [Ludwig-Maximilians-Universitaet Muenchen, Garching (Germany); Habs, Dietrich [Max-Planck-Institut fuer Quantenoptik, Garching (Germany); Ludwig-Maximilians-Universitaet Muenchen, Garching (Germany)

    2012-07-01

    We present for the first time a concept for a seeded {gamma} quantum Free Electron Laser (QFEL) at 478 keV (transition in {sup 7}Li). To produce a highly intense and coherent {gamma} beam, we intend to use a seeded FEL scheme. Important for the production of a highly brilliant and coherent {gamma} beam are novel refractive {gamma} lenses for focusing and an efficient monochromator, allowing to generate a very intense and coherent seed beam. To realize such a coherent {gamma} beam at 478 keV (1/38 A), it is suitable to use a quantum FEL design based on a new ''asymmetric'' laser-electron Compton back scattering scheme as pursued for the MeGaRay and ELI-NP facilities. Here the pulse length of the laser is much longer than the electron bunch length, equivalent to a {gamma}-FEL with laser wiggler. The coherence of a seeded QFEL can open up totally new areas of fundamental physics and applications. Especially, 478 keV can be attractive for ''green energy'' and life-science research, such as the detection of Li deposition in the brain for manic-depressive psychosis treatment with high spatial resolution or isotope-specific nuclear waste management and treatment.

  7. FERMI(at)Elettra FEL Design Technical Optimization Final Report

    International Nuclear Information System (INIS)

    Fawley, William; Penn, Gregory; Allaria, Enrico; De Ninno, Giovanni; Graves, William

    2006-01-01

    This is the final report of the FEL Design Group for the Technical Optimization Study for the FERMI(at)ELETTRA project. The FERMI(at)ELETTRA project is based on the principle of harmonic upshifting of an initial ''seed'' signal in a single pass, FEL amplifier employing multiple undulators. There are a number of FEL physics principles which underlie this approach to obtaining short wavelength output: (1) the energy modulation of the electron beam via the resonant interaction with an external laser seed (2) the use of a chromatic dispersive section to then develop a strong density modulation with large harmonic overtones (3) the production of coherent radiation by the microbunched beam in a downstream radiator. Within the context of the FERMI project, we discuss each of these elements in turn

  8. Optical klystron FELs based on tandem electrostatic accelerators

    International Nuclear Information System (INIS)

    Gover, A.; Friedman, A.

    1989-01-01

    The operation of tandem electrostatic accelerator FELs in an optical klystron configuration makes it possible to take advantage of the high quality (low emittance and low energy spread) of the electron beam in electrostatic accelerators. With evolving microwiggler technology, state-of-the-art moderate energy (6-14-MeV) tandem electrostatic accelerators may be used for the development of highly coherent tunable radiation sources in the entire IR region. The authors present the general design considerations and the predicted operating characteristics of such devices and refer in specifics to a design of a 10-1000-μm FEL based on the parameters of a 5-6-MeV high current tandem accelerator. The operating wavelength of FELs is determined by the Doppler shift formula

  9. Optimization of single-step tapering amplitude and energy detuning for high-gain FELs

    Science.gov (United States)

    Li, He-Ting; Jia, Qi-Ka

    2015-01-01

    We put forward a method to optimize the single-step tapering amplitude of undulator strength and initial energy tuning of electron beam to maximize the saturation power of high gain free-electron lasers (FELs), based on the physics of longitudinal electron beam phase space. Using the FEL simulation code GENESIS, we numerically demonstrate the accuracy of the estimations for parameters corresponding to the linac coherent light source and the Tesla test facility.

  10. The SPARX Project R&D Activity towards X-rays FEL Sources

    CERN Document Server

    Alesini, David; Bertolucci, Sergio; Biagini, M E; Boni, R; Boscolo, Manuela; Castellano, Michele; Clozza, A; Di Pirro, G; Drago, A; Esposito, A; Ferrario, Massimo; Filippetto, D; Fusco, V; Gallo, A; Ghigo, A; Guiducci, Susanna; Incurvati, M; Ligi, C; Marcellini, F; Migliorati, Mauro; Mostacci, Andrea; Palumbo, Luigi; Pellegrino, L; Preger, Miro; Raimondi, Pantaleo; Ricci, R; Sanelli, C; Serio, Mario; Sgamma, F; Spataro, Bruno; Stecchi, A; Stella, A; Tazzioli, Franco; Vaccarezza, Cristina; Vescovi, Mario; Vicario, C

    2004-01-01

    SPARX is an evolutionary project proposed by a collaboration among ENEA-INFN-CNR-Università di Roma Tor Vergata aiming at the construction of a FEL-SASE X-ray source in the Tor Vergata Campus. The first phase of the SPARX project, funded by Government Agencies, will be focused on the R&D activity on critical components and techniques for future X-ray facilities. The R&D plans for the FEL source will be developped along two lines: (a) use of the SPARC high brightness photo-injector to develop experimental test on RF compression techniques and other beam physics issues, like emittance degradation in magnetic compressors due to CSR; (b) development of new undulator design concepts and up-grading of the FEL SPARC source to enhance the non linear harmonic generation mechanism, design and test of e-beam conditioning, prebunching and seeding. A parallel program will be aimed at the development of high repetition rate S-band gun, high Quantum Efficiency cathodes, high gradient X-band RF acceleratin...

  11. FEL gain optimisation and spontaneous radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bali, L.M.; Srivastava, A.; Pandya, T.P. [Lucknow Univ. (India)] [and others

    1995-12-31

    Colson have evaluated FEL gains for small deviations from perfect electron beam injection, with radiation of the same polarisation as that of the wiggler fields. We find that for optimum gain the polarisation of the optical field should be the same as that of the spontaneous emission under these conditions. With a helical wiggler the axial oscillations resulting from small departures from perfect electron beam injection lead to injection dependent unequal amplitudes and phases of the spontaneous radiation in the two transverse directions. Viewed along the axis therefore the spontaneous emission is elliptically polarised. The azimuth of the ellipse varies with the difference of phase of the two transverse components of spontaneous emission but the eccentricity remains the same. With planar wigglers the spontaneous emission viewed in the axial direction is linearly polarised, again with an injection dependent azimuth. For optimum coherent gain of a radiation field its polarisation characteristics must be the same as those of the spontaneous radiation with both types of wiggler. Thus, with a helical wiggler and the data reported earlier, an increase of 10% in the FEL gain at the fundamental frequency and of 11% at the fifth harmonic has been calculated in the small gain per pass limit. Larger enhancements in gain may result from more favourable values of input parameters.

  12. Electron bunch length measurement at the Vanderbilt FEL

    Energy Technology Data Exchange (ETDEWEB)

    Amirmadhi, F.; Brau, C.A.; Mendenhall, M. [Vanderbilt Free-Electron-Laser Center, Nashville, TN (United States)] [and others

    1995-12-31

    During the past few years, a number of experiments have been performed to demonstrate the possibility to extract the longitudinal charge distribution from spectroscopic measurements of the coherent far-infrared radiation emitted as transition radiation or synchrotron radiation. Coherent emission occurs in a spectral region where the wavelength is comparable to or longer than the bunch length, leading to an enhancement of the radiation intensity that is on the order of the number of particles per bunch, as compared to incoherent radiation. This technique is particularly useful in the region of mm and sub-mm bunch lengths, a range where streak-cameras cannot be used for beam diagnostics due to their limited time resolution. Here we report on experiments that go beyond the proof of principle of this technique by applying it to the study and optimization of FEL performance. We investigated the longitudinal bunch length of the Vanderbilt FEL by analyzing the spectrum of coherent transition radiation emitted by the electron bunches. By monitoring the bunch length while applying a bunch-compression technique, the amount of the compression could be easily observed. This enabled us to perform a systematic study of the FEL performance, especially gain and optical pulse width, as a function of the longitudinal electron distribution in the bunch. The results of this study will be presented and discussed.

  13. First Model of the Edge-Focusing Wiggler for SASE

    CERN Document Server

    Kashiwagi, Shigeru; Kato, Ryukou; Kobayashi, Kenji; Noda, Takanori

    2004-01-01

    We are developing a new type of wiggler named the edge-focusing (EF) wiggler, which produces the strong transverse focusing field incorporated with the normal wiggler field. The idea of the EF wiggler* and development of permanent magnet blocks with small magnetization errors for the wiggler** were reported at the two preceding FEL conferences. We have fabricated the first model of the EF wiggler to evaluate its performance. It is a five-period planar wiggler with an edge angle of 2 degrees and a period length of 60 mm. The magnetic field in the wiggler is measured with a Hole probe at a magnet gap of 30 mm. It is experimentally confirmed that a high field gradient of 1.0 T /m is realized along the beam axis in the EF wiggler. In this paper, we will report results of the magnetic field measurement and its analysis for the first mode of the EF wiggler.

  14. A method for measuring the FEL radiation power along an undulator

    CERN Document Server

    Reiche, S

    2000-01-01

    A highly desirable measurement in Free Electron Laser (FEL) experiments is the dependency of the radiation power along the undulator. Most designs of undulators prohibit detection of the radiation power within the undulator or extracting the electron beam at arbitrary positions. Transport of both, the radiation field and the electron beam, through the entire undulator, and thus an ongoing FEL interaction, is unavoidable. If there are many correction magnets distributed along the beam pipe, one can think of exciting a large orbit distortion downstream from any of these correctors. For a gain length comparable to or larger than the beta function this excitation of a coherent betatron oscillation might degrade the FEL amplification to a level, for which the radiation power does not further grow over the remaining length of the undulator. This paper presents the efficiency of this method for the parameters of the VUV FEL at the TESLA Test Facility.

  15. Production of transform-limited X-ray pulses through self-seeding at the European X-ray FEL

    International Nuclear Information System (INIS)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2011-09-01

    An important goal for any advanced X-ray FEL is an option for providing Fourier-limited X-ray pulses. In this way, no monochromator is needed in the experimental hall. Self-seeding is a promising approach to significantly narrow the SASE bandwidth to produce nearly transform-limited pulses. These are important for many experiments including 3D diffraction imaging.We discuss the implementation of a single-crystal self-seeding scheme in the hard X-ray lines of the European XFEL. For this facility, transform-limited pulses are particularly valuable since they naturally support the extraction of more FEL power than at saturation by exploiting tapering in the tunable-gap baseline undulators. Tapering consists of a stepwise change of the undulator gap from segment to segment. Based on start-to-end simulations dealing with the up-to-date parameters of the European XFEL, we show that the FEL power reaches about 400 GW, or one order of magnitude higher power than the SASE saturation level (20 GW). This analysis indicates that our self-seeding scheme is not significantly affected by non-ideal electron phase-space distribution, and yields about the same performance as in the case for an electron beam with ideal parameters. The self-seeding scheme with a single crystal monochromator is extremely compact (about 5 m long), and cost estimations are low enough to consider adding it to the European XFEL capabilities from the very beginning of the operation phase. (orig.)

  16. Production of transform-limited X-ray pulses through self-seeding at the European X-ray FEL

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2011-09-15

    An important goal for any advanced X-ray FEL is an option for providing Fourier-limited X-ray pulses. In this way, no monochromator is needed in the experimental hall. Self-seeding is a promising approach to significantly narrow the SASE bandwidth to produce nearly transform-limited pulses. These are important for many experiments including 3D diffraction imaging.We discuss the implementation of a single-crystal self-seeding scheme in the hard X-ray lines of the European XFEL. For this facility, transform-limited pulses are particularly valuable since they naturally support the extraction of more FEL power than at saturation by exploiting tapering in the tunable-gap baseline undulators. Tapering consists of a stepwise change of the undulator gap from segment to segment. Based on start-to-end simulations dealing with the up-to-date parameters of the European XFEL, we show that the FEL power reaches about 400 GW, or one order of magnitude higher power than the SASE saturation level (20 GW). This analysis indicates that our self-seeding scheme is not significantly affected by non-ideal electron phase-space distribution, and yields about the same performance as in the case for an electron beam with ideal parameters. The self-seeding scheme with a single crystal monochromator is extremely compact (about 5 m long), and cost estimations are low enough to consider adding it to the European XFEL capabilities from the very beginning of the operation phase. (orig.)

  17. Optimization of a high efficiency FEL amplifier

    International Nuclear Information System (INIS)

    Schneidmiller, E.A.; Yurkov, M.V.

    2014-10-01

    The problem of an efficiency increase of an FEL amplifier is now of great practical importance. Technique of undulator tapering in the post-saturation regime is used at the existing X-ray FELs LCLS and SACLA, and is planned for use at the European XFEL, Swiss FEL, and PAL XFEL. There are also discussions on the future of high peak and average power FELs for scientific and industrial applications. In this paper we perform detailed analysis of the tapering strategies for high power seeded FEL amplifiers. Application of similarity techniques allows us to derive universal law of the undulator tapering.

  18. FEL diagnostics and user control

    NARCIS (Netherlands)

    Knippels, G.M.H.; van der Meer, A. F. G.

    1998-01-01

    The most recent upgrades and improvements to the free-electron laser (FEL) facility FELIX are presented. Special attention is paid to the improved beam-handling and diagnostic station. In this evacuated beam station a device is implemented that is capable of selecting single micropulses with

  19. Physical optics simulations with PHASE for SwissFEL beamlines

    Energy Technology Data Exchange (ETDEWEB)

    Flechsig, U.; Follath, R.; Reiche, S. [Paul Scherrer Institut, Swiss Light Source, 5232 Villigen PSI (Switzerland); Bahrdt, J. [Helmholtz Zentrum Berlin (Germany)

    2016-07-27

    PHASE is a software tool for physical optics simulation based on the stationary phase approximation method. The code is under continuous development since about 20 years and has been used for instance for fundamental studies and ray tracing of various beamlines at the Swiss Light Source. Along with the planning for SwissFEL a new hard X-ray free electron laser under construction, new features have been added to permit practical performance predictions including diffraction effects which emerge with the fully coherent source. We present the application of the package on the example of the ARAMIS 1 beamline at SwissFEL. The X-ray pulse calculated with GENESIS and given as an electrical field distribution has been propagated through the beamline to the sample position. We demonstrate the new features of PHASE like the treatment of measured figure errors, apertures and coatings of the mirrors and the application of Fourier optics propagators for free space propagation.

  20. Research and Development Toward a 4.5-1.5 Angstrom Linac Coherent Light Source (LCLS) at SLAC

    International Nuclear Information System (INIS)

    Tatchyn, R.; Arthur, J.; Baltay, M.

    1995-08-01

    In recent years significant studies have been initiated on the feasibility of utilizing a portion of the 3km S-band accelerator at SLAC to drive a short wavelength (4.5-1.5 A) Linac Coherent Light Source (LCLS), a Free Electron Laser (FEL) operating in the Self- Amplified Spontaneous Emission (SASE) regime. Electron beam requirements for single-pass saturation in a minimal time include: (1) a peak current in the 7 kA range, (2) a relative energy spread of <0.05%, and (3) a transverse emittance, ε[r-m], approximating the diffraction limit condition ε = λ / 4π, where lambda(m) is the output wavelength. Requirements on the insertion device include field error levels of 0.02% for keeping the electron bunch centered on and in phase with the amplified photons, and a focusing beta of 8 m/rad for inhibiting the dilution of its transverse density. Although much progress has been made in developing individual components and beam processing techniques necessary for LCLS operation down to approx. 20 A, a substantial amount of research and development is still required in a number of theoretical and experimental areas leading to the construction and operation of a 4.5-1.5 A LCLS. In this paper we report on a research and development program underway and in planning at SLAC for addressing critical questions in these areas

  1. Coherent imaging at FLASH

    International Nuclear Information System (INIS)

    Chapman, H N; Bajt, S; Duesterer, S; Treusch, R; Barty, A; Benner, W H; Bogan, M J; Frank, M; Hau-Riege, S P; Woods, B W; Boutet, S; Cavalleri, A; Hajdu, J; Iwan, B; Seibert, M M; Timneanu, N; Marchesini, S; Sakdinawat, A; Sokolowski-Tinten, K

    2009-01-01

    We have carried out high-resolution single-pulse coherent diffractive imaging at the FLASH free-electron laser. The intense focused FEL pulse gives a high-resolution low-noise coherent diffraction pattern of an object before that object turns into a plasma and explodes. In particular we are developing imaging of biological specimens beyond conventional radiation damage resolution limits, developing imaging of ultrafast processes, and testing methods to characterize and perform single-particle imaging.

  2. HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS.

    Energy Technology Data Exchange (ETDEWEB)

    BEN-ZVI, ILAN, DAYRAN, D.; LITVINENKO, V.

    2005-08-21

    Historically, the first demonstration of the optical FEL was in an amplifier configuration at Stanford University [l]. There were other notable instances of amplifying a seed laser, such as the LLNL PALADIN amplifier [2] and the BNL ATF High-Gain Harmonic Generation FEL [3]. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance FEL's with average power of 100 kW or more. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting Energy Recovery Linacs (ERL) combine well with the high-gain FEL amplifier to produce unprecedented average power FELs. This combination has a number of advantages. In particular, we show that for a given FEL power, an FEL amplifier can introduce lower energy spread in the beam as compared to a traditional oscillator. This properly gives the ERL based FEL amplifier a great wall-plug to optical power efficiency advantage. The optics for an amplifier is simple and compact. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department.

  3. The SDUV-FEL vacuum interlock system

    International Nuclear Information System (INIS)

    Qi Binchuan; Zhu Haijun; Ding Jiangguo

    2011-01-01

    Shanghai Deep Ultraviolet Free Electron Laser (SDUV-FEL) test facility is an integrated multi-purpose test bed for FEL principles. In this paper, we focus on the development of an interlock system for SDUV-FEL vacuum protection. Hardware and software of the system implementations are introduced. A distributed control system composed of a PLC, an embedded computer and consoles based on EPICS toolkit is described in details. The system has been used for cascaded HGHG FEL experiment. Stability and reliability has been demonstrated. (authors)

  4. High Average Power Optical FEL Amplifiers

    CERN Document Server

    Ben-Zvi, I; Litvinenko, V

    2005-01-01

    Historically, the first demonstration of the FEL was in an amplifier configuration at Stanford University. There were other notable instances of amplifying a seed laser, such as the LLNL amplifier and the BNL ATF High-Gain Harmonic Generation FEL. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance a 100 kW average power FEL. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting energy recovery linacs combine well with the high-gain FEL amplifier to produce unprecedented average power FELs with some advantages. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Li...

  5. Performance of a Combined System Using an X-Ray FEL Oscillator and a High-Gain FEL Amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, L.; Lindberg, R.; Kim, K. -J.

    2017-06-01

    The LCLS-II at SLAC will feature a 4 GeV CW superconducting (SC) RF linac [1] that can potentially drive a 5th harmonic X-Ray FEL Oscillator (XFELO) to produce fully coherent, 1 MW photon pulses with a 5 meV bandwidth at 14.4 keV [2]. The XFELO output can serve as the input seed signal for a high-gain FEL amplifier employing fs electron beams from the normal conducting SLAC linac, thereby generating coherent, fs x-ray pulses with TW peak powers using a tapered undulator after saturation [3]. Coherent, intense output at several tens of keV will also be feasible if one considers a harmonic generation scheme. Thus, one can potentially reach the 42 keV photon energy required for the MaRIE project [4] by beginning with an XFELO operating at the 3rd harmonic to produce 14.0 keV photons using a 12 GeV SCRF linac, and then subsequently using the high-gain harmonic generation scheme to generate and amplify the 3th harmonic at 42 keV [5]. We report extensive GINGER simulations that determine an optimized parameter set for the combined system.

  6. The Linac Coherent Light Source

    Energy Technology Data Exchange (ETDEWEB)

    White, William E., E-mail: wewhite@slac.stanford.edu; Robert, Aymeric; Dunne, Mike [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

    2015-04-21

    The present status of the Linac Coherent Light Source as a user facility is presented. Opportunities and challenges as well as the scientific impact of X-ray free-electron lasers are discussed. The Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory was the first hard X-ray free-electron laser (FEL) to operate as a user facility. After five years of operation, LCLS is now a mature FEL user facility. Our personal views about opportunities and challenges inherent to these unique light sources are discussed.

  7. Beam Line Commissioning of a UV/VUV FEL at Jefferson Lab

    Energy Technology Data Exchange (ETDEWEB)

    Benson, Stephen; Blackburn, Keith; Bullard, Daniel; Clavero Perez, Cesar; Coleman, James; Dickover, Cody; Douglas, David; Ellingsworth, Forrest; Evtushenko, Pavel; Hernandez-Garcia, Carlos; Gould, Christopher; Gubeli, Joseph; Hardy, David; Jordan, Kevin; Klopf, John; James, Kortze; Legg, Robert; Marchlik, Matthew; Moore, Steven; Neil, George; Powers, Thomas; Sexton, Daniel; Shinn, Michelle D; Tennant, Christopher; Walker, Richard; Williams, Gwyn; Wilson, Frederick

    2011-08-01

    Many novel applications in photon sciences require very high brightness and/or short pulses in the vacuum ultra-violet (VUV). Jefferson Lab has commissioned a UV oscillator with high gain and has transported the third harmonic of the UV to a user lab. The experimental performance of the UV FEL is much better than simulated performance in both gain and efficiency. This success is important for efforts to push towards higher gain FELs at short wavelengths where mirrors absorb strongly. We will report on efforts to characterize the UV laser and the VUV coherent harmonics as well as designs to lase directly in the VUV wavelength range.

  8. Considerations on Beam Quality Control in MIT X-Ray FEL

    CERN Document Server

    Wang, Dong; Graves, William; Huang, Gang; Wang, Defa; Wu, Juhao; Zwart, Townsend

    2005-01-01

    The next generation of x-ray FEL requires very high quality electron beams for producing unprecedented x-ray radiations. In proposed x-ray FEL facilities, especially those that use multi-stage high gain high harmonic (HGHG) principle to obtain coherence in both transverse and longitudinal dimensions, the arrival timing of electron bunches must be very precise to ensure the seed laser overlap the desired sections of the electron bunch. A scheme is proposed to achieve 10s fs level of arrival timing control level.

  9. The ARC-EN-CIEL FEL proposal

    Science.gov (United States)

    Couprie, M. E.; Desmons, M.; Chubar, O.; Gilquin, B.; Garzella, D.; Jablonka, M.; Lambert, G.; Loulergue, A.; Marquès, J. R.; Ortega, J. M.; Méot, F.; Monot, P.; Mosnier, A.; Nahon, L.; Rousse, A.

    2005-08-01

    We propose an accelerator based 4th generation source to provide coherent femtosecond light pulses down to the soft X ray range to the user community. The project is based on a CW 700 MeV to 1 GeV superconducting linear accelerator delivering high charge, subpicosecond, low emittance electron bunches with high repetition rate. This facility allows for providing High Gain Harmonic Generation seeded with high harmonics in gases, covering a spectral range down to 0.8 nm. In addition, two beam loops are foreseen to increase the beam current in using the energy recovery technique. They will accommodate fs synchrotron radiation sources in the IR, VUV and X ray ranges together with a FEL oscillator in the 10 nm range. A particular emphasis is put on the synergy between accelerator and laser communities. In particular, electron plasma acceleration will be tested. Hard X ray femtosecond radiation will be produced by Thomson Scattering. The first phase of the project, ARC-EN-CIEL phase 1, is now under study. A general overview is given.

  10. Optimization Issues in a Harmonic Cascade FEL

    CERN Document Server

    De Ninno, G

    2005-01-01

    Presently there is significant interest by multiple groups (e.g. BNL, ELETTRA, LBNL, BESSY, MIT) to reach short output wavelengths via a harmonic cascade FEL using an external seed laser. In a multistage device, there are a number of "free" parameters such as the nominal power of the input seed, the lengths of the individual modulator and radiator undulators, the strengths (i.e. the R56's) of the dispersive sections, the choice of the actual harmonic numbers to reach a given wavelength, etc., whose optimization is a non-trivial exercise. In particular, one can choose whether to operate predominantly in the "high gain" regime such as was proposed by Yu [1] in which case each radiator undulator is many gain lengths long or, alternatively, in the "low gain" regime in which case all undulators (except possibly the last radiator) are a couple gain lengths or less long and the output from each radiator essentially corresponds to coherent spontaneous emission from a pre-bunched beam. With particular emphasis upon th...

  11. Effectiveness of a Science Agricultural Summer Experience (SASE) in Recruiting Students to Natural Resources Management

    Science.gov (United States)

    Martinez, Edward; Lindline, Jennifer; Petronis, Michael S.; Pilotti, Maura

    2012-12-01

    The Bureau of Labor Statistics projects an increase in Natural Resource Management (NRM) jobs within the next 10 years due to baby-boomer retirements and a 12% increase in demand for these occupations. Despite this trend, college enrollment in NRM disciplines has declined. Even more critical is the fact that the soon-to-be-majority Hispanic population is underrepresented in NRM disciplines. The goal of the present study was to determine if an in-residence, two-week, summer science program for underrepresented minorities would not only increase interest in science, actual science knowledge, and perceived science knowledge, but also have an overall impact on underrepresented minority students' decisions to attend college, major in a scientific discipline and pursue a career in science. During a four-year period, 76 high school students participated in a Science Agricultural Summer Experience (SASE) in Northern New Mexico. A pre/post science-knowledge exam and satisfaction survey were administered to participants. We demonstrate that participants improved significantly ( p Students not only found science exciting and approachable after participation, but also exhibited increased interest in pursuing a degree and career in science. Of the 76 SASE participants within graduation age ( n = 44), all graduated from high school; and 86% enrolled in college. These findings suggest that the implemented SASE initiative was effective in recruiting and increasing the confidence and abilities of underrepresented minority students in science.

  12. Optimization of a dedicated bio-imaging beamline at the European X-ray FEL

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2012-09-15

    We recently proposed a basic concept for design and layout of the undulator source for a dedicated bio-imaging beamline at the European XFEL. The goal of the optimized scheme proposed here is to enable experimental simplification and performance improvement. The core of the scheme is composed by soft and hard X-ray self-seeding setups. Based on the use of an improved design for both monochromators it is possible to increase the design electron energy up to 17.5 GeV in photon energy range between 2 keV and 13 keV, which is the most preferable for life science experiments. An advantage of operating at such high electron energy is the increase of the X-ray output peak power. Another advantage is that 17.5 GeV is the preferred operation energy for SASE1 and SASE2 beamline users. Since it will be necessary to run all the XFEL lines at the same electron energy, this choice will reduce the interference with other undulator lines and increase the total amount of scheduled beam time. In this work we also propose a study of the performance of the self-seeding scheme accounting for spatiotemporal coupling caused by the use of a single crystal monochromator. Our analysis indicates that this distortion is easily suppressed by the right choice of diamond crystal planes and that the proposed undulator source yields about the same performance as in the case for a X-ray seed pulse with no coupling. Simulations show that the FEL power reaches 2 TW in the 3 keV-5 keV photon energy range, which is the most preferable for single biomolecule imaging.

  13. Coherence properties of the radiation from FLASH

    International Nuclear Information System (INIS)

    Schneidmiller, E.A.; Yurkov, M.V.

    2015-02-01

    FLASH is the first free electron laser user facility operating in the vacuum ultraviolet and soft x-ray wavelength range. Many user experiments require knowledge of the spatial and temporal coherence properties of the radiation. In this paper we present an analysis of the coherence properties of the radiation for the fundamental and for the higher odd frequency harmonics. We show that temporal and spatial coherence reach maximum close to the FEL saturation but may degrade significantly in the post-saturation regime. We also find that the pointing stability of short FEL pulses is limited due to the fact that non-azimuthal FEL eigenmodes are not sufficiently suppressed. We discuss possible ways for improving the degree of transverse coherence and the pointing stability.

  14. Coherent methods in X-ray scattering

    International Nuclear Information System (INIS)

    Gorobtsov, Oleg

    2017-05-01

    X-ray radiation has been used to study structural properties of materials for more than a hundred years. Construction of extremely coherent and bright X-ray radiation sources such as free electron lasers (FELs) and latest generationstorage rings led to rapid development of experimental methods relying on high radiation coherence. These methods allow to perform revolutionary studies in a wide range of fields from solid state physics to biology. In this thesis I focus on several important problems connected with the coherent methods. The first part considers applications of dynamical diffraction theory on crystals to studies with coherent X-ray radiation. It presents the design of a high-resolution spectrometer for free electron lasers that should allow to resolve spectral structure of individual FEL pulses. The spectrometer is based on the principle of dynamical diffraction focusing. The knowledge of individual FEL pulse spectra is necessary for understanding FEL longitudinal coherence. In the same part I present quasi-kinematical approximation to dynamical theory which allows to treat analytically phase effects observed in X-ray coherent imaging on nanocrystals. These effects may play a big role when methods such as ptychography are used to study crystalline samples. The second part deals with measurements of FEL coherence properties using intensity - intensity interferometry. Results of several experiments performed at FELs FLASH and LCLS are revealed in this section. I have developed models and theories to explain the behavior observed in experiments on FLASH. These models allowed to extract information about external positional jitter of FEL pulses and secondary beams present in FEL radiation. In the LCLS experiment the Hanbury Brown and Twiss type interferometry was performed on Bragg peaks from colloidal crystal. This did not require additional measurements without the sample and information was extracted directly from diffraction patterns. Therefore intensity

  15. Coherent methods in X-ray scattering

    Energy Technology Data Exchange (ETDEWEB)

    Gorobtsov, Oleg

    2017-05-15

    X-ray radiation has been used to study structural properties of materials for more than a hundred years. Construction of extremely coherent and bright X-ray radiation sources such as free electron lasers (FELs) and latest generationstorage rings led to rapid development of experimental methods relying on high radiation coherence. These methods allow to perform revolutionary studies in a wide range of fields from solid state physics to biology. In this thesis I focus on several important problems connected with the coherent methods. The first part considers applications of dynamical diffraction theory on crystals to studies with coherent X-ray radiation. It presents the design of a high-resolution spectrometer for free electron lasers that should allow to resolve spectral structure of individual FEL pulses. The spectrometer is based on the principle of dynamical diffraction focusing. The knowledge of individual FEL pulse spectra is necessary for understanding FEL longitudinal coherence. In the same part I present quasi-kinematical approximation to dynamical theory which allows to treat analytically phase effects observed in X-ray coherent imaging on nanocrystals. These effects may play a big role when methods such as ptychography are used to study crystalline samples. The second part deals with measurements of FEL coherence properties using intensity - intensity interferometry. Results of several experiments performed at FELs FLASH and LCLS are revealed in this section. I have developed models and theories to explain the behavior observed in experiments on FLASH. These models allowed to extract information about external positional jitter of FEL pulses and secondary beams present in FEL radiation. In the LCLS experiment the Hanbury Brown and Twiss type interferometry was performed on Bragg peaks from colloidal crystal. This did not require additional measurements without the sample and information was extracted directly from diffraction patterns. Therefore intensity

  16. Spatio-temporal coherence of free-electron laser radiation in the extreme ultraviolet determined by a Michelson interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Hilbert, V.; Rödel, C.; Zastrau, U., E-mail: ulf.zastrau@uni-jena.de [Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität, Max-Wien-Platz 1, 07743 Jena (Germany); Brenner, G.; Düsterer, S.; Dziarzhytski, S.; Harmand, M.; Przystawik, A.; Redlin, H.; Toleikis, S. [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg (Germany); Döppner, T.; Ma, T. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Fletcher, L. [Department of Physics, University of California, Berkeley, California 94720 (United States); Förster, E. [Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität, Max-Wien-Platz 1, 07743 Jena (Germany); Helmholtz-Institut Jena, Fröbelstieg 3, 07743 Jena (Germany); Glenzer, S. H.; Lee, H. J. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Hartley, N. J. [Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Kazak, L.; Komar, D.; Skruszewicz, S. [Institut für Physik, Universität Rostock, 18051 Rostock (Germany); and others

    2014-09-08

    A key feature of extreme ultraviolet (XUV) radiation from free-electron lasers (FELs) is its spatial and temporal coherence. We measured the spatio-temporal coherence properties of monochromatized FEL pulses at 13.5 nm using a Michelson interferometer. A temporal coherence time of (59±8) fs has been determined, which is in good agreement with the spectral bandwidth given by the monochromator. Moreover, the spatial coherence in vertical direction amounts to about 15% of the beam diameter and about 12% in horizontal direction. The feasibility of measuring spatio-temporal coherence properties of XUV FEL radiation using interferometric techniques advances machine operation and experimental studies significantly.

  17. A proposed VUV oscillator-based FEL upgrade at Jefferson Lab

    Energy Technology Data Exchange (ETDEWEB)

    Benson, S. V. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Douglas, D. R. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Evtushenko, P. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Hannon, F. E. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Hernandez-Garcia, C. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Klopf, J. M. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Legg, R. A. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Neil, G. R. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Shinn, M. D. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Tennant, C. D. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Zhang, S. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Williams, G. P. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2011-09-20

    Advances in superconducting linac technology offer the possibility of an upgrade of the Jefferson Lab Free Electron Laser (JLab FEL) facility to an oscillator-based VUV-FEL that would produce 6 x 10{sup 12} coherent 100 eV photons per pulse at multi-MHz repetition rates in the fundamental. At present JLab operates a pair of oscillator-based continuous-wave Free Electron Lasers (FELs) as a linac-based next generation light source in the IR and UV, with sub-picosecond pulses up to 75 MHz. Harmonics upwards of 10 eV are produced and the fully coherent nature of the source results in peak and average brightness values that are several orders of magnitude higher than storage rings. The accelerator uses an energy recovered linac design for efficiency of operation. New style superconducting linac cryomodules with higher gradient, combined with a new injector and beam transport system allow the development of the FEL to higher photon energies.

  18. Parametric x-ray FEL operating with external Bragg reflectors

    International Nuclear Information System (INIS)

    Baryshevsky, V.G.; Batrakov, K.G.; Dubovskaya, I.Ya.

    1995-01-01

    In the crystal X-ray FELs using channeling and parametric quasi-Cherenkov mechanisms of spontaneous radiation were considered as versions of FEL allowing, in principle, to obtain coherent X-ray source. In this case a crystal is both radiator and resonator for X-rays emitted by a particle beam passing through crystal. However, it is well-known that a beam current density required for lasing is extremely high in X-ray spectral range for any radiation mechanisms and it is very important to find a way to lower its magnitude. The application of three-dimensional distributed feedback formed by dynamical diffraction of emitted photons permitted to reduce starting beam current density 10 2 -10 4 times up to 10 9 . One of ways to lower the starting current is the formation of multi-wave distributed feedback the another one is the application of external reflectors. The thing is that lasing regime was shown to be produced at frequencies in the vicinity of degeneration point for roots of dispersion equation describing radiation modes excited in an active medium (crystal plus particle beam). Unfortunately, in case of parametric quasi-Cherenkov FEL this region coincides with the region of strong self-absorption of radiation inside a crystal. That fact, obviously, increases the starting beam current. In this report we have shown that the application of external Bragg reflectors gives the possibility to lower radiation self-absorption inside a crystal by modifying radiation modes excited in the active medium under consideration. The corresponding dispersion equation and the expression for excited modes are derived. The generation equation determining starting conditions for lasing is obtained. Using these expressions we have shown that the application of external Bragg reflectors permits to reduce starting beam current density more than 10 times

  19. Self-seeding scheme with gas monochromator for narrow-bandwidth soft X-ray FELs

    International Nuclear Information System (INIS)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2011-03-01

    Self-seeding schemes, consisting of two undulators with a monochromator in between, aim at reducing the bandwidth of SASE X-ray FELs. We recently proposed to use a new method of monochromatization exploiting a single crystal in Bragg transmission geometry for self-seeding in the hard X-ray range. Here we consider a possible extension of this method to the soft X-ray range using a cell filled with resonantly absorbing gas as monochromator. The transmittance spectrum in the gas exhibits an absorbing resonance with narrow bandwidth. Then, similarly to the hard X-ray case, the temporal waveform of the transmitted radiation pulse is characterized by a long monochromatic wake. In fact, the FEL pulse forces the gas atoms to oscillate in a way consistent with a forward-propagating, monochromatic radiation beam. The radiation power within this wake is much larger than the equivalent shot noise power in the electron bunch. Further on, the monochromatic wake of the radiation pulse is combined with the delayed electron bunch and amplified in the second undulator. The proposed setup is extremely simple, and composed of as few as two simple elements. These are the gas cell, to be filled with noble gas, and a short magnetic chicane. The installation of the magnetic chicane does not perturb the undulator focusing system and does not interfere with the baseline mode of operation. In this paper we assess the features of gas monochromator based on the use of He and Ne.We analyze the processes in the monochromator gas cell and outside it, touching upon the performance of the differential pumping system as well. We study the feasibility of using the proposed self-seeding technique to generate narrow bandwidth soft X-ray radiation in the LCLS-II soft X-ray beam line. We present conceptual design, technical implementation and expected performances of the gas monochromator self-seeding scheme. (orig.)

  20. JAERI FEL applications in nuclear energy industries

    International Nuclear Information System (INIS)

    Minehara, Eisuke J.

    2005-01-01

    The JAERI FEL has first discovered the new FEL lasing of 255fs ultra fast pulse, 6-9% high efficiency, 1GW high peak power, a few kilowatts average power, and wide tunability of medium and far infrared wavelength regions at the same time. Using the new lasing and energy-recovery linac technology, we could extend a more powerful and more efficient free-electron laser (FEL) than 10kW and 25%, respectively, for nuclear energy industries, and others. In order to realize such a tunable, highly-efficient, high average power, high peak power and ultra-short pulse FEL, we need the efficient and powerful FEL driven by the JAERI compact, stand alone and zero boil-off super-conducting RF linac with an energy-recovery geometry. Our discussions on the FEL will cover the application of non-thermal peeling, cutting, and drilling to prevent cold-worked stress-corrosion cracking failures in nuclear energy and other heavy industries. (author)

  1. Optical beam transport system at FEL-SUT

    CERN Document Server

    Nomaru, K; Yokoyama, M; Oda, F; Nakayama, A; Koike, H; Kuroda, H

    2000-01-01

    Kawasaki Heavy Industries Ltd. has installed an FEL beam transport system at the IR FEL Research Center of the Science University of Tokyo (FEL-SUT). This system transports the FEL output beam from the FEL machine room to the optical diagnostic room through a vacuum tube. The in-vacuum multi-mirror synchronized system operated from the FEL control room enables the operator to control the multiple mirrors simultaneously on or off axis of the FEL beam and to distribute the FEL output to one of the laboratories. The essential component of the transport system is the passive control optics that is composed of an elliptical and parabolic mirror couple. Once the control optics is aligned, a parallel FEL beam with a good pointing stability is obtained without any active operation to tune the optical system for different wavelengths.

  2. High Power Operation of the JLab IR FEL Driver Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Kevin Beard; Stephen Benson; George Biallas; James Boyce; Donald Bullard; James Coleman; David Douglas; H. Dylla; Richard Evans; Pavel Evtushenko; Christopher Gould; Albert Grippo; Joseph Gubeli; David Hardy; Carlos Hernandez-Garcia; J. Hovater; Kevin Jordan; John Klopf; Rui Li; Steven Moore; George Neil; Benard Poelker; Thomas Powers; Joseph Preble; Robert Rimmer; Daniel Sexton; Michelle D. Shinn; Christopher Tennant; Richard Walker; Gwyn Williams; Shukui Zhang

    2007-08-01

    Operation of the JLab IR Upgrade FEL at CW powers in excess of 10 kW requires sustained production of high electron beam powers by the driver ERL. This in turn demands attention to numerous issues and effects, including: cathode lifetime; control of beamline and RF system vacuum during high current operation; longitudinal space charge; longitudinal and transverse matching of irregular/large volume phase space distributions; halo management; management of remnant dispersive effects; resistive wall, wake-field, and RF heating of beam vacuum chambers; the beam break up instability; the impact of coherent synchrotron radiation (both on beam quality and the performance of laser optics); magnetic component stability and reproducibility; and RF stability and reproducibility. We discuss our experience with these issues and describe the modus vivendi that has evolved during prolonged high current, high power beam and laser operation.

  3. Certain features of FELs with short bunches

    International Nuclear Information System (INIS)

    Lebedev, A.N.

    2006-01-01

    The report is devoted to physics of free electron lasers operating in the short-wave domain where the bunch length could be less than the undulator length in the proper frame. Then the current component of the signal is locked within the bunch as in a cavity, while the electromagnetic component propagates freely. In contrast with gyrotrons where this regime can be of interest only for wavelengths comparable with the bunch length, we consider short waves in a bunch of arbitrary profile. Both amplification of an external harmonic signal and SASE regime, i.e. selective amplification of proper noises, are investigated

  4. Variable height slot-outcoupling for the compact UH THz-FEL

    Science.gov (United States)

    Tecimer, M.; Jiang, H.; Hallman, S.; Elias, L.

    2004-08-01

    The quest for tunable, compact coherent radiation sources in the THz region of the electro-magnetic spectrum is growing and stimulating further developments and research activities in this area. The THz-FEL Group of the University of Hawaii (UH) pursues the concept of minimizing size and cost of a recirculating-beam electrostatic accelerator THz-FEL. The system employs a low voltage (1.7 MeV) pelletron accelerator in conjunction with a short period ( λu=8 mm) hybrid undulator and miniature beam line components. The continuous tunability offered by the system over a spectral range between 230 and 640 μm necessitates a broad-band outcoupling mechanism. Holes on the axis in resonator mirrors have been previously employed in long wavelength FELs as a means to couple out optical radiation from the cavity. The UH THz-FEL adopted a parallel plate waveguide resonator design introducing a height adjustable slot-aperture on one of the cylindrical metal mirrors. Based on the mode-matching method employed in treating waveguide discontinuities, we examine the characteristics of the chosen outcoupling mechanism and its influence on the intracavity optical fields.

  5. Accelerator design of the KHI FEL device

    CERN Document Server

    Yokoyama, M; Nakayama, A; Nomaru, K; Kawai, M

    1999-01-01

    Kawasaki Heavy Industries, Ltd. (KHI) has designed a compact free electron laser device that can provide a powerful and tunable (5-16 mu m) light source. The FEL device consists of a 32 MeV accelerator, a beam transport system with two 25-degree bending magnets, an undulator of 40 periods and 32 mm period length, and a cavity mirror system. Using some computer codes to optimize the beam optics of the accelerator could provide a high-quality beam for the FEL.

  6. The role of radiation reaction in Lienard-Wiechert description of FEL interaction

    Energy Technology Data Exchange (ETDEWEB)

    Kimel, I.; Elias, L.R. [Univ. of Central Florida, Orlando, FL (United States)

    1995-12-31

    The most common theoretical analysis of the FEL interaction is based on the set of equations consisting of Lorentz and wave equations. This approach explains most of FEL features and, in particular, works well to describe operation in the amplifier mode. In that approach however, there are some difficulties in describing operation in oscillator mode, as well as self amplified spontaneous emission. In particular, it is not possible to describe the start up stage since there is no wave to start with. It is clear that a different approach is required in such situations. That is why we have pursued the study of the FEL interaction in the framework of Lorentz plus Lienard-Wiechert equations. The Lienard-Wiechert Lorentz equation approach however, presents its own set of problems. Variation in energy of the electrons is given exclusively by the Lorentz equation. Thus, the energy lost due to the radiation process is not properly taken into account. This, of course, is a long standing problem in classical electrodynamics. In order to restore energy conservation radiation reaction has to be incorporated into the framework. The first question in that regard has to do with which form of the radiation reaction equations is the most convenient for computations in the FEL process. This has to do with the fact that historically, radiation reaction has been added in an ad hoc manner instead of being derived from the fundamental equations. Another problem discussed is how to take into account the radiation reaction in a collective manner in the interaction among electrons. Also discussed is the radiation reaction vis a vi the coherence properties of the FEL process.

  7. The CSU Accelerator and FEL Facility

    NARCIS (Netherlands)

    Milton, S.V.; Biedron, S.G.; Burleson, T.; Carrico, C.; Edelenbos, J.; Hall, C.; Horovitz, K.; Morin, A.; Rand, L.; Sipahi, N.; Sipahi, T.; van der Slot, P.; Yehudah, H.; Dong, A.; Tanaka, T.; Schaa, V.R.W.

    2013-01-01

    The Colorado State University (CSU) Accelerator Facility will include a 6-MeV L-Band electron linear accelerator (linac) with a free-electron laser (FEL) system capable of producing Terahertz (THz) radiation, a laser laboratory, a microwave test stand, and a magnetic test stand. The photocathode

  8. Design Studies for a High-Repetition-Rate FEL Facility at LBNL.

    Energy Technology Data Exchange (ETDEWEB)

    CORLETT, J.; BELKACEM, A.; BYRD, J. M.; FAWLEY, W.; KIRZ, J.; LIDIA, S.; MCCURDY, W.; PADMORE, H.; PENN, G.; POGORELOV, I.; QIANG, J.; ROBIN, D.; SANNIBALE, F.; SCHOENLEIN, R.; STAPLES, J.; STEIER, C.; VENTURINI, M.; WAN, W.; WILCOX, R.; ZHOLENTS, A.

    2007-10-04

    Lawrence Berkeley National Laboratory (LBNL) is working to address the needs of the primary scientific Grand Challenges now being considered by the U.S. Department of Energy, Office of Basic Energy Sciences: we are exploring scientific discovery opportunities, and new areas of science, to be unlocked with the use of advanced photon sources. A partnership of several divisions at LBNL is working to define the science and instruments needed in the future. To meet these needs, we propose a seeded, high-repetition-rate, free-electron laser (FEL) facility. Temporally and spatially coherent photon pulses, of controlled duration ranging from picosecond to sub-femtosecond, are within reach in the vacuum ultraviolet (VUV) to soft X-ray regime, and LBNL is developing critical accelerator physics and technologies toward this goal. We envision a facility with an array of FELs, each independently configurable and tunable, providing a range of photon-beam properties with high average and peak flux and brightness.

  9. First operation of a powerful FEL with two-dimensional distributed feedback

    CERN Document Server

    Agarin, N V; Bobylev, V B; Ginzburg, N S; Ivanenko, V G; Kalinin, P V; Kuznetsov, S A; Peskov, N Yu; Sergeev, A S; Sinitsky, S L; Stepanov, V D

    2000-01-01

    A W-band (75 GHz) FEL of planar geometry driven by a sheet electron beam was realised using the pulse accelerator ELMI (0.8 MeV/3 kA/5 mu s). To provide the spatial coherence of radiation from different parts of the electron beam with a cross-section of 0.4x12 cm two-dimensional distributed feedback systems have been employed using a 2-D Bragg resonator of planar geometry. The resonator consisted of two 2-D Bragg reflectors separated by a regular waveguide section. The total energy in the microwave pulse of microsecond duration was 100 J corresponding to a power of approx 100 MW. The main component of the FEL radiation spectrum was at 75 GHz that corresponded to the zone of effective Bragg reflection found from 'cold' microwave testing of the resonator. The experimental data compared well with the results of theoretical analysis.

  10. SwissFEL - Conceptual design report

    International Nuclear Information System (INIS)

    Ganter, R.

    2010-07-01

    This report issued by the Paul Scherrer Institute (PSI) in Switzerland takes a look at the design concepts behind the institute's SwissFEL X-ray Laser facility. The goal of SwissFEL is to provide a source of extremely bright and short X-ray pulses enabling scientific discoveries in a wide range of disciplines to be made, from fundamental research through to applied science. The eminent scientific need for such an X-ray source which is well documented in the SwissFEL Science Case Report is noted. The technical design of SwissFEL has to keep a delicate balance between the demand by experimentalists for breathtaking performance in terms of photon beam properties on the one hand, and essential requirements for a user facility, such as confidence in technical feasibility, reliable and stable functioning and economy of installation and operation on the other hand. The baseline design which has been defined is discussed. This relies entirely on state-of-the-art technologies without fundamental feasibility issues. This SwissFEL Conceptual Design Report describes the technical concepts and parameters used for this baseline design. The report discusses the design strategy, the choice of parameters and the simulation of the accelerator unit and undulator. The photon beam layout is discussed, as is the installation's tera hertz pump source. The components of the facility, including the laser and radio-frequency systems, timing and synchronisation systems, magnets, undulators, and mechanical support systems are discussed. Further, the concepts behind electron beam diagnostics, vacuum equipment as well as control and feedback systems are discussed. The building layout is described and safety issues are discussed. An appendix completes the report

  11. The 'Fresh-Bunch' technique in FELs

    International Nuclear Information System (INIS)

    Ben-Zvi, I.; Yang, K.M.; Yu, L.H.

    1991-01-01

    The 'Fresh Bunch' technique is being proposed as a method of increasing the gain and power of FEL amplifiers in which the length of the optical radiation pulse is shorter than the length of the electron bunch. In multi-stage FEL, electron beam energy spread is increased by the FEL interaction in the early stages. In the 'Fresh Bunch' technique, the low energy spread of the electron beam is recovered by shifting the radiation pulse to an undisturbed part of the electron bunch, thus improving the gain and trapping fraction in later stages. A test case for the application of the Fresh Bunch method is demonstrated by numerical simulation. In this particular example we examine a subharmonically seeded VUV Free-Electron Laser. We begin with the generation of harmonic radiation, which takes place over one part of the electron bunch. Then the radiation is shifted by means of a strong dispersive section to a fresh part of the bunch for exponential amplification and tapered wiggler amplification. By starting over with a new ensemble of electrons, the energy spread introduced by the bunching in the fundamental is removed, leading to an increased gain. Furthermore, it is possible to use a much stronger seed in the fundamental without incurring the penalty of a large energy spread later on. We note that more than a single application of the 'Fresh Bunch' method may be done in a single FEL multiplier-amplifier. Thus x-ray wavelengths may be reached by successive multiplication in a chain of FEL amplifiers starting from a tunable seed laser. 5 refs., 2 figs., 2 tabs

  12. Online diagnostics of time-resolved electron beam properties with femtosecond resolution for X-ray FELs

    International Nuclear Information System (INIS)

    Yan, Minjie

    2016-07-01

    The European X-ray Free-electron Laser (XFEL) puts high demands on the quality of the highbrightness driving electron beam with bunch lengths in the femtosecond regime. Longitudinal diagnostics is requested to optimize and control the longitudinal profile, the longitudinal phase space, the slice energy spread and the slice emittance of the electron bunch, all of which are crucial to the generation of Self-Amplified Spontaneous Emission (SASE). The high bunch repetition rate of the super-conducting accelerator renders diagnostic method that is (quasi) non-destructive to the generation of SASE possible. In this thesis, three online diagnostic sections utilizing transverse deflecting structures (TDS) have been designed for the European XFEL, providing access to all parameters of interest with a longitudinal resolution down to below 10 fs.The requirement on the non-destructive capability has been realized by the implementation of fast kickermagnets and off-axis screens, which has been validated experimentally using an installation of the same concept at the Free-electron Laser in Hamburg. A special slicing procedure has been developed to significantly enhance the accuracy of slice energy spread measurements. Suppression of coherence effects, which impede the beam imaging in the TDS diagnostics, has been first demonstrated experimentally using the spatial separation method with scintillator screens. Comparison of the results of emittance measurements using the quadrupole scan method with those using the multi-screen method has proved the reliability of the latter method, which has been modelled intensively for the European XFEL.

  13. The SwissFEL Experimental Laser facility.

    Science.gov (United States)

    Erny, Christian; Hauri, Christoph Peter

    2016-09-01

    The hard X-ray laser SwissFEL at the Paul Scherrer Institute is currently being commissioned and will soon become available for users. In the current article the laser facility is presented, an integral part of the user facility, as most time-resolved experiments will require a versatile optical laser infrastructure and precise information about the relative delay between the X-ray and optical pulse. The important key parameters are a high availability and long-term stability while providing advanced laser performance in the wavelength range from ultraviolet to terahertz. The concept of integrating a Ti:sapphire laser amplifier system with subsequent frequency conversion stages and drift compensation into the SwissFEL facility environment for successful 24 h/7 d user operation is described.

  14. Numerical studies of (partial-) waveguide FELs

    CERN Document Server

    Tecimer, M

    2002-01-01

    We investigate two different approaches to analyze the excitation of 3D-time dependent fields by short electron bunches in parallel-plate waveguide FELs. In the first approach the Lienard-Wiechert solution of the four vector electromagnetic wave equation is adopted to the waveguide-FEL problem by means of image currents method. The second approach is based on the commonly used method of solving paraxial wave equation for the amplitudes of the excited waveguide modes in time and axial dimension. The loss mechanism in a partially waveguided cavity with toroidal mirrors is incorporated into the latter formalism accounting for the outcoupling of the radiation fields through a hole, mode conversion and clipping-off due to the waveguide apertures.

  15. FEL system with homogeneous average output

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, David R.; Legg, Robert; Whitney, R. Roy; Neil, George; Powers, Thomas Joseph

    2018-01-16

    A method of varying the output of a free electron laser (FEL) on very short time scales to produce a slightly broader, but smooth, time-averaged wavelength spectrum. The method includes injecting into an accelerator a sequence of bunch trains at phase offsets from crest. Accelerating the particles to full energy to result in distinct and independently controlled, by the choice of phase offset, phase-energy correlations or chirps on each bunch train. The earlier trains will be more strongly chirped, the later trains less chirped. For an energy recovered linac (ERL), the beam may be recirculated using a transport system with linear and nonlinear momentum compactions M.sub.56, which are selected to compress all three bunch trains at the FEL with higher order terms managed.

  16. Harmonic Content of the BESSY FEL Radiation

    CERN Document Server

    Meseck, Atoosa

    2005-01-01

    BESSY proposes a linac-based cascaded High-Gain Harmonic-Generation (HGHG) free electron laser (FEL) multi-user facility. The BESSY soft X-ray FEL will consist of three undulator lines. The associated tunable lasers will cover the spectral range of 230nm to 460nm. Two to four HGHG stages reduce the seed wavelength to the desired radiation range of 1.24nm < λ < 51nm. The harmonic content of the high-intensity radiator output can be used to reduce the number of necessary HGHG stages. Moreover the higher harmonic content of the final output extends the offered spectral range and thus is of high interest for the user community. In this paper, the higher harmonic content of the final output as well as of the output of several radiators are investigated. The main parameters such as output power, pulse duration and bandwidth as well as their suitability for seeding are discussed.

  17. Extending the photon energy coverage of an x-ray self-seeding FEL via the reverse taper enhanced harmonic generation technique

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kaiqing; Qi, Zheng [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Feng, Chao, E-mail: fengchao@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Deng, Haixiao [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Dong, E-mail: wangdong@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhao, Zhentang [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

    2017-05-11

    In this paper, a simple method is proposed to extend the photon energy range of a soft x-ray self-seeding free-electron laser (FEL). A normal monochromator is first applied to purify the FEL spectrum and provide a coherent seeding signal. This coherent signal then interacts with the electron beam in the following reverse tapered undulator section to generate strong coherent microbunchings while maintain the good quality of the electron beam. After that, the pre-bunched electron beam is sent into the third undulator section which resonates at a target high harmonic of the seed to amplify the coherent radiation at shorter wavelength. Three dimensional simulations have been performed and the results demonstrate that the photon energy gap between 1.5 keV and 4.5 keV of the self-seeding scheme can be fully covered and 100 GW-level peak power can be achieved by using the proposed technique.

  18. The BESSY Soft X-Ray FEL User Facility

    CERN Document Server

    Kraemer, Dieter

    2005-01-01

    The user requests for an optimized 2nd generation FEL facility in the VUV to soft X-ray range demand for ultra short photon pulses (t = 20 fs) at a peak power of several GW. A high shot to shot reproducibility of the pulse shape and pulse power allowing for fs-synchronization for pump-probe experiments is feasible in a seeded FEL approach. Free selectable photon polarization and wavelength tuning is essential for any 2nd generation FEL source like the proposed BESSY-Soft X-ray FEL user facility. Freely selectable pulse repetition rates and freely selectable pulse patterns, including fast switching to different parallel operating FEL-Lines are necessary ingredients, feasible with a suitable injector in combination with a CW-superconducting linac. The status of the BESSY HGHG-FEL project will be reviewed.

  19. Duke storage rink UV/VUV FEL: Status and prospects

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko, V.N.; Burnham, B.; Madey, J.M.J. [Duke Univ., Durham, NC (United States)] [and others

    1995-12-31

    The 1 GeV Duke storage ring was successfully commissioned with parameters exceeding initial specification. The OK-4 FEL has arrived at the Duke FEL laboratory from the Novosibirsk Institute of Nuclear Physics. The OK-4 installation and commissioning is in progress. In this paper we describe the up-to-date status of the Duke storage ring and the OK-4 FEL. The projected performance of the OK-4 UV/VUV FEL is presented based on the electron beam parameters achieved. Initial plans to operate the OK-4 UV/VUV FEL at the Duke 1 GeV storage ring are outlined. Future plans and prospects of both the OK-4 FEL and the Duke storage ring are discussed.

  20. A proposed visible FEL Facility at Boeing

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, D.H.; Adamski, J.L.; Hayward, T.D. [Boeing Defense & Space Group, Seattle, WA (United States)] [and others

    1995-12-31

    A 1-kW average power, visible wavelength FEL is described, based on a 120-MeV, 0.1. A macropulse average current linac operating at a duty factor of 0. 6% and having average beam power of 70 kW. The accelerator will employ a demonstrated photoinjector, 18-MeV, 433-MHz linac as an injector, followed by a 1300-MHz longitudinal phase space {open_quotes} linearizer,{close_quotes} a magnetic buncher chicane, and seven 1300-MHz, pulsed traveling wave linac sections. The magnets used to transport the beam from the linac to the FEL centerline, the 5-m THUNDER wiggler, and the optical resonator will be reclaimed from previous FEL demonstration experiments. We expect to attain pulse lengths of 7 ps for 3.5 nC, with minimal distortion of the pulse profile and normalized rms emittance of 7.5 {+-} 2.5 {pi} mm-mr. FELEX projects a laser conversion efficiency of 4.3 %, yielding average output of 3 kW.

  1. A proposed visible FEL Facility at Boeing

    International Nuclear Information System (INIS)

    Dowell, D.H.; Adamski, J.L.; Hayward, T.D.

    1995-01-01

    A 1-kW average power, visible wavelength FEL is described, based on a 120-MeV, 0.1. A macropulse average current linac operating at a duty factor of 0. 6% and having average beam power of 70 kW. The accelerator will employ a demonstrated photoinjector, 18-MeV, 433-MHz linac as an injector, followed by a 1300-MHz longitudinal phase space open-quotes linearizer,close quotes a magnetic buncher chicane, and seven 1300-MHz, pulsed traveling wave linac sections. The magnets used to transport the beam from the linac to the FEL centerline, the 5-m THUNDER wiggler, and the optical resonator will be reclaimed from previous FEL demonstration experiments. We expect to attain pulse lengths of 7 ps for 3.5 nC, with minimal distortion of the pulse profile and normalized rms emittance of 7.5 ± 2.5 π mm-mr. FELEX projects a laser conversion efficiency of 4.3 %, yielding average output of 3 kW

  2. Renewal of KU-FEL Facility

    CERN Document Server

    Kii, Toshiteru; Masuda, Kai; Murakami, Shio; Ohgaki, Hideaki; Yamazaki, Tetsuo; Yoshikawa, Kiyoshi; Zen, Heishun

    2004-01-01

    Users demands to a high power tunable IR laser are increasing in Japan in energy-related science, such as basic study of high-efficiency solar cells, generation of new energy source of alcohol and/or H2 from polluted gas, and separation of DNA and/or RNA. To satisfy these demands, we decided to renew our FEL facility more user friendly and to operate more flexibly. Construction and fundamental studies on the KU-FEL have been carried out at a building of Institute of Chemical Research where few other accelerators are operating. Therefore, available machine time for our experiments is quite limited. We are now modifying the room by adding concrete walls of 2-m thickness and some space for users will be available. The present FEL system will be moved to the room A photocathode RF-gun system will be nearly added to the system and the present thermionic RF-gun will be used ternatively according to the demands of users. The photocathode material will be Cs2Te. The room with the shielding will be completed in June, ...

  3. SCADA software for cute-fel

    International Nuclear Information System (INIS)

    Tiwari, Shradha; Deshpande, P.P.; Bhanage, V.P.; Navathe, C.P.

    2009-01-01

    A SCADA system for RF power conditioning of LINAC and measurement of transmission through undulator has been designed, developed and commissioned as a part of Compact Ultrafast TErahertz Free Electron Laser (CUTE-FEL)project at RRCAT. The present setup consists of pulsed thermionic gun, Linear Accelerator (LINAC), Beam transport line (BTL) and undulator assembly, which form Free Electron Laser (FEL) cavity. There are various ancillary systems, which takes care of vacuum in LINAC and BTL, gas pressure in wave-guide assembly, radiation monitors, beam position monitors (BPM), pulse monitors and RF power monitor. Since the equipment room, where the machine is present is a high radiation zone, the remote operation of the machine was mandatory. All control signals and current status of the machine must be transparently available to the user in the control room in order to operate the machine. This method of machine interaction through powerful graphical user interface (GUI) by the control of variety of hardware is the essence of virtual instrumentation. The SCADA package developed for the control of the CUTE-FEL machine utilises and implements these virtual instrumentation features. The package provides complete operation of the machine from the control room. It provides powerful data logging and report generation features. (author)

  4. Industrial Applications of High Average Power FELS

    CERN Document Server

    Shinn, Michelle D

    2005-01-01

    The use of lasers for material processing continues to expand, and the annual sales of such lasers exceeds $1 B (US). Large scale (many m2) processing of materials require the economical production of laser powers of the tens of kilowatts, and therefore are not yet commercial processes, although they have been demonstrated. The development of FELs based on superconducting RF (SRF) linac technology provides a scaleable path to laser outputs above 50 kW in the IR, rendering these applications economically viable, since the cost/photon drops as the output power increases. This approach also enables high average power ~ 1 kW output in the UV spectrum. Such FELs will provide quasi-cw (PRFs in the tens of MHz), of ultrafast (pulsewidth ~ 1 ps) output with very high beam quality. This talk will provide an overview of applications tests by our facility's users such as pulsed laser deposition, laser ablation, and laser surface modification, as well as present plans that will be tested with our upgraded FELs. These upg...

  5. Design of the SRF Driver ERL for the Jefferson Lab UV FEL

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, David R; Benson, Stephen; Biallas, George; Blackburn, Keith; Boyce, James; Bullard, Donald; Coleman, James; Dickover, Cody; Ellingsworth, Forrest; Evtushenko, Pavel; Gould, Christopher; Gubeli, Joseph; Hannon, Fay; Hardy, David; Hernandez-Garcia, Carlos; Jordan, Kevin; Klopf, Michael; Kortze, James; Marchlik, Matthew; Moore, Steven; Neil, George; Powers, Thomas; Sexton, Daniel; Shinn, Michelle D; Tennant, Christopher; Walker, Richard; Wilson, Frederick; Zhang, Shukui

    2011-03-01

    We describe the design of the SRF Energy-Recovering Linac (ERL) providing the CW electron drive beam at the Jefferson Lab UV FEL. Based on the same 135 MeV linear accelerator as and sharing portions of the recirculator with the Jefferson Lab 10 kW IR Upgrade FEL, the UV driver ERL uses a novel bypass geometry to provide transverse phase space control, bunch length compression, and nonlinear aberration compensation (including correction of RF curvature effects) without the use of magnetic chicanes or harmonic RF. Stringent phase space requirements at the wiggler, low beam energy, high beam current, and use of a pre-existing facility and legacy hardware subject the design to numerous constraints. These are imposed not only by the need for both transverse and longitudinal phase space management, but also by the potential impact of collective phenomena (space charge, wakefields, beam break-up (BBU), and coherent synchrotron radiation (CSR)), and by interactions between the FEL and the accelerator RF system. This report addresses these issues and presents the accelerator design solution that is now in operation.

  6. Design of the SRF Driver ERL for the Jefferson Lab UV FEL

    International Nuclear Information System (INIS)

    We describe the design of the SRF Energy-Recovering Linac (ERL) providing the CW electron drive beam at the Jefferson Lab UV FEL. Based on the same 135 MeV linear accelerator as - and sharing portions of the recirculator with - the Jefferson Lab 10 kW IR Upgrade FEL, the UV driver ERL uses a novel bypass geometry to provide transverse phase space control, bunch length compression, and nonlinear aberration compensation (including correction of RF curvature effects) without the use of magnetic chicanes or harmonic RF. Stringent phase space requirements at the wiggler, low beam energy, high beam current, and use of a pre-existing facility and legacy hardware subject the design to numerous constraints. These are imposed not only by the need for both transverse and longitudinal phase space management, but also by the potential impact of collective phenomena (space charge, wakefields, beam break-up (BBU), and coherent synchrotron radiation (CSR)), and by interactions between the FEL and the accelerator RF system. This report addresses these issues and presents the accelerator design solution that is now in operation.

  7. FERMI @ Elettra A Seeded Harmonic Cascade FEL for EUV and Soft X-Rays

    CERN Document Server

    Bocchetta, C J; Craievich, P; D'Auria, G; Danailov, M B; De Ninno, G; Di Mitri, S; Diviacco, B; Ferianis, M; Gomezel, A; Iazzourene, F; Karantzoulis, E; Penco, G; Trovò, M

    2005-01-01

    We describe the machine layout and major performance parameters for the FERMI FEL project funded for construction at Sincrotrone Trieste, Italy. The project will be the first user facility based on seeded harmonic cascade FELs, providing controlled, high peak-power pulses. With a high-brightness rf photocathode gun, and using the existing 1.2 GeV S-band linac, the facility will provide tunable output over a range from ~100 nm to ~10 nm, with pulse duration from 40 fs to ~ 1ps, and with fully variable output polarization. Initially, two FEL cascades are planned; a single-stage harmonic generation to operate > 40 nm, and a two-stage cascade operating from ~40 nm to ~10 nm or shorter wavelength. The output is spatially and temporally coherent, with peak power in the GW range. Lasers provide modulation to the electron beam, as well as driving the photocathode and other systems, and the facility will integrate laser systems with the accelerator infrastructure, including a state-of-the-art optical timing sys...

  8. SwissFEL injector conceptual design report. Accelerator test facility for SwissFEL

    International Nuclear Information System (INIS)

    Pedrozzi, M.

    2010-07-01

    This comprehensive report issued by the Paul Scherrer Institute (PSI) in Switzerland takes a look at the design concepts behind the institute's SwissFEL X-ray Laser facility - in particular concerning the conceptual design of the injector system. The SwissFEL X-ray FEL project at PSI, involves the development of an injector complex that enables operation of a FEL system operating at 0.1 - 7 nm with permanent-magnet undulator technology and minimum beam energy. The injector pre-project was motivated by the challenging electron beam requirements necessary to drive the SwissFEL accelerator facility. The report takes a look at the mission of the test facility and its performance goals. The accelerator layout and the electron source are described, as are the low-level radio-frequency power systems and the synchronisation concept. The general strategy for beam diagnostics is introduced. Low energy electron beam diagnostics, the linear accelerator (Linac) and bunch compressor diagnostics are discussed, as are high-energy electron beam diagnostics. Wavelength selection for the laser system and UV pulse shaping are discussed. The laser room for the SwissFEL Injector and constructional concepts such as the girder system and alignment concepts involved are looked at. A further chapter deals with beam dynamics, simulated performance and injector optimisation. The facility's commissioning and operation program is examined, as are operating regimes, software applications and data storage. The control system structure and architecture is discussed and special subsystems are described. Radiation safety, protection systems and shielding calculations are presented and the lateral shielding of the silo roof examined

  9. Proposed uv-FEL user facility at BNL

    International Nuclear Information System (INIS)

    Ben-Zvi, I.; Di Mauro, L.F.; Krinsky, S.; White, M.G.; Yu, L.H.; Batchelor, K.; Friedman, A.; Fisher, A.S.; Halama, H.; Ingold, G.; Johnson, E.D.; Kramer, S.; Rogers, J.T.; Solomon, L.; Wachtel, J.; Zhang, X.

    1991-01-01

    The NSLS at Brookhaven National Laboratory is proposing the construction of a UV-FEL operating in the wavelength range from visible to 750 Angstrom. Nano-Coulomb electron pulses will be generated at a laser photo-cathode RF gun at a repetition rate of 10 KHz. The 6 ps pulses will be accelerated to 250 MeV in a superconducting linac. The FEL output will serve four stations with independent wavelength tuning, using two wigglers and two rotating mirror beam switches. Seed radiation for the FEL amplifiers will be provided by conventional tunable lasers, and the final frequency multiplication from the visible or near UV to the VUV will be carried out in the FEL itself. Each FEL will comprise of an initial wiggler resonant to the seed wavelength, a dispersion section, and a second wiggler resonant to the output wavelength. The facility will provide pump probe capability, FEL or FEL, and FEL on synchrotron light from an insersion device on the NSLS X-Ray ring. 15 refs., 2 figs., 3 tabs

  10. First Results from the DUV-FEL Upgrade at BNL

    CERN Document Server

    Wang, Xijie; Murphy, James; Pinayev, Igor; Rakowsky, George; Rose, James; Shaftan, Timur; Sheehy, Brian; Skaritka, John; Wu, Zilu; Yu Li Hua

    2005-01-01

    The DUV-FEL at BNL is the world’s only facility dedicated to laser-seeded FEL R&D and its applications. Tremendous progress was made in both HGHG FEL and its applications in the last couple years.*,** In response to the requests of many users to study chemical science at the facility, the DUV-FEL linac was upgraded from 200 to 300 MeV to enable the HGHG FEL to produce 100 uJ pulses of 100 nm light. This will establish the DUV FEL as a premier user facility for ultraviolet radiation and enable state-of-the-art gas phase photochemistry research. The upgraded facility will also make possible key R&D experiments such as higher harmonic HGHG (n>5) that would lay the groundwork for future X-ray FEL based on HGHG. The upgraded HGHG FEL will operate at the 4th harmonic with the seed laser at either 800 nm or 400nm. The increase of the electron beam energy will be accomplished by installing a 5th linac cavity and two 45 MW klystrons. New HGHG modulator and dispersion sections vacuum chambers w...

  11. Tunability and Power Characteristics of the LEBRA Infrared FEL

    CERN Document Server

    Tanaka, Toshinari; Hayakawa, Yasushi; Mori, Akira; Nogami, Kyoko; Sato, Isamu; Yokoyama, Kazue

    2004-01-01

    Application of the infrared (IR) Free-Electron Laser (FEL) was started in October 2003 at the Laboratory for Electron Beam Research and Application (LEBRA) of Nihon University. The FEL system consisted of silver-coated copper mirrors has demonstrated wavelength tunability ranged from 940 to 6100 nm as a function of the electron energy and the undulator K-value. Wavelength dependence of the FEL output power has been measured in term of different electron beam currents, electron energies and the undulator K-values. Approximate 25 mJ/macropulse has been obtained in the range 2 to 3 microns, which corresponds to peak power of 2 MW, provided that the FEL pulse length is 0.4 ps as resulted from the measurement by an interferometric method. The power decrease observed in the longer wavelength range is due to a large diffraction loss in the FEL guiding optics and the vacuum ducts.

  12. Experimental and numerical study of short pulse effects in FELs

    CERN Document Server

    Khodyachykh, S; Genz, H; Hessler, C; Richter, A; Asgekar, V

    2004-01-01

    We report the experimental and numerical investigations of the influence of short pulse effects occurring in FELs in different operational regimes for electron bunch lengths which are of the order of the slippage distance. Several observables such as the small signal gain, the macropulse power and the spectral distribution of the FEL radiation were determined experimentally within the constraints of the stable focus regime at the infrared FEL at the S- DALINAC and for the limit cycle regime at the Dutch near infrared FEL FELIX. The experimental findings were compared to predictions of numerical simulations based on the 1D time dependent code FEL1D-OSC. The agreement between experiment and simulation is good. Furthermore, the simulations reveal a chaotic behavior of the macropulses for specific values of the slippage as well as period-doubling, two effects that are predicted to show up in the spectral distribution.

  13. A soft x-ray free electron laser (FEL) using a two-beam elliptical pill-box wake-field cavity

    International Nuclear Information System (INIS)

    Kim, S.H.; Chen, K.W.

    1988-01-01

    Stimulated bremsstrahlung in an undulating electric field in the lasing beam direction (electric wiggler) was shown to be possible from the quantum- mechanical viewpoint. Herein, this possibility is scrutinized from the viewpoint of classical electrodynamics. It is found that if stimulated bremsstrahlung in a transverse undulating magnetic field (magnetic wiggler) occurs, stimulated bremsstrahlung in the electric wiggler must also occur. We further show that a free electron laser (FEL) using a magnetic wiggler to provide a catalyzer field for stimulated bremsstrahlung cannot serve as a practical FEL operating in the soft x-ray region from both theoretical and experimental viewpoints. On the other hand, the authors demonstrate that the FEL using a traveling wake field in a two-beam elliptical pill-box cavity is well suited as a source of coherent radiation in the soft x-ray region

  14. Towards diffractive imaging with single pulses of FEL radiation. Dynamics within irradiatied samples and their influence on the analysis of imaging data

    International Nuclear Information System (INIS)

    Wang, Fenglin

    2010-08-01

    3D single particle coherent diffraction imaging (CDI) of bioparticles (such as proteins, macromolecules and viruses) is one of the main possible applications of the new generation of light sources: free-electron lasers (FELs), which are now available at FLASH (Hamburg, Germany) and LCLS (Stanford, U.S.A.). The extremely bright and ultrashort FEL pulses potentially enable CDI to achieve high resolution down to subnanometer length scale. However, intense FEL pulses cause serious radiation damage in bioparticles, even during single shots, which may set the resolution limits for CDI with FELs. Currently, since the signal-to-noise ratio is very low for small biological particles, direct experimental study of radiation damage in the single particle imaging is fairly difficult. Single atomic (noble gas) clusters become good objects to reveal effects of radiation damage processes on CDI with FEL radiation. This thesis studies three aspects of the radiation damage problem, which are treated in three independent chapters: (1) Molecular Dynamics simulations to quantitively describe radiation damage processes within irradiated atomic clusters during single pulses; (2) reconstruction analysis of single-shot CDI diffraction patterns of atomic clusters, which may potentially help to understand the radiation damage occurring in biological samples; and (3) testing the effects of coating water layers in CDI, which is supposed to minimize the radiation damage in irradiated bioparticles. (orig.)

  15. Towards diffractive imaging with single pulses of FEL radiation. Dynamics within irradiatied samples and their influence on the analysis of imaging data

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Fenglin

    2010-08-15

    3D single particle coherent diffraction imaging (CDI) of bioparticles (such as proteins, macromolecules and viruses) is one of the main possible applications of the new generation of light sources: free-electron lasers (FELs), which are now available at FLASH (Hamburg, Germany) and LCLS (Stanford, U.S.A.). The extremely bright and ultrashort FEL pulses potentially enable CDI to achieve high resolution down to subnanometer length scale. However, intense FEL pulses cause serious radiation damage in bioparticles, even during single shots, which may set the resolution limits for CDI with FELs. Currently, since the signal-to-noise ratio is very low for small biological particles, direct experimental study of radiation damage in the single particle imaging is fairly difficult. Single atomic (noble gas) clusters become good objects to reveal effects of radiation damage processes on CDI with FEL radiation. This thesis studies three aspects of the radiation damage problem, which are treated in three independent chapters: (1) Molecular Dynamics simulations to quantitively describe radiation damage processes within irradiated atomic clusters during single pulses; (2) reconstruction analysis of single-shot CDI diffraction patterns of atomic clusters, which may potentially help to understand the radiation damage occurring in biological samples; and (3) testing the effects of coating water layers in CDI, which is supposed to minimize the radiation damage in irradiated bioparticles. (orig.)

  16. Design and implementation of Web-based SDUV-FEL engineering database system

    International Nuclear Information System (INIS)

    Sun Xiaoying; Shen Liren; Dai Zhimin; Xie Dong

    2006-01-01

    A design of Web-based SDUV-FEL engineering database and its implementation are introduced. This system will save and offer static data and archived data of SDUV-FEL, and build a proper and effective platform for share of SDUV-FEL data. It offers usable and reliable SDUV-FEL data for operators and scientists. (authors)

  17. FEL induced molecular operation on cultured fibroblast and cholesterol ester

    International Nuclear Information System (INIS)

    Awazu, Kunio; Ogino, Seiji; Nishimura, Eiichi; Tomimasu, Takio; Yasumoto, Masato.

    1997-01-01

    Free Electron Lasers can be used to molecular operation such as the delivery of a number of molecules into cells or the separation of cholesterol ester. First, cultured NIH3T3 cells are exposed to high-intensity short pulse Free Electron Laser (FEL). The FEL is tuned to an absorption maximum wavelength, 6.1 μm, which was measured by microscopic FTIR. A fluorescence dye in the cell suspension is more absorbed into the cell with the FEL exposure due to the FEL-induced mechanical stress to the cell membrane. A quantitative fluorescence microscopy is used to determine the efficiency of delivery. Second, as a compound in a lipid cell, cholesterol ester was exposed to 5.75 μm FEL. FTIR measurement was done to evaluate the modification of the cholesterol ester. The result showed that the fluorescence intensity of sample cells were higher than that of control cells, and there was significant difference between the control and the sample group. Blebbing and the colony formation of the cells were observed for cells with mechanical stress. As for the cholesterol ester, it can be modified by the FEL irradiation. These results showed that FEL can be used as a molecular operational tool by photo-chemical and photo-mechanical interaction. (author)

  18. Spontaneous emission effects in optically pumped x-ray FEL

    Energy Technology Data Exchange (ETDEWEB)

    Smetanin, I.V.; Grigor`ev, S.V. [P.N. Lebedev Physics Institute, Moscow (Russian Federation)

    1995-12-31

    An effect of spontaneous emission in both quantum and classical regimes of the optically pumped X-ray free electron laser (FEL) in investigated. The quantum properties of an FEL are determined by the ratio of the separation {h_bar} between the absorption and emission lines (i.e. the quanta emitted) and their effective width {Delta}{epsilon} {eta}={h_bar}/{Delta}{epsilon}. In the conventional classical regime {eta} {much_lt} 1 an electron emits and absorbes a great number of shortwavelength photons over the interaction region, the gain in FEL being the result of these competitive processes. In the quantum limit {eta} {much_gt} 1 the emission and absorption lines are completely separated and thus the FEL becomes a two-level quantum oscillator with a completely inverted active medium. Spontaneous emission causes the electron to leave the range of energies where resonant interaction with the laser field occurs, thus effectively reducing the number of particles that take part in generating the induced X-ray signal. This effect is found to be crucial for lasing in optically pumped X-ray FEL. The characteristic relaxation times are calculated for both classical and quantum FEL regimes. It is shown that spontaneous emission results in FEL electron beam threshold current, which is of rather high value. An optimal range of pumping laser intensities is determined.

  19. The Present Applications of IR FEL at Peking University

    CERN Document Server

    Yang Li Min; Zhao, Kui

    2004-01-01

    In this study the sections of human tissues were treated under 9.5 μm FEL in the BFEL based on the vibrational spectroscopic investigation that significant differences occur between normal and malignant tissues. Under the defocus condition, the burning of tissue section at some part while other part remains unchanged, suggesting that the FEL can selectively destroy some part of tissue. Vibrational spectroscopic and microscopic methods have shown that the FEL can induce decomposition of malignant tissues. The application of FEL whose wavelength is on the characteristic bands of malignant tissues may provide a new method to kill cancer cells with higher selectivity. For understanding the interactions between FEL and biological tissues, structure changes of substances under irradiation by FEL of 9.414 μm and 6.228 μm were measured using FTIR spectroscopy. The samples include ATP, ADP, AMP, and D-ribose, etc. The FTIR spectra of the molecules before and after irradiation of FEL indicate...

  20. High-power FEL design issues - a critical review

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko, V.N.; Madey, J.M.J.; O`Shea, P.G. [Duke Univ., Durham, NC (United States)

    1995-12-31

    The high-average power capability of FELs has been much advertised but little realized. In this paper we provide a critical analysis of the technological and economic issues associated with high-average power FEL operation from the UV to near IR. The project of IR FEL for the Siberian Center of photochemical researches is described. The distinguished features of this project are the use of the race-track microtron-recuperator and the {open_quotes}electron output of radiation{close_quotes}. The building for the machine is under reconstruction now. About half of hardware has been manufactured. The assembly of installation began.

  1. Optical properties of infrared FELs from the FELI Facility II

    Energy Technology Data Exchange (ETDEWEB)

    Saeki, K.; Okuma, S.; Oshita, E. [Free Electron Laser Institute, Osaka (Japan)] [and others

    1995-12-31

    The FELI Facility II has succeeded in infrared FEL oscillation at 1.91 {mu} m using a 68-MeV, 40-A electron beam from the FELI S-band linac in February 27, 1995. The FELI Facility II is composed of a 3-m vertical type undulator ({lambda}u=3.8cm, N=78, Km a x=1.4, gap length {ge}20mm) and a 6.72-m optical cavity. It can cover the wavelength range of 1-5{mu}m. The FELs can be delivered from the optical cavity to the diagnostics room through a 40-m evacuated optical pipeline. Wavelength and cavity length dependences of optical properties such as peak power, average power, spectrum width, FEL macropulse, FEL transverse profile are reported.

  2. Study on silicon isotope separation at FEL-SUT

    International Nuclear Information System (INIS)

    Nomaru, Keiji; Chernyshev, A.V; Nakajima, Noriaki; Kuroda, Haruo

    2002-01-01

    Aiming for the study of the isotope separation of silicon by the FEL, multi-photon dissociation of SiF 3 I by the irradiation with the light of TEA-CO 2 laser and by the co-irradiation with the lights from IR-FEL and TEA-CO 2 laser was investigated. By the irradiation of the FEL, the vibrational bands of SiF 3 I were red-shifted and the dissociation cross-section for the TEA-CO 2 laser increased. By the co-irradiation with FEL light at the frequency of 975 cm -1 , the maximum dissociation rate was enhanced up to three times. (author)

  3. Milestone experiments for single pass UV/X-ray FELs

    International Nuclear Information System (INIS)

    Ben-Zvi, I.

    1994-01-01

    In the past decade, significant advances have been made in the theory and technology of high brightness electron beams and single pass FELS. These developments facilitate the construction of practical UV and X-ray FELs and has prompted proposals to the DOE for the construction of such facilities. There are several important experiments to be performed before committing to the construction of dedicated user facilities. Two experiments are under construction in the IR, the UCLA Self Amplified Spontaneous Emission experiment and the BNL laser seeded Harmonic Generation experiment. A multi-institution collaboration is being organized about a 210 MeV electron linac available at BNL and the 10 meter tong NISUS wiggler. This experiment will be done in the UV and will test various experimental aspects of electron beam dynamics, FEL exponential regime with gain guiding, start up from noise, seeding and harmonic generation. These experiments will advance the state of FEL research and lead towards future dedicated users' facilities

  4. Perspective: Opportunities for ultrafast science at SwissFEL

    Directory of Open Access Journals (Sweden)

    Rafael Abela

    2017-11-01

    Full Text Available We present the main specifications of the newly constructed Swiss Free Electron Laser, SwissFEL, and explore its potential impact on ultrafast science. In light of recent achievements at current X-ray free electron lasers, we discuss the potential territory for new scientific breakthroughs offered by SwissFEL in Chemistry, Biology, and Materials Science, as well as nonlinear X-ray science.

  5. Short Pulses THz FEL for the Oxford Accelerator Science Laboratory

    OpenAIRE

    Chanwattana, Thakonwat; Bartolini, Riccardo; Seryi, Andrei; Bartolini, Riccardo; Tsesmelis, Emmanuel

    2014-01-01

    The Accelerator Science Laboratory (ASL) is under development at the John Adams Institute in Oxford with the aim of fostering advanced accelerator concepts and applications. The option to install a short pulse THz FEL based on a conventional RF accelerator driven by a RF photocathode gun is being investigated. This report presents the concept of the facility, the accelerator physics and FEL studies and engineering integration in the University physics department.

  6. Analysis and comparison between electric and magnetic power couplers for accelerators in Free Electron Lasers (FEL)

    Science.gov (United States)

    Serpico, C.; Grudiev, A.; Vescovo, R.

    2016-10-01

    Free-electron lasers represent a new and exciting class of coherent optical sources possessing broad wavelength tunability and excellent optical-beam quality. The FERMI seeded free-electron laser (FEL), located at the Elettra laboratory in Trieste, is driven by a 200 m long, S-band linac: the high energy part of the linac is equipped with 6 m long backward traveling wave (BTW) structures. The structures have small iris radius and a nose cone geometry which allows for high gradient operation. Development of new high-gradient, S-band accelerating structures for the replacement of the existing BTWs is under consideration. This paper investigates two possible solutions for the RF power couplers suitable for a linac driven FEL which require reduced wakefields effects, high operating gradient and very high reliability. The first part of the manuscript focuses on the reduction of residual field asymmetries, while in the second analyzes RF performances, the peak surface fields and the expected breakdown rate. In the conclusion, two solutions are compared and pros and cons are highlighted.

  7. Harmonic Cascade FEL Designs for LUX, a Facilty for Ultrafast X-ray Science

    CERN Document Server

    John, Corlett; Penn, Gregory; Zholents, Alexander A

    2004-01-01

    LUX is a proposed facility for ultrafast X-ray science, based on an electron beam accelerated to ~3-GeV energy in a superconducting, recirculating linac.Included in the design are multiple FEL beamlines which use the harmonic cascade approach to produce coherent XUV & soft X-ray emission beginning with a strong input external laser seed at ~200 nm wavelength. Each cascade module generally operates in the low-gain regime and is composed of a radiator together with a modulator section, separated by a magnetic chicane. The chicane temporally delays the electron beam pulse in order that a "virgin" pulse region (with undegraded energy spread) be brought into synchronism with the radiation pulse. For each cascade, the output photon energy can be selected over a wide range by varying the seed laser wavelength and the field strength in the undulators. We present numerical simulation results, as well as those from analytical models, to examine predicted FEL performance. We also discuss lattice considerations perti...

  8. Single-shot beam profile diagnostics for x-ray FEL's using gas fluorescence

    Science.gov (United States)

    Feng, Yiping; Zhu, Diling; Weninger, Clemens; Alonso-Mori, Roberto; Chollet, Matthieu; Damiani, Daniel S.; Glownia, James M.; Hastings, Jerome B.; Nelson, Silke; Song, Sanghoon; Robert, Aymeric

    2017-06-01

    We report experimental demonstration of capturing single-shot X-ray Free-electron Laser (FEL) beam profiles using gas fluorescence. The measurement was carried out at the Linac Coherent Light Source using 7 keV hard X-rays propagating through ambient air. The nitrogen fluorescence emitted upon the passage of the X-ray FEL beam were imaged using a highly sensitive optical setup, and there was sufficient optical yield that single-shot measurements were feasible. By taking two orthogonal and simultaneous images, the beam trajectory could be determined in a nearly non-invasive manner, and is best suited for photon energies in the soft X-ray regime, where such a diagnostic capability has been largely unavailable previously. The integrated intensity of the images could also serve as a non-invasive intensity monitor, complementary to current implementations of gas- and solidbased monitors. High repetition-rate Free-electron Lasers can greatly benefit from such a new diagnostic tool for eliminating potential thermal damages.

  9. Accessible coherence and coherence distribution

    Science.gov (United States)

    Ma, Teng; Zhao, Ming-Jing; Zhang, Hai-Jun; Fei, Shao-Ming; Long, Gui-Lu

    2017-04-01

    The definition of accessible coherence is proposed. Through local measurement on the other subsystem and one-way classical communication, a subsystem can access more coherence than the coherence of its density matrix. Based on the local accessible coherence, the part that cannot be locally accessed is also studied, which we call it remaining coherence. We study how the bipartite coherence is distributed by partition for both l1 norm coherence and relative entropy coherence, and the expressions for local accessible coherence and remaining coherence are derived. We also study some examples to illustrate the distribution.

  10. Electron Beam Diagnostics Of The JLAB UV FEL

    Energy Technology Data Exchange (ETDEWEB)

    Evtushenko, Pavel; Benson, Stephen; Biallas, George; Coleman, James; Dickover, Cody; Douglas, David; Marchlik, Matthew; Sexton, Daniel; Tennant, Christopher

    2011-03-01

    In this contribution we describe various systems and aspects of the electron beam diagnostics of the JLab UV FEL. The FEL is installed on a new bypass beam line at the existing 10 kW IR Upgrade FEL. Here, we describe a set of the following systems. A combination of OTR and phosphor viewers is used for measurements of the transverse beam profile, transverse emittance, and Twiss parameters. This system is also used for alignment of the optical cavity of the UV oscillator and to ensure the overlap between the electron beam and optical mode in the FEL wiggler. A system of beam position monitors equipped with log-amp based BPM electronics. Bunch length on the order of 120 fs RMS is measured with the help of a modified Martin-Puplett interferometer. The longitudinal transfer function measurement system is used to set up bunch compression in an optimal way, such that the LINAC RF curvature is compensated using only higher order magnetic elements of the beam transport. This set of diagnostic systems made a significant contribution in achieving first lasing of the FEL after only about 60 hours of beam operation.

  11. Injection System for Microtron-Based Terahertz FEL

    CERN Document Server

    Kazakevich, G M

    2005-01-01

    A reliable injection system of the widely tunable microtron-based terahertz Free Electron Laser (FEL) has been developed and during last few years provides stable operation of the FEL for users. The system is based on the long-life thermionic cathode assembly using 2.5 mm-in diameter monocrystalline LaB6 emitter, heated by the tungsten cylindrical filament with the power consumption less than 50 W. The cathode emits the macro-pulse current in the range of 1-1.4 A providing operation of the terahertz FEL during more than 1000 h. The cathode assembly is installed on the cover of the I-type microtron accelerating cavity in location providing an efficient injection for the acceleration with variable number of orbits. This variation widely changes the energy of the electron beam and allows on-the-fly retuning of the FEL in the range of 1-3 THz. Pulse-signal system stabilizing the emission current prevents randomized break-downs in the accelerating cavity and decreases macro-pulse power fluctuations of the FEL radi...

  12. Prospects of the BESSY High-Energy FEL

    CERN Document Server

    Goldammer, K; Follath, R; Meseck, A

    2005-01-01

    BESSY proposes a linac-based High-Gain Harmonic-Generation (HGHG) free electron laser (FEL) facility with three independent FEL lines. In the BESSY High-Energy-FEL (HE-FEL), a seed laser wavelength of 280nm is downconverted to 1.24nm by a cascade of four HGHG-stages. This procedure requires a high brightness electron beam and a high power seed laser. With the nominal set of beam parameters, radiation power in the range of GWs can be achieved. However, the signal to noise ratio degrades in each HGHG stage. This motivated intensive studies on the possibilities to further optimize the performance of the BESSY HE-FEL. In this paper, we report on three methods aiming to control the signal to noise ratio. They include simulation studies of new seeding schemes with HHG-lasers at shorter wavelengths and seeding with higher seed powers. Also, a concept for the integration of monochromators between two HGHG-stages has been worked out, see also [1]. All methods were studied extensively with regard to their influence on ...

  13. Coherent Synchrotron Radiation as a Diagnostic Tool for the LCLS Longitudinal Feedback System

    CERN Document Server

    Wu, Juhao; Huang, Zhirong

    2005-01-01

    The Linac Coherent Light Source (LCLS) will be the world's first x-ray free-electron laser (FEL). To ensure the vitality of FEL lasing, a longitudinal feedback system is required together with other diagnostics. In this paper, we study the possibility of using Coherent Synchrotron Radiation (CSR) from the chicane as the diagnostic tool for bunch length feedback. Calculations show that CSR is a good candidate, even for the non-Gaussian, double-horn longitudinal charge distribution. We further check the feasibility for low and high charge options, and also the possibility for detecting the microbunching.

  14. PAL Linac Upgrade for a 1-3 XFEL

    CERN Document Server

    Oh, J O

    2004-01-01

    With the successful SASE FEL saturation at 80 nm wavelength at TTF1, TTF2 will begin re-commissioning in the fall of 2004 as an FEL user facility to 6 nm with 1 GeV beams. The high gain harmonic generation is also confirmed by the DUV-FEL experiments at 266 nm with seeding wavelength at 800 nm. In order to realize a hard X-ray SASE FEL (SASE XFEL) with a lower energy beams, we need a long in-vacuum mini-gap undulator and a GeV-scale FEL driving linac that can supply an extremely low slice emittance, a high peak current, and an extremely low slice energy spread. PAL is operating a 2.5 GeV electron linac as a full-energy injector to the PLS storage ring. By adding an RF photo-cathode gun, two bunch compressors, and a 0.5 GeV S-band injector linac to the existing PLS linac, and by installing a 60 m long in-vacuum undulator, the PLS linac can be converted to a SASE XFEL facility (PAL XFEL) which supplies coherent X-ray down to 0.3 nm wavelength. The third harmonic enhancement technique can supply coherent hard X-...

  15. Coherence limits and chirp control in long pulse free electron laser oscillator

    Directory of Open Access Journals (Sweden)

    Y. Socol

    2005-08-01

    Full Text Available We report experimental studies of the spectral linewidth and chirp characteristics of the mm-wave rf radiation of the Israeli Electrostatic-Accelerator free electron laser (EA-FEL, along with theory and numerical simulations. The simulations, matching the experimental data, were carried out using a space-frequency-domain model. EA-FELs have the capacity to generate long pulses of tens microseconds and more, that in principle can be elongated indefinitely (cw operation. Since a cold beam FEL is by nature a “homogeneously broadened laser,” EA-FEL can operate, unlike other kinds of FELs, at a single longitudinal mode (single frequency. This allows the generation of very coherent radiation. The current status of the Israeli Tandem Electrostatic-Accelerator FEL, which is based on an electrostatic Van de Graaff accelerator, allows the generation of pulses of tens microseconds duration. It has been operated recently past saturation, and produced single-mode coherent radiation of record narrow inherent relative linewidth ∼Δf/f=10^{-6} at frequencies near 100 GHz. A frequency chirp was observed during the pulses of tens of microseconds (0.3–0.5  MHz/ms. This is essentially a drifting “frequency-pulling effect,” associated with the accelerator voltage drop during the pulse. Additionally, damped relaxation of the FEL oscillator was experimentally measured at the beginning and the end of the lasing pulse, in good correspondence to our theory and numerical simulations. We propose using the chirped signal of the pulsed EA-FEL for single pulse sweep spectroscopy of very fine resolution. The characteristics of this application are analyzed based on the experimental data.

  16. High-gain ring FEL as a master oscillator for X-ray generation

    Energy Technology Data Exchange (ETDEWEB)

    Vinokurov, N.A. E-mail: n.a.vinokurov@inp.nsk.su; Shevchenko, O.A

    2004-08-01

    High-gain free electron laser (FEL) with bends between undulator sections is discussed. Such FEL configuration may be used for the mirror-free master oscillator in X-ray band. The oscillator linewidth is estimated. Results of computation for the state-of-art electron beam parameters show the feasibility of the X-ray oscillator FEL.

  17. Beam transport design for a recirculating-linac FEL driver

    International Nuclear Information System (INIS)

    Neuffer, D.; Douglas, D.; Li, Z.; Cornacchia, M.; Garren, A.

    1996-01-01

    The beam transport system for the CEBAF Industrial FEL includes a two-pass transport of the beam with acceleration from injector to wiggler, followed by energy recovery transport from wiggler to dump. From that context, the authors discuss the general problem of multi-pass energy-recovery beam transport for FELs. Tunable, nearly-isochronous, large-momentum-acceptance transport systems are required. The entire transport must preserve beam quality, particularly in the acceleration transport to the wiggler, and have low losses throughout the entire system. Various possible designs are presented, and results of dynamic analyses are discussed

  18. Third-harmonic lasing at JAERI-FEL

    CERN Document Server

    Hajima, R; Nishimori, N; Kikuzawa, N; Minehara, E J

    2001-01-01

    We have demonstrated FEL lasing at the third harmonic in JAERI-FEL driven by a superconducting linac. The lasing was achieved with a super enhanced gold-coated mirror tuned to 7 mu m, which is a gold-coated copper mirror with Zn-Se multi-layer deposited on the surface. Lasing at the third harmonic is in the single-supermode regime with an average power of 15 W. The small-signal gain is estimated from the cavity-length detuning curve found to be 7.5%.

  19. Parameter analysis for a high-gain harmonic generation FEL using a recently developed 3D polychromatic code

    CERN Document Server

    Biedron, S G; Yu, L H

    2000-01-01

    One possible design for a fourth-generation light source is the high-gain harmonic generation (HGHG) free-electron laser (FEL). Here, a coherent seed with a wavelength at a subharmonic of the desired output radiation interacts with the electron beam in an energy-modulating section. This energy modulation is then converted into spatial bunching while traversing a dispersive section (a three-dipole chicane). The final step is passage through an undulator tuned to the desired higher harmonic output wavelength. The coherent seed serves to suppress and can be at a much lower subharmonic of the output radiation. Recently, a 3D code that includes multiple frequencies, multiple undulators (both in quantity and/or type), quadrupole magnets, and dipole magnets was developed to easily simulate HGHG. Here, a brief review of the HGHG theory, the code development, the Accelerator Test Facility's (ATF) HGHG FEL experimental parameters, and the parameter analysis from simulations of this specific experiment will be discussed...

  20. The FEL-TNO uniform open systems model

    NARCIS (Netherlands)

    Luiijf, H.A.M.; Overbeek, P.L.

    1989-01-01

    The FEL-TNO Uniform Open Systems Model is based upon the IS0/0SI Basic Reference Model and integrates operating systems, (OSI) networks, equipment and media into one single uniform nodel. Usage of the model stimulates the development of operating systen and network independent applications and puts

  1. Towards imaging of ultrafast molecular dynamics using FELs

    NARCIS (Netherlands)

    Rouzee, A.; Johnsson, P.; Rading, L.; Siu, W.; Huismans, Y.; Duesterer, S.; Redlin, H.; Tavella, F.; Stojanovic, N.; Al-Shemmary, A.; Lepine, F.; Holland, D. M. P.; Schlathölter, Thomas; Hoekstra, R.; Fukuzawa, H.; Ueda, K.; Vrakking, M. J. J.; Hundertmark, A.

    2013-01-01

    The dissociation dynamics induced by a 100 fs, 400 nm laser pulse in a rotationally cold Br-2 sample was characterized by Coulomb explosion imaging (CEI) using a time-delayed extreme ultra-violet (XUV) FEL pulse, obtained from the Free electron LASer in Hamburg (FLASH). The momentum distribution of

  2. Dispersion relations for 1D high-gain FELs

    International Nuclear Information System (INIS)

    Webb, S.D.; Litvinenko, V.N.

    2010-01-01

    We present analytical results for the one-dimensional dispersion relation for high-gain FELs. Using kappa-n distributions, we obtain analytical relations between the dispersion relations for various order kappa distributions. Since an exact solution exists for the kappa-1 (Lorentzian) distribution, this provides some insight into the number of modes on the way to the Gaussian distribution.

  3. Status of the project of Novosibirsk high power FEL

    Energy Technology Data Exchange (ETDEWEB)

    Pinayev, I.V.; Erg, G.I.; Gavrilov, N.G. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation)] [and others

    1995-12-31

    The project of IR FEL for the Siberian Center of photochemical researches is described. The distinguished features of this project are the use of the race-track microtron-recuperator and the {open_quotes}electron output of radiation{close_quotes}. The building for the machine is under reconstruction now. About half of hardware has been manufactured. The assembly of installation began.

  4. Milestone experiments for single pass UV/X-ray FELs

    Science.gov (United States)

    Ben-Zvi, Ilan

    1995-04-01

    In the past decade, significant advances have been made in the theory and technology of high brightness electron beams and single pass FELs. These developments facilitate the construction of practical UV and X-ray FELs and has prompted proposals to the DOE for the construction of such facilities. There are several important experiments to be performed before committing to the construction of dedicated user facilities. Two experiments are under construction in the IR, the UCLA self-amplified spontaneous emission experiment and the BNL laser seeded harmonic generation experiment. A multi-institution collaboration is being organized about a 210 MeV electron linac available at BNL and the 10 m long NISUS wiggler. This experiment will be done in the UV and will test various experimental aspects of electron beam dynamics, FEL exponential regime with gain guiding, start-up from noise, seeding and harmonic generation. These experiments will advance the state of FEL research and lead towards future dedicated users' facilities.

  5. Colorado State University (CSU) accelerator and FEL facility

    NARCIS (Netherlands)

    Milton, S.; Biedron, S.; Harris, J.; Martinez, J.; D'Audney, A.; Edelen, J.; Einstein, J.; Hall, C.; Horovitz, K.; Morin, A.; Sipahi, N.; Sipahi, T.; Williams, J.; Carrico, C.; Van Der Slot, P. J M

    2014-01-01

    The Colorado State University (CSU) Accelerator Facility will include a 6-MeV L-Band (1.3 GHz) electron linear accelerator (linac) with a free-electron laser (FEL) system capable of producing Terahertz (THz) radiation, a laser laboratory, a microwave test laboratory, and a magnetic test laboratory.

  6. Emittance measurements of FEL accelerators using optical transition radiation methods

    International Nuclear Information System (INIS)

    Fiorito, R.B.; Rule, D.W.; Lumpkin, A.H.; Tokar, R.L.; Dowell, D.H.; Sellyey, W.C.; Lowrey, A.R.

    1991-01-01

    Measurements of the emittance of the Boeing FEL accelerator operating at 107 Mev, were performed using optical transition radiation (OTR). The results of the three measurement methods: measurement of beam spot size as a function of magnetic quadrupole focusing strength, two screen beam spot measurements, and beam spot-divergence measurements using a OTR interferometer are compared and shown to be in excellent agreement

  7. FEL-Oscillator simulations with Genesis 1.3

    NARCIS (Netherlands)

    Karssenberg, J.G.; van der Slot, Petrus J.M.; Verschuur, Jeroen W.J.; Volokhine, I.; Boller, Klaus J.

    2006-01-01

    Modeling free-electron laser (FEL) oscillators requires calculation of both the light-beam interaction within the undulator and the propagation of the light outside the undulator. We present a paraxial Optical Propagation Code (OPC) based on the Spectral Method and Fresnel Diffraction Integral,

  8. Modelling mirror aberrations in FEL oscillators using OPC

    NARCIS (Netherlands)

    van der Slot, Petrus J.M.; Karssenberg, J.G.; Boller, Klaus J.

    2007-01-01

    Several high power free-electron lasers (FELs) are currently under design, operational or being upgraded. One central issue is the beam outcoupling and mirror deformation due to absorbed power. Here we present an extension to the OPC code that allows it to model mirror distorions. We use this code

  9. Design study of a 7 kW, visible wavelength FEL

    International Nuclear Information System (INIS)

    Chen, S.C.; Danly, B.G.; Temkin, R.J.; Wurtele, J.; Yang, B.

    1990-01-01

    The MIT Lincoln Laboratory is investigating the possibility of building a free electron laser (FEL) operating at an average power of about 7 kW at wavelengths of 500--600 nm. Additional specifications for the FEL include a bandwidth of less than 0.1 cm -1 and a micropulse separation of less than 10 ns. The design study has investigated the basic design parameters of the FEL including an analysis of the electron accelerator, beam line, wiggler and optical cavity. A nonlinear model of the FEL has been used to calculate the FEL gain and efficiency. The required output power appears achievable from an FEL operating at more than 1% efficiency with a conventional RF accelerator. Details of the FEL design are presented in this report which represent the final report for the year from September 1, 1989 to August 31, 1990. 28 refs., 13 figs., 5 tabs

  10. Operation of the OK-4/Duke storage ring FEL below 200 nm

    CERN Document Server

    Litvinenko, V N; Pinayev, I V; Wu Yin

    2001-01-01

    For a number of years the wavelength of 200 nm was a psychological barrier for FEL oscillators. The progress towards short wavelength was marginal since the OK-4/VEPP-3 storage ring FEL lased at 240 nm in 1988. After 10 years, in 1998, the OK-4/Duke FEL and the NIJI-IV FEL group moved the limit to 217 and 212 nm, respectively. Improvements of the OK-4/Duke storage ring FEL gain above 10% and the use of custom manufactured mirror coatings brought the success in August 1999. The OK-4 FEL lased in the range from 193.7 to 209.8 nm using electron energies from 500 to 800 MeV. In this paper, we present the description of the OK-4/Duke FEL up-grades and the lasing results below 200 nm obtained in August and October of 1999.

  11. Generation of Coherent Synchrotron Radiation from JAERI-ERL

    CERN Document Server

    Hajima, R; Kikuzawa, N; Minehara, E J; Nagai, R; Nishitani, T; Sawamura, M

    2005-01-01

    An electron beam with high-average current and short bunch length can be accelerated by energy-recovery linac. Coherent synchrotron radiation (CSR) from such an electron beam will be a useful light source around millimeter wavelength. We report results from a preliminary measurement of CSR emitted from a bending magnet of JAERI-ERL. Possible enhancement of CSR power by FEL micro-bunching is also discussed.

  12. Analysis of coherence properties of 3-rd generation synchrotron sources and free-electron lasers

    International Nuclear Information System (INIS)

    Vartanyants, I.A.; Singer, A.

    2009-07-01

    A general theoretical approach based on the results of statistical optics is used for the analysis of the transverse coherence properties of 3-rd generation synchrotron sources and X-ray free-electron lasers (XFEL). Correlation properties of the wave elds are calculated at different distances from an equivalent Gaussian Schell-model source. This model is used to describe coherence properties of the five meter undulator source at the synchrotron storage ring PETRA III. In the case of XFEL sources the decomposition of the statistical fields into a sum of independently propagating transverse modes is used for the analysis of the coherence properties of these new sources. A detailed calculation is performed for the parameters of the SASE1 undulator at the European XFEL. It is demonstrated that only a few modes contribute significantly to the total radiation field of that source. (orig.)

  13. Cavity-mirror degradation in the deep-UV FEL

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, K.; Yamazaki, T.; Sei, N. [Electrotechnical Lab., Ibaraki (Japan)] [and others

    1995-12-31

    It is known that the degradation of dielectric multilayer mirrors used in short wavelength free-electron lasers (FELs) is caused by the carbon contamination on the mirror surface and the defects inside the dielectrics. We reported last year that the degraded dielectric multilayer mirrors can be repaired with both surface treatment by RF-induced oxygen plasma and thermal annealing. However, such a mirror degradation is still one of the most critical issues in the deep ultraviolet (UV) FELs, because the fundamental undulator radiation resonating in the laser cavity, the intensity of which is much higher than that of higher harmonics, can be sufficiently energetic to cause the mirror degradation through photochemical reactions. We are investigating the mirror degradation mainly in the deep UV region down to 240 nm. The experimental results will be shown. The mirror degradation mechanism will be discussed.

  14. FEL and Libera both Push Performance into New Frontiers

    CERN Document Server

    Ursic, Rok

    2004-01-01

    Free Electron Lasers and Libera electron beam position processor share a common vocation – they both push performance into new frontiers. Advances in electron accelerator technology that enabled FELs to fulfill their earliest days promises have also been due to the recent developments in the beam instrumentation. Libera that has till know been successfully employed in the light sources projects promises to become an indispensable tool also in the FEL field. The three main advantages of Libera are: all-in-one, customization and connectivity. All-in-one is the concept of unification of various building blocks and thus various functionalities in one product. The customization is enabled by the product’s reconfigurability that allows it to grow and support new requirements and application without changing hardware. The consequence of the two is the capacity of the single instrument to perform a variety of tasks that before were split among different devices. Connectivity improves the communication between contr...

  15. Terahertz IFEL/FEL Microbunching for Plasma Beatwave Accelerators

    CERN Document Server

    Sung, Chieh; Joshi, Chandrashekhar; Musumeci, Pietro; Pellegrini, Claudio; Ralph, Joseph; Reiche, Sven; Rosenzweig, James E; Tochitsky, Sergei Ya

    2005-01-01

    In order to obtain monoenergetic acceleration of electrons, phase-locked injection using electron microbunches shorter than the accelerating structure is necessary. For a laser-driven plasma beatwave accelerator experiment, we propose to microbunch the electrons by interaction with terahertz (THz) radiation in an undulator via two mechanisms– free electron laser (FEL) and inverse free electron laser (IFEL). Since the high power FIR radiation will be generated via difference frequency mixing in GaAs by the same CO2 beatwave used to drive the plasma wave, electrons could be phase-locked and pre-bunched into a series of microbunches separated with the same periodicity. Here we examine the criteria for undulator design and present simulation results for both IFEL and FEL approaches. Using different CO2 laser lines, electrons can be microbunched with different periodicity 300 – 100 mm suitable for injection into plasma densities in the range 1016 – 1017 cm-3, respectively. The requiremen...

  16. Feedback Control Of Dynamical Instabilities In Classical Lasers And Fels

    CERN Document Server

    Bielawski, S; Szwaj, C

    2005-01-01

    Dynamical instabilities lead to unwanted full-scale power oscillations in many classical lasers and FEL oscillators. For a long time, applications requiring stable operation were typically performed by working outside the problematic parameter regions. A breakthrough occurred in the nineties [1], when emphasis was made on the practical importance of unstable states (stationary or periodic) that coexist with unwanted oscillatory states. Indeed, although not observable in usual experiments, unstable states can be stabilized, using a feedback control involving arbitrarily small perturbations of a parameter. This observation stimulated a set of works leading to successful suppression of dynamical instabilities (initially chaos) in lasers, sometimes with surprisingly simple feedback devices [2]. We will review a set of key results, including in particular the recent works on the stabilization of mode-locked lasers, and of the super-ACO, ELETTRA and UVSOR FELs [3].

  17. A wiggler magnet for FEL low voltage operation

    Energy Technology Data Exchange (ETDEWEB)

    Al-Shamma`a, A.; Stuart, R.A.; Lucas, J.

    1995-12-31

    In low voltage FELs (ie, 200kV), operation is necessarily in the microwave frequency range for wiggler periods of the order of cms., so that a waveguide system is mandatory. Also, because of the relatively low velocity of the electron beam, the wiggle amplitude of the electron beam can be much larger than is normal for highly relativistic FELs. Both these factors mean that the electron trajectory must be carefully controlled to avoid beam collision with the waveguide walls. A wiggler system with half poles at entrance and exit is not an acceptable solution because of the offset is gives rise to the electron trajectory. Consequently, we have designed and constructed a wiggler magnet with exponential entrance and exit tapers for a minimal deflection and displacement of the electron beam. Simulations and experimental measurements showed that an on axis trajectory is easily obtainable.

  18. Help system for control of JAERI FEL (Free Electron laser)

    International Nuclear Information System (INIS)

    Sugimoto, Masayoshi

    1993-01-01

    The control system of JAERI FEL (Free Electron Laser) has a help system to provide the information necessary to operate the machine and to develop the new user interface. As the control software is constructed on the MS-Windows 3.x, the hyper-text feature of the Windows help system can be accessed. It consists of three major parts: (1) on-line help, (2) full document, and (3) tutorial system. (author)

  19. Status of the tandem FEL project development in Israel

    International Nuclear Information System (INIS)

    Benzvi, I.; Sokolowski, J.; Jerby, E.; Chomski, D.; Ruschin, S.

    1989-01-01

    The authors report the status of a collaborative research project development aimed toward construction of an IR FEL based on the EN tandem electrostatic accelerator of the Weizmann Institute of Science. A preliminary feasibility demonstration project yielded encouraging progress in three aspects: (1) Electron gun and accelerator conversion: A 50-kV 1-A electron gun injector was designed, built, tested, and assembled on the 6-MeV tandem accelerator which was previously converted and conditioned to operate as an electron accelerator in a positively charged HV terminal configuration. Contrary to the configuration of the only electrostatic accelerator FEL demonstrated so far, the electron gun and multistage depressed collector are connected to the ground, and the wiggler is placed in the HV terminal of the straight geometry tandem accelerator. This configuration promises to provide a high current high quality e-beam. (2) Electron-beam transport: The first installation of the electron optical beam recovery system yielded transport efficiency of 80%. Substantial improvement is expected with planned electron optics modifications. An effect, highly significant for realizing long pulse (quasi-cw) FEL operation, was observed experimentally. Due to the damping effect of the accelerator column capacitance network, the voltage terminal stayed constant for milliseconds even with poor beam transport efficiency. This points to the possibility of developing a long pulse FEL which may operate at a single longitudinal mode. (3) Wiggler development: A conventional 4.4-cm period SmCo planar wiggler was acquired and evaluated using a recently constructed floating wire magnetic field measurement setup

  20. A Study of \\"Esme-fel\\" (Gerund in Arabic

    Directory of Open Access Journals (Sweden)

    2010-09-01

    Full Text Available A Study of "Esme-fel" (Gerund in Arabic     Qasem Mokhtari *     Abstract   ''Esme-felha'' (gerund is one of the classifications of word in Arabic. Some linguists and grammarians have classified words into four groups: noun, verb, letter, and ''esme-fel". ''Esmefel" refers to a kind of verb consisting of meaning, action and tense, but it does not get the inflections. ''Esmefel" has some uses including exaggeration in meaning, abridgement of word, and extension of word in interpretation.   ''Esme-felha'' is classified based on different aspects. In terms of reference to verbs, they are classified into "Manghoul" , "Mortajal" , and "Madoul" in terms of rhythm into "Samaee"and "Ghiasee" in terms of "Marate" and ''nakave" into "vajeb-atavif" "vajeb-atankiv", "javaz-otaviz" and "tamkiv" and in terms of tense they are classified into past and present.   ''Esmefel-ha" are similar to verbs in some aspects and different in some other aspects. The similarity of ''esme-felha" with verbs include: 1 meaning, 2 being transitive and intransitive, and 3 displaying subjects and pronouns .The differences of ''esmefel-ha" with verbs contain: 1 not preceding the verbs, 2 not having "fathe" with verbs with present tense in reply to ''esme-felha", 3 not using ''esmefel-ha" with omitted form, 4 not being "motasrref", and 5not accepting the inflection of verbs.   ''Esme-felha" are similar to nouns in terms of receiving "Tanvin", being "mossanna" and plural, being "Mozaf", receiving the definite article "Alef" and "lam ", and the possibility of appearing in diminutive forms (tasghir paziree. In terms of "Morab" and "Mabny", there exist different opinions. However, it seems appropriate to consider them as "esme fel" as separate entities with no "Erab" for them.     Key words : Esme-fel, Noun, Verb, Arabic language   * Assistant Professor, Department of Arabic Language and Literature, University of Arak

  1. The JAERI superconducting RF linac-based FELS and THEIR cryogenics

    International Nuclear Information System (INIS)

    Minehara, Eisuke J.

    2003-01-01

    In the 21st century, we need a powerful and efficient free-electron laser (FEL) for academic and industrial uses in almost all fields. In order to realize such a tunable, highly-efficient, high average power, high peak power and ultra-short pulse FEL, the JAERI FEL group and I have developed an industrial FEL driven by a compact, stand-alone and zero-boil off super-conducting rf linac with an energy-recovery geometry. Our discussions on the JAERI FEL and cryogenics will cover market-requirements for the industrial FELs, some answers from the JAERI compact, stand-alone and zero-boil off cryostat concept and operational experiences over these 9 years, our discovery of the new, highly-efficient, high-power, and ultra-short pulse lasing mode, and the energy-recovery geometry. (author)

  2. Present and next steps of the JAERI superconducting rf linac based FEL program

    International Nuclear Information System (INIS)

    Minehara, E.J.; Yamauchi, T.; Sugimoto, M.

    2000-01-01

    The JAERI superconducting rf linac based FEL has successfully been lased to produce a 0.3 kW FEL light and 100 kW or larger electron beam output in quasi continuous wave operation in 1999. The 1 kW class output as our present program goal will be achieved to improve the optical out coupling method in the FEL optical resonator, the electron gun, and the electron beam optics in the JAERI FEL driver. As our next 5 year program goal is the 100 kW class FEL light and a few tens MW class electron beam output in average, quasi continuous wave operation of the light and electron beam will be planned in the JAERI superconducting rf linac based FEL facility. Conceptual design options needed for such a very high power operation and shorter wavelength light sources will be discussed to improve and to upgrade the exciting facility. (author)

  3. An advanced UV optical cavity for the European FEL project

    CERN Document Server

    Poole, M W; Chesworth, A A; Clarke, J A; Fell, B; Hill, C; Marl, R; Mullacrane, I D; Reid, R J

    2000-01-01

    A European collaboration is constructing a short wavelength FEL for the ELETTRA storage ring. The optical cavity has been designed and constructed at Daresbury Laboratory for delivery to Sincrotrone Trieste in Autumn 1999, following commissioning tests over the Summer. Initial FEL operation will be at 350 nm but subsequently down to 200 nm or less and mirrors will be 40 mm diameter. The 32 m optical cavity is controllable to 0.01 mu rad in mirror pitch and yaw using digital piezo translators. A novel feature is the simultaneous presence of three remotely interchangeable mirrors to extend the tuning range and also to interchange damaged mirrors immediately. In addition, a transfer arm and load-lock arrangement will permit a mirror to be withdrawn from the chamber and replaced without disruption to the UHV system. The FEL is designed to operate at high power (1-10 W) and multi-watt spontaneous emission is also present: power loading has been investigated by FEA analysis and has necessitated specification of a w...

  4. Temporal stability of the UVSOR-FEL micropulse

    CERN Document Server

    Hosaka, M; Yamazaki, J; Hama, H

    2000-01-01

    Optical cavity and control system of the UVSOR-FEL have been newly developed to improve performances and to obtain better availability for user application experiment. Lasings at visible and UV wavelength regions were successfully obtained in test experiments. By optimizing reflectivity and transmission of cavity mirrors, an average out-coupled power of more than 15 mW was achieved at a wavelength of 270 nm. Though a CW lasing zone at the top of a detuning curve was clearly obtained, an oscillation of FEL micropulse time jitter with 60 Hz appeared, which is probably due to a mechanical vibration of the cavity mirror caused by 'sound noise' of the environment. Observed macrotemporal structure has been examined by a computer simulation including both effects of the mirror oscillation and the cavity length detuning. Results suggest that the mirror vibration should be reduced to less than 0.1 mu m to suppress the amplitude of the time jitter comparable to an intrinsic temporal width of the FEL micropulse.

  5. Optical alignment and diagnostics for the ATF microundulator FEL oscillator

    International Nuclear Information System (INIS)

    Babzien, M.; Ben-Zvi, I.; Fang, J.M.

    1995-01-01

    The microundulator FEL oscillator has a wiggler period of 8.8 mm, and is designed for initial lasing at 0.5 microns with a 50 MeV electron beam. The design and performance of the optical diagnostics and alignment are discussed. A HeNe coalignment laser is mode-matched to the resonator cavity for transverse alignment. Interference fringes are observed in the cavity with a pellicle, allowing an alignment tolerance of +/- 10 micro-radians. The same pellicle is used to produce transition radiation by the electron beam. This enables precise transverse alignment of the electron beam to the resonator axis. The HeNe laser is also used to align the wiggler by backlighting its bore. This method aligns the wiggler to the optic axis to a tolerance of +/- 50 microns. A frequency-doubled,pulsed Nd:YAG laser that produces the electron bunch train is also mode-matched to the FEL cavity. The cavity length is adjusted to resonate with this pulse train. Light from the FEL is transported to the diagnostic room using two separate paths: one for the single pass spontaneous emission, and the second for the multipass cavity output. Several diagnostics (CCD camera, photodiode, photomultiplier tube, joulemeter, spectrometer, and streak camera) are used to characterize the light. These instruments measure light energy per micropulse ranging from 10 femto-Joules to 10 micro-Joules

  6. Lightning control system using high power microwave FEL

    Science.gov (United States)

    Shiho, M.; Watanabe, A.; Kawasaki, S.; Ishizuka, H.; Takayama, K.; Kishiro, J.; Shindo, T.; Fujioka, T.

    1996-02-01

    A research project for developing a thunder lightning control system using an induction linac based high power microwave free electron laser (FEL) was started at JAERI. The system will produce a weakly ionized plasma rod in the atmosphere by high power microwaves and control a lightning path, away from, e.g., nuclear power stations and rocket launchers. It has been known that about 1 MW/cm 2 power density is enough for the atmospheric breakdown in the microwave region, which means that a high power microwave FEL with GW level output power is feasible for atmospheric breakdown, and accordingly is feasible for a thunder lightning control tool by making a conductive plasma channel in the atmosphere. From the microwave attenuation consideration in the atmosphere, FELs of 35 GHz (0.13 dB/km), 90 GHz (0.35 dB/km), 140 GHz (1.7 dB/km), and of 270 GHz (4.5 dB/km) are the best candidates for the system. Compared with other proposed lightning control systems using a visible or an ultraviolet laser, the system using microwave has the advantage that microwave has a smaller attenuation with rain or snow which always exists in the real atmospheric circumstances when lightning occurs. A detailed description and feasibility study of the system will be given.

  7. Mode distortion measurements on the Jefferson lab IR FEL

    CERN Document Server

    Benson, S V; Shinn, M

    2002-01-01

    We have previously reported on the analytical calculations of mirror distortion in a high-power FEL with a near-concentric cavity. This analysis allowed us to estimate the power level at which the FEL interaction would be affected, though no exact theory of FEL power vs. distortion exists at this point. Recently we have directly measured the mode size and beam quality as a function of power using a resonator with a center wavelength of 5 mu m. The resonator mirrors were calcium fluoride. This particular material exhibits a large amount of distortion for a given power but, due to the negative slope of refractive index vs. temperature, adds almost no optical phase distortion on the laser output. The mode in the cavity can thus be directly calculated from the measurements at the resonator output. The presence of angular jitter produced raw measurements inconsistent with cold cavity expectations. Removing the effects of the angular jitter, we derive results in agreement with cold cavity measurements. The result i...

  8. Tolerance Studies of a Seeded REVOLVER-Undulator FEL

    CERN Document Server

    Meseck, A

    2005-01-01

    Wide-range wavelength-tunability is one of the key aspects of proposed FEL facilities. Once the electron beam energy and undulator period length is given, the span of the available K-values determines the achievable wavelength range, according to the resonance condition. As the usable range of the K-values is limited by technical considerations like minimum acceptable gap or permanent magnet technology etc, alternatives to enlarge the output wavelength range are of high interest. Using revolver-undulator design, different magnetic structures can be incorporated in the same undulator segment. Thus it is possible to switch between different undulator periods, covering a wider wavelength range at a given FEL-line. Because of the transverse-positions dependency of the magnetic field, the alignment reproducibility of the revolver-undulators is of concern, in particular for the APPEL type devices. Simulation studies have been performed taking the BESSY FEL-lines as examples to investigate the alignment tolerances o...

  9. Numerical study of optical-cavity misalignment effects for a far-infrared FEL

    CERN Document Server

    Sobajima, M; Yokoyama, M; Oda, F; Kawai, M; Miura, H

    2002-01-01

    A far-infrared FEL will be newly installed in the IR FEL Research Center at the Science University of Tokyo (FEL-SUT) in 2002. In this study, optical cavity misalignment effects for the far-infrared FEL are researched by using the simulation code that has been developed at Kawasaki Heavy Industries, Ltd. Results show not only cavity losses but also the gain reduction by the tilt and the offset of the mirror and the offset of the electron beam. The required alignment accuracy is also obtained in this study.

  10. Thin-film deposition method assisted by mid-infrared-FEL

    CERN Document Server

    Yasumoto, M; Ishizu, A; Tsubouchi, N; Awazu, K; Umesaki, N

    2001-01-01

    We propose the novel application of the mid-infrared (MIR) FEL to the thin-film fabrication process. During the application, a substrate on which a thin film is being fabricated by a conventional method is simultaneously irradiated by the MIR FEL. The MIR FEL induces the fabricated molecules into the excited state of the stretching vibration energy, when the photon energy of the MIR FEL corresponds to one of the molecules. Therefore, the method can assist the thin-film fabrication quasi-independent of the substrate temperature. The method has the advantages of application on a temperature sensitive substrate and selective fabrication due to the tunable wavelength of the MIR FEL. In order to realize the method, we developed two thin film fabrication devices; an MIR FEL assisted RF sputtering device and an MIR FEL assisted laser ablation deposition device. For the method, the intensity of the assisted MIR FEL is an important problem. Thus the cross-section of the MIR FEL intensity profile is shown and the propa...

  11. Proposal to generate 10 TW level femtosecond X-ray pulses from a baseline undulator in conventional SASE regime at the European XFEL

    Energy Technology Data Exchange (ETDEWEB)

    Serkez, Svitozar; Kocharyan, Vitali; Saldin, Evgeni; Zagorodnov, Igor [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany)

    2013-08-15

    Output characteristics of the European XFEL have been previously studied assuming an operation point at 5 kA peak current. In this paper we explore the possibility to go well beyond such nominal peak current level. In order to illustrate the potential of the European XFEL accelerator complex we consider a bunch with 0.25 nC charge, compressed up to a peak current of 45 kA. An advantage of operating at such high peak current is the increase of the X-ray output peak power without any modification to the baseline design. Based on start-to-end simulations, we demonstrate that such high peak current, combined with undulator tapering, allows one to achieve up to a 100-fold increase in a peak power in the conventional SASE regime, compared to the nominal mode of operation. In particular, we find that 10 TW-power level, femtosecond x-ray pulses can be generated in the photon energy range between 3 keV and 5 keV, which is optimal for single biomolecule imaging. Our simulations are based on the exploitation of all the 21 cells foreseen for the SASE3 undulator beamline, and indicate that one can achieve diffraction to the desired resolution with 15 mJ (corresponding to about 3.10{sup 13} photons) in pulses of about 3 fs, in the case of a 100 nm focus at the photon energy of 3.5 keV.

  12. Proposal to generate 10 TW level femtosecond X-ray pulses from a baseline undulator in conventional SASE regime at the European XFEL

    International Nuclear Information System (INIS)

    Serkez, Svitozar; Kocharyan, Vitali; Saldin, Evgeni; Zagorodnov, Igor; Geloni, Gianluca

    2013-08-01

    Output characteristics of the European XFEL have been previously studied assuming an operation point at 5 kA peak current. In this paper we explore the possibility to go well beyond such nominal peak current level. In order to illustrate the potential of the European XFEL accelerator complex we consider a bunch with 0.25 nC charge, compressed up to a peak current of 45 kA. An advantage of operating at such high peak current is the increase of the X-ray output peak power without any modification to the baseline design. Based on start-to-end simulations, we demonstrate that such high peak current, combined with undulator tapering, allows one to achieve up to a 100-fold increase in a peak power in the conventional SASE regime, compared to the nominal mode of operation. In particular, we find that 10 TW-power level, femtosecond x-ray pulses can be generated in the photon energy range between 3 keV and 5 keV, which is optimal for single biomolecule imaging. Our simulations are based on the exploitation of all the 21 cells foreseen for the SASE3 undulator beamline, and indicate that one can achieve diffraction to the desired resolution with 15 mJ (corresponding to about 3.10 13 photons) in pulses of about 3 fs, in the case of a 100 nm focus at the photon energy of 3.5 keV.

  13. A possible experiment at LEUTL to characterize surface roughness Wakefield effects

    International Nuclear Information System (INIS)

    Wakefield effects due to internal vacuum chamber roughness may increase the electron beam energy spread and so have become an immediate concern for future x-ray free-electron laser (FEL) project developments such as the SLAC Linac Coherent Light Source (LCLS) and the DESY TESLA x-ray FEL. We describe a possible experiment to characterize the effects of surface roughness on an FEL driven by self-amplified spontaneous emission (SASE) operation. Although the specific system described is not completely identical to the above-proposed projects, much useful scaling information could be obtained and applied to shorter wavelength systems

  14. A Review of X-ray Free-Electron Laser Theory

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhirong; /SLAC; Kim, Kwang-Je; /ANL, APS

    2006-12-18

    High-gain free-electron lasers (FELs) are being developed as extremely bright sources for a next-generation x-ray facility. In this paper, we review the basic theory of the startup, the exponential growth, and the saturation of the high-gain process, emphasizing the self-amplified spontaneous emission (SASE). The radiation characteristics of an x-ray FEL, including its transverse coherence, temporal characteristics, and harmonic content, are discussed. FEL performance in the presence of machine errors and undulator wakefields is examined. Various enhancement schemes through seeding and beam manipulations are summarized.

  15. X-ray FEL based on harmonics generation and electron beam outcoupling

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko, V.N.; Burnham, B. [Duke Univ., Durham, NC (United States)

    1995-12-31

    Electron beam outcoupling was suggested by N. A. Vinokurov as a method of optics independent outcoupling for high power FELs. The bunching of the electron beam is provided in a master oscillator. The prebunched electron beam then radiates coherently into an additional wiggler called the radiator. The electron beam is turned by an achromatic bend into this wiggler and its radiation propagates with a small angle with respect to the OK-4 optical axis. Thus, the radiation will pass around the mirror of the master oscillator optical cavity and can then be utilized. This scheme is perfectly suited for harmonic generation if the radiator wiggler is tuned on one of the master oscillator wavelength harmonics. This system is reminiscent of a klystron operating on a harmonic of the reference frequency. In this paper we present the theory of this device, its spectral and spatial characteristics of radiation, the optimization of the master oscillator, the achromatic bend and bunching for harmonic generation, and influence of beam parameters (energy spread, emittance, etc.) on generated power. Examples of possible storage ring and linac driven systems are discussed.

  16. Design study of the bending sections between harmonic cascade FEL stages

    International Nuclear Information System (INIS)

    Wan, Weishi; Corlett, John; Fawley, William; Zholents, A.

    2004-01-01

    The present design of LUX (linac based ultra-fast X-ray facility) includes a harmonic cascade FEL chain to generate coherent EUV and soft X-ray radiation. Four cascade stages, each consisting of two undulators acting as a modulator and a radiator, respectively, are envisioned to produce photons of approximate wavelengths 48 nm, 12 nm, 4 nm and 1 nm. Bending sections may be placed between the modulator and the radiator of each stage to adjust and maintain bunching of the electrons, to separate, in space, photons of different wavelengths and to optimize the use of real estate. In this note, the conceptual design of such a bending section, which may be used at all four stages, is presented. Preliminary tracking results show that it is possible to maintain bunch structure of nm length scale in the presence of errors, provided that there is adequate orbit correction and there are 2 families of trim quads and trim skew quads, respectively, in each bending section

  17. Compression of XUV FEL pulses in the few-femtosecond regime

    International Nuclear Information System (INIS)

    Frassetto, Fabio; Giannessi, Luca; Poletto, Luca

    2008-01-01

    This work presents the design of a grating compressor for XUV FEL pulses able to compress chirped pulses from some hundreds to some tens of femtoseconds. The instrument adopts the conical diffraction mounts of gratings to reach high efficiency. We discuss the general design of the compressor and present an example of application to FEL emission at 13.5 nm

  18. Real time diagnostic for operation at a CW low voltage FEL

    Energy Technology Data Exchange (ETDEWEB)

    Balfour, C.; Shaw, A.; Mayhew, S.E. [and others

    1995-12-31

    At Liverpool University, a system for single user control of an FEL has been designed to satisfy the low voltage FEL (ie 200kV) operational requirements. This system incorporates many aspects of computer automation for beam diagnostics, radiation detection and vacuum system management. In this paper the results of the development of safety critical control systems critical control systems are reported.

  19. The Upgrade of the DUV-FEL Facility at the BNL

    CERN Document Server

    Wang, Xijie; Murphy, James; Rakowsky, George; Rose, James; Sheehy, Brian; Shen, Yuzhen; Skaritka, John; Wu, Zilu; Yu Li Hua

    2004-01-01

    The DUV-FEL at BNL, is the world's only facility dedicated to laser-seeded FEL R&D and its applications. The HGHG at the DUV-FEL reached saturation at 266 nm with 800 nm seeding [1] in 2002. Since then, the first chemical science experiment ? ion pair imaging, was successfully completed [2].The DUV-FEL linac is being upgraded from 200 to 300 MeV to enable the HGHG FEL to produce 100 μJ pulses of 100 nm light. This will establish the DUV FEL as a premier user facility for XUV radiation. The upgraded facility will also enable several critical R&Ds for a future X-ray FEL based on HGHG, such as cascaded HGHG and higher harmonic HGHG (n>5). The upgraded HGHG will operate at the 4th harmonic with the seed laser at 400nm. The increase of the electron beam energy will be accomplished by installing a 5th linac cavity and two 45 MW klystrons. New modulator and dispersion sections vacuum chambers will be manufactured to accommodate new matching optics and 8th harmonic HGHG. The status of the DUV-FEL upgra...

  20. Lattice design for a high-power infrared FEL

    International Nuclear Information System (INIS)

    Douglas, D.R.

    1997-01-01

    A 1 kW infrared FEL, funded by the U.S. Navy, is being built at Jefferson Lab. It will be driven by a compact energy-recovering CW superconducting radio-frequency (SRF)-based linear accelerator. Stringent phase space requirements at the wiggler, low beam energy, and high beam current subject the design to numerous constraints. This report addresses these issues and presents a design solution for an accelerator transport lattice meeting the requirements imposed by physical phenomena and operational necessities

  1. Characteristics of the FEL project for the MUH experiment

    International Nuclear Information System (INIS)

    Ciocci, F.; Doria, A.; Fascetti, M.; Gallerano, G.P.; Giannessi, L.; Giovenale, E.; Messina, G.; Picardi, L.; Renieri, A.; Ronci, G.; Ronsivalle, C.; Vignati, A.

    1999-01-01

    The design characteristics of a compact Free Electron Laser (FEL) operating in the far infrared spectral range between 200 and 600 μm are presented in this report. The device can be employed in a fundamental physics experiment to be performed in collaboration with INFN-Trieste and the Paul Sherrer Institute- Villigen. Spectroscopic measurements in the above spectral region will allow one to determine the energy difference between the levels 3D-3P in the μP system with great accuracy [it

  2. Design Study of a Compact Megawatt Class FEL Amplifier Based on the VISA Undulator

    CERN Document Server

    Watanabe, T; Murphy, J B; Pinayev, I P; Rose, J; Shaftan, T V; Skaritka, J; Tanabé, T; Tsang, Thomas; Wang, X J; Yu, L H

    2005-01-01

    The design of a Short Rayleigh Length (SRL) FEL amplifier based on the strong focusing VISA undulator [1] is presented in this study. The SRL FEL amplifier will be operating in the IR (0.8 - 1 μm), and consists of a two-meter VISA undulator with a peak seed laser power of about 1 kW. The FEL power and transverse mode evolution along the undulator were investigated using the three-dimensional numerical code GENESIS1.3. The evolution of the FEL output from the undulator exit to the first downstream optics is also studied. The possibility of using the proposed amplifier for a two-stage cascaded HGHG FEL [2] at the BNL SDL is also explored. The design parameters and the numerical results will be presented.

  3. Workshop on scientific applications of short wavelength coherent light sources

    International Nuclear Information System (INIS)

    Spicer, W.; Arthur, J.; Winick, H.

    1993-02-01

    This report contains paper on the following topics: A 2 to 4nm High Power FEL On the SLAC Linac; Atomic Physics with an X-ray Laser; High Resolution, Three Dimensional Soft X-ray Imaging; The Role of X-ray Induced Damage in Biological Micro-imaging; Prospects for X-ray Microscopy in Biology; Femtosecond Optical Pulses?; Research in Chemical Physics Surface Science, and Materials Science, with a Linear Accelerator Coherent Light Source; Application of 10 GeV Electron Driven X-ray Laser in Gamma-ray Laser Research; Non-Linear Optics, Fluorescence, Spectromicroscopy, Stimulated Desorption: We Need LCLS' Brightness and Time Scale; Application of High Intensity X-rays to Materials Synthesis and Processing; LCLS Optics: Selected Technological Issues and Scientific Opportunities; Possible Applications of an FEL for Materials Studies in the 60 eV to 200 eV Spectral Region

  4. Advanced Electron Beam Diagnostics for the FERMI FEL

    CERN Document Server

    Ferianis, M; D'Auria, G; Di Mitri, S

    2005-01-01

    Fermi is the fourth generation light source currently under design at ELETTRA: based on the Harmonic Generation (HG) scheme it will generate FEL radiation in the 100-10nm range. The successful implementation of the HG scheme calls also for precise knowledge of electron beam emittances and energy spread as well as for very accurate control on the photon to electron interaction, in the Undulator sections. In this paper we present our design for two fundamental Diagnostics foreseen for the new FERMI LINAC: the Beam Position Monitors (BPM) and the Transverse Deflecting cavity set-up. Sensitivity studies on transverse beam displacement effects on global stability of FEL output radiation dictate the ultimate performance to be provided by the BPM system. Due to non negligible longitudinal occupancy of a cavity type BPM, some efforts have been put to study compact cavity BPM configuration. A proper set-up of RF deflecting cavity combined with the vertical ramp foreseen at the end of the LINAC provide a powerful tool ...

  5. Design and simulations of CAEP THz FEL resonator

    Science.gov (United States)

    Dou, Yuhuan; Shu, Xiaojian; Deng, Derong; Yang, Xingfan; Li, Ming

    2015-02-01

    A high power China Academy of Engineering Physics(CAEP) THz free electron laser (FEL) is designed and optimized in a radiation frequency range of 1~3 THz and average output power of about 10 W. The main work focuses on the optimization of different schemes through physical analysis. The wiggler peak field strength and electron beam energy have been selected with eleven frequencies ranging from 1 THz to 3 THz. It is found that the values of the gain and output power of the cavity are largest at 2.6 THz. So we can test the facility at this frequency. While the value of the output power is less than the design goal at the lower frequency region of about 1.0 THz due to the serious slippage between the electron bunch and radiation pulse. To increase the output power at the lower frequency region, the scheme of elliptical hole-coupling optical resonator is proposed to solve this problem. The simulation results show that the elliptical hole-coupling output is effective and applicable for the THz FEL and the output power can be increased by more than 30%.

  6. ETHERNET BASED EMBEDDED SYSTEM FOR FEL DIAGNOSTICS AND CONTROLS

    Energy Technology Data Exchange (ETDEWEB)

    Jianxun Yan; Daniel Sexton; Steven Moore; Albert Grippo; Kevin Jordan

    2006-10-24

    An Ethernet based embedded system has been developed to upgrade the Beam Viewer and Beam Position Monitor (BPM) systems within the free-electron laser (FEL) project at Jefferson Lab. The embedded microcontroller was mounted on the front-end I/O cards with software packages such as Experimental Physics and Industrial Control System (EPICS) and Real Time Executive for Multiprocessor System (RTEMS) running as an Input/Output Controller (IOC). By cross compiling with the EPICS, the RTEMS kernel, IOC device supports, and databases all of these can be downloaded into the microcontroller. The first version of the BPM electronics based on the embedded controller was built and is currently running in our FEL system. The new version of BPM that will use a Single Board IOC (SBIOC), which integrates with an Field Programming Gate Array (FPGA) and a ColdFire embedded microcontroller, is presently under development. The new system has the features of a low cost IOC, an open source real-time operating system, plug&play-like ease of installation and flexibility, and provides a much more localized solution.

  7. Detection and spectral measurements of coherent synchrotron radiation at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Behrens, Christopher

    2010-02-15

    The operation of high-gain free-electron laser (FEL) underlies tremendous demands on high quality electron beams with high peak currents. At the Free-Electron-Laser in Hamburg (FLASH), two magnetic bunch compressors are used to compress the electron bunches longitudinally. In the bunch compressor magnets, these short electron bunches generate coherent synchrotron radiation (CSR). This CSR contains information on the longitudinal bunch profile, which is relevant for driving an FEL. In order to investigate coherent synchrotron radiation at the second bunch compressor BC3 at FLASH, a new setup behind the last dipole was installed. For the detection of coherent synchrotron radiation, which is emitted in the infrared regime, pyroelectric detectors were used. These pyroelectric detectors have been calibrated at the free-electron laser FELIX in the wavelength range from 5 {mu}m to 110 {mu}m. For characterisation of the emitted radiation, a transverse scanning device was used to measure the transverse intensity distribution. Various transmission filters were used to obtain additional information about the spectral content. In order to get spectral information with high resolution over a wide wavelength range, a rotating mirror spectrometer using reflective blazed gratings was installed. Using this spectrometer, the first spectral measurements of coherent synchrotron radiation at FLASH in a wavelength range from 10 {mu}m to 160 {mu}m were done. (orig.)

  8. Characteristics of the FEL project for the MUH experiment; Stato del progetto FEL per l`esperimeto MUH

    Energy Technology Data Exchange (ETDEWEB)

    Ciocci, F.; Doria, A.; Fascetti, M.; Gallerano, G.P.; Giannessi, L.; Giovenale, E.; Messina, G.; Picardi, L.; Renieri, A.; Ronci, G.; Ronsivalle, C.; Vignati, A. [ENEA, Centro Ricerche Frascati, Rome (Italy). Dip. Innovazione

    1999-01-01

    The design characteristics of a compact Free Electron Laser (FEL) operating in the far infrared spectral range between 200 and 600 {mu}m are presented in this report. The device can be employed in a fundamental physics experiment to be performed in collaboration with INFN-Trieste and the Paul Sherrer Institute- Villigen. Spectroscopic measurements in the above spectral region will allow one to determine the energy difference between the levels 3D-3P in the {mu}P system with great accuracy. [Italiano] In questo rapporto vengono presentate le caratteristiche di progetto di un Laser ad Elettroni Liberi (FEL) compatto operante nel lontano infrarosso a lunghezze d`onda comprese tra 200 e 600 {mu}m. Tale laser potra` essere impiegato in un esperimento di fisica fondamentale su idrogeno muonico in collaborazione con INFN-Trieste ed il Paul Sherrer Institute-Villigen. Le misure spettroscopiche nella regione spettrale del lontano infrarosso consentiranno di determinare con grande accuratezza la differenza di energia dei livelli 3D-3P nel sistema {mu}P. Attraverso la misura di questa transizione sara` possibile effettuare un test delle correzioni di Meccanica Quantistica (QED) alle energie di legame, migliorando di un ordine di grandezza l`accuratezza della misura della polarizzazione del vuoto.

  9. TREDI: fully 3D beam dynamics simulation of RF guns, bendings and FELs

    CERN Document Server

    Giannessi, L; Quattromini, M

    1999-01-01

    We describe a three-dimensional code modelling the propagation of charged beams in accelerator devices. The inclusion of space charge fields is taken into account by means of the Lienard-Wiechert retarded potentials. As an illustration of the capabilities of the program, the results of a simulation are given that, describe the beam dynamics from the cathode to the undulator through the whole accelerating system. Evidence of bunching in the undulator, as an indication of SASE is observed.

  10. Longitudinal beam dynamics and FEL interaction on a negative momentum compaction storage ring

    CERN Document Server

    Hama, H

    1999-01-01

    A simulation study for longitudinal phase space of the electron bunch including effects of potential-well distortion and FEL interaction has been performed for both positive and negative momentum compaction factors on a storage ring. The trend of the bunch lengthening is well interpreted by the wake field due to inductive impedance. In spite of large energy spread in the case of the negative momentum compaction, FEL oscillation may be possible. The peak power of Q-switched lasing is higher than that in positive momentum compaction. There was, however, no significant difference in FEL power and particle distribution in the longitudinal phase space at the equilibrated state.

  11. Strategies for minimizing emittance growths in high intensity CW FEL injectors

    International Nuclear Information System (INIS)

    Liu, Hongxiu

    1996-01-01

    We discuss beam emittance growths in high intensity CW FEL injectors due to linear and non-linear space charge fields, phase space bifurcation, skew-quad effect, longitudinal momentum modification by space charges in bends, and equipartitioning, etc. We generalize Kim's RF laser gun theory to DC laser guns. We discuss the traditional free energy theory of emittance growth. The best strategies for designing high-intensity CW FEL injectors are derived, and their application to the design analysis of the CEBAF 10 MeV DC laser gun CW FEL injector test stand is discussed

  12. VUV Optics Development for the Elettra Storage Ring FEL

    CERN Document Server

    Guenster, Stefan

    2004-01-01

    Vacuum ultraviolet optical components for the storage ring FEL at Elettra are under continuous development in the European research consortium EUFELE. Target of the project is the progress to shorter lasing wavelengths in the VUV spectral range. The current status allows lasing with oxide mirror systems down to 190 nm. The main obstacles for the development of optical coatings for shorter wavelengths is the high energetic background of the synchrotron radiation impinging onto the front mirror in the laser cavity. Investigations in single layer systems and multilayer stacks of oxide or fluoride materials demonstrate that fluoride mirrors reach highest reflectivity values down to 140 nm, and oxide coatings possess a satisfactory resistance against the high energetic background irradiation. However, pure oxide multilayer stacks exhibit significant absorption below 190 nm and pure fluoride stacks suffer from strong degradation effects under synchrotron radiation. A solution could be hybrid systems, combining fluo...

  13. A 300-nm compact mm-wave linac FEL design

    Energy Technology Data Exchange (ETDEWEB)

    Nassiri, A.; Kustom, R.L.; Kang, Y.W. [Argonne National Lab., IL (United States)

    1995-12-31

    Microfabrication technology offers an alternative method for fabricating precision, miniature-size components suitable for use in accelerator physics and commercial applications. The original R&D work at Argonne, in collaboration with the University of Illinois at Chicago, has produced encouraging results in the area of rf accelerating structure design, optical and x-ray masks production, deep x-ray lithography (LIGA exposures), and precision structural alignments. In this paper we will present a design study for a compact single pass mm-linac FEL to produce short wavelength radiation. This system will consists of a photocathode rf gun operated at 30 GHz, a 50-MeV superconducting constant gradient structure operated at 60 GHz, and a microundulator with 1-mm period. Initial experimental results on a scale model rf gun and microundulator will be presented.

  14. Lasing attempts with a microwiggler on the Los Alamos FEL

    International Nuclear Information System (INIS)

    Warren, R.W.; O'Shea, P.G.; Bender, S.C.; Carlsten, B.E.; Early, J.W.; Feldman, D.W.; Fortgang, C.M.; Goldstein, J.C.; Schmitt, M.J.; Stein, W.E.; Wilke, M.D.; Zaugg, T.J.; Newnam, B.E.; Sheffield, R.L.

    1992-01-01

    The APEX FEL normally lases near a wavelength of 3μm using a permanent magnet wiggler with a 2.7-cm period and a linear accelerator of 40-MeV energy. Los Alamos National Laboratory is conducting a series of experiments with the goal of lasing at significantly shorter wavelengths with the same accelerator and the same kind of near-concentric resonator, but using a novel pulsed microwiggler of 0.5-cm period capable of generating a peak field of several tesla. We plan to lase on a fundamental wavelength of ∼0.8 μm and on the third harmonic at 0.25 μm

  15. Development of web database system for JAERI ERL-FEL

    International Nuclear Information System (INIS)

    Kikuzawa, Nobuhiro

    2005-01-01

    The accelerator control system for the JAERI ERL-FEL is a PC-based distributed control system. The accelerator status record is stored automatically through the control system to analyze the influence on the electron beam. In order to handle effectively a large number of stored data, it is necessary that the required data can be searched and visualized in easy operation. For this reason, a web database (DB) system which can search of the required data and display visually on a web browser was developed by using open source software. With introduction of this system, accelerator operators can monitor real-time information anytime, anywhere through a web browser. Development of the web DB system is described in this paper. (author)

  16. Ultrafast coherent diffractive imaging of nanoparticles using X-ray free-electron laser radiation

    International Nuclear Information System (INIS)

    Kassemeyer, Stephan

    2014-01-01

    Coherent diffractive imaging with X-ray free-electron lasers (X-FEL) promises high-resolution structure determination of single microscopic particles without the need for crystallization. The diffraction signal of small samples can be very weak, a difficulty that can not be countered by merely increasing the number of photons because the sample would be damaged by a high absorbed radiation dose. Traditional X-ray crystallography avoids this problem by bringing many sample particles into a periodic arrangement, which amplifies the individual signals while distributing the absorbed dose. Depending on the sample, however, crystallization can be very difficult or even impossible. This thesis presents algorithms for a new imaging approach using X-FEL radiation that works with single, non-crystalline sample particles. X-FELs can deliver X-rays with a peak brilliance many orders of magnitude higher than conventional X-ray sources, compensating for their weak interaction cross sections. At the same time, FELs can produce ultra-short pulses down to a few femtoseconds. In this way it is possible to perform ultra-fast imaging, essentially ''freezing'' the atomic positions in time and terminating the imaging process before the sample is destroyed by the absorbed radiation. This thesis primarily focuses on the three-dimensional reconstruction of single (and not necessarily crystalline) particles using coherent diffractive imaging at X-FELs: in order to extract three-dimensional information from scattering data, two-dimensional diffraction patterns from many different viewing angles must be combined. Therefore, the diffraction signal of many identical sample copies in random orientations is measured. The main result of this work is a globally optimal algorithm that can recover the sample orientations solely based on the diffraction signal, enabling three-dimensional imaging for arbitrary samples. The problem of finding three-dimensional orientations is

  17. Accelerator-driven X-ray Sources

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Dinh Cong [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-09

    After an introduction which mentions x-ray tubes and storage rings and gives a brief review of special relativity, the subject is treated under the following topics and subtopics: synchrotron radiation (bending magnet radiation, wiggler radiation, undulator radiation, brightness and brilliance definition, synchrotron radiation facilities), x-ray free-electron lasers (linac-driven X-ray FEL, FEL interactions, self-amplified spontaneous emission (SASE), SASE self-seeding, fourth-generation light source facilities), and other X-ray sources (energy recovery linacs, Inverse Compton scattering, laser wakefield accelerator driven X-ray sources. In summary, accelerator-based light sources cover the entire electromagnetic spectrum. Synchrotron radiation (bending magnet, wiggler and undulator radiation) has unique properties that can be tailored to the users’ needs: bending magnet and wiggler radiation is broadband, undulator radiation has narrow spectral lines. X-ray FELs are the brightest coherent X-ray sources with high photon flux, femtosecond pulses, full transverse coherence, partial temporal coherence (SASE), and narrow spectral lines with seeding techniques. New developments in electron accelerators and radiation production can potentially lead to more compact sources of coherent X-rays.

  18. Proceedings of the Laser Issues for Electron RF Photoinjectors Workshop

    CERN Document Server

    Bolton, P

    2003-01-01

    The Linac Coherent Light Source (LCLS) proposed for SLAC is a SASE FEL designed to generate high brightness, coherent, ultrashort x-ray pulses. The injector of choice is the RF photoinjector, which is capable of producing suitably low emittance electron beams. It is well established that the performance of the SASE FEL depends critically on properties of the electron beam generated by the injector and therefore on the injector laser beam parameters. This workshop was established specifically to provide a forum for discussion of photoinjector laser systems. Laser design requirements and technical challenges common to RF photoinjectors were highlighted and some solutions were explored. This included not only details of laser systems but also those of laser-based diagnostics envisioned for monitoring ultrashort electron microbunches on a single shot basis. Sixty-one registrants representing twenty-three institutions from Italy, Germany, Japan and the United States attended. The program listing shows that the twe...

  19. About the scheme of the infrared FEL system for the accelerator based on HF wells

    Energy Technology Data Exchange (ETDEWEB)

    Kabanov, V.S.; Dzergach, A.I. [Moscow Radiotechnical Institute (Russian Federation)

    1995-12-31

    Accelerators, based on localization of plasmoids in the HF wells (RF traps) of the axially-symmetric electromagnetic field E {sub omn} in an oversized (m,n>>1) resonant system, can give accelerating gradients {approximately}100 kV/{lambda}, e.g. 10 GV/m if {lambda}=10 {mu}m. One of possible variants of HF feeding for these accelerators is based on using the powerful infrared FEL System with 2 frequencies. The corresponding FEL`s may be similar to the Los Alamos compact Advanced FEL ({lambda}{sub 1,2}{approximately}10 pm, e-beam energy {approximately}15 MeV, e-beam current {approximately}100 A). Their power is defined mainly by the HF losses in the resonant system of the supposed accelerator.

  20. Linac Coherent Light Source (LCLS) Conceptual Design Report

    Energy Technology Data Exchange (ETDEWEB)

    Nuhn, Heinz-Dieter

    2002-11-25

    The Stanford Linear Accelerator Center, in collaboration with Argonne National Laboratory, Brookhaven National Laboratory, Los Alamos National Laboratory, Lawrence Livermore National Laboratory, and the University of California at Los Angeles, have collaborated to create a conceptual design for a Free-Electron-Laser (FEL) R&D facility operating in the wavelength range 1.5-15 {angstrom}. This FEL, called the ''Linac Coherent Light Source'' (LCLS), utilizes the SLAC linac and produces sub-picosecond pulses of short wavelength x-rays with very high peak brightness and full transverse coherence. The first two-thirds of the SLAC linac are used for injection into the PEP-II storage rings. The last one-third will be converted to a source of electrons for the LCLS. The electrons will be transported to the SLAC Final Focus Test Beam (FFTB) Facility, which will be extended to house a 122-m undulator system. In passing through the undulators, the electrons will be bunched by the force of their own synchrotron radiation to produce an intense, spatially coherent beam of x-rays, tunable in energy from 0.8 keV to 8 keV. The LCLS will include two experiment halls as well as x-ray optics and infrastructure necessary to make use of this x-ray beam for research in a variety of disciplines such as atomic physics, materials science, plasma physics and biosciences. This Conceptual Design Report, the authors believe, confirms the feasibility of constructing an x-ray FEL based on the SLAC linac.

  1. A simple method for particle tracking with coherent synchrotron radiation

    International Nuclear Information System (INIS)

    Borland, M.

    2001-01-01

    Coherent synchrotron radiation (CSR) is of great interest to those designing accelerators as drivers for free-electron lasers (FELs). Although experimental evidence is incomplete, CSR is predicted to have potentially severe effects on the emittance of high-brightness electron beams. The performance of an FEL depends critically on the emittance, current, and energy spread of the beam. Attempts to increase the current through magnetic bunch compression can lead to increased emittance and energy spread due to CSR in the dipoles of such a compressor. The code elegant [1] was used for design and simulation of the bunch compressor [2] for the Low-Energy Undulator Test Line (LEUTL) FEL [3] at the Advanced Photon Source (APS). In order to facilitate this design, a fast algorithm was developed based on the 1-D formalism of Saldin and coworkers [4]. In addition, a plausible method of including CSR effects in drift spaces following the chicane magnets was developed and implemented. The algorithm is fast enough to permit running hundreds of tolerance simulations including CSR for 50 thousand particles. This article describes the details of the implementation and shows results for the APS bunch compressor

  2. The Effect of Liner Induced Phase Fluctuations on the Gain of a Cerenkov FEL

    CERN Document Server

    De la Fuente, Isabel; Van der Slot, Peter

    2004-01-01

    It is well known that wiggler errors can degrade the gain of a FEL. A similar process takes places in a Cerenkov FEL where the phase velocity of the amplified EM wave is determined by parameters of the dielectric liner. Thus deviations in the inner radius (Rd) of the liner will result in fluctuations of the phase velocity of the EM wave. E.g., for a quartz liner (εr=4.4) with Rd = 1.5 mm and outer radius of 4 mm, the derivative of the longitudinal wavenumber with respect to Rd is about 105 m-2 for a frequency of 50 GHz. Thus fluctuations in the Rd induce phase fluctuations that may degrade the gain of a Cerenkov FEL. In contrast to the undulator FEL, where the relative phase fluctuations are a result from deviations in the electron trajectories, the phase fluctuations are a result of pertubations in the radiation field for a Cerenkov FEL. As an example of the influence of pertubations in the inner radius of the liner on the gain we will present results of an analysis for a 100 kV Cerenkov FEL oper...

  3. Development of a novel thermionic RF electron gun applied on a compact THz-FEL facility

    Science.gov (United States)

    Hu, T. N.; Pei, Y. J.; Qin, B.; Liu, K. F.; Feng, G. Y.

    2018-04-01

    The current requirements from civil and commercial applications lead to the development of compact free-electron laser (FEL)-based terahertz (THz) radiation sources. A picosecond electron gun plays an important role in an FEL-THz facility and attracts significant attention, as machine performance is very sensitive to initial conditions. A novel thermionic gun with an external cathode (EC) and two independently tunable cavities (ITCs) has been found to be a promising alternative to conventional electron sources due to its remarkable characteristics, and correspondingly an FEL injector can achieve a balance between a compact layout and high brightness benefitting from the velocity bunching properties and RF focusing effects in the EC-ITC gun. Nevertheless, the EC-ITC gun has not been extensively examined as part of the FEL injector in the past years. In this regard, to fill this gap, a development focusing on the experimental setup of an FEL injector based on an EC-ITC gun is described in detail. Before assembly, dynamic beam simulations were performed to investigate the optimal mounting position for the Linac associated with the focusing coils, and a suitable radio-frequency (RF) system was established based on a power coupling design and allocation. The testing bench proved to be fully functional through basic experiments using typical diagnostic approaches for estimating primary parameters. Associated with dynamic beam calculations, a performance evaluation for an EC-ITC gun was established while providing indirect testing results for an FEL injector.

  4. PROCEEDING OF THE SEEDED X-RAY FREE ELECTRON LASER WORKSHOP.

    Energy Technology Data Exchange (ETDEWEB)

    WANG,X.J.; MURPHY,J.B.; YU,L.H.; FAATZ,B.; HUANG,Z.; REICHE,S.; ZOLOTOREV,M.

    2002-12-13

    The underlying theory of a high gain free electron laser (FEL) has existed for two decades [1-2], but it is only in the last few years that these novel radiation sources have been realized experimentally. Several high gain FELs have successfully reached saturation in the infrared, visible and the VUV portion of the spectrum: the High Gain Harmonic Generation (HGHG) free electron lasers [3] at BNL and the Self Amplified Spontaneous Emission (SASE) FELs at LEUTL, VISA and TTF [4-6]. The outstanding challenges for future FELs are to extend high gain FELs to the X-ray regime, improve the longitudinal coherence of the radiation using seeded FEL schemes and generate ultrashort pulses (<100 fs). The National Synchrotron Light Source (NSLS) of the Brookhaven National Laboratory (BNL) sponsored a Seeded X-ray Free Electron Laser Workshop on December 13-14, 2002 to explore these challenging issues. Representatives from BNL, DESY, LBNL, SLAC and UCLA made presentations on the novel schemes under consideration at their laboratories. Workshop participants had a lively discussion on the feasibility, performance and R&D issues associated with the seeded XFEL schemes. An improvement of the electron beam quality will certainly be necessary to drive the XFEL. Self-seeding SASE, cascaded HGHG, and SASE pulse compression FELs show the most promise for producing short pulse X-rays. Of these, only the self-seeded and HGHG schemes generate longitudinally coherent radiation. While the pulse length in the self-seeded scheme is determined by the electron bunch length ({approx}100 fs), the pulse length in the HGHG scheme is determined by the short pulse seed laser, and so can be much shorter ({approx} 20 fs).

  5. Coherence and Sense of Coherence

    DEFF Research Database (Denmark)

    Dau, Susanne

    2014-01-01

    of coherence is both related to conditional matters as learning environments, structure, clarity and linkage but also preconditioned matters and prerequisites among participants related to experiences and convenience. It is stressed that this calls for continuous assessment and reflections upon these terms...

  6. Los Alamos High-Brightness Accelerator FEL (HIBAF) facility

    Energy Technology Data Exchange (ETDEWEB)

    Cornelius, W.D.; Bender, S.; Meier, K.; Thode, L.E.; Watson, J.M.

    1989-01-01

    The 10-/mu/m Los Alamos free-electron laser (FEL) facility is being upgraded. The conventional electron gun and bunchers have been replaced with a much more compact 6-MeV photoinjector accelerator. By adding existing parts from previous experiments, the primary beam energy will be doubled to 40 MeV. With the existing 1-m wiggler (/lambda//sub w/ = 2.7 cm) and resonator, the facility can produce photons with wavelengths from 3 to 100 /mu/m when lasing on the fundamental mode and produce photons in the visible spectrum with short-period wigglers or harmonic operation. After installation of a 150/degree/ bend, a second wiggler will be added as an amplifier. The installation of laser transport tubes between the accelerator vault and an upstairs laboratory will provide experimenters with a radiation-free environment for experiments. Although the initial experimental program of the upgraded facility will be to test the single accelerator-master oscillator/power amplifier configuration, some portion of the operational time of the facility can be dedicated to user experiments. 13 refs., 5 figs., 6 tabs.

  7. Beam dynamics simulations for linacs driving short-wavelength FELs

    International Nuclear Information System (INIS)

    Ferrario, M.; Tazzioli, F.

    1999-01-01

    The fast code HOMDYN has been recently developed, in the framework of the TTF (Tesla test facility) collaboration, in order to study the beam dynamics of linacs delivering high brightness beams as those needed for short wavelength Fel experiments. These linacs are typically driven by radio-frequency photo-injectors, where correlated time dependent space charge effects are of great relevance: these effects cannot be studied by standard beam optics codes (TRACE3D, etc.) and they have been modeled so far by means of multi-particle (Pic or quasistatic) codes requiring heavy cpu time and memory allocations. HOMDYN is able to describe the beam generation at the photo-cathode and the emittance compensation process in the injector even running on a laptop with very modest running rimes (less than a minute). In this paper it is showed how this capability of the code is exploited so to model a whole linac up to the point where the space charge dominated regime is of relevance (200 MeV)

  8. Design and test of SX-FEL cavity BPM

    International Nuclear Information System (INIS)

    Yuan Renxian; Zhou Weimin; Chen Zhichu; Yu Luyang; Wang Baopen; Leng Yongbin

    2013-01-01

    This paper reports the design and cold test of the cavity beam position monitor (CBPM) for SX-FEL to fulfill the requirement of beam position measurement resolution of less than 1 μm, even 0.1 μm. The CBPM was optimized by using a coupling slot to damp the TM 010 mode in the output signal. The isolation of TM 010 mode is about 117 dB, and the shunt impedance is about 200 Ω@4.65 GHz with the quality factor 80 from MAFIA simulation and test result. A special antenna was designed to load power for reducing excitation of other modes in the cavity. The resulting output power of TM 110 mode was about 90 mV/mm when the source was 6 dBm, and the accomplishable minimum voltage was about 200 μV. The resolution of the CBPM was about 0.1 μm from the linear fitting result based on the cold test. (authors)

  9. Extension of the spectral range of the CLIO FEL

    Energy Technology Data Exchange (ETDEWEB)

    Marcouille, O.; Boyer, J.C.; Corlier, M. [LURE, Orsay (France)] [and others

    1995-12-31

    The CLIO FEL has been designed to lase between 2 and 20 {mu}m. The electrons are produced by a 32/50 MeV RF linear accelerator. The injector is a 100 keV thermoionic gun, followed by a subharmonic prebuncher at 0.5 GHz and a buncher at 3 GHz. The electron beam is then accelerated in a 4.5 m long travelling wave accelerating section, to the nominal energy. The undulator consisted of 48 periods of 40 mm and the optical cavity is 4.8 m long which corresponds to a 1.2 m Rayleigh length. The peak power extracted by a ZnSe Brewster plate is 10 MW at 10 {mu}. But, beyond 11{mu}m, the laser power decreases rapidely and no laser oscillation appears above 17 {mu}m. In order to lase at farther wavelengths, few changes have been made: First of all, the power limit is due to the diffraction losses of the undulator vaccuum chamber (7 mm height and 2 m long). Numerical calculations have been made and show that cavity losses reach 55 % at 15 {mu}m whereas the measured gain is 60 %. Consequently, the undulator vaccuum chamber have been replaced by a approximately twice bigger one. Then, the minimum gap is increased and the maximum deflection parameter K is reduced by a factor 2: laser tunability is greatly reduced. This why a new undulator has been built. The main characteristics are summarized.

  10. Quadrupole magnets for IR-FEL at RRCAT

    International Nuclear Information System (INIS)

    Ruwali, Kailash; Singh, Kushraj; Mishra, Anil Kumar; Biswas, Bhaskar

    2013-01-01

    The IR-FEL project at RRCAT needs quadrupole magnets for focusing 15 to 35 MeV electron beam through a dog-leg type beam line. This bend needs tighter relative tolerances on the central quadrupole triplet . The magnetic design, fabrication and magnetic characterization of five quadrupole magnets were carried out. The poles are detachable and wider than the coils. This significantly improves the good field region of the magnet. The magnet cross-section was optimized using 2D POISON code and entry-exit tapers were optimized using 3D code TOSCA.. The aperture radius of the magnet is 30 mm and the total core length is 180 mm. The integrated gradient of magnet is 0.51 T. The magnetic measurements were carried out using Danfysik make rotating coil bench model 690. Integrated gradient and multipoles present in the magnet aperture were measured at various excitation levels. The details of magnetic development and the magnetic measurements are discussed in this paper. (author)

  11. The drive laser for the APS LEUTL FEL Rf photoinjector

    International Nuclear Information System (INIS)

    Arnold, N.; Koldenhoven, R.; Travish, G.

    1999-01-01

    The APS LEUTL free-electron laser (FEL) is a high-gain, short-wavelength device requiring a high-current, low-emittance beam. An rf photoinjector driven by a laser is used to provide the requisite beam. The drive laser consists of a diode-pumped Nd:Glass oscillator and a chirped pulse amplification (CPA) system consisting of a grating stretcher, a flashlamp-pumped Nd:Glass regenerative amplifier, and a grating compressor. The system generates 4-mj pulses in the R with a pulse length as short as 2 ps FWHM and a repetition rate of 6 Hz. Nonlinear doubling crystals are used to generate fourth-harmonic output of ∼500 microJ in the UV (263 nm), which is required to exceed the work function of the copper cathode in the gun. This paper describes the drive laser as well as the extensive controls implemented to allow for remote operation and monitoring. Performance measurements as well as the operating experience are presented

  12. Midinfrared ablation of dentin with the Vanderbilt FEL

    Science.gov (United States)

    Harris, David M.; Reinisch, Lou; Edwards, Glenn S.; Yessik, Michael J.; Ashrafi, Shahid; Santos-Sacchi, Joseph

    1996-04-01

    Absorption spectra of 0.1 - 0.2 mm thick, dehydrated sections of human teeth were measured in the transmission mode with a Bruker FT-IR spectrometer from 2.5 - 20 micrometers . Absorption peaks for amide I, II and III, carbonate and phosphate were identified. Craters were ablated in dentin and enamel using a tunable FEL at 6.45 micrometers at various fluences. Pulse duration: 3 microsecond(s) ; spot size (Gaussian, FWHM): 300 micrometers ; repetition rate: 10 Hz. Crater depth and width were measured from digitized optical images. Ablation rates were computed from crater depth and volume data. Selected specimens were examined with scanning electron microscopy to determine ablation surface characteristics. Depth of thermal damage and dentinal tubule morphology were estimated from SEM examination of fractures through ablation sites. Functions describing crater depth vs. number of pulses (quadratic function) were not the same as crater volume vs. number of pulses (linear function). Crater depth decreases with successive pulses, concurrently, the crater width increases. Thus, each pulse removes approximately a constant volume. Material was observed to flow through the dentinal tubules during and after ablation. Patent tubules on crater walls and floor were observed with SEM. Ablation rates in dentin were approximately 3X those in enamel at 6.45 micrometers . Ablation rates and surface characteristics varied across wavelengths from 5.8 to 8.0 micrometers .

  13. Validity and reliability of the Fels physical activity questionnaire for children.

    Science.gov (United States)

    Treuth, Margarita S; Hou, Ningqi; Young, Deborah R; Maynard, L Michele

    2005-03-01

    The aim was to evaluate the reliability and validity of the Fels physical activity questionnaire (PAQ) for children 7-19 yr of age. A cross-sectional study was conducted among 130 girls and 99 boys in elementary (N=70), middle (N=81), and high (N=78) schools in rural Maryland. Weight and height were measured on the initial school visit. All the children then wore an Actiwatch accelerometer for 6 d. The Fels PAQ for children was given on two separate occasions to evaluate reliability and was compared with accelerometry data to evaluate validity. The reliability of the Fels PAQ for the girls, boys, and the elementary, middle, and high school age groups range was r=0.48-0.76. For the elementary school children, the correlation coefficient examining validity between the Fels PAQ total score and Actiwatch (counts per minute) was 0.34 (P=0.004). The correlation coefficients were lower in middle school (r=0.11, P=0.31) and high school (r=0.21, P=0.006) adolescents. The sport index of the Fels PAQ for children had the highest validity in the high school participants (r=0.34, P=0.002). The Fels PAQ for children is moderately reliable for all age groups of children. Validity of the Fels PAQ for children is acceptable for elementary and high school students when the total activity score or the sport index is used. The sport index was similar to the total score for elementary students but was a better measure of physical activity among high school students.

  14. Undulator physics and coherent harmonic generation at the MAX-lab electron storage ring

    International Nuclear Information System (INIS)

    Werin, Sverker.

    1991-01-01

    This work presents the undulator and harmonic generation project at the electron storage ring MAX-lab at University of Lund. The theory of undulator radiation, laser coherent harmonic generation, optical klystron amplifiers and FELs is treated in one uniform way, with complete solutions of the necessary equations. The permanent magnet undulator is described in some detail, along with the installation of the undulator in the storage ring. Details regarding the emitted radiation, the electron beam path in the undulator and other results are analysed. Finally harmonic generation using a Nd:YAG laser and the creation of coherent photons at the third harmonic (355 nm) is described. (author)

  15. Linac Coherent Light Source (LCLS) Design Study Report

    Energy Technology Data Exchange (ETDEWEB)

    Cornacchia, Massimo

    1998-12-04

    The Stanford Linear Accelerator Center, in collaboration with Los Alamos National Laboratory, Lawrence Livermore National Laboratory, and the University of California at Los Angeles, is proposing to build a Free-Electron-Laser (FEL) R and D facility operating in the wavelength range 1.5-15 {angstrom}. This FEL, called the ''Linac Coherent Light Source'' (LCLS), utilizes the SLAC linac and produces sub-picosecond pulses of short wavelength x-rays with very high peak brightness and full transverse coherence. Starting in FY 1998, the first two-thirds of the SLAC linac will be used for injection into the B factory. This leaves the last one-third free for acceleration to 15 GeV. The LCLS takes advantage of this opportunity, opening the way for the next generation of synchrotron light sources with largely proven technology and cost effective methods. This proposal is consistent with the recommendations of the Report of the Basic Energy Sciences Advisory Committee (Synchrotron Radiation Light Source Working Group, October 18-19, 1997). The report recognizes that ''fourth-generation x-ray sources...will in all likelihood be based on the free electron laser concepts. If successful, this technology could yield improvements in brightness by many orders of magnitude.'' This Design Study, the authors believe, confirms the feasibility of constructing an x-ray FEL based on the SLAC linac. Although this design is based on a consistent and feasible set of parameters, some components require more research and development to guarantee the performance. Given appropriate funding, this R and D phase can be completed in 2 years.

  16. Status report on the development of a high-power UV/IR FEL at CEBAF

    Energy Technology Data Exchange (ETDEWEB)

    Benson, S.; Bohn, C.; Dylla, H.F. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States)] [and others

    1995-12-31

    Last year we presented a design for a kilowatt industrial UV FEL based on a superconducting RF accelerator delivering 5 mA of electron-beam current at 200 MeV with energy recovery to enhance efficiency. Since then, we have progressed toward resolving several issues associated with that design. More exact simulations of the injector have resulted in a more accurate estimate of the injector performance. A new injection method has reduced the longitudinal and transverse emittance at the linac entrance. A more compact lattice has been designed for the UV FEL, and a new recirculation scheme has been identified which greatly increases the threshold for longitudinal instabilities. We decided to use a wiggler from the Advanced Photon Source which leads to a robust high-gain FEL. Analysis of the stability of an RF control system based on CEBAF control modules indicates that only minor modifications will be needed to apply them to this FEL. Detailed magnet specifications, vacuum-chamber beam apertures, and diagnostic specifications have been developed for the recirculation arcs. The design of the optical cavity has been conceptualized, and control systems have been devised to regulate mirror distortion. A half-scale model of one of the end-corner cubes has been built and tested. Finally, three-dimensional simulations have been carried out which indicate that the FEL should exceed its minimum design goals with adequate performance margin.

  17. PFM2: a 32 × 32 processor for X-ray diffraction imaging at FELs

    Science.gov (United States)

    Manghisoni, M.; Fabris, L.; Re, V.; Traversi, G.; Ratti, L.; Grassi, M.; Lodola, L.; Malcovati, P.; Vacchi, C.; Pancheri, L.; Benkechcache, M. E. A.; Dalla Betta, G.-F.; Xu, H.; Verzellesi, G.; Ronchin, S.; Boscardin, M.; Batignani, G.; Bettarini, S.; Casarosa, G.; Forti, F.; Giorgi, M.; Paladino, A.; Paoloni, E.; Rizzo, G.; Morsani, F.

    2016-11-01

    This work is concerned with the design of a readout chip for application to experiments at the next generation X-ray Free Electron Lasers (FEL). The ASIC, named PixFEL Matrix (PFM2), has been designed in a 65 nm CMOS technology and consists of 32 × 32 pixels. Each cell covers an area of 110 × 110 μm2 and includes a low-noise charge sensitive amplifier (CSA) with dynamic signal compression, a time-variant shaper used to process the preamplifier output signal, a 10-bit successive approximation register (SAR) analog-to-digital converter (ADC) and digital circuitry for channel control and data readout. Two different solutions for the readout channel, based on different versions of the time-variant filter, have been integrated in the chip. Both solutions can be operated in such a way to cope with the high frame rate (exceeding 1 MHz) foreseen for future X-ray FEL machines. The ASIC will be bump bonded to a slim/active edge pixel sensor to form the first demonstrator for the PixFEL X-ray imager. This work has been carried out in the frame of the PixFEL project funded by Istituto Nazionale di Fisica Nucleare (INFN), Italy.

  18. A table-top x-ray FEL based on a laser wakefield accelerator-undulator system

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, K.; Kawakubo, T.; Nakanishi, H. [National Lab. for High Energy Physics, Ibaraki-ken (Japan)] [and others

    1995-12-31

    Ultrahigh-gradient electron acceleration has been confirmed owing to the laser wakefield acceleration mechanism driven by an intense short laser wakefield acceleration mechanism driven by an intense short laser pulse in an underdense plasma. The laser wakefield acceleration makes it possible to build a compact electron linac capable of producing an ultra-short bunched electron beam. While the accelerator is attributed to longitudinal wakefields, transverse wakefields simultaneously generated by a short laser pulse can serve as a plasma undulator with a very short wavelength equal to a half of the plasma wavelength. We propose a new FEL concept for X-rays based on a laser wakefield accelerator-undulator system driven by intense short laser pulses delivered from table-top terawatt lasers. The system is composed of the accelerator stage and the undulator stage in a table-top size. A low energy electron beam is accelerated an bunched into microbunches due to laser wakefields in the accelerator stage. A micro-bunched beam travelling to the opposite direction of driving laser pulses produces coherent X-ray radiation in the undulator stage. A practical configuration and its analyses are presented.

  19. Wake monochromator in asymmetric and symmetric Bragg and Laue geometry for self-seeding the European X-ray FEL

    International Nuclear Information System (INIS)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni; Serkez, Svitozar; Tolkiehn, Martin

    2013-01-01

    We discuss the use of self-seeding schemes with wake monochromators to produce TW power, fully coherent pulses for applications at the dedicated bio-imaging beamline at the European X-ray FEL, a concept for an upgrade of the facility beyond the baseline previously proposed by the authors. We exploit the asymmetric and symmetric Bragg and Laue reflections (sigma polarization) in diamond crystal. Optimization of the bio-imaging beamline is performed with extensive start-to-end simulations, which also take into account effects such as the spatio-temporal coupling caused by the wake monochromator. The spatial shift is maximal in the range for small Bragg angles. A geometry with Bragg angles close to π/2 would be a more advantageous option from this viewpoint, albeit with decrease of the spectral tunability. We show that it will be possible to cover the photon energy range from 3 keV to 13 keV by using four different planes of the same crystal with one rotational degree of freedom.

  20. Wake monochromator in asymmetric and symmetric Bragg and Laue geometry for self-seeding the European X-ray FEL

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni; Serkez, Svitozar; Tolkiehn, Martin [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2013-01-15

    We discuss the use of self-seeding schemes with wake monochromators to produce TW power, fully coherent pulses for applications at the dedicated bio-imaging beamline at the European X-ray FEL, a concept for an upgrade of the facility beyond the baseline previously proposed by the authors. We exploit the asymmetric and symmetric Bragg and Laue reflections (sigma polarization) in diamond crystal. Optimization of the bio-imaging beamline is performed with extensive start-to-end simulations, which also take into account effects such as the spatio-temporal coupling caused by the wake monochromator. The spatial shift is maximal in the range for small Bragg angles. A geometry with Bragg angles close to {pi}/2 would be a more advantageous option from this viewpoint, albeit with decrease of the spectral tunability. We show that it will be possible to cover the photon energy range from 3 keV to 13 keV by using four different planes of the same crystal with one rotational degree of freedom.

  1. The DarkLight Experiment at the JLab FEL

    Science.gov (United States)

    Fisher, Peter

    2013-10-01

    DarkLight will study the production of gauge bosons associated with Dark Forces theories in the scattering of 100 MeV electrons on proton a target. DarkLight is a spectrometer to measure all the final state particles in e- + p -->e- + p +e- +e+ . QED allows this process and the invariant mass distribution of the e+e- pair is a continuum from nearly zero to nearly the electron beam energy. Dark Forces theories, which allow the dark matter mass scale to be over 1 TeV, predict a gauge boson A' in the mass range of 10-1,000 MeV and decays to an electron-positron pair with an invariant mass of mA'. We aim to search for this process using the 100 MeV, 10 mA electron beam at the JLab Free Electron Laser impinging on a hydrogen target with a 1019 cm-2 density. The resulting luminosity of 6 ×1035/cm2-s gives the experiment enough sensitivity to probe A' couplings of 10-9 α . DarkLight is unique in its design to detect all four particles in the final state. The leptons will be measured in a large high-rate TPC and a silicon sensor will measure the protons. A 0.5 T solenoidal magnetic field provides the momentum resolution and focuses the copious Møller scattering background down the beam line, away from the detectors. A first beam test has shown the FEL beam is compatible with the target design and that the hall backgrounds are manageable. The experiment has been approved by Jefferson Lab for first running in 2017.

  2. The FERMI@Elettra free-electron-laser source for coherent X-ray physics: photon properties, beam transport system, and applications

    Energy Technology Data Exchange (ETDEWEB)

    Allaria, Enrico; Callegari, Carlo; Cocco, Daniele; Fawley, William M.; Kiskinova, Maya; Masciovecchio, Claudio; Parmigiani, Fulvio

    2010-04-05

    FERMI@Elettra is comprised of two free electron lasers (FELs) that will generate short pulses (tau ~;; 25 to 200 fs) of highly coherent radiation in the XUV and soft X-ray region. The use of external laser seeding together with a harmonic upshift scheme to obtain short wavelengths will give FERMI@Elettra the capability to produce high quality, longitudinal coherent photon pulses. This capability together with the possibilities of temporal synchronization to external lasers and control of the output photon polarization will open new experimental opportunities not possible with currently available FELs. Here we report on the predicted radiation coherence properties and important configuration details of the photon beam transport system. We discuss the several experimental stations that will be available during initial operations in 2011, and we give a scientific perspective on possible experiments that can exploit the critical parameters of this new light source.

  3. A photocathode rf gun design for a mm-wave linac-based FEL

    International Nuclear Information System (INIS)

    Nassiri, A.; Berenc, T.; Foster, J.; Waldschmidt, G.; Zhou, J.

    1995-01-01

    In recent years, advances in the rf gun technology have made it possible to produce small beam emittances suitable for short period microundulators which take advantage of the low emittance beam to reduce the wavelength of FELs. At the Advanced Photon Source, we are studying the design of a compact 50-MeV superconducting mm-wave linac-based FEL for the production of short wavelengths (∼300 nm) to carry out FEL demonstration experiments. The electron source considered for the linac is a 30- GHz, 3 1/2-cell π-mode photocathode rf gun. For cold model rf measurements a 15-GHz prototype structure was fabricated. Here we report on the design, numerical modelling and the initial cold-model rf measurement results on the 15-GHz prototype structure

  4. DC High Voltage Conditioning of Photoemission Guns at Jefferson Lab FEL

    International Nuclear Information System (INIS)

    DC high voltage photoemission electron guns with GaAs photocathodes have been used to produce polarized electron beams for nuclear physics experiments for about 3 decades with great success. In the late 1990s, Jefferson Lab adopted this gun technology for a free electron laser (FEL), but to assist with high bunch charge operation, considerably higher bias voltage is required compared to the photoguns used at the Jefferson Lab Continuous Electron Beam Accelerator Facility. The FEL gun has been conditioned above 400 kV several times, albeit encountering non-trivial challenges with ceramic insulators and field emission from electrodes. Recently, high voltage processing with krypton gas was employed to process very stubborn field emitters. This work presents a summary of the high voltage techniques used to high voltage condition the Jefferson Lab FEL photoemission gun.

  5. IR-FEL-induced green fluorescence protein (GFP) gene transfer into plant cell

    CERN Document Server

    Awazu, K; Tamiya, E

    2002-01-01

    A Free Electron Laser (FEL) holds potential for various biotechnological applications due to its characteristics such as flexible wavelength tunability, short pulse and high peak power. We could successfully introduce the Green Fluorescent Protein (GFP) gene into tobacco BY2 cells by IR-FEL laser irradiation. The irradiated area of the solution containing BY2 cells and plasmid was about 0.1 mm sup 2. FEL irradiation at a wavelength of 5.75 and 6.1 mu m, targeting absorption by the ester bond of the lipid and the amide I bond of the protein, respectively, was shown to cause the introduction of the fluorescent dye into the cell. On the other hand, transient expression of the GFP fluorescence was only observed after irradiation at 5.75 mu m. The maximum transfer efficiency was about 0.5%.

  6. Experimental study of compact FEL with micro wiggler and electrostatic accelerator

    International Nuclear Information System (INIS)

    Fujii, S.; Fujita, T.; Mizuno, T.; Ohshima, T.; Kawai, M.; Saito, H.; Kuroki, S.; Koshiji, K.

    2001-01-01

    A compact FEL for submillimeter and far infrared regions is studied at the Institute of Space and Astronautical Science. The FEL can be compact by using an electrostatic accelerator and a micro wiggler. The electrostatic accelerator (DISKTRON) with a diameter of 1 m can generate up to 1 MV continuously. The micro wiggler is fabricated using permanent magnets made from Nd-Fe-B. (period: 8 mm, total length: 248 mm, gap: 2-10 mm, K parameter: 0.07-0.7) An electron beam of high quality is generated by means of a photo cathode. (731 kV, 1.5 A, 25 ns, 2 mmphi, ΔE/E:0.18%) In the preliminary phase, detection of the FEL at the millimeter wave region of 96 GHz is conducted. The electron beam is injected into a resonator with Distributed Bragg Reflector. A small millimeter wave signal has been detected

  7. Start-to-end simulation for the LCLS X-ray FEL

    CERN Document Server

    Reiche, S; Rosenzweig, J; Emma, P; Krejcik, P

    2002-01-01

    X-ray FELs, such as the LCLS and TESLA FEL, require electron beams with large peak current and very small emittance. The X-ray peak power, temporal and spectral properties, depend significantly on details of the electron beam phase space distribution. The electron beam distribution is determined by many effects, as the emission process at the gun photo-cathode, bunch compression, acceleration and wakefields within the undulator. Although analytical results can give an estimate of the expected performance, the complexity of the electron beam generation, acceleration and compression can only be evaluated using a numerical simulation of all these processes, a start-to-end simulation. In this presentation we discuss the LCLS X-Ray FEL performance estimated by a start-to-end simulation, and we compare the results with those obtained using a simpler model.

  8. A photocathode rf gun design for a mm-wave linac-based FEL

    Energy Technology Data Exchange (ETDEWEB)

    Nassiri, A.; Berenc, T,; Foster, J.; Waldschmidt, G.; Zhou, J.

    1995-07-01

    In recent years, advances in the rf gun technology have made it possible to produce small beam emittances suitable for short period microundulators which take advantage of the low emittance beam to reduce the wavelength of FELs. At the Advanced Photon Source, we are studying the design of a compact 50-MeV superconducting mm-wave linac-based FEL for the production of short wavelengths ({approximately}300 nm) to carry out FEL demonstration experiments. The electron source considered for the linac is a 30- GHz, 3 1/2-cell {pi}-mode photocathode rf gun. For cold model rf measurements a 15-GHz prototype structure was fabricated. Here we report on the design, numerical modelling and the initial cold-model rf measurement results on the 15-GHz prototype structure.

  9. EXPERIENCE AND PLANS OF THE JLAB FEL FACILITY AS A USER FACILITY

    Energy Technology Data Exchange (ETDEWEB)

    Michelle D. Shinn

    2007-08-26

    Jefferson Lab's IR Upgrade FEL building was planned from the beginning to be a user facility, and includes an associated 600 m2 area containing seven laboratories. The high average power capability (multikilowatt-level) in the near-infrared (1-3 microns), and many hundreds of watts at longer wavelengths, along with an ultrafast (~ 1 ps) high PRF (10's MHz) temporal structure makes this laser a unique source for both applied and basic research. In addition to the FEL, we have a dedicated laboratory capable of delivering high power (many tens of watts) of broadband THz light. After commissioning the IR Upgrade, we once again began delivering beam to users in 2005. In this presentation, I will give an overview of the FEL facility and its current performance, lessons learned over the last two years, and a synopsis of current and future experiments.

  10. The Los Alamos POP Project: FEL oscillator experiments in the ultraviolet and beyond

    International Nuclear Information System (INIS)

    Newnam, B.E.; Warren, R.W.; Goldstein, J.C.; Schmitt, M.J.; Bender, S.C.; Carlsten, B.E.; Feldman, D.W.; O'Shea, P.G.

    1992-01-01

    The Los Alamos POP Project will include a series of proof-of-principle FEL oscillator experiments in 1992 designed to extend FEL operation into the ultraviolet (UV) and vacuum ultraviolet (VUV). With beam energy extended to 50 MeV, enhanced beam brightness with a photoinjector, and appropriate UV and VUV resonator optics, the Los Alamos FEL oscillator should have sufficient single-pass gain (20--30%) to reach below 200 nm. The first goal will be lasing at 250 nm utilizing a permanent-magnet undulator with 5-mm period or alternatively on the third harmonic with a 1-cm period. To operate at VUV wavelengths of 200 and 150 nm (third harmonic), pulsed electromagnetic microwigglers with periods of 5.7- and 4.3 mm will be employed. 23 refs

  11. An Optimized Low-Charge Configuration of the LINAC Coherent Light Source

    CERN Document Server

    Emma, Paul; Huang, Zhirong; Limborg-Deprey, Cecile; Reiche, Sven; Wu, Juhao; Zolotorev, Max S

    2005-01-01

    The Linac Coherent Light Source (LCLS) is an x-ray free-electron laser (FEL) project based on the SLAC linac. The nominal parameter set is founded on a 1-nC bunch charge and normalized emittance of about 1 micron. The most challenging issues, such as emittance generation, wakefields, and coherent synchrotron radiation (CSR), are associated with the high bunch charge. In the LCLS in particular, with its strong linac wakefields, the bunch compression process produces sharp temporal horns at the head and tail of the bunch with degraded local emittance, effectively wasting much of the charge. The sharp horns intensify CSR in the bends and further drive a strong resistive-wall wakefield in the long FEL undulator. Although these issues are not insurmountable, they suggest a lower bunch charge may be more suitable. This study uses a 0.2-nC bunch charge and 0.85-micron emittance with only 30 A of peak current in the injector, producing the same FEL saturation length. The resulting performance is more stable, has negl...

  12. Coherence and Sense of Coherence

    DEFF Research Database (Denmark)

    Dau, Susanne

    2014-01-01

    examined is how activating of models of blended learning in undergraduate education for teacher and radiograph affects the knowledge development. This is approached by mixed methods. The empirical data consist of data from surveys as well as focus group interviews and some observation studies. These data...... are analyzed and interpreted through a critical hermeneutical process of prefiguration, configuration and re-figuration. The findings illustrate significantly importance of sense of coherence among participants as a condition for implementing new designs and new learning environments. It is revealed that sense...

  13. Analysis of longitudinal bunching in an FEL driven two-beam accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Lidia, S.; Gardelle, J.; Lefevre, T.; Donohue, J.T.; Gouard, P.; Rullier, J.L.; Vermare, C.

    2000-08-01

    Recent experiments have explored the use of a free-electron laser (FEL) as a buncher for a microwave two-beam accelerator, and the subsequent driving of a standing-wave rf output cavity. Here the authors present a deeper analysis of the longitudinal dynamics of the electron bunches as they are transported from the end of the FEL and through the output cavity. In particular, the authors examine the effect of the transport region and cavity aperture to filter the bunched portion of the beam.

  14. Analysis of longitudinal bunching in an FEL driven two-beam accelerator

    International Nuclear Information System (INIS)

    Lidia, S.; Gardelle, J.; Lefevre, T.; Donohue, J.T.; Gouard, P.; Rullier, J.L.; Vermare, C.

    2000-01-01

    Recent experiments have explored the use of a free-electron laser (FEL) as a buncher for a microwave two-beam accelerator, and the subsequent driving of a standing-wave rf output cavity. Here the authors present a deeper analysis of the longitudinal dynamics of the electron bunches as they are transported from the end of the FEL and through the output cavity. In particular, the authors examine the effect of the transport region and cavity aperture to filter the bunched portion of the beam

  15. High-performance UV/VUV optics for the Storage Ring FEL at ELETTRA

    CERN Document Server

    Gatto, A; Kaiser, N; Ristau, D; Guenster, S; Kohlhaas, J; Marsi, M; Trovò, M; Walker, R P

    2002-01-01

    Going to shorter wavelengths beyond the deep ultraviolet involves the development of dedicated optics for FEL with devoted coating techniques and characterizations. Low loss, high reflectivity dielectric mirrors with a long lifetime in a strongly harsh synchrotron radiation environment are required. In February 2001, lasing at 189.7 nm was obtained with Al sub 2 O sub 3 /SiO sub 2 Ion Beam Sputtering mirrors, the shortest wavelength obtained so far with FEL oscillators. In July 2001, 330 mW extracted power was measured with optimized transmission mirrors. Coating research and development correlated to lasing performance obtained so far is reported.

  16. High-performance UV/VUV optics for the Storage Ring FEL at ELETTRA

    Energy Technology Data Exchange (ETDEWEB)

    Gatto, A. E-mail: alexandre.gatto@iof.fraunhofer.de; Heber, J.; Kaiser, N.; Ristau, D.; Guenster, S.; Kohlhaas, J.; Marsi, M.; Trovo' , M.; Walker, R.P

    2002-05-01

    Going to shorter wavelengths beyond the deep ultraviolet involves the development of dedicated optics for FEL with devoted coating techniques and characterizations. Low loss, high reflectivity dielectric mirrors with a long lifetime in a strongly harsh synchrotron radiation environment are required. In February 2001, lasing at 189.7 nm was obtained with Al{sub 2}O{sub 3}/SiO{sub 2} Ion Beam Sputtering mirrors, the shortest wavelength obtained so far with FEL oscillators. In July 2001, 330 mW extracted power was measured with optimized transmission mirrors. Coating research and development correlated to lasing performance obtained so far is reported.

  17. Time-resolved protein dynamics using synchronized Ti sapphire regenerative amplifier/infrared FEL

    Energy Technology Data Exchange (ETDEWEB)

    Stanley, R.J.; Haar, P.; Boxer, S.G. [Stanford Univ., CA (United States)

    1995-12-31

    We have synchronized a femtosecond 5 kHz Ti Sapphire regenerative amplifier (regen) to the Stanford Superconducting Accelerator/Free Electron laser (SCA/FEL) to within 2 picoseconds time jitter. We are using this capability to measure the time resolved spectral evolution of the radical cation band of the initial electron donor from bacterial reaction centers (Rb sphaeroides) after the initiation of electron transfer using a {approximately} 120 fs NIR pulse from the regen. The FEL is used to probe for the appearance of the radical cation band at {approximately} 4 {mu}m.

  18. Use of Multipass Recirculation and Energy Recovery In CW SRF X-FEL Driver Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, David; Akers, Walt; Benson, Stephen V.; Biallas, George; Blackburn, Keith; Boyce, James; Bullard, Donald; Coleman, James; Dickover, Cody; Ellingsworth, Forrest; Evtushenko, Pavel; Fisk, Sally; Gould, Christopher; Gubeli, Joseph; Hannon, Fay; Hardy, David; Hernandez-Garcia, Carlos; Jordan, Kevin; Klopf, John; Kortze, J.; Legg, Robert; Li, Rui; Marchlik, Matthew; Moore, Steven W.; Neil, George; Powers, Thomas; Sexton, Daniel; Shin, Ilkyoung; Shinn, Michelle D.; Tennant, Christopher; Terzic, Balsa; Walker, Richard; Williams, Gwyn P.; Wilson, G.; Zhang, Shukui

    2010-08-01

    We discuss the use of multipass recirculation and energy recovery in CW SRF drivers for short wavelength FELs. Benefits include cost management (through reduced system footprint, required RF and SRF hardware, and associated infrastructure - including high power beam dumps and cryogenic systems), ease in radiation control (low drive beam exhaust energy), ability to accelerate and deliver multiple beams of differing energy to multiple FELs, and opportunity for seamless integration of multistage bunch length compression into the longitudinal matching scenario. Issues include all those associated with ERLs compounded by the challenge of generating and preserving the CW electron drive beam brightness required by short wavelength FELs. We thus consider the impact of space charge, BBU and other environmental wakes and impedances, ISR and CSR, potential for microbunching, intra-beam and beam-residual gas scattering, ion effects, RF transients, and halo, as well as the effect of traditional design, fabrication, installation and operational errors (lattice aberrations, alignment, powering, field quality). Context for the discussion is provided by JLAMP, the proposed VUV/X-ray upgrade to the existing Jefferson Lab FEL.

  19. Using a Neural Network Control Policy for Rapid Switching Between Beam Parameters in an FEL

    NARCIS (Netherlands)

    Edelen, A.L.; Biedron, S.G.; Edelen, J.P.; Milton, S.V.; van der Slot, P.J.M.

    2017-01-01

    FEL user facilities often must accommodate requests for a variety of beam parameters. This usually requires skilled operators to tune the machine, reducing the amount of available time for users. In principle, a neural network control policy that is trained on a broad range of operating states could

  20. Status and prospects of a compact FIR FEL driven by a magnetron-based microtron

    International Nuclear Information System (INIS)

    Jeong, Young Uk; Kazakevitch, Grigori M.; Lee, Byung Cheol; Kim, Sun Kook; Cho, Sung Oh; Gavrilov, Nicolai G.; Lee, Jongmin

    2002-01-01

    A magnetron-based microtron as a driver of FIR FEL has several prominent advantages in cost, size, beam quality and operation convenience. However, it has some disadvantages due to the instability of the RF frequency and a low current. In order to overcome these disadvantages, the frequency stability of the magnetron was improved, and the interaction between the electron beam and the FIR radiation was enhanced by using a high-performance undulator and a low-loss waveguide-mode optical resonator. The FEL is now under upgrade in order to extend the wavelength range to cover 90-300 μm, which can be done by increasing the energy range of electron beam to 4.3-7 MeV. In this paper, we report the results of investigations on output characteristics of the FEL depending on cavity detuning, electron beam matching, and RF instability. Based on the results, we discuss the prospects of wide-band FIR FELs driven by magnetron-based microtrons as potent sources of radiation for scientific applications

  1. OCELOT: A software framework for synchrotron light source and FEL studies

    Energy Technology Data Exchange (ETDEWEB)

    Agapov, I., E-mail: ilya.agapov@xfel.eu [European XFEL GmbH, Hamburg (Germany); Geloni, G. [European XFEL GmbH, Hamburg (Germany); Tomin, S. [NRC Kurchatov Institute, Moscow (Russian Federation); Zagorodnov, I. [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany)

    2014-12-21

    OCELOT is a novel multiphysics simulation toolkit, which has been in development at European XFEL in collaboration with NRC Kurchatov Institute and DESY since 2011. In this paper we describe its architecture, implementation, and applications in the area of synchrotron light sources and FELs.

  2. Mine-detection test facilities at TNO-FEL test location "Waalsdorp"

    NARCIS (Netherlands)

    Rhebergen, J.B.; Zwamborn, A.P.M.

    1998-01-01

    As part of the TNO-FEL Ultra-Wide-Band Ground-Penetrating-Radar (UWB-GPR) project, a test facility for controlled GPR experiments was planned. Construction of this sand-box test facility has recently been completed. At the same site another test facility, for evaluating various commercial of the

  3. Camera for coherent diffractive imaging and holography with a soft-x-ray free-electron laser

    International Nuclear Information System (INIS)

    Bajt, Sasa; Chapman, Henry N.; Spiller, Eberhard A.; Alameda, Jennifer B.; Woods, Bruce W.; Frank, Matthias; Bogan, Michael J.; Barty, Anton; Boutet, Sebastien; Marchesini, Stefano; Hau-Riege, Stefan P.; Hajdu, Janos; Shapiro, David

    2008-01-01

    We describe a camera to record coherent scattering patterns with a soft-x-ray free-electron laser (FEL). The camera consists of a laterally graded multilayer mirror, which reflects the diffraction pattern onto a CCD detector. The mirror acts as a bandpass filter for both the wavelength and the angle, which isolates the desired scattering pattern from nonsample scattering or incoherent emission from the sample. The mirror also solves the particular problem of the extreme intensity of the FEL pulses, which are focused to greater than 10 14 W/cm 2 . The strong undiffracted pulse passes through a hole in the mirror and propagates onto a beam dump at a distance behind the instrument rather than interacting with a beam stop placed near the CCD. The camera concept is extendable for the full range of the fundamental wavelength of the free electron laser in Hamburg (FLASH) FEL (i.e., between 6 and 60 nm) and into the water window. We have fabricated and tested various multilayer mirrors for wavelengths of 32, 16, 13.5, and 4.5 nm. At the shorter wavelengths mirror roughness must be minimized to reduce scattering from the mirror. We have recorded over 30,000 diffraction patterns at the FLASH FEL with no observable mirror damage or degradation of performance

  4. A helical optical for circular polarized UV-FEL project at the UVSOR

    Energy Technology Data Exchange (ETDEWEB)

    Hama, Hiroyuki [Institute for Molecular Science, Okazaki (Japan)

    1995-12-31

    Most of existing storage ring free electron lasers (SRFEL) are restricted those performances by degradation of mirrors in optical cavities. In general, the SRFEL gain at the short wavelength region with high energy electrons is quite low, and the high reflectivity mirrors such as dielectric multilayer mirrors are therefore required. The mirror degradation is considered as a result of irradiation of higher harmonic photons that are simultaneously emitted from planar optical klystron (OK) type undulators, which are commonly used in SRFEL. This problem is getting severer as the lasing wavelength becomes shorter. The UVSOR-FEL had been originally scheduled to be shutdown by 1996 because another undulator project for spectroscopic studies with circular polarized photon would take the FEL`s place. According to suggestion of the insertion device group of the SPring-8, we have designed a helical undulator that is able to vary degree and direction of the polarization easily. In addition, the undulator can be converted into a helical OK by replacing magnets at the center part of undulator in order to coexist with further FEL experiments. Using a calculated magnetic field for magnet configurations of the OK mode, the radiation spectrum at wide wavelength range was simulated by a Fourier transform of Lienard-Wiechert potentials. As a matter of course, some higher harmonics are radiated on the off-axis angle. However it was found out that the higher harmonics is almost negligible as far as inside a solid angle of the Gaussian laser mode. Moreover the gain at the UV region of 250 nm is expected to be much higher than our present FEL because of high brilliant fundamental radiation. The calculated spatial distribution of higher harmonics and the estimated instantaneous gain is presented. Advantages of the helical OK for SRFEL will be discussed in view of our experience, and a possibility of application two-color experiment with SR will be also mentioned.

  5. High-field strong-focusing undulator designs for X-ray Linac Coherent Light Source (LCLS) applications

    International Nuclear Information System (INIS)

    Caspi, S.; Schlueter, R.; Tatchyn, R.

    1995-01-01

    Linac-driven X-Ray Free Electron Lasers (e.g., Linac Coherent Light Sources (LCLSs)), operating on the principle of single-pass saturation in the Self-Amplified Spontaneous Emission (SASE) regime typically require multi-GeV beam energies and undulator lengths in excess of tens of meters to attain sufficient gain in the 1 angstrom--0.1 angstrom range. In this parameter regime, the undulator structure must provide: (1) field amplitudes B 0 in excess of 1T within periods of 4cm or less, (2) peak on-axis focusing gradients on the order of 30T/m, and (3) field quality in the 0.1%--0.3% range. In this paper the authors report on designs under consideration for a 4.5--1.5 angstrom LCLS based on superconducting (SC), hybrid/PM, and pulsed-Cu technologies

  6. The Influence of the Seed Pulse Shape on the Output Performance of the BESSY Multi-stage HGHG-FEL

    CERN Document Server

    Meseck, Atoosa; Kuske, Bettina

    2004-01-01

    The BESSY soft X-ray FEL is planned as a High Gain Harmonic Generation (HGHG) FEL multi-user facility covering the VUV to soft X-ray spectral range. In the HGHG scheme, the properties of the radiation output are dominated by the characteristics of the laser seed. In this connection, the influence of the laser pulse shape on the output, in particular on the output spectrum is of interest. Simulation studies for the BESSY-HGHG-FELs are presented and the output performance for different shapes of the laser pulse is discussed.

  7. Spectral Phase Modulation and chirped pulse amplification in High Gain Harmonic Generation

    CERN Document Server

    Wu, Zilu; Krinsky, Sam; Loos, Henrik; Murphy, James; Shaftan, Timur; Sheehy, Brian; Shen, Yuzhen; Wang, Xijie; Yu Li Hua

    2004-01-01

    High Gain Harmonic Generation (HGHG), because it produces longitudinally coherent pulses derived from a coherent seed, presents remarkable possibilities for manipulating FEL pulses. If spectral phase modulation imposed on the seed modulates the spectral phase of the HGHG in a deterministic fashion, then chirped pulse amplification, pulse shaping, and coherent control experiments at short wavelengths become possible. In addition, the details of the transfer function will likely depend on electron beam and radiator dynamics and so prove to be a useful tool for studying these. Using the DUVFEL at the National Synchrotron Light Source at Brookhaven National Laboratory, we present spectral phase analyses of both coherent HGHG and incoherent SASE ultraviolet FEL radiation, applying Spectral Interferometry for Direct Electric Field Reconstruction (SPIDER), and assess the potential for employing compression and shaping techniques.

  8. Temporal characterization of FEL micropulses as function of cavity length detuning using frequency-resolved optical gating

    Energy Technology Data Exchange (ETDEWEB)

    Richman, B.A. [Stanford Univ., CA (United States); DeLong, K.W.; Trebino, R. [Sandia National Lab., Livermore, CA (United States)

    1995-12-31

    Results of frequency resolved optical gating (FROG) measurements on the Stanford mid-IR FEL system show the effect of FEL cavity length detuning on the micropulse temporal structure. The FROG technique enables the acquisition of complete and uniquely invertible amplitude and phase temporal dependence of optical pulses. Unambiguous phase and amplitude profiles are recovered from the data. The optical pulses are nearly transform limited, and the pulse length increases with cavity length detuning.

  9. Much Ado about Microbunching: Coherent Bunching in High Brightness Electron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Ratner, Daniel [Stanford Univ., CA (United States)

    2011-05-01

    The push to provide ever brighter coherent radiation sources has led to the creation of correspondingly bright electron beams. With billions of electrons packed into normalized emittances (phase space) below one micron, collective effects may dominate both the preservation and use of such ultra-bright beams. An important class of collective effects is due to density modulations within the bunch, or microbunching. Microbunching may be deleterious, as in the case of the Microbunching Instability (MBI), or it may drive radiation sources of unprecedented intensity, as in the case of Free Electron Lasers (FELs). In this work we begin by describing models of microbunching due to inherent beam shot noise, which sparks both the MBI as well as SLAC's Linac Coherent Light Source, the world's first hard X-ray laser. We first use this model to propose a mechanism for reducing the inherent beam shot noise as well as for predicting MBI effects. We then describe experimental measurements of the resulting microbunching at LCLS, including optical radiation from the MBI, as well as the first gain length and harmonic measurements from a hard X-ray FEL. In the final chapters, we describe schemes that use external laser modulations to microbunch light sources of the future. In these sections we describe coherent light source schemes for both both linacs and storage rings.

  10. A simple method for simulation of coherent synchrotron radiation in a tracking code

    International Nuclear Information System (INIS)

    Borland, M.

    2000-01-01

    Coherent synchrotron radiation (CSR) is of great interest to those designing accelerators as drivers for free-electron lasers (FELs). Although experimental evidence is incomplete, CSR is predicted to have potentially severe effects on the emittance of high-brightness electron beams. The performance of an FEL depends critically on the emittance, current, and energy spread of the beam. Attempts to increase the current through magnetic bunch compression can lead to increased emittance and energy spread due to CSR in the dipoles of such a compressor. The code elegant was used for design and simulation of the bunch compressor for the Low-Energy Undulator Test Line (LEUTL) FEL at the Advanced Photon Source (APS). In order to facilitate this design, a fast algorithm was developed based on the 1-D formalism of Saldin and coworkers. In addition, a plausible method of including CSR effects in drift spaces following the chicane magnets was developed and implemented. The algorithm is fast enough to permit running hundreds of tolerance simulations including CSR for 50 thousand particles. This article describes the details of the implementation and shows results for the APS bunch compressor

  11. FEL induced electron bunch heating observed by a method based on synchronous phase detection

    CERN Document Server

    Hosaka, M; Katoh, M; Yamazaki, J; Hama, H

    2001-01-01

    A new method for monitoring instantaneous bunch length has been developed on the UVSOR storage ring. Based on the bunch length dependence of the loss factor, the bunch length can be derived from the synchronous phase shift. Experiments using this method were performed to observe the bunch lengthening associated with the free electron laser (FEL) power variation. From the detuning dependence of the bunch heating, it was found that additional energy spread mostly has a constant ratio to the intracavity laser power normalized by the beam current. However, at the best synchronism region, the induced energy spread exhibits a strong non-linearity against the normalized FEL power and hence the power saturation is accomplished.

  12. OPERATION AND COMMISSIONING OF THE JEFFERSON LAB UV FEL USING AN SRF DRIVER ERL

    Energy Technology Data Exchange (ETDEWEB)

    R. Legg; S. Benson; G. Biallas; K. Blackburn; J. Boyce; D. Bullard; J. Coleman; C. Dickover; D. Douglas; F. Ellingsworth; P. Evtushenko; F. Hannon; C. Hernandez-Garcia; C. Gould; J. Gubeli; D. Hardy; K. Jordan; M. Klopf; J. Kortze; M. Marchlik; W. Moore; G. Neil; T. Powers; D. Sexton; Michelle D. Shinn; C. Tennant; R. Walker; G. Wilson

    2011-03-01

    We describe the operation and commissioning of the Jefferson Lab UV FEL using a CW SRF ERL driver. Based on the same 135 MeV linear accelerator as the Jefferson Lab 10 kW IR Upgrade FEL, the UV driver ERL uses a bypass geometry to provide transverse phase space control, bunch length compression, and nonlinear aberration compensation necessitating a unique set of commissioning and operational procedures. Additionally, a novel technique to initiate lasing is described. To meet these constraints and accommodate a challenging installation schedule, we adopted a staged commissioning plan with alternating installation and operation periods. This report addresses these issues and presents operational results from on-going beam operations.

  13. BEAM OPTIMIZATION STUDY FOR AN X-RAY FEL OSCILLATOR AT THE LCLS-II

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Weilun; Huang, S.; Liu, K.X.; Huang, Z; Ding, Y.; Maxwell, T.J.; Kim, K.-J.

    2016-06-01

    The 4 GeV LCLS-II superconducting linac with high repetition beam rate enables the possibility to drive an X-Ray FEL oscillator at harmonic frequencies *. Compared to the regular LCLS-II machine setup, the oscillator mode requires a much longer bunch length with a relatively lower current. Also a flat longitudinal phase space distribution is critical to maintain the FEL gain since the X-ray cavity has extremely narrow bandwidth. In this paper, we study the longitudinal phase space optimization including shaping the initial beam from the injector and optimizing the bunch compressor and dechirper parameters. We obtain a bunch with a flat energy chirp over 400 fs in the core part with current above 100 A. The optimization was based on LiTrack and Elegant simulations using LCLS-II beam parameters.

  14. Design of RF chopper system for improving beam quality in FEL injector with thermionic gun

    International Nuclear Information System (INIS)

    Chen, Q.; Qin, B.; Tan, P.; Hu, T.; Pei, Y.; Zhang, F.

    2014-01-01

    For a linac-based Free Electron Laser (FEL), good beam quality largely contributes to the success of the final radiation. An imperfection confronted with the HUST THz-FEL facility is the long beam tail that emerges in the electron gun and exists through the whole beam line. This paper proposes to deploy a chopper system after the electron gun to truncate the beam tails before they enter into the linac. Physical dimensions of the chopper cavity are discussed in detail and we have developed and derived new analytical expressions applying to all frequencies for the optimal design. Also, technical issues of the cavity are considered. Beam dynamic simulation is performed to examine the truncation effect and the results show that more than 78% of the beam tail can be removed effectively, while preserving the emittance and energy spread in acceptable level

  15. Stabilization of the microtron-injector for a wide band compact FIR FEL

    CERN Document Server

    Kazakevitch, Grigori M; Pavlov, Viatcheslav M; Lee Byung Cheol

    2004-01-01

    To provide parameters of a simple and inexpensive magnetron-driven microtron-injector acceptable for a wide band FIR FEL, the microtron has been improved through stabilization of the beam current and the magnetron frequency. The beam current was stabilized during the macro-pulse by increasing the magnetron anode current. The pulse stabilization of the emission current makes possible the microtron operation with the maximal accelerated current, without risk of break-downs in the cavity and keeps the instability of the accelerated current at approximately 1% during long-time experiments. The magnetron frequency was stabilized using the microtron accelerating cavity as a stabilizing external resonator in a simple scheme that involved the cavity loading of the magnetron through a ferrite insulator. The scheme provides stabilization of the magnetron frequency with a coefficient of 3.5. The stabilization of current and the frequency at the microtron FIR FEL-injector provides satisfactory intrapulse stability of the...

  16. EUV stimulated emission from MgO pumped by FEL pulses

    Directory of Open Access Journals (Sweden)

    Philippe Jonnard

    2017-09-01

    Full Text Available Stimulated emission is a fundamental process in nature that deserves to be investigated and understood in the extreme ultra-violet (EUV and x-ray regimes. Today, this is definitely possible through high energy density free electron laser (FEL beams. In this context, we give evidence for soft-x-ray stimulated emission from a magnesium oxide solid target pumped by EUV FEL pulses formed in the regime of travelling-wave amplified spontaneous emission in backward geometry. Our results combine two effects separately reported in previous works: emission in a privileged direction and existence of a material-dependent threshold for the stimulated emission. We develop a novel theoretical framework, based on coupled rate and transport equations taking into account the solid-density plasma state of the target. Our model accounts for both observed mechanisms that are the privileged direction for the stimulated emission of the Mg L2,3 characteristic emission and the pumping threshold.

  17. Preliminary Design of a Synchronized Narrow Bandwidth FEL for Taiwan Light Source

    CERN Document Server

    Keung Lau Wai; Ching Fan, Tai; Zone Hsiao Feng; Tung Hsu Kuo; Hwang, Ching Shiang; Cheng Kuo Chin; Huei Luo Guo; Jen Wang Duan; Ping Wang Jau; Huey Wang Min

    2004-01-01

    Design study of a narrow line-width, high power IR-FEL facility has been carried out at NSRRC. This machine is designed to synchronize with the U9 undulator radiation of Taiwan Light Source and therefore provide new opportunity for chemical dynamics and condensed matter research. It has been proposed to use a super-conducting linac to provide a 60 MeV high quality electron beam to drive a 2.5-10 microns FEL oscillator with U5 undulator. Operating this linac in energy recovery mode will also be considered as an option to improve overall system effeciency and reduce heat loss and radiation dosage at the beam dump. Performance requirements and outcomes from this preliminary design study will be reported.

  18. Intense inverse compton {gamma}-ray source from Duke storage ring FEL

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko, V.N.; Madey, J.M.J. [Duke Univ., Durham, NC (United States)

    1995-12-31

    We suggest using FEL intracavity power in the Duke storage ring fortrays production via Inverse Compton Backscattering (ICB). The OK-4 FEL driven by the Duke storage ring will tens of watts of average lasing power in the UV/VUV range. Average intracavity power will be in kilowatt range and can be used to pump ICB source. The {gamma}-rays with maximum energy from 40 MeV to 200 MeV with intensity of 0.1-5 10{sup 10}{gamma} per second can be generated. In this paper we present expected parameters of {gamma}-ray beam parameters including its intensity and distribution. We discuss influence of e-beam parameters on collimated {gamma}-rays spectrum and optimization of photon-electron interaction point.

  19. Nearly copropagating sheared laser pulse FEL undulator for soft x-rays

    International Nuclear Information System (INIS)

    Lawler, J E; Yavuz, D; Bisognano, J; Bosch, R A; Chiang, T C; Green, M A; Jacobs, K; Miller, T; Wehlitz, R; York, R C

    2013-01-01

    A conceptual design for a soft x-ray free-electron laser (FEL) using a short-pulsed, high energy near infrared laser undulator and a low-emittance modest-energy (∼170 MeV) electron beam is described. This low-cost design uses the laser undulator beam in a nearly copropagating fashion with respect to the electron beam, instead of the traditional ‘head-on’ fashion. The nearly copropagating geometry reduces the Doppler shift of scattered radiation to yield soft, rather than hard x-rays. To increase the FEL gain a sheared laser pulse from a Ti : sapphire or other broadband laser is used to extend the otherwise short interaction time of the nearly copropagating laser undulator beam with a relativistic electron beam. (paper)

  20. A hybrid type undulator for far-infrared FELs at FELI

    Energy Technology Data Exchange (ETDEWEB)

    Zako, A.; Miyauchi, Y.; Koga, A. [Free Electron Laser Research Institute, Inc., Osaka (Japan)] [and others

    1995-12-31

    Two FEL facilities of the FELI are now operating in the wavelength range of 1-20 {mu}m. A 3.2-m hybrid type undulator ({lambda}{sub u}=80mm, N=40) has been designed for far-infrared FELs and will be installed in December. It can cover the wavelength of 20-60 {mu}m by changing K-value from 1 to 2.7 for a 28.0-MeV electron beam. It is composed of ferrite magnetic poles and Sm-Co permanent magnets. Commonly wound coils induce alternating magnetic field in ferrite poles. Combination of the induced field and the permanent magnet field can controls the magnetic field between the undulator gap.

  1. Cohering power of quantum operations

    Energy Technology Data Exchange (ETDEWEB)

    Bu, Kaifeng, E-mail: bkf@zju.edu.cn [School of Mathematical Sciences, Zhejiang University, Hangzhou 310027 (China); Kumar, Asutosh, E-mail: asukumar@hri.res.in [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094 (India); Zhang, Lin, E-mail: linyz@zju.edu.cn [Institute of Mathematics, Hangzhou Dianzi University, Hangzhou 310018 (China); Wu, Junde, E-mail: wjd@zju.edu.cn [School of Mathematical Sciences, Zhejiang University, Hangzhou 310027 (China)

    2017-05-18

    Highlights: • Quantum coherence. • Cohering power: production of quantum coherence by quantum operations. • Study of cohering power and generalized cohering power, and their comparison for differentmeasures of quantum coherence. • Operational interpretation of cohering power. • Bound on cohering power of a generic quantum operation. - Abstract: Quantum coherence and entanglement, which play a crucial role in quantum information processing tasks, are usually fragile under decoherence. Therefore, the production of quantum coherence by quantum operations is important to preserve quantum correlations including entanglement. In this paper, we study cohering power–the ability of quantum operations to produce coherence. First, we provide an operational interpretation of cohering power. Then, we decompose a generic quantum operation into three basic operations, namely, unitary, appending and dismissal operations, and show that the cohering power of any quantum operation is upper bounded by the corresponding unitary operation. Furthermore, we compare cohering power and generalized cohering power of quantum operations for different measures of coherence.

  2. Damage threshold of amorphous carbon mirror for 177 eV FEL radiation

    Czech Academy of Sciences Publication Activity Database

    Farahani, S.D.; Chalupský, Jaromír; Burian, Tomáš; Chapman, H.; Gleeson, A.J.; Hájková, Věra; Juha, Libor; Jurek, M.; Klinger, D.; Sinn, H.; Sobierajski, R.; Störmer, M.; Tiedtke, K.; Toleikis, S.; Tschentscher, T.; Wabnitz, H.; Gaudin, J.

    2011-01-01

    Roč. 635, č. 1 (2011), S39-S42 ISSN 0168-9002 R&D Projects: GA MŠk LC510; GA MŠk(CZ) LC528; GA ČR(CZ) GAP108/11/1312 Institutional research plan: CEZ:AV0Z10100523 Keywords : X-ray mirror * FEL radiation * damage Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.207, year: 2011

  3. Dynamical aspects on FEL interaction in single passage and storage ring devices

    Energy Technology Data Exchange (ETDEWEB)

    Dattoli, G.; Renieri, A. [ENEA, Frascati (Italy)

    1995-12-31

    The dynamical behaviour of the free-electron lasers is investigated using appropriate scaling relations valid for devices operating in the low and high gain regimes, including saturation. The analysis is applied to both single passage and storage ring configurations. In the latter case the interplay between the interaction of the electron bean with the laser field and with the accelerator environment is investigated. In particular we discuss the effect of FEL interaction on the microwave instability.

  4. Status of RF system for the JAERI energy-recovery linac FEL

    International Nuclear Information System (INIS)

    Sawamura, Masaru; Nagai, Ryoji

    2006-01-01

    The two types of the RF sources are used for the JAERI ERL-FEL. One is an all-solid state amplifier and the other is an inductive output tube (IOT). There are advantages of little failure and wide bandwidth for the all-solid state amplifier, low cost and high efficiency for IOT. The property of low cost with the IOT is suitable for a large machine like an energy recovery linac (ERL)

  5. Short Rayleigh length free electron laser simulations in expanding coordinates / Proceedings of the 2004 FEL Conference

    OpenAIRE

    Armstead, R.L.; Colson, W.B.; Blau, J.

    2004-01-01

    For compact short-Rayleigh length free electron lasers (FELs), the area of the optical beam can be thousands of times greater at the mirrors than at the beam waist. A fixed numerical grid of sufficient resolution to represent the narrow mode at the waist and the broad mode at the mirrors would be prohibitively large. To accommodate this extreme change of scale with no loss of information, we employ a coordinate system that expands with the diffracting optical mode. The...

  6. Nonlinear absorption and transmission properties of Ge, Te and InAs using tuneable IR FEL

    Energy Technology Data Exchange (ETDEWEB)

    Amirmadhi, F.; Becker, K.; Brau, C.A. [Vanderbilt Univ., Nashville, TN (United States)

    1995-12-31

    Nonlinear absorption properties of Ge, Te and InAs are being investigated using the transmission of FEL optical pulses through these semiconductors (z-scan method). Wavelength, intensity and macropulse dependence are used to differentiate between two-photon and free-carrier absorption properties of these materials. Macropulse dependence is resolved by using a Pockles Cell to chop the 4-{mu}s macropulse down to 100 ns. Results of these experiments will be presented and discussed.

  7. Partially coherent imaging and spatial coherence wavelets

    International Nuclear Information System (INIS)

    Castaneda, Roman

    2003-03-01

    A description of spatially partially coherent imaging based on the propagation of second order spatial coherence wavelets and marginal power spectra (Wigner distribution functions) is presented. In this dynamics, the spatial coherence wavelets will be affected by the system through its elementary transfer function. The consistency of the model with the both extreme cases of full coherent and incoherent imaging was proved. In the last case we obtained the classical concept of optical transfer function as a simple integral of the elementary transfer function. Furthermore, the elementary incoherent response function was introduced as the Fourier transform of the elementary transfer function. It describes the propagation of spatial coherence wavelets form each object point to each image point through a specific point on the pupil planes. The point spread function of the system was obtained by a simple integral of the elementary incoherent response function. (author)

  8. Energy stability in recirculating, energy-recovering linacs in the presence of a FEL

    International Nuclear Information System (INIS)

    Merminga, L.; Bisognano, J.; Delayen, J.R.

    1996-01-01

    Recirculating, energy-recovering linacs can be used as driver accelerators for high power FELs (free electron lasers). Instabilities which arise from fluctuations of the cavity fields are investigated. Energy changes can cause beam loss on apertures, or, when coupled to M 56 , phase oscillations. Both effects change the beam induced voltage in the cavities and can lead to unstable variations of the accelerating field. An analytical model which includes amplitude and phase feedback, has been developed to study the stability of the system for small perturbations from equilibrium. The interaction of the electron beam with the FEL is a major perturbation which affects both the stability of the system and development of startup and recovery scenarios. To simulate the system's response to such large parameter variations, a numerical model of the beam-cavity interaction has been developed which includes low level rf feedback, phase oscillations and beam loss instabilities and the FEL interaction. Agreement between the numerical model and the linear theory has been demonstrated in the limit of small perturbations. In addition, the model has been benchmarked against experimental data obtained during CEBAF's high current operation. Numerical simulations have been performed for the high power IR DEMO approved for construction at CEBAF

  9. The Posterior Sustained Negativity Revisited—An SPN Reanalysis of Jacobsen and Höfel (2003

    Directory of Open Access Journals (Sweden)

    Thomas Jacobsen

    2018-01-01

    Full Text Available Symmetry is an important cue for the aesthetic judgment of beauty. Using a binary forced-choice format in a cued mixed design, Jacobsen and Höfel (2003 compared aesthetic judgments of beauty and symmetry judgments of novel graphic patterns. A late posterior sustained negativity elicited by symmetric patterns was observed in the symmetry judgment condition, but not in the beauty judgement condition. Therefore, this negativity appeared to be mainly driven by the task.In a series of studies, Bertamini, Makin, and colleagues observed a comparable sustained posterior negativity (SPN to symmetric stimuli, mainly taken to reflect obligatory symmetry processing independent of task requirements. We reanalyzed the data by Jacobsen and Höfel (2003 using similar parameters for data analysis as Bertamini, Makin, and colleagues to examine these apparent differences. The reanalysis confirmed both a task-driven effect on the posterior sustained negativity/SPN to symmetric patterns in the symmetry judgment condition and a strong symmetry-driven SPN to symmetric patterns. Differences between the references used for analyses of the electroencephalogram (EEG had an effect. Based on the reanalysis, the Jacobsen and Höfel (2003 data also fit well with Bertamini’s, Makin’s, and colleagues’ account of obligatory symmetry processing.

  10. Commissioning experience and beam physics measurements at the SwissFEL Injector test Facility

    CERN Document Server

    Schietinger, T.; Aiba, M.; Arsov, V.; Bettoni, S.; Beutner, B.; Calvi, M.; Craievich, P.; Dehler, M.; Frei, F.; Ganter, R.; Hauri, C. P.; Ischebeck, R.; Ivanisenko, Y.; Janousch, M.; Kaiser, M.; Keil, B.; Löhl, F.; Orlandi, G. L.; Ozkan Loch, C.; Peier, P.; Prat, E.; Raguin, J.-Y.; Reiche, S.; Schilcher, T.; Wiegand, P.; Zimoch, E.; Anicic, D.; Armstrong, D.; Baldinger, M.; Baldinger, R.; Bertrand, A.; Bitterli, K.; Bopp, M.; Brands, H.; Braun, H. H.; Brönnimann, M.; Brunnenkant, I.; Chevtsov, P.; Chrin, J.; Citterio, A.; Csatari Divall, M.; Dach, M.; Dax, A.; Ditter, R.; Divall, E.; Falone, A.; Fitze, H.; Geiselhart, C.; Guetg, M. W.; Hämmerli, F.; Hauff, A.; Heiniger, M.; Higgs, C.; Hugentobler, W.; Hunziker, S.; Janser, G.; Kalantari, B.; Kalt, R.; Kim, Y.; Koprek, W.; Korhonen, T.; Krempaska, R.; Laznovsky, M.; Lehner, S.; Le Pimpec, F.; Lippuner, T.; Lutz, H.; Mair, S.; Marcellini, F.; Marinkovic, G.; Menzel, R.; Milas, N.; Pal, T.; Pollet, P.; Portmann, W.; Rezaeizadeh, A.; Ritt, S.; Rohrer, M.; Schär, M.; Schebacher, L.; Scherrer, St.; Schlott, V.; Schmidt, T.; Schulz, L.; Smit, B.; Stadler, M.; Steffen, Bernd; Stingelin, L.; Sturzenegger, W.; Treyer, D. M.; Trisorio, A.; Tron, W.; Vicario, C.; Zennaro, R.; Zimoch, D.

    2016-10-26

    The SwissFEL Injector Test Facility operated at the Paul Scherrer Institute between 2010 and 2014, serving as a pilot plant and test bed for the development and realization of SwissFEL, the x-ray Free Electron Laser facility under construction at the same institute. The test facility consisted of a laser-driven rf electron gun followed by an S-band booster linac, a magnetic bunch compression chicane and a diagnostic section including atransverse deflecting rf cavity. It delivered electron bunchesof up to200 pC chargeand up to 250 MeV beam energy at a repetition rate of 10 Hz. The measurements performed at the test facility not only demonstrated the beam parameters required to drive the first stage of a FEL facility, but also led to significant advances in instrumentation technologies, beam characterization methods and the generation, transport and compression of ultralow-emittance beams. We give a comprehensive overview of the commissioning experience of the principal subsystems and the beam physics measureme...

  11. A Multistage HGHG-Scheme for the BESSY Soft X-ray FEL Multiuser Facility

    CERN Document Server

    Krämer, Dietrich

    2004-01-01

    BESSY recently finalized the Technical Design Report for a multi-user FEL-facility in the VUV to soft X-ray spectral range. A cascaded HGHG-approach has been adopted, allowing to generate stable, reproducible multi-GW pulses at selectable pulse duration down to <20 fs. Three independent FEL-lines with three beamlines each are proposed. The FELs are driven by a most flexible superconducting CW linac based on the TESLA 9-cell cavities[1]. 18 modules of 8 cavities are needed to accelerate the beam to a final energy of 2.3 GeV at a modest field of < 16 MV/m. A 1 kHz repetition frequency rf-photoinjector, similar to the PITZ-gun [2], will be used in the beginning, to be replaced later on by a CW-photoinjector to produce arbitrary pulse patterns as needed by the experimenters. A summary of the project plans and present activities will be given.

  12. FTIR Spectroscopy on Basic Materials in THz Region for Compact FEL-Based Imaging

    CERN Document Server

    Cha, H J; Lee, B C; Park, S H

    2005-01-01

    We are making experiments on THz(terahertz) imaging using a compact high power FEL (free-electron laser) which is operating as a users facility at KAERI. The wavelength range of output pulses is 100~1200 μm, which corresponds to 0.3~3 THz in the frequency region. We should select the optimum wavelength for the constituents of specimens to realize the imaging based on the THz FEL. A FTIR (Fourier-transform infrared) spectrometer was modified to measure the optical constants of the specimens in THz region. A polyester film of which thickness is 3.7 μm was used as a beam splitter of the spectrometer. In the case of normal incidence, the transmittance of the film was measured to be more than 90%, and the estimated loss by absorption was approximately 2% at the FEL frequency of 3 THz. Several tens of nanometer-thick-silver was coated on the polyester film to balance both transmission and reflection of THz waves in the beam splitter. We investigated FTIR spectroscopy on air, vapor and liquid water...

  13. Primary experimental studies on mid-infrared FEL irradiation on dental substances at BFEL

    CERN Document Server

    Biao, Z J; Gao Xue Ju; He Wei; Huang Yu Ying; Li Yong Gui; LiuNianQing; Wang Min Kai; Wu Gan; Yan Xue Pin; Zhang Guo Qing

    2001-01-01

    A free electron laser (FEL) with its characteristics of wide wavelength tunability, ultrashort pulse time structure, and high peak power density is predominantly superior to all other conventional lasers in applications. Several experimental studies on mid-infrared FEL irradiation on dental enamel and dentine were performed at the Beijing FEL. Experimental aims were to investigate changes in the hardness, ratios of P to Ca and Cs before and after irradiation on samples with a characteristic absorption wavelength of 9.66 mu m, in the colors of these sample surfaces after irradiation with different wavelengths around the peak wavelength. The time dependence of temperature of the dentine sample was measured with its ps pulse effects compared to that with a continuous CO sub 2 laser. FTIR absorption spectra in the range of 2.5-15.4 mu m for samples of these hard dental substances and pure hydroxyapatite were first examined to decide their chemical components and absorption maximums. Primary experimental results w...

  14. Commissioning experience and beam physics measurements at the SwissFEL Injector Test Facility

    Directory of Open Access Journals (Sweden)

    T. Schietinger

    2016-10-01

    Full Text Available The SwissFEL Injector Test Facility operated at the Paul Scherrer Institute between 2010 and 2014, serving as a pilot plant and test bed for the development and realization of SwissFEL, the x-ray Free-Electron Laser facility under construction at the same institute. The test facility consisted of a laser-driven rf electron gun followed by an S-band booster linac, a magnetic bunch compression chicane and a diagnostic section including a transverse deflecting rf cavity. It delivered electron bunches of up to 200 pC charge and up to 250 MeV beam energy at a repetition rate of 10 Hz. The measurements performed at the test facility not only demonstrated the beam parameters required to drive the first stage of an FEL facility, but also led to significant advances in instrumentation technologies, beam characterization methods and the generation, transport and compression of ultralow-emittance beams. We give a comprehensive overview of the commissioning experience of the principal subsystems and the beam physics measurements performed during the operation of the test facility, including the results of the test of an in-vacuum undulator prototype generating radiation in the vacuum ultraviolet and optical range.

  15. High-gain Seeded FEL Amplifier Tunable in the Terahertz Range

    CERN Document Server

    Sung, C; Pellegrini, C; Ralph, J E; Reiche, S; Rosenzweig, J B; Tochitsky, Sergei Ya

    2005-01-01

    The lack of a high-power, relatively low-cost and compact terahertz (THz) source in the range 0.3-3x10(12) Hz is the major obstacle in progressing on biomedical and material studies at these wavelengths. A high-gain, single pass seeded FEL technique allows to obtain high power THz pulses of a high spectral brightness. We describe an ongoing project at the Neptune laboratory where a ~ 1kW seed pulse generated by difference frequency mixing of CO2 laser lines in a GaAs nonlinear crystal is injected into a waveguide FEL amplifier. The FEL is driven by a 5 ps (r.m.s) long electron pulse with a peak current up to 100A provided by a regular S-band photoinjector. According to 3-D, time dependent simulations, up to ~ 10 MW THz power can be generated using a 2 meter long planar undulator. By mixing different pairs of CO2 laser lines and matching resonant energy of the electron beam, tunability in the 100-400 mm range is expected. A tunable Fabri-Perot interferometer will be used to select a high-power 5ps THz pulse. T...

  16. Linac coherent light source (LCLS) undulator RF BPM system

    International Nuclear Information System (INIS)

    Lill, R.; Waldschmidt, G.; Morrison, L.; Smith, S.; Straumann, T; Li, Z.; Johnson, R.

    2006-01-01

    The Linac Coherent Light Source (LCLS) will be the world's first x-ray free-electron laser (FEL) when it becomes operational in 2009. The LCLS is currently in the construction phase. The beam position monitor (BPM) system planned for the LCLS undulator will incorporate a high-resolution X-band cavity BPM system described in this paper. The BPM system will provide high-resolution measurements of the electron beam trajectory on a pulse-to-pulse basis and over many shots. The X-band cavity BPM size, simple fabrication, and high resolution make it an ideal choice for LCLS beam position detection. We will discuss the system specifications, design, and prototype test results.

  17. Linac Coherent Light Source Undulator RF BPM System

    Energy Technology Data Exchange (ETDEWEB)

    Lill, R.M.; Morrison, L.H.; Waldschmidt, G.J.; Walters, D.R.; /Argonne; Johnson, R.; Li, Z.; Smith, S.; Straumann, T.; /SLAC

    2007-04-17

    The Linac Coherent Light Source (LCLS) will be the world's first x-ray free-electron laser (FEL) when it becomes operational in 2009. The LCLS is currently in the construction phase. The beam position monitor (BPM) system planned for the LCLS undulator will incorporate a high-resolution X-band cavity BPM system described in this paper. The BPM system will provide high-resolution measurements of the electron beam trajectory on a pulse-to-pulse basis and over many shots. The X-band cavity BPM size, simple fabrication, and high resolution make it an ideal choice for LCLS beam position detection. We will discuss the system specifications, design, and prototype test results.

  18. Linac Coherent Light Source Undulator RF BPM System

    International Nuclear Information System (INIS)

    Lill, R.M.; Morrison, L.H.; Waldschmidt, G.J.; Walters, D.R.; Argonne; Johnson, R.; Li, Z.; Smith, S.; Straumann, T.; SLAC

    2007-01-01

    The Linac Coherent Light Source (LCLS) will be the world's first x-ray free-electron laser (FEL) when it becomes operational in 2009. The LCLS is currently in the construction phase. The beam position monitor (BPM) system planned for the LCLS undulator will incorporate a high-resolution X-band cavity BPM system described in this paper. The BPM system will provide high-resolution measurements of the electron beam trajectory on a pulse-to-pulse basis and over many shots. The X-band cavity BPM size, simple fabrication, and high resolution make it an ideal choice for LCLS beam position detection. We will discuss the system specifications, design, and prototype test results

  19. Linac coherent light source (LCLS) undulator RF BPM system.

    Energy Technology Data Exchange (ETDEWEB)

    Lill, R.; Waldschmidt, G.; Morrison, L.; Smith, S.; Straumann, T; Li, Z.; Johnson, R.; SLAC

    2006-01-01

    The Linac Coherent Light Source (LCLS) will be the world's first x-ray free-electron laser (FEL) when it becomes operational in 2009. The LCLS is currently in the construction phase. The beam position monitor (BPM) system planned for the LCLS undulator will incorporate a high-resolution X-band cavity BPM system described in this paper. The BPM system will provide high-resolution measurements of the electron beam trajectory on a pulse-to-pulse basis and over many shots. The X-band cavity BPM size, simple fabrication, and high resolution make it an ideal choice for LCLS beam position detection. We will discuss the system specifications, design, and prototype test results.

  20. Technical Design and Optimization Study for the FERMI at Elettra FEL Photoinjector

    International Nuclear Information System (INIS)

    Lidia, Steven M.; Penco, Giuseppe; Trovo', Mauro

    2006-01-01

    The FERMI (at) Elettra FEL project will provide a novel, x-ray free electron laser user facility at Sincrotrone Trieste based on seeded and cascade FEL techniques. The electron beam source and injector systems play a crucial role in the success of the facility by providing the highest quality electron beams to the linac and FEL undulators. This Technical Note examines the critical technology components that make up the injector system, and demonstrates optimum beam dynamics solutions to achieve the required high quality electron beams. Section 2 provides an overview of the various systems and subsystems that comprise the photoinjector. The different operating modes of the injector are described as they pertain to the different linac configurations driven by the FEL and experimental design. For each mode, the required electron beam parameters are given. Sections 3 and 4 describe the critical beamline elements in the injector complex: the photocathode and drive laser, and the RF gun. The required drive laser parameters are given at the end of Section 3. Additional details on the design of the photoinjector drive laser systems are presented in a separate Technical Note. Design considerations for the RF gun are extensively presented in Section 4. There, we describe the variation of the cavity geometry to optimize the efficiency of the energy transfer to the electron beam. A study of the power coupling into the various cavity modes that interact within the bandwidth of the RF drive pulse is presented, followed by a study of the transient cavity response under several models and, finally, the effects on extracted beam quality. Section 5 describes the initial design for the low energy, off-axis diagnostic beamline. Beam dynamics simulations using ASTRA, elegant, and MAD are presented. Section 6 presents the optimization studies for the beam dynamics in the various operating modes. The optimized baseline configurations for the beamline and incident drive laser pulse are

  1. COHERENCE PROPERTIES OF ELECTROMAGNETIC RADIATION,

    Science.gov (United States)

    ELECTROMAGNETIC RADIATION , COHERENT SCATTERING), (*COHERENT SCATTERING, ELECTROMAGNETIC RADIATION ), LIGHT, INTERFERENCE, INTENSITY, STATISTICAL FUNCTIONS, QUANTUM THEORY, BOSONS, INTERFEROMETERS, CHINA

  2. Monte Carlo studies of the radiation fields in the linac coherent light source undulators and of the corresponding signals in the Cerenkov beam loss monitors

    International Nuclear Information System (INIS)

    Santana Leitner, Mario; Fasso, Alberto; Fisher, Alan S.; Nuhn, Heinz D.; Dooling, Jeffrey C.; Berg, William; Yang, Bin. X.

    2010-01-01

    In 2009 the Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Center started free electron laser (FEL) operation. In order to continue to produce the bright and short-pulsed x-ray laser demanded by FEL scientists, this pioneer hard x-ray FEL requires a perfectly tailored magnetic field at the undulators, so that the photons generated at the electron wiggling path interact at the right phase with the electron beam. In such a precise system, small (>0.01%) radiation-induced alterations of the magnetic field in the permanent magnets could affect FEL performance. This paper describes the simulation studies of radiation fields in permanent magnets and the expected signal in the detectors. The transport of particles from the radiation sources (i.e. diagnostic insert) to the undulator magnets and to the beam loss monitors (BLM) was simulated with the intra nuclear cascade codes FLUKA and MARS15. In order to accurately reproduce the optics of LCLS, lattice capabilities and magnetic fields were enabled in FLUKA and betatron oscillations were validated against reference data. All electron events entering the BLMs were printed in data files. The paper also introduces the Radioactive Ion Beam Optimizer (RIBO) Monte Carlo 3-D code, which was used to read from the event files, to compute Cerenkov production and then to simulate the optical coupling of the BLM detectors, accounting for the transmission of light through the quartz. (author)

  3. Generation and Amplification of Coherent Radiation with Optical Orbital Angular Momentum in a Free-Electron Laser

    Science.gov (United States)

    Hemsing, Erik Willard

    The object of this work is to examine how coherent light that carries orbital angular momentum (OAM) can be generated and amplified in a single pass, high-gain free-electron laser (FEL) at the fundamental operating frequency. This concept unites two rapidly expanding, but at present largely non-overlapping fields of study: high-order OAM light modes, which interact in new ways with matter, and FELs, in which a relativistically energetic electron beam emits coherent, ultra high-brightness, highly frequency-tunable light. The ability to generate OAM light in an FEL enables new regimes of laser interaction physics to be explored at wavelengths down to hard x-rays. The theoretical portion of this dissertation attempts to provide a new predictive mathematical framework. It builds on existing work, and describes the three-dimensional electromagnetic field of the high-gain FEL as a sum of OAM modes such that the amplification properties of individual modes can be characterized. The effects of uncorrelated energy spread, longitudinal space charge, energy detuning, and transverse emittance in the electron beam are included, as is the diffraction of the laser light. Theoretical predictions are corroborated by detailed numerical Genesis 1.3 simulations. When the theory is extended to frequency harmonics, a novel interaction is uncovered that generates a helical electron beam density distribution. These predictions are also supported by numerical Tredi simulations. This type of highly correlated structure is shown to naturally emit OAM light, and forms the basis of a new high-gain, high-mode generation (HGHMG) scheme proposed in its entirety here. The experimental section examines the helical microbunching concept in a proof-of-principle experiment dubbed HELIX, performed at the UCLA Neptune laboratory. We present detailed measurement of the coherent transition radiation emitted by the 12.5 MeV electron beam that is microbunched in a second harmonic interaction with an input

  4. JAERI 10kW High Power ERL-FEL and Its Applications in Nuclear Energy Industries

    CERN Document Server

    Minehara, E J; Iijima, H; Kikuzawa, N; Nagai, R; Nishimori, N; Nishitani, T; Sawamura, M; Yamauchi, T

    2005-01-01

    The JAERI high power ERL-FEL has been extended to the more powerful and efficient free-electron laser (FEL) than 10kW for nuclear energy industries, and other heavy industries like defense, shipbuilding, chemical industries, environmental sciences, space-debris, and power beaming and so on. In order to realize such a tunable, highly-efficient, high average power, high peak power and ultra-short pulse FEL, we need the efficient and powerful FEL driven by the JAERI compact, stand-alone and zero boil-off super-conducting RF linac with an energy-recovery geometry. Our discussions on the ERL-FEL will cover the current status of the 10kW upgrading and its applications of non-thermal peeling, cutting, and drilling to decommission the nuclear power plants, and to demonstrate successfully the proof of principle prevention of cold-worked stress-corrosion cracking failures in nuclear power reactors under routine operation using small cubic low-Carbon stainless steel samples.

  5. Femtosecond resolution timing jitter correction on a TW scale Ti:sapphire laser system for FEL pump-probe experiments.

    Science.gov (United States)

    Csatari Divall, Marta; Mutter, Patrick; Divall, Edwin J; Hauri, Christoph P

    2015-11-16

    Intense ultrashort pulse lasers are used for fs resolution pump-probe experiments more and more at large scale facilities, such as free electron lasers (FEL). Measurement of the arrival time of the laser pulses and stabilization to the machine or other sub-systems on the target, is crucial for high time-resolution measurements. In this work we report on a single shot, spectrally resolved, non-collinear cross-correlator with sub-fs resolution. With a feedback applied we keep the output of the TW class Ti:sapphire amplifier chain in time with the seed oscillator to ~3 fs RMS level for several hours. This is well below the typical pulse duration used at FELs and supports fs resolution pump-probe experiments. Short term jitter and long term timing drift measurements are presented. Applicability to other wavelengths and integration into the timing infrastructure of the FEL are also covered to show the full potential of the device.

  6. THE SECOND STAGE OF FERMI at ELETTRA: A SEEDED FEL IN THE SOFT X-RAY SPECTRAL RANGE

    International Nuclear Information System (INIS)

    Allaria, E.; DeNinno, G.; Fawley, W.M.

    2009-01-01

    The second stage of the FERMI FEL, named FEL-2, is based on the principle of high-gain harmonic generation and relies on a double-seeded cascade. Recent developments stimulated a revision of the original setup, which was designed to cover the spectral range between 40 and 10 nm. The numerical simulations we present here show that the nominal (expected) electron-beam performance allows extension of the FEL spectral range down to 4 nm. A significant amount of third harmonic power can be also expected. We also show that the proposed setup is flexible enough for exploiting future developments of new seed sources, e.g., high harmonic generation in gases.

  7. Parameter Analysis For A High-Gain Harmonic Generation FEL By Numerical Calculation Based On 1D Theory

    CERN Document Server

    Li, Yuhui; Zhang, Shancai

    2004-01-01

    The high-gain harmonic generation (HGHG) free-electron laser (FEL) is an important candidate for a fourth-generation light source. Lots of theoretical work has been performed. Recently a further 1D theory about HGHG FEL has been developed. It considers the effects of different parameters for the whole process. An initial program based on this theory has been made. In this paper, a brief comparison of the results from this 1D program and from TDA (3D code) is discussed. It also analyses the parameters for Shanghai deep ultra violate free-electron laser source (SDUV-FEL), including electron beam energy spread, seed laser power, strength of dispersion section etc.

  8. Far-infrared transition and diffraction radiation. Pt. 2. The THz beamline at the VUV-FEL linac

    International Nuclear Information System (INIS)

    Casalbuoni, S.; Schmidt, B.; Schmueser, P.; Steffen, B.; Hamburg Univ.

    2006-01-01

    In order to facilitate longitudinal bunch diagnostics with high-resolution interferometric or spectroscopic devices outside the VUV-FEL tunnel we have designed a Tera-Hertz beamline at the 140 m position of the VUV-FEL linac. The vacuum chamber housing the transition and diffraction radiation screens is located between the last acceleration module and the collimator section in front of the undulator. In Part I of this report we have presented a general scheme for computing the generation, diffraction and optical propagation of transition and diffraction radiation. In the present Part II we describe the design, technical layout and optical performance of the THz beamline at the VUV-FEL and show first measurements. (orig.)

  9. Design of broadly tuned FIR FEL based on a variable-period microwiggler

    Energy Technology Data Exchange (ETDEWEB)

    Qing-Xiang Liu [Institute of Applied Electronics, Sichuan (China)]|[Southwest Jiaotong Univ., Sichuan (China); Yong Xu [Southwest Jiatong Univ., Sichuan (China)

    1995-12-31

    A varible-period microwiggler is proposed and investigated. The fundamental period of the microwiggler is designed as {lambda}o=2mm, and the period of the microwiggler can be turned from {lambda}o to n{lambda}o (n=1,2,3,{hor_ellipsis}) The wiggler fields with the period 3{lambda}o, 4{lambda}o, and 5{lambda}o are measured and compared with the theoretical results. Finally, a broadly tuned FIR FEL is designed based on the performance of the variable-period microwiggler.

  10. Heat treatment of long pulse operation for the JAERI ERL-FEL

    International Nuclear Information System (INIS)

    Sawamura, Masaru; Nagai, Ryoji; Kikuzawa, Nobuhiro; Hajima, Ryoichi; Minehara, Eisuke

    2005-01-01

    RF power sources are replaced from all-solid-state amplifiers to IOT amplifiers for the superconducting accelerators (SCAs) and a vacuum tube amplifier for the SHB of the JAERI ERL-FEL. A long pulse operation increased the pressure in the cryostat of the SCA. The single-cell SCA can be operated in 9% duty according to the time constant of the pressure decay in the cryostat. SHB can be operated in 4% duty which is limited by the frequency range of the tuners. The result of the ABAQUS calculation shows the more duty operation. (author)

  11. A new undulator for the extension of the spectral range of the CLIO FEL

    Energy Technology Data Exchange (ETDEWEB)

    Marcouille, O.; Berset, J.M.; Glotin, F. [LURE, Orsay (France)] [and others

    1995-12-31

    We built a new undulator in order to extend the lasing range of the CLIO infrared FEL. Presently, CLIO operates in the wavelength range 2 - 17 {mu}m. Beyond 14 {mu}m, the power decreases rapidly, because of the diffraction losses of the vacuum chamber (7 mm height and 2 m long). Thus, lasing at higher wavelengths implies installing a chamber with a height approximately twice. Then the minimum gap is increased and the maximum deflection parameter, K, is reduced from 2 to 1 : the laser tunability is greatly reduced. This is why a new undulator has been built.

  12. New autocorrelation technique for the IR FEL optical pulse width measurements

    Energy Technology Data Exchange (ETDEWEB)

    Amirmadhi, F.; Brau, K.A.; Becker, C. [Vanderbilt Univ., Nashville, TN (United States)] [and others

    1995-12-31

    We have developed a new technique for the autocorrelation measurement of optical pulse width at the Vanderbilt University FEL center. This method is based on nonlinear absorption and transmission characteristics of semiconductors such as Ge, Te and InAs suitable for the wavelength range from 2 to over 6 microns. This approach, aside being simple and low cost, removes the phase matching condition that is generally required for the standard frequency doubling technique and covers a greater wavelength range per nonlinear material. In this paper we will describe the apparatus, explain the principal mechanism involved and compare data which have been acquired with both frequency doubling and two-photon absorption.

  13. Dynamical behaviour of FEL devices operating with two undulators having opposite circular polarizations

    International Nuclear Information System (INIS)

    Dattoli, G.; Ottaviani, P. L.; Bucci, L.

    2000-01-01

    Optical-Klystron FELs operating with undulators having opposite circular polarizations are characterized by a spontaneous emission spectrum which does not exhibit the characteristic interference pattern. The use of the Madey theorem may allow the conclusion that, for such configuration, the dispersive section does not provide any gain enhancement. In this paper it has been analyzed the problem from a dynamical point of view and clarify how the optical field evolve, what is the role of the bunching and how the consequences of the Madey theorem should be correctly understood [it

  14. Coherent Raman spectroscopy

    CERN Document Server

    Eesley, G L

    1981-01-01

    Coherent Raman Spectroscopy provides a unified and general account of the fundamental aspects of nonlinear Raman spectroscopy, also known as coherent Raman spectroscopy. The theoretical basis from which coherent Raman spectroscopy developed is described, along with its applications, utility, and implementation as well as advantages and disadvantages. Experimental data which typifies each technique is presented. This book is comprised of four chapters and opens with an overview of nonlinear optics and coherent Raman spectroscopy, followed by a discussion on nonlinear transfer function of matter

  15. Electromagnetic spatial coherence wavelets

    International Nuclear Information System (INIS)

    Castaneda, R.; Garcia-Sucerquia, J.

    2005-10-01

    The recently introduced concept of spatial coherence wavelets is generalized for describing the propagation of electromagnetic fields in the free space. For this aim, the spatial coherence wavelet tensor is introduced as an elementary amount, in terms of which the formerly known quantities for this domain can be expressed. It allows analyzing the relationship between the spatial coherence properties and the polarization state of the electromagnetic wave. This approach is completely consistent with the recently introduced unified theory of coherence and polarization for random electromagnetic beams, but it provides a further insight about the causal relationship between the polarization states at different planes along the propagation path. (author)

  16. Nano structured materials studied by coherent X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Gulden, Johannes

    2013-03-15

    following chapter focuses on experiments carried out at synchrotron sources showing the potential of applying SAB-CDI to colloidal crystals. An experiment on GaAs nanowires proves the prospects of this method for other nano structured materials. To investigate dynamics, especially on the ultrafast time scale, FEL sources are needed. The next chapter therefore presents two experiments performed at the FLASH facility in Hamburg, showing that SAB-CDI can also be applied at FELs on an artificial crystal and an experiment performed on colloidal crystals to investigate the ultra fast dynamics with a pump-probe experiment. The technical advances in synchrotron radiation creation have opened the field to applications with the coherent part of the X-rays. The combination of iterative phase retrieval methods with crystallographic methods yields the unique opportunity to measure the internal structure of nano structured samples. This thesis gives an introduction into this exciting new field.

  17. Nano structured materials studied by coherent X-ray diffraction

    International Nuclear Information System (INIS)

    Gulden, Johannes

    2013-03-01

    following chapter focuses on experiments carried out at synchrotron sources showing the potential of applying SAB-CDI to colloidal crystals. An experiment on GaAs nanowires proves the prospects of this method for other nano structured materials. To investigate dynamics, especially on the ultrafast time scale, FEL sources are needed. The next chapter therefore presents two experiments performed at the FLASH facility in Hamburg, showing that SAB-CDI can also be applied at FELs on an artificial crystal and an experiment performed on colloidal crystals to investigate the ultra fast dynamics with a pump-probe experiment. The technical advances in synchrotron radiation creation have opened the field to applications with the coherent part of the X-rays. The combination of iterative phase retrieval methods with crystallographic methods yields the unique opportunity to measure the internal structure of nano structured samples. This thesis gives an introduction into this exciting new field.

  18. Photon-in photon-out hard X-ray spectroscopy at the Linac Coherent Light Source

    International Nuclear Information System (INIS)

    Alonso-Mori, Roberto; Sokaras, Dimosthenis; Zhu, Diling; Kroll, Thomas; Chollet, Mathieu; Feng, Yiping; Glownia, James M.; Kern, Jan; Lemke, Henrik T.; Nordlund, Dennis; Robert, Aymeric; Sikorski, Marcin; Song, Sanghoon; Weng, Tsu-Chien; Bergmann, Uwe

    2015-01-01

    A description of hard X-ray photon-in photon-out spectroscopy techniques for X-ray free electron laser applications is given. A discussion of the instrumentation suitable for taking full advantage of these new sources and a description of recent measurements performed and related examples are also presented. X-ray free-electron lasers (FELs) have opened unprecedented possibilities to study the structure and dynamics of matter at an atomic level and ultra-fast timescale. Many of the techniques routinely used at storage ring facilities are being adapted for experiments conducted at FELs. In order to take full advantage of these new sources several challenges have to be overcome. They are related to the very different source characteristics and its resulting impact on sample delivery, X-ray optics, X-ray detection and data acquisition. Here it is described how photon-in photon-out hard X-ray spectroscopy techniques can be applied to study the electronic structure and its dynamics of transition metal systems with ultra-bright and ultra-short FEL X-ray pulses. In particular, some of the experimental details that are different compared with synchrotron-based setups are discussed and illustrated by recent measurements performed at the Linac Coherent Light Source

  19. Coherence, Cohesion, and Deixis.

    Science.gov (United States)

    Foster, Dan

    Composition theory accounts of coherence have tended to look at relationships within the text rather than at those between the text and the real world. In fact, empirical evidence suggests that the relationships between the text and the real world may be just as important for coherence. Forty-eight short papers were selected at random from those…

  20. Comments on advanced, time-resolved imaging techniques for free-electron laser (FEL) experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H.

    1992-01-01

    An extensive set of time-resolved imaging experiments has been performed on rf-linac driven free-electron lasers (FELs) over the past few years. These experiments have addressed both micropulse and macropulse timescales on both the charged-particle beam and the wiggler/undulator outputs (spontaneous emission and lasing). A brief review of first measurements on photoinjecter micropulse elongation, submacropulse phase slew in drive lasers, submacropulse wavelength shifts in lasers, etc. is presented. This is followed by discussions of new measurements of 35-MeV electron beam micropulse bunch length (<10 ps) using optical transition radiation, some of the first single bend synchrotron radiation beam profile measurements at gamma <80, and comments on the low-jitter synchroscan streak camera tuner. These techniques will be further developed on the 200-650 MeV linac test stand at the Advanced Photon Source (APS) in the next few years. Such techniques should be adaptable to many of the present FEL designs and to some aspects of the next generation of light sources.

  1. Comments on advanced, time-resolved imaging techniques for free-electron laser (FEL) experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H.

    1992-11-01

    An extensive set of time-resolved imaging experiments has been performed on rf-linac driven free-electron lasers (FELs) over the past few years. These experiments have addressed both micropulse and macropulse timescales on both the charged-particle beam and the wiggler/undulator outputs (spontaneous emission and lasing). A brief review of first measurements on photoinjecter micropulse elongation, submacropulse phase slew in drive lasers, submacropulse wavelength shifts in lasers, etc. is presented. This is followed by discussions of new measurements of 35-MeV electron beam micropulse bunch length (<10 ps) using optical transition radiation, some of the first single bend synchrotron radiation beam profile measurements at gamma <80, and comments on the low-jitter synchroscan streak camera tuner. These techniques will be further developed on the 200-650 MeV linac test stand at the Advanced Photon Source (APS) in the next few years. Such techniques should be adaptable to many of the present FEL designs and to some aspects of the next generation of light sources.

  2. Digital low level RF control system for the DESY TTF VUV-FEL Linac

    International Nuclear Information System (INIS)

    Ayvazyan, V.; Choroba, S.; Matyushin, A.; Moeller, G.; Petrosyan, G.; Rehlich, K.; Simrock, S.N.; Vetrov, P.

    2005-01-01

    In the RF system for the Vacuum Ultraviolet Free Electron Laser (VUV-FEL) Linac each klystron supplies RF power to up to 32 cavities. The superconducting cavities are operated in pulsed mode and high accelerating gradients close to the performance limit. The RF control of the cavity fields to the level of 10 -4 for amplitude and 0.1 degree for phase however presents a significant technical challenge due to the narrow bandwidth of the cavities which results in high sensitivity to perturbations of the resonance frequency by mechanical vibrations (microphonics) and Lorenz force detuning. The VUV-FEL Linac RF control system employs a completely digital feedback system to provide flexibility in the control algorithms, precise calibration of the accelerating field vector-sum, and extensive diagnostics and exception handling capabilities. The RF control algorithm is implemented in DSP (Digital Signal Processor) firmware and DOOCS (Distributed Object Oriented Control System) servers. The RF control system design objectives are discussed. Hardware and software design of the DSP based RF control are presented. (orig.)

  3. FAST: a three-dimensional time-dependent FEL simulation code

    International Nuclear Information System (INIS)

    Saldin, E.L.; Schneidmiller, E.A.; Yurkov, M.V.

    1999-01-01

    In this report we briefly describe the three-dimensional, time-dependent FEL simulation code FAST. The equations of motion of the particles and Maxwell's equations are solved simultaneously taking into account the slippage effect. Radiation fields are calculated using an integral solution of Maxwell's equations. A special technique has been developed for fast calculations of the radiation field, drastically reducing the required CPU time. As a result, the developed code allows one to use a personal computer for time-dependent simulations. The code allows one to simulate the radiation from the electron bunch of any transverse and longitudinal bunch shape; to simulate simultaneously an external seed with superimposed noise in the electron beam; to take into account energy spread in the electron beam and the space charge fields; and to simulate a high-gain, high-efficiency FEL amplifier with a tapered undulator. It is important to note that there are no significant memory limitations in the developed code and an electron bunch of any length can be simulated

  4. Electron Gun and Injector Designs for State-of-the-Art FELs

    CERN Document Server

    Blüm, H P; Christina, V; Cole, M D; Falletta, M; Holmes, D; Peterson, E; Rathke, J; Schultheiss, T; Todd, A M M; Wong, R

    2005-01-01

    Reliable, high-brightness, high-power injector operation is a critical technology issue for energy recovery linac drivers of high-power free electron lasers (FEL). Advanced Energy Systems is involved in three ongoing injector programs that target up to 0.5 Ampere current levels at emittance values consistent with the requirements of the FEL. One is a DC photocathode gun and superconducting RF (SRF) booster cryomodule. A 748.5 MHz injector of this type is being assembled and will be tested up to 100 mA at the Thomas Jefferson National Accelerator Facility (JLAB) beginning in 2007. The second approach being explored is a high-current normal-conducting RF photoinjector. A 700 MHz gun, presently under fabrication, will undergo thermal test in 2006 at Los Alamos National Laboratory (LANL). Finally, a half-cell 703.75 MHz SRF gun is presently being designed and will be tested to 0.5 Ampere at Brookhaven National Laboratory (BNL) in 2007. The status and projected performance for each of these injector projects is pr...

  5. Production and detection of axion-like particles at the VUV-FEL. Letter of intent

    International Nuclear Information System (INIS)

    Koetz, U.; Ringwald, A.; Tschentscher, T.

    2006-06-01

    Recently, the PVLAS collaboration has reported evidence for an anomalously large rotation of the polarization of light generated in vacuum in the presence of a transverse magnetic field. This may be explained through the production of a new light spin-zero particle coupled to two photons. In this Letter of Intent, we propose to test this hypothesis by setting up a photon regeneration experiment which exploits the photon beam of the Vacuum-UltraViolet Free-Electron Laser VUV-FEL, sent along the transverse magnetic field of a linear arrangement of dipole magnets of size B L ∼ 30 Tm. The high photon energies available at the VUV-FEL increase substantially the expected photon regeneration rate in the mass range implied by the PVLAS anomaly, in comparison to the rate expected at visible lasers of similar power. We find that the particle interpretation of the PVLAS result can be tested within a short running period. The pseudoscalar vs. scalar nature can be determined by varying the direction of the magnetic field with respect to the laser polarization. The mass of the particle can be measured by running at different photon energies. The proposed experiment offers a window of opportunity for a firm establishment or exclusion of the particle interpretation of the PVLAS anomaly before other experiments can compete. (Orig.)

  6. Investigation of short pulse effects in IR FELs and new simulation results

    CERN Document Server

    Asgekar, Vivek; Brunken, M; Casper, Lars; Genz, Harald; Grigore, Maria; Hessler, Christoph; Khodyachykh, Sergiy; Richter, Achim; Van der Meer, Alex F G

    2003-01-01

    The Darmstadt IR FEL is designed to generate wavelengths between 3 and 10 mum and driven by the superconducting electron linear accelerator. The pulsed electron beam has a peak current of 2.7 A leading to a small signal gain of 5%. Currently, investigations of the energy transfer process inside the undulator are performed using the 1D time-dependent simulation code FAST1D-OSC. We present simulation results for the power vs. different desynchronization and tapering parameters as well as a comparison with experimental data from the S-DALINAC IR-FEL. Furthermore, a compact autocorrelation system assuring a background-free measurement of the optical pulse length is described. In a first test experiment at FELIX, the autocorrelator has been tested at wavelengths 5.7 less than approximately equals lambda less than approximately equals 9.0 mum. The frequency doubling in a 2 mm-long ZnGeP//2-crystal resulted in a time resolution of 300 fs and a conversion efficiency of 5%.

  7. Normal-Conducting High Current RF Photoinjector for High Power CW FEL

    CERN Document Server

    Kurennoy, Sergey; Nguyen, Dinh C; Rathke, John; Schrage, Dale L; Schultheiss, Tom; Wood, Richard L; Young, Lloyd M

    2005-01-01

    An RF photoinjector capable of producing high average current with low emittance and energy spread is a key enabling technology for high power CW FEL. The design of a 2.5-cell, pi-mode, 700-MHz normal-conducting RF photoinjector cavity with magnetic emittance compensation is completed. With average gradients of 7, 7, and 5 MV/m in its three accelerating cells, the photoinjector will produce a 2.5-MeV electron beam with 3-nC charge per bunch and transverse rms emittance below 7 mm-mrad. Electromagnetic modeling has been used extensively to optimize ridge-loaded tapered waveguides and RF couplers, and led to a new, improved coupler iris design. The results, combined with a thermal and stress analysis, show that the challenging problem of cavity cooling can be successfully solved. Fabrication of a demo 100-mA (at 35 MHz bunch repetition rate) photoinjector is underway. The design is scalable to higher average currents by increasing the electron bunch repetition rate, and provides a path to a MW-class FEL. This p...

  8. THz wiggler applied for measurements of electron bunch longitudinal structure in FEL

    Science.gov (United States)

    Syresin, E.; Kostromin, S.; Krasilnikov, M.; Makarov, R.; Morozov, N.; Petrov, D.

    2015-01-01

    The infrared undulator manufactured at JINR and installed at FLASH in 2007 is used for longitudinal bunch shape measurements in the range of several tenths of a micrometer. The presented electromagnetic wiggler is intended for generating a narrow-band THz radiation to measure the longitudinal electron bunch structure in FELs with an electron energy of several tens of MeV. This is a planar electromagnetic device with six regular periods, each 30 cm long. The K parameter is varied in the range 0.5-7.12 corresponding to the range B = 0.025-0.356 T of the peak field on the axis. The wiggler is simulated for 19.8 MeV/ c corresponding to the possible FEL option at PITZ. The wavelength range is 126 μm - 5.1 mm for this electron beam momentum. The 3D Opera simulations of the THz wiggler are discussed. A new PITZ photocathode laser system is proposed for the optimized performance of the high-brightness electron beam. The main goal is a production of 3D ellipsoidal electron bunches with homogeneous charge density. The electromagnetic wiggler is supposed to be used for measuring the longitudinal shape of these electron bunches.

  9. Application of the green function formalism to nonlinear evolution of the low gain FEL oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Shvets, G. [Princeton Plasma Physics Lab., NJ (United States); Wurtele, J.S.; Gardent, D. [Massachusetts Institute of Technology, Cambridge, MA (United States)] [and others

    1995-12-31

    A matrix formalism for the optical pulse evolution in the frequency domain, is applied to the nonlinear regime of operation. The formalism was previously developed for studies of the linear evolution of the low-gain FEL oscillator with an arbitrary shape of the electron beam. By varying experimentally controllable parameters, such as cavity detunning and cavity losses, different regimes of operation of the FEL oscillator, such as a steady state saturation and limit cycle saturation, are studied numerically. It is demonstrated that the linear supermodes, numerically obtained from the matrix formalism, provide an appropriate framework for analyzing the periodic change in the output power in the limit cycle regime. The frequency of this oscillation is related to the frequencies of the lowest-order linear supermodes. The response of the output radiation to periodic variation of the electron energy is studied. It is found that the response is enhanced when the frequency of the energy variation corresponds to the difference of per-pass phase advances of the lowest linear supermodes. Finally, various nonlinear models are tested to capture the steady state saturation and limit cycle variation of the EM field in the oscillator cavity.

  10. End-to-end simulation of a visible 1 kW FEL

    International Nuclear Information System (INIS)

    Parazzoli, Claudio G.; Koltenbah, Benjamin E.C.

    2000-01-01

    In this paper we present the complete numerical simulation of the 1 kW visible Free Electron Laser under construction in Seattle. We show that the goal of producing 1.0 kW at 0.7 μm is well within the hardware capabilities. We simulate in detail the evolution of the electron bunch phase space in the entire e-beam line. The e-beam line includes the photo-injector cavities, the 433.33 MHz accelerator, the magnetic buncher, the 1300 MHz accelerator, the 180 deg. bend and the matching optics into the wiggler. The computed phase space is input for a three-dimensional time-dependent code that predicts the FEL performance. All the computations are based on state of the art software, and the limitations of the current software are discussed. We believe that this is the first time that such a thorough numerical simulation has been carried out and that such a realistic electron phase space has been used in FEL performance calculations

  11. Performance of an undulator for visible and UV FELs at FELI

    Energy Technology Data Exchange (ETDEWEB)

    Miyauchi, Y.; Zako, A.; Koga, A. [Free Electron Laser Research Institute, Inc., Osaka (Japan)] [and others

    1995-12-31

    Two infrared free electron lasers (FELs) of the FELI project are now operating in the wavelength range of 1-20{mu}m. A 2.68-m undulator has been constructed for visible and UV FELs covering the wavelength of 1-0.2{mu}m for 100-165 MeV electron beams. It generates alternating, horizontal magnetic field, and wiggles electron beam on a vertical plane. The undulator length and period are 2.68m and 40mm, respectively. The gap of undulator magnets can be changed remotely by using servomotors with an accuracy of 1 {mu}m from the control room. The maximum K-value and related magnetic field strength are 1.9 and 0.5T, respectively, when its gap is set to the minimum value of 16mm. In order to minimize magnetic field reduction due to radiation damage, Sm-Co permanent magnet was adopted. Its structure and the results of magnetic field measurement will be reported.

  12. Scalable coherent interface

    International Nuclear Information System (INIS)

    Alnaes, K.; Kristiansen, E.H.; Gustavson, D.B.; James, D.V.

    1990-01-01

    The Scalable Coherent Interface (IEEE P1596) is establishing an interface standard for very high performance multiprocessors, supporting a cache-coherent-memory model scalable to systems with up to 64K nodes. This Scalable Coherent Interface (SCI) will supply a peak bandwidth per node of 1 GigaByte/second. The SCI standard should facilitate assembly of processor, memory, I/O and bus bridge cards from multiple vendors into massively parallel systems with throughput far above what is possible today. The SCI standard encompasses two levels of interface, a physical level and a logical level. The physical level specifies electrical, mechanical and thermal characteristics of connectors and cards that meet the standard. The logical level describes the address space, data transfer protocols, cache coherence mechanisms, synchronization primitives and error recovery. In this paper we address logical level issues such as packet formats, packet transmission, transaction handshake, flow control, and cache coherence. 11 refs., 10 figs

  13. Coherent Polariton Laser

    Science.gov (United States)

    Kim, Seonghoon; Zhang, Bo; Wang, Zhaorong; Fischer, Julian; Brodbeck, Sebastian; Kamp, Martin; Schneider, Christian; Höfling, Sven; Deng, Hui

    2016-01-01

    The semiconductor polariton laser promises a new source of coherent light, which, compared to conventional semiconductor photon lasers, has input-energy threshold orders of magnitude lower. However, intensity stability, a defining feature of a coherent state, has remained poor. Intensity noise many times the shot noise of a coherent state has persisted, attributed to multiple mechanisms that are difficult to separate in conventional polariton systems. The large intensity noise, in turn, limits the phase coherence. Thus, the capability of the polariton laser as a source of coherence light is limited. Here, we demonstrate a polariton laser with shot-noise-limited intensity stability, as expected from a fully coherent state. This stability is achieved by using an optical cavity with high mode selectivity to enforce single-mode lasing, suppress condensate depletion, and establish gain saturation. Moreover, the absence of spurious intensity fluctuations enables the measurement of a transition from exponential to Gaussian decay of the phase coherence of the polariton laser. It suggests large self-interaction energies in the polariton condensate, exceeding the laser bandwidth. Such strong interactions are unique to matter-wave lasers and important for nonlinear polariton devices. The results will guide future development of polariton lasers and nonlinear polariton devices.

  14. Coherent Polariton Laser

    Directory of Open Access Journals (Sweden)

    Seonghoon Kim

    2016-03-01

    Full Text Available The semiconductor polariton laser promises a new source of coherent light, which, compared to conventional semiconductor photon lasers, has input-energy threshold orders of magnitude lower. However, intensity stability, a defining feature of a coherent state, has remained poor. Intensity noise many times the shot noise of a coherent state has persisted, attributed to multiple mechanisms that are difficult to separate in conventional polariton systems. The large intensity noise, in turn, limits the phase coherence. Thus, the capability of the polariton laser as a source of coherence light is limited. Here, we demonstrate a polariton laser with shot-noise-limited intensity stability, as expected from a fully coherent state. This stability is achieved by using an optical cavity with high mode selectivity to enforce single-mode lasing, suppress condensate depletion, and establish gain saturation. Moreover, the absence of spurious intensity fluctuations enables the measurement of a transition from exponential to Gaussian decay of the phase coherence of the polariton laser. It suggests large self-interaction energies in the polariton condensate, exceeding the laser bandwidth. Such strong interactions are unique to matter-wave lasers and important for nonlinear polariton devices. The results will guide future development of polariton lasers and nonlinear polariton devices.

  15. Coherence, Complexity and Creativity

    Science.gov (United States)

    Arecchi, Fortunato Tito

    We review the ideas and experiments that established the onset of laser coherence beyond a suitable threshold. That threshold is the first of a chain of bifurcations in a non linear dynamics, leading eventually to deterministic chaos in lasers. In particular, the so called HC behavior has striking analogies with the electrical activity of neurons. Based on these considerations, we develop a dynamical model of neuron synchronization leading to coherent global perceptions. Synchronization implies a transitory control of neuron chaos. Depending on the time duration of this control, a cognitive agent has different amounts of awareness. Combining this with a stream of external inputs, one can point at an optimal use of internal resources, that is called cognitive creativity. While coherence is associated with long range correlations, complexity arises whenever an array of coupled dynamical systems displays multiple paths of coherence. What is the relation among the three concepts in the title? While coherence is associated with long range correlations, complexity arises whenever an array of coupled dynamical systems displays multiple paths of coherence. Creativity corresponds to a free selection of a coherence path within a complex nest. As sketched above, it seems dynamically related to chaos control.

  16. Experimental results of a sheet-beam, high power, FEL amplifier with application to magnetic fusion research

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, S.; Destler, W.W.; Granatstein, V.L. [Univ. of Maryland, College Park, MD (United States)] [and others

    1995-12-31

    The experimental study of sheet-beam FELs as candidate millimeter-wave sources for heating magnetic fusion plasmas has achieved a major milestone. In a proof-of-principle, pulsed experiment, saturated FEL amplifier operation was achieved with 250 kW of output power at 86 GHz. Input microwave power was 1 kW, beam voltage was 450 kV and beam current was 17 A. The planar wiggler had a peak value of 3.8 kG, a period of 0.96 cm and was 71 cm long. The linear gain of 30 dB, saturated gain of 24 dB and saturated efficiency of 3% all are in good agreement with theoretical prediction. Follow-on work would include development of a thermionic sheet-beam electron-gun compatible with CW FEL operation, adding a section of tapered wiggler to increase the output power to levels in excess of 1 megawatt, and increasing the FEL frequency.

  17. Design of a high average-power FEL driven by an existing 20 MV electrostatic-accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Kimel, I.; Elias, L.R. [Univ. of Central Florida, Orlando, FL (United States)

    1995-12-31

    There are some important applications where high average-power radiation is required. Two examples are industrial machining and space power-beaming. Unfortunately, up to date no FEL has been able to show more than 10 Watts of average power. To remedy this situation we started a program geared towards the development of high average-power FELs. As a first step we are building in our CREOL laboratory, a compact FEL which will generate close to 1 kW in CW operation. As the next step we are also engaged in the design of a much higher average-power system based on a 20 MV electrostatic accelerator. This FEL will be capable of operating CW with a power output of 60 kW. The idea is to perform a high power demonstration using the existing 20 MV electrostatic accelerator at the Tandar facility in Buenos Aires. This machine has been dedicated to accelerate heavy ions for experiments and applications in nuclear and atomic physics. The necessary adaptations required to utilize the machine to accelerate electrons will be described. An important aspect of the design of the 20 MV system, is the electron beam optics through almost 30 meters of accelerating and decelerating tubes as well as the undulator. Of equal importance is a careful design of the long resonator with mirrors able to withstand high power loading with proper heat dissipation features.

  18. Transient absorption spectroscopy in biology using the Super-ACO storage ring FEL and the synchrotron radiation combination

    CERN Document Server

    Renault, E; De Ninno, G; Garzella, D; Hirsch, M; Nahon, L; Nutarelli, D

    2001-01-01

    The Super-ACO storage ring FEL, covering the UV range down to 300 nm with a high average power (300 mW at 350 nm) together with a high stability and long lifetime, is a unique tool for the performance of users applications. We present here the first pump-probe two color experiments on biological species using a storage ring FEL coupled to the synchrotron radiation. The intense UV pulse of the Super-ACO FEL is used to prepare a high initial concentration of chromophores in their first singlet electronic excited state. The nearby bending magnet synchrotron radiation provides, on the other hand a pulsed, white light continuum (UV-IR), naturally synchronized with the FEL pulses and used to probe the photochemical subsequent events and the associated transient species. We have demonstrated the feasibility with a dye molecule (POPOP) observing a two-color effect, signature of excited state absorption and a temporal signature with Acridine. Applications on various chromophores of biological interest are carried out,...

  19. Discovering and annotating fish early life-stage (FELS) adverse outcome pathways: Putting the research strategy into practice

    Science.gov (United States)

    In May 2012, a HESI-sponsored expert workshop yielded a proposed research strategy for systematically discovering, characterizing, and annotating fish early life-stage (FELS) adverse outcome pathways (AOPs) as well as prioritizing AOP development in light of current restrictions ...

  20. Comparison of different undulator schemes with superimposed alternating gradients for the VUV-FEL at the TESLA Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    Pflueger, J.; Nikitina, Y.M. [DESY/HASYLAB, Hamburg (Germany)

    1995-12-31

    For the VUV-FEL at the TESLA Test Facility an undulator with a total length of 30 m is needed. In this study three different approaches to realize an undulator with a sinusoidal plus a superimposed quadrupolar field were studied with the 3D code MAFIA.

  1. Relativistic cloud-in-cell simulation of free-electron laser (FEL) with considering space charge effects

    International Nuclear Information System (INIS)

    Zhang Jiatai; Xu Linbao; Chang Tieqiang

    1990-04-01

    An one and a half dimensional (one space dimension and two velocity components) relativistic electromagnetic cloud-in-cell simulation code CIC-R, which is suitable for simulating FEL process, has been developed. By using this code the temporal evolution of FEL is simulated and the linear growth rate of unstable spectra (For one simulation the growth rate is 0.07 which is in good agreement with the theoretical data.), dispersion relations of coupling of pump waves, the electromagnetic and electrostatic waves are obtained. Other results such as the behaviour of electron distribution function, electrons bunching in phase space, nonlinear saturation and efficiency of energy conversion are also considered. Besides the multi-mode particle simulation, a single-mode wave-particle code (SMWPC) is developed. It is based on the simplified single-mode theory which was obtained from equations of electron motion and radiation field derived strictly under one dimension assumption and single-mode approximation. Using this code a 3.459 mm Raman FEL has been simulated. The higher gamma and tapered wiggler of FEL are also simulated. The results show that the efficiency can reach to 48% if the tapered wiggler field and other parameters are properly designed

  2. Neutron dose rate at the SwissFEL injector test facility: first measurements

    International Nuclear Information System (INIS)

    Hohmann, E.; Frey, N.; Fuchs, A.; Harm, C.; Hoedlmoser, H.; Luescher, R.; Mayer, S.; Morath, O.; Philipp, R.; Rehmann, A.; Schietinger, T.

    2014-01-01

    At the Paul Scherrer Institute, the new SwissFEL Free Electron Laser facility is currently in the design phase. It is foreseen to accelerate electrons up to a maximum energy of 7 GeV with a pulsed time structure. An injector test facility is operated at a maximum energy of 300 MeV and serves as the principal test and demonstration plant for the SwissFEL project. Secondary radiation is created in unavoidable interactions of the primary beam with beamline components. The resulting ambient dose-equivalent rate due to neutrons was measured along the beamline with different commercially available survey instruments. The present study compares the readings of these neutron detectors (one of them is specifically designed for measurements in pulsed fields). The experiments were carried out in both, a normal and a diagnostic mode of operation of the injector. Measurements were taken at the SwissFEL injector test facility using three different types of commercially available survey instruments for normal and diagnostic mode of operation at different positions inside the accelerator vault. During normal operation, the doses indicated by the different instruments agree within the measurement uncertainty except for the beam dump region. There, due to its limited energy range and high sensitivity, the LB6411 shows significantly lower dose values than the other instruments. The photon background in the vault associated with each pulse causes the scintillator used by the LB6419 to saturate. As a result, only the channel using the delayed 12 C(n,p)12-reaction could be used during the measurements. The highest doses per pulse were measured next to the beam dump and the bunch compressor. For the optimisation of the accelerator, luminescent screens can be inserted into the beam path causing a dose distributed over several metres depending on the screen type. The dose arise to 40 % from neutrons with energies of >20 MeV. Although the charge of each pulse were reduced to decrease

  3. Macroscopic coherent magnetic islands

    International Nuclear Information System (INIS)

    Porcelli, F.; Airoldi, A.; Angioni, C.

    2001-01-01

    We present experimental and theoretical investigations on the dynamics of coherent magnetic islands in high temperature, magnetically confined plasmas of thermonuclear interest, and of their effects on plasma transport. (author)

  4. Coherence in Industrial Transformation

    DEFF Research Database (Denmark)

    Jørgensen, Ulrik; Lauridsen, Erik Hagelskjær

    2003-01-01

    The notion of coherence is used to illustrate the general finding, that the impact of environmental management systems and environmental policy is highly dependent of the context and interrelatedness of the systems, procedures and regimes established in society....

  5. Intracoronary optical coherence tomography

    DEFF Research Database (Denmark)

    Tenekecioglu, Erhan; Albuquerque, Felipe N; Sotomi, Yohei

    2017-01-01

    By providing valuable information about the coronary artery wall and lumen, intravascular imaging may aid in optimizing interventional procedure results and thereby could improve clinical outcomes following percutaneous coronary intervention (PCI). Intravascular optical coherence tomography (OCT)...

  6. Coherence and chaos

    International Nuclear Information System (INIS)

    Sudarshan, E.C.G.

    1993-01-01

    The annihilation operator for harmonic oscillator is a weighted shift operator and can be realized on a family of over complete coherent states. Shift operators arise in dynamical maps of systems exhibiting deterministic chaos. Generalized coherent states, called harmonious states, realize these maps in a simple manner. By analytic continuation the spectral family can be altered, thus furnishing an alternative perspective on resonant scattering. Singular distributions are necessary to reproduce the rich structure of chaotic and scattering systems

  7. Analysis of the superconducting wiggler magnets for the ATF Harmonic Generation FEL experiment

    International Nuclear Information System (INIS)

    Zhang, X.; Ben-Zvi, I.; Ingold, G.; Krinsky, S.; Yu, L.H.

    1992-01-01

    In this paper, we consider the superconducting wiggler magnet under construction for the High Gain Harmonic Generation experiment (HGHG) at the Accelerator Test Facility (ATF) at BNL. This wiggler consists of an energy modulation section, a dispersion magnet and a radiator section. We present an analysis of the dispersion magnet and the end effects in the other wiggler sections. The purpose of the dispersion magnet is to convert energy modulation of the electron beam into spatial bunching. For the dispersion magnet, we discuss the physical requirements, analyze the magnetic design, determine the focusing properties, and consider the effect of departures from ideal behavior on the FEL gain. In the modulator and radiator wigglers we analyze the effects due to the ends of the wiggler and discuss their correction. In addition, the localized field produced by a trim coil for horizontal beam steering is investigated

  8. TDA - a three-dimensional axisymmetric code for free-electron-laser (FEL) simulation

    International Nuclear Information System (INIS)

    Tran, T.M.; Wurtele, J.S.

    1988-09-01

    A particle simulation code, TDA, which models the single-pass amplification process in a free-electron-laser (FEL) is developed and tested. The code allows for the treatment of the fully three-dimensional electron dynamics, thus taking into account the transverse betatron motion as well as the longitudinal bunching of the electrons. The paraxial wave equation that governs the growth and the diffraction of the selfconsistent radiation field (assumed to be axisymmetrtic), is discretized in the radial direction by the finite difference method. The benchmark study indicates that the single-pass gain, as well as the optical guiding phenomena can be well described by the code with a reasonable number of simulation particles (N ∼ 1000) and a radial mesh number not exceeding 64. A detailed discussion of the numerical method is presented. (author) 6 figs., 1 tab., 17 refs

  9. DEMONSTRATION OF 3D EFFECTS WITH HIGH GAIN AND EFFICIENCY IN A UV FEL OSCILLATOR

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Benson; George Biallas; Keith Blackburn; James Boyce; Donald Bullard; James Coleman; Cody Dickover; David Douglas; Forrest Ellingsworth; Pavel Evtushenko; Carlos Hernandez-Garcia; Christopher Gould; Joseph Gubeli; David Hardy; Kevin Jordan; John Klopf; James Kortze; Robert Legg; Matthew Marchlik; Steven Moore; George Neil; Thomas Powers; Daniel Sexton; Michelle D. Shinn; Christopher Tennant; Richard Walker; Anne Watson; Gwyn Williams; Frederick Wilson; Shukui Zhang

    2011-03-01

    We report on the performance of a high gain UV FEL oscillator operating on an energy recovery linac at Jefferson Lab. The high brightness of the electron beam leads to both gain and efficiency that cannot be reconciled with a one-dimensional model. Three-dimensional simulations do predict the performance with reasonable precision. Gain in excess of 100% per pass and an efficiency close to 1/2NW, where NW is the number of wiggler periods, is seen. The laser mirror tuning curves currently permit operation in the wavelength range of 438 to 362 nm. Another mirror set allows operation at longer wavelengths in the red with even higher gain and efficiency.

  10. Optimization of a Cryogenic System at Temperature 2 K for the PKU-FEL Facility

    Science.gov (United States)

    Hao, Jian-Kui; Lin, Lin; Huang, Sen-Lin; Zhao, Kui

    2006-10-01

    The conceptual design of a cryogenic system at temperature 2 K for the Peking University Free Electron Laser (PKU-FEL) facility is carried out. In order to minimize the scale of the cryogenic system and the running cost, the superconducting accelerator and the superconducting injector will mainly run at a long-pulsed mode. Optimization of the 2-K cryogenic system is carried out based on the heat load estimation and running parameters. Total cooling power of 52.5 W for the long-pulsed mode is necessary for the PKU cryogenic system. The PKU cryogenic system will be the first 2-K system for accelerators in China and will provide experience for similar facilities.

  11. Demonstration Of 3D Effects With High Gain And Efficiency In A UV FEL Oscillator

    International Nuclear Information System (INIS)

    Benson, Stephen; Biallas, George; Blackburn, Keith; Boyce, James; Bullard, Donald; Coleman, James; Dickover, Cody; Douglas, David; Ellingsworth, Forrest; Evtushenko, Pavel; Hernandez-Garcia, Carlos; Gould, Christopher; Gubeli, Joseph; Hardy, David; Jordan, Kevin; Klopf, John; Kortze, James; Legg, Robert; Marchlik, Matthew; Moore, Steven; Neil, George; Powers, Thomas; Sexton, Daniel; Shinn, Michelle; Tennant, Christopher; Walker, Richard; Watson, Anne; Williams, Gwyn; Wilson, Frederick; Zhang, Shukui

    2011-01-01

    We report on the performance of a high gain UV FEL oscillator operating on an energy recovery linac at Jefferson Lab. The high brightness of the electron beam leads to both gain and efficiency that cannot be reconciled with a one-dimensional model. Three-dimensional simulations do predict the performance with reasonable precision. Gain in excess of 100% per pass and an efficiency close to 1/2NW, where NW is the number of wiggler periods, is seen. The laser mirror tuning curves currently permit operation in the wavelength range of 438 to 362 nm. Another mirror set allows operation at longer wavelengths in the red with even higher gain and efficiency.

  12. Circular polarization with crossed-planar undulators in high-gain FELs

    CERN Document Server

    Kim, K J K J

    2000-01-01

    We propose a crossed undulator configuration for a high-gain free-electron laser to allow versatile polarization control. This configuration consists of a long (saturation length) planar undulator, a dispersive section, and a short (a few gain lengths) planar undulator oriented perpendicular to the first one. In the first undulator, a radiation component linearly polarized in the x-direction is amplified to saturation. In the second undulator, the x-polarized component propagates freely, while a new component, polarized in the y-direction, is generated and reaches saturation in a few gain lengths. By adjusting the strength of the dispersive section, the relative phase of two radiation components can be adjusted to obtain a suitable polarization for the total radiation field, including the circular polarization. The operating principle of the high-gain crossed undulator, which is quite different from that of the crossed undulator for spontaneous radiation, is illustrated in terms of 1-D FEL theory.

  13. Photocathode driven linac at UCLA for FEL and plasma wakefield acceleration experiments

    International Nuclear Information System (INIS)

    Hartman, S.; Aghamir, F.; Barletta, W.; Cline, D.; Dodd, J.; Katsouleas, T.; Kolonko, J.; Park, S.; Pellegrini, C.; Rosenzweig, J.; Smolin, J.; Terrien, J.; Davis, J.; Hairapetian, G.; Joshi, C.; Luhmann, N. Jr.; McDermott, D.

    1991-01-01

    The UCLA compact 20-MeV/c electron linear accelerator is designed to produce a single electron bunch with a peak current of 200 A, an rms energy spread of 0.2% or less, and a short 1.2 picosecond rms pulse duration. The linac is also designed to minimize emittance growth down the beamline so as to obtain emittances of the order of 8πmm-mrad in the experimental region. The linac will feed two beamlines, the first will run straight into the undulator for FEL experiments while the second will be used for diagnostics, longitudinal bunch compression, and other electron beam experiments. Here the authors describe the considerations put into the design of the accelerating structures and the transport to the experimental areas

  14. Progress in the design of a DC FEL power source using a pelletron driver

    International Nuclear Information System (INIS)

    Larson, D.J.; Cline, D.B.; Anderson, D.R.; Rosenzweig, J.B.; Mills, F.E.; Sundquist, M.L.; Adney, J.R.; Dehais, S.J.

    1987-01-01

    The authors discuss progress in the design of a DC Free Electron Laser power source using a Pelletron electrostatic accelerator as a driver. Such a power source should deliver up to 200 kW DC power in wavelengths ranging from a few microns to a few centimeters. The advantages of this system for use as a power source for future acceleration techniques are its efficiency, tunability and high average power. In order to achieve DC operation of the system extremely high electron recovery efficiencies are required. It is also likely that FEL operation will result in a large spread of electron energies. These design constraints require the development of a highly efficient electron beam collector as well as beam optic capable of recirculating beams with a large energy spread. The authors present collector and beamline designs and include electron optics studies for the full range of operating conditions

  15. Some issues and subtleties in numerical simulation of X-ray FEL's

    International Nuclear Information System (INIS)

    Fawley, William M.

    2002-01-01

    Part of the overall design effort for x-ray FEL's such as the LCLS and TESLA projects has involved extensive use of particle simulation codes to predict their output performance and underlying sensitivity to various input parameters (e.g. electron beam emittance). This paper discusses some of the numerical issues that must be addressed by simulation codes in this regime. We first give a brief overview of the standard approximations and simulation methods adopted by time-dependent(i.e. polychromatic) codes such as GINGER, GENESIS, and FAST3D, including the effects of temporal discretization and the resultant limited spectral bandpass,and then discuss the accuracies and inaccuracies of these codes in predicting incoherent spontaneous emission (i.e. the extremely low gain regime)

  16. Analytical studies of constraints on the performance for EEHG FEL seed lasers

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2011-11-15

    Laser seeding technique have been envisioned to produce nearly transform-limited pulses at soft X-ray FELs. Echo-Enabled Harmonic Generation (EEHG) is a promising, recent technique for harmonic generation with an excellent up-conversion to very high harmonics, from the standpoint of electron beam physics. This paper explores the constraints on seed laser performance for reaching wavelengths of 1 nm. We show that the main challenge in implementing the EEHG scheme at extreme harmonic factors is the requirement for accurate control of temporal and spatial quality of the seed laser pulse. For example, if the phase of the laser pulse is chirped before conversion to an UV seed pulse, the chirp in the electron beam microbunch turns out to be roughly multiplied by the harmonic factor. In the case of a Ti:Sa seed laser, such factor is about 800. For such large harmonic numbers, generation of nearly transform-limited soft X-ray pulses results in challenging constraints on the Ti:Sa laser. In fact, the relative discrepancy of the time-bandwidth product of the seed-laser pulse from the ideal transform-limited performance should be no more than one in a million. The generated electron beam microbunching is also very sensitive to distortions of the seed laser wavefront, which are also multiplied by the harmonic factor. In order to have minimal reduction of the FEL input coupling factor, it is desirable that the size-angular bandwidth product of the UV seed laser beam be very close to the ideal i.e. diffraction-limited performance in the waist plane at the middle of the modulator undulator. (orig.)

  17. Analytical studies of constraints on the performance for EEHG FEL seed lasers

    International Nuclear Information System (INIS)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2011-11-01

    Laser seeding technique have been envisioned to produce nearly transform-limited pulses at soft X-ray FELs. Echo-Enabled Harmonic Generation (EEHG) is a promising, recent technique for harmonic generation with an excellent up-conversion to very high harmonics, from the standpoint of electron beam physics. This paper explores the constraints on seed laser performance for reaching wavelengths of 1 nm. We show that the main challenge in implementing the EEHG scheme at extreme harmonic factors is the requirement for accurate control of temporal and spatial quality of the seed laser pulse. For example, if the phase of the laser pulse is chirped before conversion to an UV seed pulse, the chirp in the electron beam microbunch turns out to be roughly multiplied by the harmonic factor. In the case of a Ti:Sa seed laser, such factor is about 800. For such large harmonic numbers, generation of nearly transform-limited soft X-ray pulses results in challenging constraints on the Ti:Sa laser. In fact, the relative discrepancy of the time-bandwidth product of the seed-laser pulse from the ideal transform-limited performance should be no more than one in a million. The generated electron beam microbunching is also very sensitive to distortions of the seed laser wavefront, which are also multiplied by the harmonic factor. In order to have minimal reduction of the FEL input coupling factor, it is desirable that the size-angular bandwidth product of the UV seed laser beam be very close to the ideal i.e. diffraction-limited performance in the waist plane at the middle of the modulator undulator. (orig.)

  18. Time-resolved study of ICD in Ne dimers using FEL radiation

    Energy Technology Data Exchange (ETDEWEB)

    Schnorr, K., E-mail: kirsten.schnorr@mpi-hd.mpg.de [Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Senftleben, A. [Universität Kassel, 34132 Kassel (Germany); Schmid, G.; Augustin, S.; Kurka, M. [Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Rudenko, A. [J.R. Macdonald Laboratory, Kansas State University, Manhattan, KS 66506 (United States); Foucar, L. [Max-Planck-Institut für medizinische Forschung, 69120 Heidelberg (Germany); Broska, A.; Meyer, K. [Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Anielski, D.; Boll, R. [Deutsches Elektronen-Synchrotron, 22607 Hamburg (Germany); Rolles, D. [J.R. Macdonald Laboratory, Kansas State University, Manhattan, KS 66506 (United States); Kübel, M.; Kling, M.F. [Physics Department, Ludwig-Maximilians-Universität München, 85748 Garching (Germany); Jiang, Y.H. [Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210 (China); Mondal, S.; Tachibana, T.; Ueda, K. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Marchenko, T.; Simon, M. [Laboratoire de Chimie Physique-Matière et Rayonnement, UPMC and CNRS, 75231 Paris (France); and others

    2015-10-15

    Interatomic Coulombic Decay (ICD) is a relaxation phenomenon, which takes place in weakly bound atomic and molecular systems, typically within a few to hundreds of femtoseconds depending on the system and the particular decay mechanism. The creation of ICD-active states requires the production of highly excited systems, usually populated by innershell ionization or excitation. To this end, XUV and X-ray radiation from synchrotrons was conventionally applied for the majority of experiments due to the desired state-selective ionization of certain sub-shells. The advent of Free-Electron Lasers (FELs) has enabled an entirely new class of experiments, which finally allow to trace ICD directly in the time domain due to the femtosecond pulse duration. Within this paper, the first time-resolved ICD measurement using an XUV-pump–XUV-probe scheme will be discussed in detail. The experiment was performed on neon dimers and ICD was triggered by removing a 2s electron from one of the neon atoms using a 58 eV pulse from the FEL in Hamburg (FLASH). The onset of ICD was probed with a delayed copy of the trigger pulse that further ionized one of the two Ne{sup +} ions emerging after ICD. Thus, the delay-dependent yield of coincident Ne{sup +} + Ne{sup 2+} ion pairs contains the lifetime of the 2s-innershell vacancy decaying via ICD. The result of 150 fs ± 50 fs is in good agreement with theory but only for those calculations that explicitly take nuclear motion into account.

  19. Stimulated coherent transition radiation

    International Nuclear Information System (INIS)

    Hung-chi Lihn.

    1996-03-01

    Coherent radiation emitted from a relativistic electron bunch consists of wavelengths longer than or comparable to the bunch length. The intensity of this radiation out-numbers that of its incoherent counterpart, which extends to wavelengths shorter than the bunch length, by a factor equal to the number of electrons in the bunch. In typical accelerators, this factor is about 8 to 11 orders of magnitude. The spectrum of the coherent radiation is determined by the Fourier transform of the electron bunch distribution and, therefore, contains information of the bunch distribution. Coherent transition radiation emitted from subpicosecond electron bunches at the Stanford SUNSHINE facility is observed in the far-infrared regime through a room-temperature pyroelectric bolometer and characterized through the electron bunch-length study. To measure the bunch length, a new frequency-resolved subpicosecond bunch-length measuring system is developed. This system uses a far-infrared Michelson interferometer to measure the spectrum of coherent transition radiation through optical autocorrelation with resolution far better than existing time-resolved methods. Hence, the radiation spectrum and the bunch length are deduced from the autocorrelation measurement. To study the stimulation of coherent transition radiation, a special cavity named BRAICER is invented. Far-infrared light pulses of coherent transition radiation emitted from electron bunches are delayed and circulated in the cavity to coincide with subsequent incoming electron bunches. This coincidence of light pulses with electron bunches enables the light to do work on electrons, and thus stimulates more radiated energy. The possibilities of extending the bunch-length measuring system to measure the three-dimensional bunch distribution and making the BRAICER cavity a broadband, high-intensity, coherent, far-infrared light source are also discussed

  20. Performance of the thermionic RF gun injector for the linac-based IR free electron laser at the FEL-SUT

    CERN Document Server

    Oda, F; Kawai, M; Koike, H; Sobajima, M

    2001-01-01

    Kawasaki Heavy Industries, Ltd. (KHI) has developed a linac-based compact IR free electron laser device and has installed it in the FEL-SUT (IR FEL Research Center of Science University of Tokyo). The FEL device adopts a combination of a multi-cell RF gun with a thermionic cathode and an alpha-magnet as an injector. The fundamental design of this RF gun is the pi/2 mode standing wave structure. It has two accelerating cells and a coupling cell located on the beam axis, a so-called 'on axis coupled structure' (OCS). Characteristics of momentum distribution and micropulse bunch length of the electron beam are compared with beam dynamics simulation results in this paper. We succeeded in obtaining sufficient peak current for FEL lasing with this injector, and the first lasing was achieved on 6 July 2000.

  1. SAR image effects on coherence and coherence estimation.

    Energy Technology Data Exchange (ETDEWEB)

    Bickel, Douglas Lloyd

    2014-01-01

    Radar coherence is an important concept for imaging radar systems such as synthetic aperture radar (SAR). This document quantifies some of the effects in SAR which modify the coherence. Although these effects can disrupt the coherence within a single SAR image, this report will focus on the coherence between separate images, such as for coherent change detection (CCD) processing. There have been other presentations on aspects of this material in the past. The intent of this report is to bring various issues that affect the coherence together in a single report to support radar engineers in making decisions about these matters.

  2. Michelson interferometer design for Linac Coherent Light Source (LCLS) applications in the 15-1.5 Aa wavelength range

    International Nuclear Information System (INIS)

    Tatchyn, Roman

    2000-01-01

    In recent years the continuing development of linac-driven X-Ray Free Electron Laser (XRFEL) designs has significantly expanded the parameter space associated with 3rd and earlier-generation synchrotron radiation sources. In particular, in contrast to the >100 ps pulse durations typical of storage rings, temporal lengths extending down to the <100 fs regime will become available. For example, for the SLAC Linac Coherent Light Source (LCLS) a pulse duration of ∼200-300 fs with finer temporal features extending down to ∼1 fs is anticipated. The characterization of the phase space distributions of such pulses poses a significant challenge for instrumentation design both with regard to the brevity of the pulse structure as well as the X-ray (15-1.5 Aa) wavelength range of the FEL line. In this paper we assess a Michelson interferometer design aimed at characterizing the coherence length of the SLAC LCLS and discuss considerations related to its operation

  3. Editorial: Focus on X-ray Beams with High Coherence

    Science.gov (United States)

    Robinson, Ian; Gruebel, Gerhard; Mochrie, Simon

    2010-03-01

    Williams, H M Quiney, A G Peele and K A Nugent Imaging of complex density in silver nanocubes by coherent x-ray diffraction R Harder, M Liang, Y Sun, Y Xia and I K Robinson Methodology for studying strain inhomogeneities in polycrystalline thin films during in situ thermal loading using coherent x-ray diffraction N Vaxelaire, H Proudhon, S Labat, C Kirchlechner, J Keckes, V Jacques, S Ravy, S Forest and O Thomas Ptychographic coherent diffractive imaging of weakly scattering specimens Martin Dierolf, Pierre Thibault, Andreas Menzel, Cameron M Kewish, Konstantins Jefimovs, Ilme Schlichting, Konstanze von König, Oliver Bunk and Franz Pfeiffer Dose requirements for resolving a given feature in an object by coherent x-ray diffraction imaging Andreas Schropp and Christian G Schroer FLASH: new opportunities for (time-resolved) coherent imaging of nanostructures R Treusch and J Feldhaus Structure of a single particle from scattering by many particles randomly oriented about an axis: toward structure solution without crystallization? D K Saldin, V L Shneerson, M R Howells, S Marchesini, H N Chapman, M Bogan, D Shapiro, R A Kirian, U Weierstall, K E Schmidt and J C H Spence Analysis of strain and stacking faults in single nanowires using Bragg coherent diffraction imaging V Favre-Nicolin, F Mastropietro, J Eymery, D Camacho, Y M Niquet, B M Borg, M E Messing, L-E Wernersson, R E Algra, E P A M Bakkers, T H Metzger, R Harder and I K Robinson Coherent science at the SwissFEL x-ray laser B D Patterson, R Abela, H-H Braun, U Flechsig, R Ganter, Y Kim, E Kirk, A Oppelt, M Pedrozzi, S Reiche, L Rivkin, Th Schmidt, B Schmitt, V N Strocov, S Tsujino and A F Wrulich Energy recovery linac (ERL) coherent hard x-ray sources Donald H Bilderback, Joel D Brock, Darren S Dale, Kenneth D Finkelstein, Mark A Pfeifer and Sol M Gruner Statistical and coherence properties of radiation from x-ray free-electron lasers E L Saldin, E A Schneidmiller and M V Yurkov Microscopic return point memory in Co

  4. The Puzzle of Coherence

    DEFF Research Database (Denmark)

    Andersen, Anne Bendix; Frederiksen, Kirsten; Beedholm, Kirsten

    2016-01-01

    Background During the past decade, politicians and healthcare providers have strived to create a coherent healthcare system across primary and secondary healthcare sectors in Denmark. Nevertheless, elderly patients with chronic diseases (EPCD) continue to report experiences of poor-quality care...... and lack of coherence in treatment and patient pathways. The aim of our study is to explore the role of healthcare providers in furthering coherence. Our ambition is to identify areas for improvement or change of collaborative practice between healthcare providers in municipalities, hospitals and general...... to an acute care ward to discharge and later in meetings with healthcare providers in general practice, outpatient clinics, home care and physiotherapy. Furthermore, field observations were conducted in general practice, home care and rehabilitation settings. Research design An explorative design based...

  5. Comparison of a ZGP OPO with a Mark-III FEL as a Potential Replacement for Mid-Infrared Soft Tissue Ablation Applications

    CERN Document Server

    Mackanos, M A

    2005-01-01

    A Mark-III FEL, tuned to 6.45 μm has demonstrated minimal collateral damage and high ablation yield in soft tissue. Further clinical advances are limited due to the overhead associated with an FEL; alternative mid-IR sources are needed. The FEL parameters needed to carry out efficient ablation with minimal damage must be determined. Studies by this author have shown that the unique pulse structure of the FEL does not play a role in this process [1]. We focused on comparing the macropulse duration of the FEL with a ZGP-OPO. No difference in pulse structure between the two laser sources with respect to the ablation threshold of water and mouse dermis was seen. There is a difference between the sources with respect to the crater depths in gelatin and mouse dermis. At 6.1 μm, the OPO craters are 8 times the depth of the FEL ones. Brightfield imaging shows the classic ablation mechanism. The timescale of the crater formation, ejection, and collapse occurs on a faster scale for the OPO. Histology ...

  6. Maintaining Web Cache Coherency

    Directory of Open Access Journals (Sweden)

    2000-01-01

    Full Text Available Document coherency is a challenging problem for Web caching. Once the documents are cached throughout the Internet, it is often difficult to keep them coherent with the origin document without generating a new traffic that could increase the traffic on the international backbone and overload the popular servers. Several solutions have been proposed to solve this problem, among them two categories have been widely discussed: the strong document coherency and the weak document coherency. The cost and the efficiency of the two categories are still a controversial issue, while in some studies the strong coherency is far too expensive to be used in the Web context, in other studies it could be maintained at a low cost. The accuracy of these analysis is depending very much on how the document updating process is approximated. In this study, we compare some of the coherence methods proposed for Web caching. Among other points, we study the side effects of these methods on the Internet traffic. The ultimate goal is to study the cache behavior under several conditions, which will cover some of the factors that play an important role in the Web cache performance evaluation and quantify their impact on the simulation accuracy. The results presented in this study show indeed some differences in the outcome of the simulation of a Web cache depending on the workload being used, and the probability distribution used to approximate updates on the cached documents. Each experiment shows two case studies that outline the impact of the considered parameter on the performance of the cache.

  7. Coherent light microscopy

    CERN Document Server

    Ferraro, Pietro; Zalevsky, Zeev

    2011-01-01

    This book deals with the latest achievements in the field of optical coherent microscopy. While many other books exist on microscopy and imaging, this book provides a unique resource dedicated solely to this subject. Similarly, many books describe applications of holography, interferometry and speckle to metrology but do not focus on their use for microscopy. The coherent light microscopy reference provided here does not focus on the experimental mechanics of such techniques but instead is meant to provide a users manual to illustrate the strengths and capabilities of developing techniques. Th

  8. A multi-channel THz and infrared spectrometer for femtosecond electron bunch diagnostics by single-shot spectroscopy of coherent radiation

    International Nuclear Information System (INIS)

    Wesch, Stephan; Schmidt, Bernhard; Behrens, Christopher; Delsim-Hashemi, Hossein; Schmueser, Peter

    2011-08-01

    The high peak current required in free-electron lasers (FELs) is realized by longitudinal compression of the electron bunches to sub-picosecond length. In this paper, a frequency-domain diagnostic method is described that is capable of resolving structures in the femtosecond regime. A novel in-vacuum spectrometer has been developed for spectroscopy of coherent radiation in the THz and infrared range. The spectrometer is equipped with five consecutive dispersion gratings and 120 parallel readout channels; it can be operated either in short wavelength mode (5-44 μm) or in long wavelength mode (45-430 μm). Fast parallel readout permits the spectroscopy of coherent radiation from single electron bunches. Test measurements at the soft X-ray free-electron laser FLASH, using coherent transition radiation, demonstrate excellent performance of the spectrometer. The high sensitivity down to a few micrometers allows study of short bunch features caused for example by microbunching e ects in magnetic chicanes. The device is planned for use as an online bunch profile monitor during regular FEL operation. (orig.)

  9. A multi-channel THz and infrared spectrometer for femtosecond electron bunch diagnostics by single-shot spectroscopy of coherent radiation

    Energy Technology Data Exchange (ETDEWEB)

    Wesch, Stephan; Schmidt, Bernhard; Behrens, Christopher; Delsim-Hashemi, Hossein; Schmueser, Peter

    2011-08-15

    The high peak current required in free-electron lasers (FELs) is realized by longitudinal compression of the electron bunches to sub-picosecond length. In this paper, a frequency-domain diagnostic method is described that is capable of resolving structures in the femtosecond regime. A novel in-vacuum spectrometer has been developed for spectroscopy of coherent radiation in the THz and infrared range. The spectrometer is equipped with five consecutive dispersion gratings and 120 parallel readout channels; it can be operated either in short wavelength mode (5-44 {mu}m) or in long wavelength mode (45-430 {mu}m). Fast parallel readout permits the spectroscopy of coherent radiation from single electron bunches. Test measurements at the soft X-ray free-electron laser FLASH, using coherent transition radiation, demonstrate excellent performance of the spectrometer. The high sensitivity down to a few micrometers allows study of short bunch features caused for example by microbunching e ects in magnetic chicanes. The device is planned for use as an online bunch profile monitor during regular FEL operation. (orig.)

  10. Millimeter-wave FEL-oscillator with a new type Bragg resonator: advantages in efficiency and selectivity

    CERN Document Server

    Ginzburg, N S; Kaminsky, A K; Peskov, N Yu; Sedykh, S N; Sergeev, A P

    2000-01-01

    An FEL-oscillator with a new type of Bragg resonator was realized on the basis of linac LIU-3000 (JINR, Dubna) (0.8 MeV/200 A/200 ns). This resonator consists of two corrugated waveguide sections having a step of phase pi between the corrugations at the point of connection. The selective properties of a resonator of this type are significantly improved in comparison with a traditional two-mirror Bragg resonator. The output power was about 50 MW at a frequency of 30.7 GHz with the optimal parameters of the resonator, which corresponds to the efficiency of 35%, which is the highest for millimeter wavelength FEL. Radiation at the fundamental mode and the two side modes with the frequencies coincided to the 'cold' microwave testing was separately observed depending on the magnetic fields of the wiggler and solenoid.

  11. Magnetic measurements of the prototype dipole for the IR-FEL at the Thomas Jefferson National Accelerator Facility

    International Nuclear Information System (INIS)

    Karn, J.; Biallas, G.; Guerra, A.; Harwood, L.

    1997-01-01

    Magnetic measurements have been performed on the prototype dipole for the high power IR-FEL presently under construction at the Thomas Jefferson National Accelerator Facility. The optics-driven requirements for these magnets include low fields, large horizontal apertures, tight field homogeneity, absolute setability of core field ampersand integrated field, and control of the horizontal ampersand vertical focusing terms designed into the magnets. A prototype dipole was fabricated and underwent several iterations of mechanical adjustment and magnetic measurement. Measurements were made to quantify the effects of field clamps on vertical focusing terms and effective length. Additional tests were made using various applications of Purcell gaps and high permeability materials in order to achieve the required homogeneity. Results from the prototype have been integrated into the design of the seven families of dipoles needed for the FEL

  12. Amplification of a bi-phase shift-key modulated signal by a mm-wave FEL

    International Nuclear Information System (INIS)

    Prosnitz, D.; Scharlemann, E.T.; Sheaffer, M.K.

    1991-10-01

    Bi-phase shift keying (BPSK) is a modulation scheme used in communications and radar in which the phase of a transmitted rf signal is switched in a coded pattern between discrete values differing by π radians. The transmitted information rate (in communications) or resolution (in imaging radar) depends on the rate at which the transmitted signal can be modulated. Modulation rates of greater than 1 GHz are generally desired. Although the instantaneous gain bandwidth of a mm-wave FEL amplifier can be much greater than 10 GHz, slippage may limit the BPSK modulation rate that can be amplified. Qualitative slippage arguments would limit the modulation rate to relatively low values; nevertheless, simulations with a time-dependent FEL code (GINGER) indicate that rates of 2 GHz or more are amplified without much loss in modulation integrity. In this paper we describe the effects of slippage in the simulations and discuss the limits of simple arguments

  13. Parity measurements of nuclear dipole excitations using FEL-generated gamma-rays at HI gamma S

    CERN Document Server

    Pietralla, N; Litvinenko, V N; Ahmed, M W; Tonchev, A P

    2002-01-01

    First Nuclear Resonance Fluorescence (NRF) experiments were performed at the storage ring FEL-driven High Intensity Gamma Source (HI gamma S) at the DFELL. Azimuthal NRF intensity ratios were measured around the polarized HI gamma S beam. Electric character was deduced for 18 dipole excitations in sup 1 sup 3 sup 8 Ba . The measurements demonstrate the superior performance of the HI gamma S facility in making such measurements. We report here on the performance of this set-up.

  14. X-ray beam splitting design for concurrent imaging at hard X-ray FELs and synchrotron facilities

    Czech Academy of Sciences Publication Activity Database

    Oberta, Peter; Mokso, R.

    2013-01-01

    Roč. 729, NOV (2013), s. 85-89 ISSN 0168-9002 R&D Projects: GA MPO FR-TI1/412 Institutional research plan: CEZ:AV0Z10100522 Keywords : diffractive-refractive optics * hard X-ray FEL * X-ray imaging Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.316, year: 2013 http://www.sciencedirect.com/science/article/pii/S0168900213009613

  15. Generation and characterization of ultra-short electron beams for single spike infrared FEL radiation at SPARC_LAB

    Science.gov (United States)

    Villa, F.; Anania, M. P.; Artioli, M.; Bacci, A.; Bellaveglia, M.; Bisesto, F. G.; Biagioni, A.; Carpanese, M.; Cardelli, F.; Castorina, G.; Chiadroni, E.; Cianchi, A.; Ciocci, F.; Croia, M.; Curcio, A.; Dattoli, G.; Gallo, A.; Di Giovenale, D.; Di Palma, E.; Di Pirro, G.; Ferrario, M.; Filippi, F.; Giannessi, L.; Giribono, A.; Marocchino, A.; Massimo, F.; Mostacci, A.; Petralia, A.; Petrarca, M.; Petrillo, V.; Piersanti, L.; Pioli, S.; Pompili, R.; Romeo, S.; Rossi, A. R.; Scifo, J.; Shpakov, V.; Vaccarezza, C.

    2017-09-01

    The technique for producing and measuring few tens of femtosecond electron beams, and the consequent generation of few tens femtoseconds single spike FEL radiation pulses at SPARC_LAB is presented. The undulator has been used in the double role of radiation source and diagnostic tool for the characterization of the electron beam. The connection between the electron bunch length and the radiation bandwidth is analyzed.

  16. A 0.1 kW operation of the JAERI superconducting RF linac-based FEL

    CERN Document Server

    Minehara, E J; Sawamura, M; Nagai, R; Kikuzawa, N; Yamanouchi, T; Nishimori, N

    1999-01-01

    First and stable laser oscillation has been obtained around a wavelength of 24 mu m using the Japan Atomic Energy Research Institute, Tokai (JAERI) superconducting RF-linac-based FEL driver and far infrared FEL device. The electron beam energy and spread are 15.8 MeV and 0.6%, respectively. The beam current varies between 2 and 4 mA, and the pulse width between 0.1 and 0.9 ms, respectively. The near-concentric optical resonator is 14.4 m long, and uses gold-coated copper mirrors 120 mm in diameter. The hybrid, planar undulator has 52 periods, 33 mm in length and K=0.7. Remote-controlled actuators precisely adjust the optical axes and distance of the mirrors in order to coincide with the electron beam and micro pulse repetition rate, respectively, before oscillation. The power has been measured and is scattered from 10 sup 7 to 10 sup 8 times higher than that of the spontaneous emission. During the first successful operation, the highest average FEL power was measured to be about a hundred watts. The FWHM of t...

  17. Coherent synchrotron radiation

    International Nuclear Information System (INIS)

    Agoh, Tomonori

    2006-01-01

    This article presents basic properties of coherent synchrotron radiation (CSR) with numerical examples and introduces the reader to important aspects of CSR in future accelerators with short bunches. We show interesting features of the single bunch instability due to CSR in storage rings and discuss the longitudinal CSR field via the impedance representation. (author)

  18. Coherence Multiplex System Topologies

    NARCIS (Netherlands)

    Meijerink, Arjan; Taniman, R.O.; Heideman, G.H.L.M.; van Etten, Wim

    2007-01-01

    Coherence multiplexing is a potentially inexpensive form of optical code-division multiple access, which is particularly suitable for short-range applications with moderate bandwidth requirements, such as access networks, LANs, or interconnects. Various topologies are known for constructing an

  19. Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Andersen, Peter E.

    2015-01-01

    Optical coherence tomography (OCT) is a noninvasive imaging technique that provides real-time two- and three-dimensional images of scattering samples with micrometer resolution. Mapping the local reflectivity, OCT visualizes the morphology of the sample, in real time or at video rate. In addition...

  20. Optical Coherence Elastography

    Science.gov (United States)

    Kennedy, Brendan F.; Kennedy, Kelsey M.; Oldenburg, Amy L.; Adie, Steven G.; Boppart, Stephen A.; Sampson, David D.

    The mechanical properties of tissue are pivotal in its function and behavior, and are often modified by disease. From the nano- to the macro-scale, many tools have been developed to measure tissue mechanical properties, both to understand the contribution of mechanics in the origin of disease and to improve diagnosis. Optical coherence elastography is applicable to the intermediate scale, between that of cells and whole organs, which is critical in the progression of many diseases and not widely studied to date. In optical coherence elastography, a mechanical load is imparted to a tissue and the resulting deformation is measured using optical coherence tomography. The deformation is used to deduce a mechanical parameter, e.g., Young's modulus, which is mapped into an image, known as an elastogram. In this chapter, we review the development of optical coherence elastography and report on the latest developments. We provide a focus on the underlying principles and assumptions, techniques to measure deformation, loading mechanisms, imaging probes and modeling, including the inverse elasticity problem.

  1. The impact of coherent synchrotron radiation on the beam transport of short bunches

    International Nuclear Information System (INIS)

    Li, R.

    1999-01-01

    Designs for next-generation accelerator, such as future linear colliders and short-wavelength FEL drivers, require beams of short (mm-length or smaller) bunches and high charge (nC-regime). As such a high charge microbunch traverses magnetic bends, the curvature effect on the bunch self-interaction, by way of coherent synchrotron radiation (CSR) and space charge force, may cause serious emittance degradation. This impact of CSR on the beam transport of short bunches has raised significant concern in the design of future machines and led to extensive investigations. This paper reviews some of the recent progress in the understanding of the CSR effect, presents analysis of and computational work on the CSR impact on short bunch transport, and addresses remaining issues

  2. Radiation Protection Aspects of the Linac Coherent Light Source Front End Enclosure

    Energy Technology Data Exchange (ETDEWEB)

    Vollaire, J.; Fasso, A.; Liu, J.C.; Mao, X.S.; Prinz, A.; Rokni, S.H.; Leitner, M.Santana; /SLAC

    2010-08-26

    The Front End Enclosure (FEE) of the Linac Coherent Light Source (LCLS) is a shielding housing located between the electron dump area and the first experimental hutch. The upstream part of the FEE hosts the commissioning diagnostics for the FEL beam. In the downstream part of the FEE, two sets of grazing incidence mirror and several collimators are used to direct the beam to one of the experimental stations and reduce the bremsstrahlung background and the hard component of the spontaneous radiation spectrum. This paper addresses the beam loss assumptions and radiation sources entering the FEE used for the design of the FEE shielding using the Monte-Carlo code FLUKA. The beam containment system prevents abnormal levels of radiations inside the FEE and ensures that the beam remains in its intended path is also described.

  3. Coherent states in quantum mechanics

    CERN Document Server

    Rodrigues, R D L; Fernandes, D

    2001-01-01

    We present a review work on the coherent states is non-relativistic quantum mechanics analysing the quantum oscillators in the coherent states. The coherent states obtained via a displacement operator that act on the wave function of ground state of the oscillator and the connection with Quantum Optics which were implemented by Glauber have also been considered. A possible generalization to the construction of new coherent states it is point out.

  4. Coherent hybrid electromagnetic field imaging

    Science.gov (United States)

    Cooke, Bradly J [Jemez Springs, NM; Guenther, David C [Los Alamos, NM

    2008-08-26

    An apparatus and corresponding method for coherent hybrid electromagnetic field imaging of a target, where an energy source is used to generate a propagating electromagnetic beam, an electromagnetic beam splitting means to split the beam into two or more coherently matched beams of about equal amplitude, and where the spatial and temporal self-coherence between each two or more coherently matched beams is preserved. Two or more differential modulation means are employed to modulate each two or more coherently matched beams with a time-varying polarization, frequency, phase, and amplitude signal. An electromagnetic beam combining means is used to coherently combine said two or more coherently matched beams into a coherent electromagnetic beam. One or more electromagnetic beam controlling means are used for collimating, guiding, or focusing the coherent electromagnetic beam. One or more apertures are used for transmitting and receiving the coherent electromagnetic beam to and from the target. A receiver is used that is capable of square-law detection of the coherent electromagnetic beam. A waveform generator is used that is capable of generation and control of time-varying polarization, frequency, phase, or amplitude modulation waveforms and sequences. A means of synchronizing time varying waveform is used between the energy source and the receiver. Finally, a means of displaying the images created by the interaction of the coherent electromagnetic beam with target is employed.

  5. Coherent Harmonic Generation using the ELETTRA Storage Ring Optical Klystron

    CERN Document Server

    De Ninno, G; Diviacco, Bruno; Ferianis, Mario; Trovò, Mauro

    2004-01-01

    The standard process leading to CHG using single-pass devices or storage rings is based on the up-frequency conversion of a high-power laser focused into the first undulator of an optical klystron. The seeding signal, which is necessary to produce the modulation of the electron density and hence to induce the coherent emission, may be provided by an external laser or, in the case of storage-ring oscillators, by the FEL itself. The latter configuration has been recently implemented at ELETTRA allowing to generate the third harmonic of an intra-cavity signal at 660 nm. In the first part of this paper, we report about the set of measurements that have been performed, for different experimental set-ups, with the aim of characterizing the power as well as the spectral and temporal characteristics of the obtained radiation. As for seeding using an external laser, a detailed campaign of simulations, reported in the second part of the paper, shows that the ELETTRA optical klystron is also well suited for the investig...

  6. Alternate Tunings for the Linac Coherent Light Source Photoinjector

    CERN Document Server

    Limborg-Deprey, Cecile

    2005-01-01

    The Linac Coherent Light Source (LCLS) is an x-ray free-electron laser (FEL) project based on the SLAC linac. The LCLS Photoinjector beamline has been designed to deliver 10 ps long electron bunches of 1nC with a normalized transverse emittance of less than 1 mm.mrad for 80% of the slices constituting the core of the bunch at 135 MeV. Tolerances and regulation requirements are tight for this tuning. The main contribution to emittance is the "cathode emittance which counts for 0.72 mm.mrad for the nominal tuning. As the "cathode emittance" scales linearly with laser spot radius, the emittance will be dramatically reduced for smaller radius, but this is only possible at lower charge. In particular, for a 0.2nC, we believe we can achieve an emittance closer to 0.4 mm.mrad. This working point will be easier to tune and the beam quality should be much easier to maintain than for the nominal one. In this paper, we also discuss how emittance could be further reduced by using the appropriate laser pulse shaping.

  7. Coherent Smith-Purcell radiation as a pulse length diagnostic

    International Nuclear Information System (INIS)

    Lampel, M.C.

    1997-01-01

    Recently, Smith-Purcell radiation has been studied as a candidate for laser-type radiation production in the submillimeter regime. With appropriate choices of beam energy, impact parameter, and grating spacing, there is good coupling to strongly polarized, forward directed radiation. Another regime of possible interest is to use Smith-Purcell radiation as a pulse length diagnostic for medium to high energy electron beams of extremely short pulse duration, on the order of tens of femtoseconds to 1000 fs. Strongly in favor of development of such a diagnostic is its relatively non-destructive nature. With the electron beam passing near, but not through, a metal grating, reaction of the beam distribution itself to the production of the radiation is reduced relative to the much stronger scattering induced by passage through a foil. By careful choice of parameters usable diagnostic radiation ought to be produced with acceptably small emittance growth for an on-line beam monitor, even for the extremely bright electron beams proposed for X-ray FELs, Compton backscatter X-ray sources, or laser/plasma accelerator schemes. In this paper coherent and incoherent Smith-Purcell radiation is examined for reasonable operating parameters of the SATURNUS system at UCLA, with comparisons with results reported from the accelerator test facility (ATF) at Brookhaven National Laboratory. (orig.)

  8. Heavy ions acceleration in RF wells of 2-frequency electromagnetic field and in the inverted FEL

    International Nuclear Information System (INIS)

    Dzergach, A.I.; Kabanov, V.S.; Nikulin, M.G.; Vinogradov, S.V.

    1995-03-01

    Last results of the study of heavy ions acceleration by electrons trapped in moving 2-frequency 3-D RF wells are described. A linearized theoretical model of ions acceleration in a polarized spheroidal plasmoid is proposed. The equilibrium state of this plasmoid is described by the modified microcanonical distribution of the Courant-Snyder invariant (open-quotes quasienergyclose quotes of electrons). Some new results of computational simulation of the acceleration process are given. The method of computation takes into account the given cylindrical field E 011 (var-phi,r,z) and the self fields of electrons and ions. The results of the computation at relatively short time intervals confirm the idea and estimated parameters of acceleration. The heavy ion accelerator using this principle may be constructed with the use of compact cm band iris-loaded and biperiodical waveguides with double-sided 2-frequency RF feeding. It can accelerate heavy ions with a charge number Z i from small initial energies ∼ 50 keV/a.u. with the rate ∼ Z i · 10 MeV/m. Semirelativistic ions may be accelerated with similar rate also in the inverted FEL

  9. Picked FEL Micro Pulse for Nano-Second Interaction with Bio-Molecule

    CERN Document Server

    Suzuki, Sachiko; Ishii, Katsonuri; Kanai, T; Naito, Y

    2004-01-01

    Laser pulse duration is a very important parameter to determine the threshold between thermal and nonthermal effects in laser surgery of biomedical tissue. Free Electron Laser (FEL) at Osaka University, Japan, has a pulse structure in which a macropulse (pulse width : 15μs) consists of equally separated micropulses, whose width and interval are ~5ps and 44.8ns, respectively. Precise control of micropulse train may establish fast optic processes because thermal relaxation time in the tissue is about 1us. A pulse-picking system was designed in order to extract single or a few micropulses from an entire macropulse using an acousto-optic modulator (AOM) in which the light path can be temporally diffracted by an external gate signal. An extracted micropulse train was monitored by a mercury-cadmium-telluride (MCT) photodetector with ~1ns response time and recorded on digital oscilloscope. A single micropulse was extracted as a result of adjusting duration of the RF wave to 50 ns which is nearly equal to the ...

  10. The RF Injector for the FERMI @ Elettra Seeded X-Ray FEL

    CERN Document Server

    Penco, G

    2005-01-01

    In the framework of the FERMI@ELETTRA project, aimed to build an x-ray FEL source based on laser-seeded harmonic generation, a crucial role is played by the electron source, which has to produce a very high quality beam, in terms of low emittance and uncorrelated energy spread. A very attractive solution is the SLAC/BNL/UCLA 1.6 cell s-band gun III based upon the demonstrated high performance of this design and its descendants. This paper describes the results of the optimization studies based on the gun III design and carried out with two space charge tracking codes (GPT and ASTRA) for nominal operating parameters. In particular two different bunch charge regimes has been explored: low (few hundreds of pC) and high (~1nC) . In the first case, the limited charge extracted from the photo-cathode allows to propagate a bunch with an initial higher density and to compress it along the linac down to a few hundreds of fs, attaining a high peak current bunch with a very low slice emittance. The second case has been ...

  11. Large-Scale Timing Distribution and RF-Synchronization for FEL Facilities

    CERN Document Server

    Kim, Jung Won; Kaertner, Franz X; Muecke, Oliver; Perrott, Michael

    2004-01-01

    For future advances in accelerator physics in general and seeding of FELs in particular, precise synchronization between seed radiation, low-level RF-systems and photo-injector laser is required. Typical synchronization methods based on direct photodetection are limited by the detector nonlinearities, which lead to amplitude-to-phase conversion and introduce timing jitter. A new synchronization scheme for extraction of low jitter RF-signals from optical pulse trains distributed by mode-locked lasers is proposed. It is robust against photodetector nonlinearities. The scheme is based on a transfer of timing information into an intensity imbalance between the two output beams from a Sagnac-loop interferometer. As a first experimental demonstration, sub-100 fs timing jitter between the extracted 2 GHz RF-signal and the 100 MHz optical pulse train from a mode-locked Ti:sapphire laser is demonstrated. Numerical simulations show that scaling to sub-femtosecond precision is possible. Together with mode-locked fiber l...

  12. Performance of a DC GaAs photocathode gun for the Jefferson lab FEL

    CERN Document Server

    Siggins, T; Bohn, C L; Bullard, D; Douglas, D; Grippo, A; Gubeli, J; Krafft, G A; Yunn, B

    2001-01-01

    The performance of the 320 kV DC photocathode gun has met the design specifications for the 1 kW IR Demo FEL at Jefferson Lab. This gun has shown the ability to deliver high average current beam with outstanding lifetimes. The GaAs photocathode has delivered 135 pC per bunch, at a bunch repetition rate of 37.425 MHz, corresponding to 5 mA average CW current. In a recent cathode lifetime measurement, 20 h of CW beam was delivered with an average current of 3.1 mA and 211 C of total charge from a 0.283 cm sup 2 illuminated spot. The cathode showed a 1/e lifetime of 58 h and a 1/e extracted charge lifetime of 618 C. We have achieved quantum efficiencies of 5% from a GaAs wafer that has been in service for 13 months delivering in excess 2400 C with only three activation cycles.

  13. Dynamical behaviour of FEL devices operating with two undulators having opposite circular polarizations

    Energy Technology Data Exchange (ETDEWEB)

    Dattoli, G. [ENEA, Divisione Fisica Applicata, Centro Ricerche Frascati, Rome (Italy); Ottaviani, P.L. [ENEA, Divisione Fisica Applicata, Centro Ricerche, Bologna (Italy); Bucci, L. [ENEA, Guest Rome (Italy)

    2000-07-01

    Optical-Klystron FELs operating with undulators having opposite circular polarizations are characterized by a spontaneous emission spectrum which does not exhibit the characteristic interference pattern. The use of the Madey theorem may allow the conclusion that, for such configuration, the dispersive section does not provide any gain enhancement. In this paper it has been analyzed the problem from a dynamical point of view and clarify how the optical field evolve, what is the role of the bunching and how the consequences of the Madey theorem should be correctly understood. [Italian] Klystron ottici operanti con ondulatori aventi polarizzazione elicoidali opposte, sono caratterizzati da uno spettro di emissione spontanea senza il termine interferenziale dovuto alla sezione dispersiva. L'uso del teorema di Madey indurrebbe alla conclusione che, per una tale configurazione, la sezione dispersiva non induce nessun aumento del guadagno. In questo lavoro analizziamo il problema da un punto di vista dinamico che chiarisce l'evoluzione del campo ottico, quale e' il ruolo del bunching e come le conseguenze del teorema di Madey debbano essere interpretate.

  14. X-Ray Production by Cascading Stages of a High-Gain Harmonic Generation Free-Electron Laser I: Basic Theory

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J

    2004-07-02

    We study a new approach to produce x-ray by cascading several stages of a High-Gain Harmonic Generation (HGHG) Free-Electron Laser (FEL). Besides the merits of a Self-Amplified Spontaneous Emission (SASE) scheme, an HGHG scheme could also provide much better stability of the radiation power, controllable short pulse length, more stable central wavelength, and radiation with better longitudinal coherence. Detailed design and optimization scheme, simulation results and analytical estimate formulae are presented. To lay results on a realistic basis, the electron bunch parameters used in this paper are restricted to be those of DESY TTF and SLAC LCLS projects; however, such sets of parameters are not necessary to be optimized for an HGHG FEL.

  15. Optical Coherence and Quantum Optics

    CERN Document Server

    Mandel, Leonard

    1995-01-01

    This book presents a systematic account of optical coherence theory within the framework of classical optics, as applied to such topics as radiation from sources of different states of coherence, foundations of radiometry, effects of source coherence on the spectra of radiated fields, coherence theory of laser modes, and scattering of partially coherent light by random media. The book starts with a full mathematical introduction to the subject area and each chapter concludes with a set of exercises. The authors are renowned scientists and have made substantial contributions to many of the topi

  16. Grating monochromator for soft X-ray self-seeding the European XFEL

    Energy Technology Data Exchange (ETDEWEB)

    Serkez, Svitozar; Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany)

    2013-02-15

    Self-seeding is a promising approach to significantly narrow the SASE bandwidth of XFELs to produce nearly transform-limited pulses. The implementation of this method in the soft X-ray wavelength range necessarily involves gratings as dispersive elements. We study a very compact self-seeding scheme with a grating monochromator originally designed at SLAC, which can be straightforwardly installed in the SASE3 type undulator beamline at the European XFEL. The monochromator design is based on a toroidal VLS grating working at a fixed incidence angle mounting without entrance slit. It covers the spectral range from 300 eV to 1000 eV. The optical system was studied using wave optics method (in comparison with ray tracing) to evaluate the performance of the self-seeding scheme. Our wave optics analysis takes into account the actual beam wavefront of the radiation from the coherent FEL source, third order aberrations, and errors from each optical element. Wave optics is the only method available, in combination with FEL simulations, for the design of a self-seeding monochromator without exit slit. We show that, without exit slit, the self-seeding scheme is distinguished by the much needed experimental simplicity, and can practically give the same resolving power (about 7000) as with an exit slit. Wave optics is also naturally applicable to calculations of the self-seeding scheme efficiency, which include the monochromator transmittance and the effect of the mismatching between seed beam and electron beam. Simulations show that the FEL power reaches 1 TW and that the spectral density for a TW pulse is about two orders of magnitude higher than that for the SASE pulse at saturation.

  17. Workshop on scientific applications of coherent x-rays

    Energy Technology Data Exchange (ETDEWEB)

    Arthur, J.; Materlik, G.; Winick, H. [Stanford Univ., CA (United States). Stanford Linear Accelerator Center]|[Stanford Univ., CA (United States). Stanford Synchrotron Radiation Lab.; Birgeneau, R.J. [Massachusetts Institute of Technology, Cambridge, MA (United States); Fadley, C.S. [Lawrence Berkeley Lab., CA (United States). Materials Science Division

    1994-02-12

    This is a report on a workshop held at SLAC on February 12, 1994 to assess the science that would become possible using high peak power, short pulses of coherent radiation from a Free Electron Laser (FEL) operating in the hard x-ray region, at wavelengths down to about 1 {angstrom}. Sixty-three people participated in the workshop. The appendices to this report give a list of participants, the workshop agenda, and the charge to the workshop. Material describing the performance parameters of several possible sources was made available to the participants along with a graph showing the spectral distribution of the spontaneous as well as the coherent radiation and a note on peak power issues. This material is also included as an appendix to this report. This report consists of an Executive Summary, brief summaries by the speaker for each of the talks that were given, and copies of some of the viewgraphs that were shown. Also included are important points raised in the discussions that followed each talk. In addition, two contributions from scientists who could not attend the workshop are included, plus one contribution received from a participant after the workshop. A serious storm on the East coast made it impossible for three speakers and several intended participants to reach Stanford. The talk by Janos Kirz was presented by Malcolm Howells using viewgraphs sent by FAX. The talks by Keith Nelson and Brian Stephenson were not given. We include summaries by them of the talks they would have given, plus copies of some of their viewgraphs, in this report.

  18. Workshop on scientific applications of coherent x-rays

    International Nuclear Information System (INIS)

    Arthur, J.; Materlik, G.; Winick, H.; Fadley, C.S.

    1994-01-01

    This is a report on a workshop held at SLAC on February 12, 1994 to assess the science that would become possible using high peak power, short pulses of coherent radiation from a Free Electron Laser (FEL) operating in the hard x-ray region, at wavelengths down to about 1 angstrom. Sixty-three people participated in the workshop. The appendices to this report give a list of participants, the workshop agenda, and the charge to the workshop. Material describing the performance parameters of several possible sources was made available to the participants along with a graph showing the spectral distribution of the spontaneous as well as the coherent radiation and a note on peak power issues. This material is also included as an appendix to this report. This report consists of an Executive Summary, brief summaries by the speaker for each of the talks that were given, and copies of some of the viewgraphs that were shown. Also included are important points raised in the discussions that followed each talk. In addition, two contributions from scientists who could not attend the workshop are included, plus one contribution received from a participant after the workshop. A serious storm on the East coast made it impossible for three speakers and several intended participants to reach Stanford. The talk by Janos Kirz was presented by Malcolm Howells using viewgraphs sent by FAX. The talks by Keith Nelson and Brian Stephenson were not given. We include summaries by them of the talks they would have given, plus copies of some of their viewgraphs, in this report

  19. Coherent dynamics in semiconductors

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher

    1998-01-01

    enhanced in quantum confined lower-dimensional systems, where exciton and biexciton effects dominate the spectra even at room temperature. The coherent dynamics of excitons are at modest densities well described by the optical Bloch equations and a number of the dynamical effects known from atomic......Ultrafast nonlinear optical spectroscopy is used to study the coherent dynamics of optically excited electron-hole pairs in semiconductors. Coulomb interaction implies that the optical inter-band transitions are dominated, at least at low temperatures, by excitonic effects. They are further...... and molecular systems are found and studied in the exciton-biexciton system of semiconductors. At densities where strong exciton interactions, or many-body effects, become dominant, the semiconductor Bloch equations present a more rigorous treatment of the phenomena Ultrafast degenerate four-wave mixing is used...

  20. Generalized hypergeometric coherent states

    International Nuclear Information System (INIS)

    Appl, Thomas; Schiller, Diethard H

    2004-01-01

    We introduce a large class of holomorphic quantum states by choosing their normalization functions to be given by generalized hypergeometric functions. We call them generalized hypergeometric states in general, and generalized hypergeometric coherent states in particular, if they allow a resolution of unity. Depending on the domain of convergence of the generalized hypergeometric functions, we distinguish generalized hypergeometric states on the plane, the open unit disc and the unit circle. All states are eigenstates of suitably defined lowering operators. We then study their photon number statistics and phase properties as revealed by the Husimi and Pegg-Barnett phase distributions. On the basis of the generalized hypergeometric coherent states we introduce new analytic representations of arbitrary quantum states in Bargmann and Hardy spaces as well as generalized hypergeometric Husimi distributions and corresponding phase distributions

  1. Spectral coherence in windturbine wakes

    Energy Technology Data Exchange (ETDEWEB)

    Hojstrup, J. [Riso National Lab., Roskilde (Denmark)

    1996-12-31

    This paper describes an experiment at a Danish wind farm to investigate the lateral and vertical coherences in the nonequilibrium turbulence of a wind turbine wake. Two meteorological masts were instrumented for measuring profiles of mean speed, turbulence, and temperature. Results are provided graphically for turbulence intensities, velocity spectra, lateral coherence, and vertical coherence. The turbulence was somewhat influenced by the wake, or possibly from aggregated wakes further upstream, even at 14.5 diameters. Lateral coherence (separation 5m) seemed to be unaffected by the wake at 7.5 diameters, but the flow was less coherent in the near wake. The wake appeared to have little influence on vertical coherence (separation 13m). Simple, conventional models for coherence appeared to be adequate descriptions for wake turbulence except for the near wake situation. 3 refs., 7 figs., 1 tab.

  2. The Puzzle of Coherence

    DEFF Research Database (Denmark)

    Andersen, Anne Bendix; Frederiksen, Kirsten; Beedholm, Kirsten

    2016-01-01

    During the past decade, politicians and health care providers have strived to create a coherent health care system across primary and secondary health care systems in Denmark. Nevertheless, elderly patients with chronic diseases (EPCD) continue to report experiences of poor-quality care and lack ...... both nationally and internationally in preparation of health agreements, implementation of new collaboration forms among health care providers, and in improvement of delegation and transfer of information and assignments across sectors in health care....

  3. Coherent radiation from pulsars

    International Nuclear Information System (INIS)

    Cox, J.L. Jr.

    1979-01-01

    Interaction between a relativistic electrom stream and a plasma under conditions believed to exist in pulsar magnetospheres is shown to result in the simultaneous emission of coherent curvature radiation at radio wavelengths and incoherent curvature radiation at X-ray wavelengths from the same spatial volume. It is found that such a stream can propagate through a plasma parallel to a very strong magnetic field only if its length is less than a critical length L/sub asterisk/ic. Charge induced in the plasma by the stream co-moves with the stream and has the same limitation in longitudinal extent. The resultant charge bunching is sufficient to cause the relatively low energy plasma particles to radiate at radio wavelengths coherently while the relatively high energy stream particles radiate at X-ray wavelengths incoherently as the stream-plasma system moves along curved magnetic field lines. The effective number of coherently radiating particles per bunch is estimated to be approx.10 14 --10 15 for a tupical pulsar

  4. Coherent laser vision system

    International Nuclear Information System (INIS)

    Sebastion, R.L.

    1995-01-01

    The Coherent Laser Vision System (CLVS) is being developed to provide precision real-time 3D world views to support site characterization and robotic operations and during facilities Decontamination and Decommissioning. Autonomous or semiautonomous robotic operations requires an accurate, up-to-date 3D world view. Existing technologies for real-time 3D imaging, such as AM laser radar, have limited accuracy at significant ranges and have variability in range estimates caused by lighting or surface shading. Recent advances in fiber optic component technology and digital processing components have enabled the development of a new 3D vision system based upon a fiber optic FMCW coherent laser radar. The approach includes a compact scanner with no-moving parts capable of randomly addressing all pixels. The system maintains the immunity to lighting and surface shading conditions which is characteristic to coherent laser radar. The random pixel addressability allows concentration of scanning and processing on the active areas of a scene, as is done by the human eye-brain system

  5. Coherent electron cooling

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko,V.

    2009-05-04

    Cooling intense high-energy hadron beams remains a major challenge in modern accelerator physics. Synchrotron radiation is still too feeble, while the efficiency of two other cooling methods, stochastic and electron, falls rapidly either at high bunch intensities (i.e. stochastic of protons) or at high energies (e-cooling). In this talk a specific scheme of a unique cooling technique, Coherent Electron Cooling, will be discussed. The idea of coherent electron cooling using electron beam instabilities was suggested by Derbenev in the early 1980s, but the scheme presented in this talk, with cooling times under an hour for 7 TeV protons in the LHC, would be possible only with present-day accelerator technology. This talk will discuss the principles and the main limitations of the Coherent Electron Cooling process. The talk will describe the main system components, based on a high-gain free electron laser driven by an energy recovery linac, and will present some numerical examples for ions and protons in RHIC and the LHC and for electron-hadron options for these colliders. BNL plans a demonstration of the idea in the near future.

  6. Time-resolved phase measurement of a self-amplified free-electron laser

    International Nuclear Information System (INIS)

    We report on the first time-resolved phase measurement on self-amplified spontaneous emission (SASE) free-electron laser (FEL) pulses. We observed that the spikes in the output of such free-electron laser pulses have an intrinsic positive chirp. We also observed that the energy chirp in the electron bunch mapped directly into the FEL output. Under certain conditions, the two chirps cancel each other. The experimental result was compared with simulations and interpreted with SASE theory

  7. Optimizing x-ray mirror thermal performance using variable length cooling for second generation FELs

    Science.gov (United States)

    Hardin, Corey L.; Srinivasan, Venkat N.; Amores, Lope; Kelez, Nicholas M.; Morton, Daniel S.; Stefan, Peter M.; Nicolas, Josep; Zhang, Lin; Cocco, Daniele

    2016-09-01

    The success of the LCLS led to an interest across a number of disciplines in the scientific community including physics, chemistry, biology, and material science. Fueled by this success, SLAC National Accelerator Laboratory is developing a new high repetition rate free electron laser, LCLS-II, a superconducting linear accelerator capable of a repetition rate up to 1 MHz. Undulators will be optimized for 200 to 1300 eV soft X-rays, and for 1000 to 5000 eV hard X-rays. To absorb spontaneous radiation, higher harmonic energies and deflect the x-ray beam to various end stations, the transport and diagnostics system includes grazing incidence plane mirrors on both the soft and Hard X-ray beamline. To deliver the FEL beam with minimal power loss and wavefront distortion, we need mirrors of height errors below 1nm rms in operational conditions. We need to mitigate the thermal load effects due to the high repetition rate. The absorbed thermal profile is highly dependent on the beam divergence, and this is a function of the photon energy. To address this complexity, we developed a mirror cradle with variable length cooling and first order curve correction. Mirror figure error is minimized using variable length water-cooling through a gallium-indium eutectic bath. Curve correction is achieved with an off-axis bender that will be described in details. We present the design features, mechanical analysis and results from optical and mechanical tests of a prototype assembly, with particular regards to the figure sensitivity to bender corrections.

  8. DOOCS based control system for FPGA based cavity simulator and controller in VUV FEL

    Energy Technology Data Exchange (ETDEWEB)

    Pucyk, P.

    2005-09-01

    The X-ray free-electron laser XFEL that is being planned at the DESY research center in cooperation with European partners will produce high-intensity ultra-short X-ray flashes with the properties of laser light. This new light source, which can only be described in terms of superlatives, will open up a whole range of new perspectives for the natural sciences. It could also offer very promising opportunities for industrial users. SIMCON (SIMulator and CONtroller) is the project of the fast, low latency digital controller dedicated for LLRF 1 system in VUV FEL experiment It is being developed by ELHEP 2 group in Institute of Electronic Systems at Warsaw University of Technology. The main purpose of the project is to create a controller for stabilizing the vector sum of fields in cavities of one cryo module in the experiment. The device can be also used as the simulator of the cavity and test bench for other devices. Ths paper describes the concept, implementation and tests of the DOOCS based control system for SIMCON. The designed system is based the concept of autonomic and extendable modules connected by well defined, unified interfaces. The communication module controls the access to the hardware. It is crucial, that all modules (this presented in thesis and developed in the future) use this interface. Direct access to the control tables let the engineers to perform algorithm development or diagnostic measurements of the LLRF system. Default control tables generator makes the whole SIMCON an autonomic device, which can start immediately the operation without any additional tools. (orig.)

  9. DOOCS based control system for FPGA based cavity simulator and controller in VUV FEL

    Energy Technology Data Exchange (ETDEWEB)

    Pucyk, P.D.

    2006-03-15

    The X-ray free-electron laser XFEL that is being planned at the DESY research center in cooperation with European partners will produce high-intensity ultra-short X-ray flashes with the properties of laser light. This new light source, which can only be described in terms of superlatives, will open up a whole range of new perspectives for the natural sciences. It could also offer very promising opportunities for industrial users. SIMCON (SIMulator and CONtroller) is the project of the fast, low latency digital controller dedicated for LLRF 1 system in VUV FEL experiment It is being developed by ELHEP 2 group in Institute of Electronic Systems at Warsaw University of Technology. The main purpose of the project is to create a controller for stabilizing the vector sum of fields in cavities of one cryo module in the experiment. The device can be also used as the simulator of the cavity and test bench for other devices. This paper describes the concept, implementation and tests of the DOOCS based control system for SIMCON. The designed system is based the concept of autonomic and extendable modules connected by well defined, unified interfaces. The communication module controls the access to the hardware. It is crucial, that all modules (this presented in thesis and developed in the future) use this interface. Direct access to the control tables let the engineers to perform algorithm development or diagnostic measurements of the LLRF system. Default control tables generator makes the whole SIMCON an autonomic device, which can start immediately the operation without any additional tools. (Orig.)

  10. Synchronous optical transmission data link integrated with FPGA for TESLA FEL SIMCON system: long data vector optical transceiver module tests

    Science.gov (United States)

    Zielinski, Jerzy S.; Pozniak, Krzysztof T.; Romaniuk, Ryszard S.

    2006-10-01

    The X-ray free-electron laser X-FEL that is being planned at the DESY research center in cooperation with European partners will produce high-intensity ultra-short X-ray flashes with the properties of laser light. This new light source, which can only be described in terms of superlatives, will open up a whole range of new possibilities for the natural sciences. It could also offer very promising opportunities for industrial users. SIMCON (SIMulator and CONtroller) is the project of the fast, low latency digital controller dedicated to the LLRF system in VUV FEL experiment. The main purpose of the project is to create a controller to stabilize the vector sum of fields in cavities of one cryo-module in the experiment. The device can be also used as the simulator of the cavity and test bench for other devices. The synchronic, optical link project was made for the accelerator X-FEL laser TESLA, the LLRF control system experiment at DESY, Hamburg. The control and diagnostic data is transmitted up to 2.5Gbit/s through a plastic fiber in a distance up to a few hundred meters. The link is synchronized once after power up, and never resynchronized when data is transmitted with maximum speed. The one way link bit error rate is less then 10 -15. The transceiver component written in VHDL that works in the dedicated Altera® Stratix® GX FPGA circuit. During the work in the PERG laboratory a 2.5Gbit/s serial link with the long vector parallel interface transceiver was created. Long-Data-Vector transceiver transmits 16bit vector each 8ns with 120ns latency.

  11. Coherent orthogonal polynomials

    International Nuclear Information System (INIS)

    Celeghini, E.; Olmo, M.A. del

    2013-01-01

    We discuss a fundamental characteristic of orthogonal polynomials, like the existence of a Lie algebra behind them, which can be added to their other relevant aspects. At the basis of the complete framework for orthogonal polynomials we include thus–in addition to differential equations, recurrence relations, Hilbert spaces and square integrable functions–Lie algebra theory. We start here from the square integrable functions on the open connected subset of the real line whose bases are related to orthogonal polynomials. All these one-dimensional continuous spaces allow, besides the standard uncountable basis (|x〉), for an alternative countable basis (|n〉). The matrix elements that relate these two bases are essentially the orthogonal polynomials: Hermite polynomials for the line and Laguerre and Legendre polynomials for the half-line and the line interval, respectively. Differential recurrence relations of orthogonal polynomials allow us to realize that they determine an infinite-dimensional irreducible representation of a non-compact Lie algebra, whose second order Casimir C gives rise to the second order differential equation that defines the corresponding family of orthogonal polynomials. Thus, the Weyl–Heisenberg algebra h(1) with C=0 for Hermite polynomials and su(1,1) with C=−1/4 for Laguerre and Legendre polynomials are obtained. Starting from the orthogonal polynomials the Lie algebra is extended both to the whole space of the L 2 functions and to the corresponding Universal Enveloping Algebra and transformation group. Generalized coherent states from each vector in the space L 2 and, in particular, generalized coherent polynomials are thus obtained. -- Highlights: •Fundamental characteristic of orthogonal polynomials (OP): existence of a Lie algebra. •Differential recurrence relations of OP determine a unitary representation of a non-compact Lie group. •2nd order Casimir originates a 2nd order differential equation that defines the

  12. Volitional Control of Neuromagnetic Coherence

    Directory of Open Access Journals (Sweden)

    Matthew D Sacchet

    2012-12-01

    Full Text Available Coherence of neural activity between circumscribed brain regions has been implicated as an indicator of intracerebral communication in various cognitive processes. While neural activity can be volitionally controlled with neurofeedback, the volitional control of coherence has not yet been explored. Learned volitional control of coherence could elucidate mechanisms of associations between cortical areas and its cognitive correlates and may have clinical implications. Neural coherence may also provide a signal for brain-computer interfaces (BCI. In the present study we used the Weighted Overlapping Segment Averaging (WOSA method to assess coherence between bilateral magnetoencephalograph (MEG sensors during voluntary digit movement as a basis for BCI control. Participants controlled an onscreen cursor, with a success rate of 124 of 180 (68.9%, sign-test p < 0.001 and 84 out of 100 (84%, sign-test p < 0.001. The present findings suggest that neural coherence may be volitionally controlled and may have specific behavioral correlates.

  13. Partially coherent isodiffracting pulsed beams

    Science.gov (United States)

    Koivurova, Matias; Ding, Chaoliang; Turunen, Jari; Pan, Liuzhan

    2018-02-01

    We investigate a class of isodiffracting pulsed beams, which are superpositions of transverse modes supported by spherical-mirror laser resonators. By employing modal weights that, for stationary light, produce a Gaussian Schell-model beam, we extend this standard model to pulsed beams. We first construct the two-frequency cross-spectral density function that characterizes the spatial coherence in the space-frequency domain. By assuming a power-exponential spectral profile, we then employ the generalized Wiener-Khintchine theorem for nonstationary light to derive the two-time mutual coherence function that describes the space-time coherence of the ensuing beams. The isodiffracting nature of the laser resonator modes permits all (paraxial-domain) calculations at any propagation distance to be performed analytically. Significant spatiotemporal coupling is revealed in subcycle, single-cycle, and few-cycle domains, where the partial spatial coherence also leads to reduced temporal coherence even though full spectral coherence is assumed.

  14. Initial observations of high-charge, low-emittance electron beams at HIBAF (High Brightness Accelerator FEL)

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H.; Feldman, R.B.; Carsten, B.E.; Feldman, D.W.; Sheffield, R.L.; Stein, W.E.; Johnson, W.J.; Thode, L.E.; Bender, S.C.; Busch, G.E.

    1990-01-01

    We report our initial measurements of bright (high-charge, low-emittance) electron beams generated at the Los Alamos High Brightness Accelerator FEL (HIBAF) Facility. Normalized emittance values of less than 50 {pi} mm-mrad for charges ranging from 0.7 to 8.7 nC were obtained for single micropulses at a y-waist and at an energy of 14.7 MeV. These measurements were part of the commissioning campaign on the HIBAF photoelectric injector. Macropulse measurements have also been performed and are compared with PARMELA simulations. 5 refs., 8 figs., 3 tabs.

  15. Planar undulator motion excited by a fixed traveling wave. Quasiperiodic averaging normal forms and the FEL pendulum

    Energy Technology Data Exchange (ETDEWEB)

    Ellison, James A.; Heinemann, Klaus [New Mexico Univ., Albuquerque, NM (United States). Dept. of Mathematics and Statistics; Vogt, Mathias [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Gooden, Matthew [North Carolina State Univ., Raleigh, NC (United States). Dept. of Physics

    2013-03-15

    We present a mathematical analysis of planar motion of energetic electrons moving through a planar dipole undulator, excited by a fixed planar polarized plane wave Maxwell field in the X-Ray FEL regime. Our starting point is the 6D Lorentz system, which allows planar motions, and we examine this dynamical system as the wave length {lambda} of the traveling wave varies. By scalings and transformations the 6D system is reduced, without approximation, to a 2D system in a form for a rigorous asymptotic analysis using the Method of Averaging (MoA), a long time perturbation theory. The two dependent variables are a scaled energy deviation and a generalization of the so- called ponderomotive phase. As {lambda} varies the system passes through resonant and nonresonant (NR) zones and we develop NR and near-to-resonant (NtoR) MoA normal form approximations. The NtoR normal forms contain a parameter which measures the distance from a resonance. For a special initial condition, for the planar motion and on resonance, the NtoR normal form reduces to the well known FEL pendulum system. We then state and prove NR and NtoR first-order averaging theorems which give explicit error bounds for the normal form approximations. We prove the theorems in great detail, giving the interested reader a tutorial on mathematically rigorous perturbation theory in a context where the proofs are easily understood. The proofs are novel in that they do not use a near identity transformation and they use a system of differential inequalities. The NR case is an example of quasiperiodic averaging where the small divisor problem enters in the simplest possible way. To our knowledge the planar prob- lem has not been analyzed with the generality we aspire to here nor has the standard FEL pendulum system been derived with associated error bounds as we do here. We briefly discuss the low gain theory in light of our NtoR normal form. Our mathematical treatment of the noncollective FEL beam dynamics problem in

  16. Diffraction coherence in optics

    CERN Document Server

    Françon, M; Green, L L

    2013-01-01

    Diffraction: Coherence in Optics presents a detailed account of the course on Fraunhofer diffraction phenomena, studied at the Faculty of Science in Paris. The publication first elaborates on Huygens' principle and diffraction phenomena for a monochromatic point source and diffraction by an aperture of simple form. Discussions focus on diffraction at infinity and at a finite distance, simplified expressions for the field, calculation of the path difference, diffraction by a rectangular aperture, narrow slit, and circular aperture, and distribution of luminous flux in the airy spot. The book th

  17. Coherent dynamics in semiconductors

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher

    1998-01-01

    Ultrafast nonlinear optical spectroscopy is used to study the coherent dynamics of optically excited electron-hole pairs in semiconductors. Coulomb interaction implies that the optical inter-band transitions are dominated, at least at low temperatures, by excitonic effects. They are further...... and molecular systems are found and studied in the exciton-biexciton system of semiconductors. At densities where strong exciton interactions, or many-body effects, become dominant, the semiconductor Bloch equations present a more rigorous treatment of the phenomena Ultrafast degenerate four-wave mixing is used...

  18. Optical coherence refractometry.

    Science.gov (United States)

    Tomlins, Peter H; Woolliams, Peter; Hart, Christian; Beaumont, Andrew; Tedaldi, Matthew

    2008-10-01

    We introduce a novel approach to refractometry using a low coherence interferometer at multiple angles of incidence. We show that for plane parallel samples it is possible to measure their phase refractive index rather than the group index that is usually measured by interferometric methods. This is a significant development because it enables bulk refractive index measurement of scattering and soft samples, not relying on surface measurements that can be prone to error. Our technique is also noncontact and compatible with in situ refractive index measurements. Here, we demonstrate this new technique on a pure silica test piece and a highly scattering resin slab, comparing the results with standard critical angle refractometry.

  19. Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Fercher, A.F.; Andersen, Peter E.

    2017-01-01

    Optical coherence tomography (OCT) is a technique that is used to peer inside a body noninvasively. Tissue structure defined by tissue absorption and scattering coefficients, and the speed of blood flow, are derived from the characteristics of light remitted by the body. Singly backscattered light...... technique can be realized by using ultrafast wavelength scanning light sources. For tissue imaging, the light source wavelengths are restricted to the red and near-infrared (NIR) region from about 600 to 1300 nm, the so-called therapeutic window, where absorption (μa ≈ 0.01 mm−1) is small enough. Transverse...

  20. Coherence generalises duality

    DEFF Research Database (Denmark)

    Carbone, Marco; Lindley, Sam; Montesi, Fabrizio

    2016-01-01

    Wadler introduced Classical Processes (CP), a calculus based on a propositions-as-types correspondence between propositions of classical linear logic and session types. Carbone et al. introduced Multiparty Classical Processes, a calculus that generalises CP to multiparty session types, by replacing...... the duality of classical linear logic (relating two types) with a more general notion of coherence (relating an arbitrary number of types). This paper introduces variants of CP and MCP, plus a new intermediate calculus of Globally-governed Classical Processes (GCP). We show a tight relation between...

  1. Development and calibration of mirrors and gratings for the soft x-ray materials science beamline at the Linac Coherent Light Source free-electron laser.

    Science.gov (United States)

    Soufli, Regina; Fernández-Perea, Mónica; Baker, Sherry L; Robinson, Jeff C; Gullikson, Eric M; Heimann, Philip; Yashchuk, Valeriy V; McKinney, Wayne R; Schlotter, William F; Rowen, Michael

    2012-04-20

    This work discusses the development and calibration of the x-ray reflective and diffractive elements for the Soft X-ray Materials Science (SXR) beamline of the Linac Coherent Light Source (LCLS) free-electron laser (FEL), designed for operation in the 500 to 2000 eV region. The surface topography of three Si mirror substrates and two Si diffraction grating substrates was examined by atomic force microscopy (AFM) and optical profilometry. The figure of the mirror substrates was also verified via surface slope measurements with a long trace profiler. A boron carbide (B4C) coating especially optimized for the LCLS FEL conditions was deposited on all SXR mirrors and gratings. Coating thickness uniformity of 0.14 nm root mean square (rms) across clear apertures extending to 205 mm length was demonstrated for all elements, as required to preserve the coherent wavefront of the LCLS source. The reflective performance of the mirrors and the diffraction efficiency of the gratings were calibrated at beamline 6.3.2 at the Advanced Light Source synchrotron. To verify the integrity of the nanometer-scale grating structure, the grating topography was examined by AFM before and after coating. This is to our knowledge the first time B4C-coated diffraction gratings are demonstrated for operation in the soft x-ray region.

  2. Coherent states and rational surfaces

    International Nuclear Information System (INIS)

    Brody, Dorje C; Graefe, Eva-Maria

    2010-01-01

    The state spaces of generalized coherent states associated with special unitary groups are shown to form rational curves and surfaces in the space of pure states. These curves and surfaces are generated by the various Veronese embeddings of the underlying state space into higher dimensional state spaces. This construction is applied to the parameterization of generalized coherent states, which is useful for practical calculations, and provides an elementary combinatorial approach to the geometry of the coherent state space. The results are extended to Hilbert spaces with indefinite inner products, leading to the introduction of a new kind of generalized coherent states.

  3. Coherent states and rational surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Brody, Dorje C; Graefe, Eva-Maria, E-mail: d.brody@imperial.ac.u [Department of Mathematics, Imperial College London, London SW7 2AZ (United Kingdom)

    2010-06-25

    The state spaces of generalized coherent states associated with special unitary groups are shown to form rational curves and surfaces in the space of pure states. These curves and surfaces are generated by the various Veronese embeddings of the underlying state space into higher dimensional state spaces. This construction is applied to the parameterization of generalized coherent states, which is useful for practical calculations, and provides an elementary combinatorial approach to the geometry of the coherent state space. The results are extended to Hilbert spaces with indefinite inner products, leading to the introduction of a new kind of generalized coherent states.

  4. Regulatory risk coherence

    International Nuclear Information System (INIS)

    Remick, F.J.

    1992-01-01

    As one of the most progressive users of risk assessment in decision making, the US Nuclear Regulatory Commission (NRC) is in a position to play an important role in influencing the development of standard government wide policies for the application of risk assessment in decision making. The NRC, with the support of the nuclear industry, should use the opportunity provided by its experience with risk assessment to actively encourage the adoption of standard national and international health-based safety goals and at the same time accelerate its own efforts to implement the safety goals it has already developed for itself. There are signs of increased recognition of the need for consistency and coherence in the application of risk assessment in government decision making. The NRC and the nuclear industry have recently taken a great step toward establishing a consistant and coherent risk assessment-based culture in the US nuclear industry. As a result of Generic Letter 88-20, which asks each commercial nuclear power plant licensee to perform an individual plant examination by September 1992, for the first time a risk assessment characterizing initiating events in each plant will exist

  5. Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Mogensen, Mette; Themstrup, Lotte; Banzhaf, Christina

    2014-01-01

    Optical coherence tomography (OCT) has developed rapidly since its first realisation in medicine and is currently an emerging technology in the diagnosis of skin disease. OCT is an interferometric technique that detects reflected and backscattered light from tissue and is often described as the o......Optical coherence tomography (OCT) has developed rapidly since its first realisation in medicine and is currently an emerging technology in the diagnosis of skin disease. OCT is an interferometric technique that detects reflected and backscattered light from tissue and is often described...... as the optical analogue to ultrasound. The inherent safety of the technology allows for in vivo use of OCT in patients. The main strength of OCT is the depth resolution. In dermatology, most OCT research has turned on non-melanoma skin cancer (NMSC) and non-invasive monitoring of morphological changes...... in a number of skin diseases based on pattern recognition, and studies have found good agreement between OCT images and histopathological architecture. OCT has shown high accuracy in distinguishing lesions from normal skin, which is of great importance in identifying tumour borders or residual neoplastic...

  6. Fermionic coherent states

    Science.gov (United States)

    Combescure, Monique; Robert, Didier

    2012-06-01

    The aim of this paper is to give a self-contained and unified presentation of a fermionic coherent state theory with the necessary mathematical details, discussing their definition, properties and some applications. After defining Grassmann algebras, it is possible to get a classical analog for the fermionic degrees of freedom in a quantum system. Following the basic work of Berezin (1966 The Method of Second Quantization (New York: Academic); 1987 Introduction to Superanalysis (Dordrecht: Reidel Publishing Company)), we show that we can compute with Grassmann numbers as we do with complex numbers: derivation, integration, Fourier transform. After that we show that we have quantization formulas for fermionic observables. In particular, there exists a Moyal product formula. As an application, we consider explicit computations for propagators with quadratic Hamiltonians in annihilation and creation operators. We prove a Mehler formula for the propagator and Mehlig-Wilkinson-type formulas for the covariant and contravariant symbols of ‘metaplectic’ transformations for fermionic states. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Coherent states: mathematical and physical aspects’.

  7. Preliminary evaluation of 1′-[18F]fluoroethyl-β-D-lactose ([18F]FEL) for detection of pancreatic cancer in nude mouse orthotopic xenografts

    International Nuclear Information System (INIS)

    Arumugam, Thiruvengadam; Paolillo, Vincenzo; Young, Daniel; Wen, XiaoXia; Logsdon, Craig D.; De Palatis, Louis; Alauddin, Mian M.

    2014-01-01

    Introduction: Early detection of pancreatic cancer could save many thousands of lives. Non-invasive diagnostic imaging, including PET with [ 18 F]FDG, has inadequate resolution for detection of small (2–3 mm) pancreatic tumours. We demonstrated the efficacy of PET imaging with an 18 F-labelled lactose derivative, [ 18 F]FEDL, that targets HIP/PAP, a biomarker that is overexpressed in the peritumoural pancreas. We developed another analogue, 1-[ 18 F]fluoroethyl lactose ([ 18 F]FEL), which is simpler to synthesise, for the same application. We conducted a preliminary evaluation of the new probe and its efficacy in detecting orthotopic pancreatic carcinoma xenografts in mice. Methods: Xenografts were developed in nude mice by injecting L3.6pl/GL + pancreatic carcinoma cells into the pancreas of each mouse. Tumour growth was monitored by bioluminescence imaging (BLI); accuracy of BLI tumour size estimates was verified by MRI in two representative mice. When the tumour size reached approximately 2–3 mm, the animals were injected with [ 18 F]FEL (3.7 MBq) and underwent static PET/CT scans. Blood samples were collected at 2, 5, 10, 20 and 60 min after [ 18 F]FEL injection to track blood clearance. Following imaging, animals were sacrificed and their organs and tumours/pancreatic tissue were collected and counted on a gamma counter. Pancreas, including tumour, was frozen, sliced and used for autoradiography and immunohistochemical analysis of HIP/PAP expression. Results: Tumour growth was rapid, as observed by BLI and MRI. Blood clearance of [ 18 F]FEL was bi-exponential, with half-lives of approximately 3.5 min and 40 min. Mean accumulation of [ 18 F]FEL in the peritumoural pancreatic tissue was 1.29 ± 0.295 %ID/g, and that in the normal pancreas of control animals was 0.090 ± 0.101 %ID/g. [ 18 F]FEL was cleared predominantly by the kidneys. Comparative analysis of autoradiographic images and immunostaining results demonstrated a correlation between [ 18 F]FEL

  8. Concept of a staged FEL enabled by fast synchrotron radiation cooling of laser-plasma accelerated beam by solenoidal magnetic fields in plasma bubble

    Science.gov (United States)

    Seryi, Andrei; Lesz, Zsolt; Andreev, Alexander; Konoplev, Ivan

    2017-03-01

    A novel method for generating GigaGauss solenoidal fields in a laser-plasma bubble, using screw-shaped laser pulses, has been recently presented. Such magnetic fields enable fast synchrotron radiation cooling of the beam emittance of laser-plasma accelerated leptons. This recent finding opens a novel approach for design of laser-plasma FELs or colliders, where the acceleration stages are interleaved with laser-plasma emittance cooling stages. In this concept paper, we present an outline of what a staged plasma-acceleration FEL could look like, and discuss further studies needed to investigate the feasibility of the concept in detail.

  9. Preliminary evaluation of 1'-[(18)F]fluoroethyl-β-D-lactose ([(18)F]FEL) for detection of pancreatic cancer in nude mouse orthotopic xenografts.

    Science.gov (United States)

    Arumugam, Thiruvengadam; Paolillo, Vincenzo; Young, Daniel; Wen, XiaoXia; Logsdon, Craig D; De Palatis, Louis; Alauddin, Mian M

    2014-01-01

    Early detection of pancreatic cancer could save many thousands of lives. Non-invasive diagnostic imaging, including PET with [(18)F]FDG, has inadequate resolution for detection of small (2-3 mm) pancreatic tumours. We demonstrated the efficacy of PET imaging with an (18)F-labelled lactose derivative, [(18)F]FEDL, that targets HIP/PAP, a biomarker that is overexpressed in the peritumoural pancreas. We developed another analogue, 1-[(18)F]fluoroethyl lactose ([(18)F]FEL), which is simpler to synthesise, for the same application. We conducted a preliminary evaluation of the new probe and its efficacy in detecting orthotopic pancreatic carcinoma xenografts in mice. Xenografts were developed in nude mice by injecting L3.6 pl/GL(+) pancreatic carcinoma cells into the pancreas of each mouse. Tumour growth was monitored by bioluminescence imaging (BLI); accuracy of BLI tumour size estimates was verified by MRI in two representative mice. When the tumour size reached approximately 2-3mm, the animals were injected with [(18)F]FEL (3.7 MBq) and underwent static PET/CT scans. Blood samples were collected at 2, 5, 10, 20 and 60 min after [(18)F]FEL injection to track blood clearance. Following imaging, animals were sacrificed and their organs and tumours/pancreatic tissue were collected and counted on a gamma counter. Pancreas, including tumour, was frozen, sliced and used for autoradiography and immunohistochemical analysis of HIP/PAP expression. Tumour growth was rapid, as observed by BLI and MRI. Blood clearance of [(18)F]FEL was bi-exponential, with half-lives of approximately 3.5 min and 40 min. Mean accumulation of [(18)F]FEL in the peritumoural pancreatic tissue was 1.29±0.295 %ID/g, and that in the normal pancreas of control animals was 0.090±0.101 %ID/g. [(18)F]FEL was cleared predominantly by the kidneys. Comparative analysis of autoradiographic images and immunostaining results demonstrated a correlation between [(18)F]FEL binding and HIP/PAP expression. [(18)F]FEL

  10. Production of Terahertz Seed Radiation for FEL/IFEL Microbunchers for Second Generation Plasma Beatwave Experiments at Neptune

    CERN Document Server

    Ralph, Joseph; Rosenzweig, James E; Sung, Chieh; Tochitsky, Sergei Ya

    2005-01-01

    To achieve phase locked injection of short electron bunches in a plasma beatwave accelerator, the Neptune Laboratory will utilize microbunching in an FEL or IFEL system. These systems require terahertz (THz) seed radiation on the order of 10 kW for the FEL and 10 MW for the IFEL bunchers. We report results of experiments on THz generation using nonlinear frequency mixing of CO2 laser lines in GaAs. A two-wavelength laser beam was split and sent onto a 2.5 cm long GaAs crystal cut for noncollinear phase matching. Low power measurements achieved ~1 W of 340 ?m radiation using 200 ns CO2 pump pulses with wavelengths 10.3?m and 10.6?m. We also demonstrated tunability of difference frequency radiation, producing 240?m by mixing two different CO2 laser lines. By going to shorter laser pulses and higher intensities, we were able to increase the conversion efficiency while decreasing the surface damage threshold. Using 200ps pulses we produced ~2 MW of 340 ?m radiation. Future studies in this area will focus on devel...

  11. Felípica, capital de la monarquia (propuestas de Pérez de Herrera para Madrid

    Directory of Open Access Journals (Sweden)

    Dolores González de la Fuente

    2002-01-01

    Full Text Available En una época de crisis donde se tambalea la hegemonía de la monarquía hispánica, Chstóbal Pérez de Herrera propone un ambicioso proyecto encaminado a sanear la soüedad cuya imagen visible será su capital, un nuevo Madrid renovado hasta en su denominación, Felípica, la corte de los Austrias españoles, en la que arquitectura y urbanismo puestos al servicio del poder político crearán el marco ideal donde se desarrolle la vida cortesana.In a period of cnsis in which the hegemony of the monarchy is in danger. Cristóbal Pérez de Herrera suggests an ambitions project designed to insure a society whose visible image will be its capital: a new and reorganized Madrid, renewed even In its ñame «Felípica», it will be the court of the Spanish Austrias, where architecture and urban development are at the disposal of the political authorities to créate the ideal framework where the Ufe of the Court will develop.

  12. Novel active signal compression in low-noise analog readout at future X-ray FEL facilities

    Science.gov (United States)

    Manghisoni, M.; Comotti, D.; Gaioni, L.; Lodola, L.; Ratti, L.; Re, V.; Traversi, G.; Vacchi, C.

    2015-04-01

    This work presents the design of a low-noise front-end implementing a novel active signal compression technique. This feature can be exploited in the design of analog readout channels for application to the next generation free electron laser (FEL) experiments. The readout architecture includes the low-noise charge sensitive amplifier (CSA) with dynamic signal compression, a time variant shaper used to process the signal at the preamplifier output and a 10-bit successive approximation register (SAR) analog-to-digital converter (ADC). The channel will be operated in such a way to cope with the high frame rate (exceeding 1 MHz) foreseen for future XFEL machines. The choice of a 65 nm CMOS technology has been made in order to include all the building blocks in the target pixel pitch of 100 μm. This work has been carried out in the frame of the PixFEL Project funded by the Istituto Nazionale di Fisica Nucleare (INFN), Italy.

  13. Coatings for FEL optics: preparation and characterization of B4C and Pt.

    Science.gov (United States)

    Störmer, Michael; Siewert, Frank; Horstmann, Christian; Buchheim, Jana; Gwalt, Grzegorz

    2018-01-01

    Large X-ray mirrors are required for beam transport at both present-day and future free-electron lasers (FELs) and synchrotron sources worldwide. The demand for large mirrors with lengths up to 1 m single layers consisting of light or heavy elements has increased during the last few decades. Accordingly, surface finishing technology is now able to produce large substrate lengths with micro-roughness on the sub-nanometer scale. At the Helmholtz-Zentrum Geesthacht (HZG), a 4.5 m-long sputtering facility enables us to deposit a desired single-layer material some tens of nanometers thick. For the European XFEL project, the shape error should be less than 2 nm over the whole 1 m X-ray mirror length to ensure the safe and efficient delivery of X-ray beams to the scientific instruments. The challenge is to achieve thin-film deposition on silicon substrates, benders and gratings without any change in mirror shape. Thin films of boron carbide and platinum with a thickness in the range 30-100 nm were manufactured using the HZG sputtering facility. This setup is able to cover areas of up to 1500 mm × 120 mm in one step using rectangular sputtering sources. The coatings produced were characterized using various thin-film methods. It was possible to improve the coating process to achieve a very high uniformity of the layer thickness. The movement of the substrate in front of the sputtering source has been optimized. A variation in B 4 C layer thickness below 1 nm (peak-to-valley) was achieved at a mean thickness of 51.8 nm over a deposition length of 1.5 m. In the case of Pt, reflectometry and micro-roughness measurements were performed. The uniformity in layer thickness was about 1 nm (peak-to-valley). The micro-roughness of the Pt layers showed no significant change in the coated state for layer thicknesses of 32 nm and 102 nm compared with the uncoated substrate state. The experimental results achieved will be discussed with regard to current

  14. Geometry of spin coherent states

    Science.gov (United States)

    Chryssomalakos, C.; Guzmán-González, E.; Serrano-Ensástiga, E.

    2018-04-01

    Spin states of maximal projection along some direction in space are called (spin) coherent, and are, in many respects, the ‘most classical’ available. For any spin s, the spin coherent states form a 2-sphere in the projective Hilbert space \

  15. The Puzzle of Coherence

    DEFF Research Database (Denmark)

    Andersen, Anne Bendix; Frederiksen, Kirsten; Beedholm, Kirsten

    2016-01-01

    During the past decade, politicians and health care providers have strived to create a coherent health care system across primary and secondary health care systems in Denmark. Nevertheless, elderly patients with chronic diseases (EPCD) continue to report experiences of poor-quality care and lack....... Method and material We use an ethnographic method and apply field observation for data collection. 10 patients older than 65 years with multiple chronic diseases are followed through their patient pathways from admission to an acute care ward to discharge and later in meetings with health care providers...... both nationally and internationally in preparation of health agreements, implementation of new collaboration forms among health care providers, and in improvement of delegation and transfer of information and assignments across sectors in health care....

  16. Coherence and correspondence in medicine

    Directory of Open Access Journals (Sweden)

    Thomas G. Tape

    2009-03-01

    Full Text Available Many controversies in medical science can be framed as tension between a coherence approach (which seeks logic and explanation and a correspondence approach (which emphasizes empirical correctness. In many instances, a coherence-based theory leads to an understanding of disease that is not supported by empirical evidence. Physicians and patients alike tend to favor the coherence approach even in the face of strong, contradictory correspondence evidence. Examples include the management of atrial fibrillation, treatment of acute bronchitis, and the use of Vitamin E to prevent heart disease. Despite the frequent occurrence of controversy stemming from coherence-correspondence conflicts, medical professionals are generally unaware of these terms and the philosophical traditions that underlie them. Learning about the coherence-correspondence distinction and using the best of both approaches could not only help reconcile controversy but also lead to striking advances in medical science.

  17. Observation of high-power coherent synchrotron radiation in the THz region from the JAEA energy recovery linac

    International Nuclear Information System (INIS)

    Takahashi, Toshiharu; Okuda, Shuichi; Minehara, Eisuke J.; Hajima, Ryoichi; Sawamura, Masaru; Nagai, Ryoji; Kikuzawa, Nobihiro; Iijima, Hokuto; Nishitani, Tomohiro; Nishimori, Nobuyuki

    2007-01-01

    The energy recovery linac (ERL) is able to generate high-power coherent synchrotron radiation (CSR) in the terahertz and the millimeter-wave regions, because it produces shorter bunches than usual storage rings and a higher current than conventional linacs. The spectrum of CSR has been measured at the JAEA-ERL in the wavenumber range from 0.5 to 15 cm -1 . The detected power was 2x10 -4 W/cm -1 at 2.5 cm -1 for the average beam current of 17.7 μA. When the infrared FEL was operated with the undulator in the ERL, the CSR spectrum was shifted to the longer wavelengths because of the energy broadening of the electron beam. (author)

  18. The 18-kDa form of cat allergen Felis domesticus 1 (Fel d 1) is associated with gelatin- and fibronectin-degrading activity

    DEFF Research Database (Denmark)

    Ring, P C; Wan, H; Schou, C

    2000-01-01

    BACKGROUND: Fel d 1, an important allergen from domestic cats, is a significant cause of asthma. In addition to directly promoting IgE synthesis, other biological activities of allergens may contribute to either allergic sensitization or the magnitude of allergic effector responses. For example...

  19. Rotational coherence spectroscopy at FLASH. Toward dynamic studies in nanosuperfluids

    Energy Technology Data Exchange (ETDEWEB)

    Kickermann, Andreas

    2013-07-15

    The field of molecular physics, which is focusing on molecular motion in the transition states of physical, chemical, and biological changes, is a wide-spread research area. It strives to reveal the structural and functional properties of molecules, the chemical bonds between atoms and the time evolution. Many processes occurring in nature upon electronic excitation proceed on the ultrafast femtosecond timescale and can be triggered by modern ultrashort femtosecond-laser sources under laboratory conditions. In the present thesis pump-probe studies were performed to follow molecular motion using ultrashort light pulses in the nanometer wavelength range provided by an XUV freeelectron laser (FEL). In detail, alignment of molecular species in space under field-free conditions was investigated. In the specific case of rotational wave packets in molecules the rotational dynamics shows characteristic temporal features, which contain a wealth of information on molecular structure and give insight into molecular coupling mechanisms, i.e. rotational constants and transition frequencies. Within this thesis, Rotational Coherence Spectroscopy (RCS) reveals wave-packet motion observed by subsequent Coulomb explosion of Raman excited carbon monoxide, which results in a time-dependent asymmetry of spatial fragmentation patterns. With the method presented here, the time resolution to elucidate the fast dynamics of strong couplings can be pushed toward a single rotational period even for the fastest rotors. This is due to large pump-probe delays with small subpicosecond step size. This kind of spectroscopy can also be expanded to molecular species, which are not accessible by other powerful spectroscopic methods, such as Fourier-transform microwave spectroscopy (FTMW). Furthermore, it allows to measure weak molecular couplings on a long timescale (large pump-probe delays), e.g. couplings of molecules in a solution or molecules dissolved in quantum fluids. This is valuable to

  20. Rotational coherence spectroscopy at FLASH. Toward dynamic studies in nanosuperfluids

    International Nuclear Information System (INIS)

    Kickermann, Andreas

    2013-07-01

    The field of molecular physics, which is focusing on molecular motion in the transition states of physical, chemical, and biological changes, is a wide-spread research area. It strives to reveal the structural and functional properties of molecules, the chemical bonds between atoms and the time evolution. Many processes occurring in nature upon electronic excitation proceed on the ultrafast femtosecond timescale and can be triggered by modern ultrashort femtosecond-laser sources under laboratory conditions. In the present thesis pump-probe studies were performed to follow molecular motion using ultrashort light pulses in the nanometer wavelength range provided by an XUV freeelectron laser (FEL). In detail, alignment of molecular species in space under field-free conditions was investigated. In the specific case of rotational wave packets in molecules the rotational dynamics shows characteristic temporal features, which contain a wealth of information on molecular structure and give insight into molecular coupling mechanisms, i.e. rotational constants and transition frequencies. Within this thesis, Rotational Coherence Spectroscopy (RCS) reveals wave-packet motion observed by subsequent Coulomb explosion of Raman excited carbon monoxide, which results in a time-dependent asymmetry of spatial fragmentation patterns. With the method presented here, the time resolution to elucidate the fast dynamics of strong couplings can be pushed toward a single rotational period even for the fastest rotors. This is due to large pump-probe delays with small subpicosecond step size. This kind of spectroscopy can also be expanded to molecular species, which are not accessible by other powerful spectroscopic methods, such as Fourier-transform microwave spectroscopy (FTMW). Furthermore, it allows to measure weak molecular couplings on a long timescale (large pump-probe delays), e.g. couplings of molecules in a solution or molecules dissolved in quantum fluids. This is valuable to

  1. International workshop on phase retrieval and coherent scattering. Coherence 2005

    International Nuclear Information System (INIS)

    Nugent, K.A.; Fienup, J.R.; Van Dyck, D.; Van Aert, S.; Weitkamp, T.; Diaz, A.; Pfeiffer, F.; Cloetens, P.; Stampanoni, M.; Bunk, O.; David, C.; Bronnikov, A.V.; Shen, Q.; Xiao, X.; Gureyev, T.E.; Nesterets, Ya.I.; Paganin, D.M.; Wilkins, S.W.; Mokso, R.; Cloetens, P.; Ludwig, W.; Hignette, O.; Maire, E.; Faulkner, H.M.L.; Rodenburg, J.M.; Wu, X.; Liu, H.; Grubel, G.; Ludwig, K.F.; Livet, F.; Bley, F.; Simon, J.P.; Caudron, R.; Le Bolloc'h, D.; Moussaid, A.; Gutt, C.; Sprung, M.; Madsen, A.; Tolan, M.; Sinha, S.K.; Scheffold, F.; Schurtenberger, P.; Robert, A.; Madsen, A.; Falus, P.; Borthwick, M.A.; Mochrie, S.G.J.; Livet, F.; Sutton, M.D.; Ehrburger-Dolle, F.; Bley, F.; Geissler, E.; Sikharulidze, I.; Jeu, W.H. de; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Naryanan, S.; Sinha, S.K.; Lal, J.; Naryanan, S.; Sinha, S.K.; Lal, J.; Robinson, I.K.; Chapman, H.N.; Barty, A.; Beetz, T.; Cui, C.; Hajdu, J.; Hau-Riege, S.P.; He, H.; Stadler, L.M.; Sepiol, B.; Harder, R.; Robinson, I.K.; Zontone, F.; Vogl, G.; Howells, M.; London, R.; Marchesini, S.; Shapiro, D.; Spence, J.C.H.; Weierstall, U.; Eisebitt, S.; Shapiro, D.; Lima, E.; Elser, V.; Howells, M.R.; Huang, X.; Jacobsen, C.; Kirz, J.; Miao, H.; Neiman, A.; Sayre, D.; Thibault, P.; Vartanyants, I.A.; Robinson, I.K.; Onken, J.D.; Pfeifer, M.A.; Williams, G.J.; Pfeiffer, F.; Metzger, H.; Zhong, Z.; Bauer, G.; Nishino, Y.; Miao, J.; Kohmura, Y.; Yamamoto, M.; Takahashi, Y.; Koike, K.; Ebisuzaki, T.; Ishikawa, T.; Spence, J.C.H.; Doak, B.

    2005-01-01

    The contributions of the participants have been organized into 3 topics: 1) phase retrieval methods, 2) X-ray photon correlation spectroscopy, and 3) coherent diffraction imaging. This document gathers the abstracts of the presentations and of the posters

  2. International workshop on phase retrieval and coherent scattering. Coherence 2005

    Energy Technology Data Exchange (ETDEWEB)

    Nugent, K.A.; Fienup, J.R.; Van Dyck, D.; Van Aert, S.; Weitkamp, T.; Diaz, A.; Pfeiffer, F.; Cloetens, P.; Stampanoni, M.; Bunk, O.; David, C.; Bronnikov, A.V.; Shen, Q.; Xiao, X.; Gureyev, T.E.; Nesterets, Ya.I.; Paganin, D.M.; Wilkins, S.W.; Mokso, R.; Cloetens, P.; Ludwig, W.; Hignette, O.; Maire, E.; Faulkner, H.M.L.; Rodenburg, J.M.; Wu, X.; Liu, H.; Grubel, G.; Ludwig, K.F.; Livet, F.; Bley, F.; Simon, J.P.; Caudron, R.; Le Bolloc' h, D.; Moussaid, A.; Gutt, C.; Sprung, M.; Madsen, A.; Tolan, M.; Sinha, S.K.; Scheffold, F.; Schurtenberger, P.; Robert, A.; Madsen, A.; Falus, P.; Borthwick, M.A.; Mochrie, S.G.J.; Livet, F.; Sutton, M.D.; Ehrburger-Dolle, F.; Bley, F.; Geissler, E.; Sikharulidze, I.; Jeu, W.H. de; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Naryanan, S.; Sinha, S.K.; Lal, J.; Naryanan, S.; Sinha, S.K.; Lal, J.; Robinson, I.K.; Chapman, H.N.; Barty, A.; Beetz, T.; Cui, C.; Hajdu, J.; Hau-Riege, S.P.; He, H.; Stadler, L.M.; Sepiol, B.; Harder, R.; Robinson, I.K.; Zontone, F.; Vogl, G.; Howells, M.; London, R.; Marchesini, S.; Shapiro, D.; Spence, J.C.H.; Weierstall, U.; Eisebitt, S.; Shapiro, D.; Lima, E.; Elser, V.; Howells, M.R.; Huang, X.; Jacobsen, C.; Kirz, J.; Miao, H.; Neiman, A.; Sayre, D.; Thibault, P.; Vartanyants, I.A.; Robinson, I.K.; Onken, J.D.; Pfeifer, M.A.; Williams, G.J.; Pfeiffer, F.; Metzger, H.; Zhong, Z.; Bauer, G.; Nishino, Y.; Miao, J.; Kohmura, Y.; Yamamoto, M.; Takahashi, Y.; Koike, K.; Ebisuzaki, T.; Ishikawa, T.; Spence, J.C.H.; Doak, B

    2005-07-01

    The contributions of the participants have been organized into 3 topics: 1) phase retrieval methods, 2) X-ray photon correlation spectroscopy, and 3) coherent diffraction imaging. This document gathers the abstracts of the presentations and of the posters.

  3. Coherent control of quantum dots

    DEFF Research Database (Denmark)

    Johansen, Jeppe; Lodahl, Peter; Hvam, Jørn Märcher

    In recent years much effort has been devoted to the use of semiconductor quantum dotsystems as building blocks for solid-state-based quantum logic devices. One importantparameter for such devices is the coherence time, which determines the number ofpossible quantum operations. From earlier...... measurements the coherence time of the selfassembledquantum dots (QDs) has been reported to be limited by the spontaneousemission rate at cryogenic temperatures1.In this project we propose to alter the coherence time of QDs by taking advantage of arecent technique on modifying spontaneous emission rates...

  4. Perturbative coherence in field theory

    International Nuclear Information System (INIS)

    Aldrovandi, R.; Kraenkel, R.A.

    1987-01-01

    A general condition for coherent quantization by perturbative methods is given, because the basic field equations of a fild theory are not always derivable from a Lagrangian. It's seen that non-lagrangian models way have well defined vertices, provided they satisfy what they call the 'coherence condition', which is less stringent than the condition for the existence of a Lagrangian. They note that Lagrangian theories are perturbatively coherent, in the sense that they have well defined vertices, and that they satisfy automatically that condition. (G.D.F.) [pt

  5. Optimally cloned binary coherent states

    Science.gov (United States)

    Müller, C. R.; Leuchs, G.; Marquardt, Ch.; Andersen, U. L.

    2017-10-01

    Binary coherent state alphabets can be represented in a two-dimensional Hilbert space. We capitalize this formal connection between the otherwise distinct domains of qubits and continuous variable states to map binary phase-shift keyed coherent states onto the Bloch sphere and to derive their quantum-optimal clones. We analyze the Wigner function and the cumulants of the clones, and we conclude that optimal cloning of binary coherent states requires a nonlinearity above second order. We propose several practical and near-optimal cloning schemes and compare their cloning fidelity to the optimal cloner.

  6. Spin Coherence in Semiconductor Nanostructures

    National Research Council Canada - National Science Library

    Flatte, Michael E

    2006-01-01

    ... dots, tuning of spin coherence times for electron spin, tuning of dipolar magnetic fields for nuclear spin, spontaneous spin polarization generation and new designs for spin-based teleportation and spin transistors...

  7. A 700 MHZ, 1 MW CW RF System for a FEL 100mA RF Photoinjector

    CERN Document Server

    Roybal, William; Reass, William; Rees, Daniel; Tallerico, Paul J; Torrez, Phillip A

    2005-01-01

    This paper describes a 700 MHz, 1 Megawatt CW, high efficiency klystron RF system utilized for a Free Electron Laser (FEL) high-brightness electron photoinjector (PI). The E2V klystron is mod-anode tube that operates with a beam voltage of 95 kV. This tube, operating with a 65% efficiency, requires ~96 watts of input power to produce in excess of 1 MW of output power. This output drives the 3rd cell of a 2½-cell, p-mode PI cavity through a pair of planar waveguide windows. Coupling is via a ridge-loaded tapered waveguide section and "dog-bone" iris. This paper will present the design of the RF, RF transport, coupling, and monitoring/protection systems that are required to support CW operations of the 100 mA cesiated, semi-porous SiC photoinjector.

  8. Quantum coherence of relic neutrinos.

    Science.gov (United States)

    Fuller, George M; Kishimoto, Chad T

    2009-05-22

    We argue that in at least a portion of the history of the Universe the relic background neutrinos are spatially extended, coherent superpositions of mass states. We show that an appropriate quantum mechanical treatment affects the neutrino mass values derived from cosmological data. The coherence scale of these neutrino flavor wave packets can be an appreciable fraction of the causal horizon size, raising the possibility of spacetime curvature-induced decoherence.

  9. Coherence matrix of plasmonic beams

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Lavrinenko, Andrei

    2013-01-01

    We consider monochromatic electromagnetic beams of surface plasmon-polaritons created at interfaces between dielectric media and metals. We theoretically study non-coherent superpositions of elementary surface waves and discuss their spectral degree of polarization, Stokes parameters, and the for...... of the spectral coherence matrix. We compare the polarization properties of the surface plasmonspolaritons as three-dimensional and two-dimensional fields concluding that the latter is superior....

  10. Coherent states with elliptical polarization

    OpenAIRE

    Colavita, E.; Hacyan, S.

    2004-01-01

    Coherent states of the two dimensional harmonic oscillator are constructed as superpositions of energy and angular momentum eigenstates. It is shown that these states are Gaussian wave-packets moving along a classical trajectory, with a well defined elliptical polarization. They are coherent correlated states with respect to the usual cartesian position and momentum operators. A set of creation and annihilation operators is defined in polar coordinates, and it is shown that these same states ...

  11. Opportunities and challenges for photon diagnostics at the soft X-ray FEL FLASH in simultaneous operation mode (Conference Presentation)

    Science.gov (United States)

    Kuhlmann, Marion; Treusch, Rolf; Plönjes-Palm, Elke; Faatz, Bart; Tiedtke, Kai; Braune, Markus; Keitel, Barbara

    2017-06-01

    FLASH operates two distinguished undulator sections driven by one linear accelerator. In the 11th year of user operation the grown demands for detailed photon beam performances are doubled approached. The more complex machine settings and setup times require a more and more efficient determination of its characteristics concerning electron- and photon-beams. The photon diagnostics systems, e.g. gas monitor detection, photon-ion spectroscopy, or diffractive tools, not only have to deal on a regular basis with fundamental wavelengths between 4nm and 90nm, also they have to be reliable from 1µJ up to 1mJ of average single pulse energy. For the success of the experiments the error bars of many diagnostics measurements need to be pushed into their current limits and developments to go further are always issued. Especial, the pulse duration in conjunction with the spectral width has been accessed in the last year. Direct approaches of fundamental wavelengths below the Nitrogene K-edge and higher harmonics in and below the water window were achieved. While in principal distinguished to each other, the photon diagnostics tools of FLASH1 and FLASH2 add-up to a more complete understanding of the other. Together they allow for a better perspective towards further developments and a more suitable use of beam times. The intermingled knowledge of electron- and photon-beams is essential for an FEL particular in simultaneous operation mode. Examples out of regular user operation and distinguished FEL-studies are given to illustrate the current state of the photon diagnostics at FLASH.

  12. Transverse-emittance measurements on an S-band photocathode RF electron gun

    CERN Document Server

    Schmerge, J F; Clendenin, J E; Decker, Franz Josef; Dowell, D H; Gierman, S M; Limborg, C G; Murphy, B F

    2002-01-01

    Proposed fourth-generation light sources using SASE FELs to generate short pulse, coherent, X-rays require demonstration of high brightness electron sources. The gun test facility at SLAC was built to test high brightness sources for the proposed linac coherent light source at SLAC. The transverse-emittance measurements are made at nearly 30 MeV by measuring the spot size on a YAG screen using the quadrupole scan technique. The emittance was measured to vary from 1 to 3.5 mm mrad as the charge is increased from 50 to 350 pC using a laser pulse width of 2 ps FWHM. The measurements are in good agreement with simulation results using the LANL version of PARMELA.

  13. Store operations to maintain cache coherence

    Energy Technology Data Exchange (ETDEWEB)

    Evangelinos, Constantinos; Nair, Ravi; Ohmacht, Martin

    2017-09-12

    In one embodiment, a computer-implemented method includes encountering a store operation during a compile-time of a program, where the store operation is applicable to a memory line. It is determined, by a computer processor, that no cache coherence action is necessary for the store operation. A store-without-coherence-action instruction is generated for the store operation, responsive to determining that no cache coherence action is necessary. The store-without-coherence-action instruction specifies that the store operation is to be performed without a cache coherence action, and cache coherence is maintained upon execution of the store-without-coherence-action instruction.

  14. Store operations to maintain cache coherence

    Energy Technology Data Exchange (ETDEWEB)

    Evangelinos, Constantinos; Nair, Ravi; Ohmacht, Martin

    2017-08-01

    In one embodiment, a computer-implemented method includes encountering a store operation during a compile-time of a program, where the store operation is applicable to a memory line. It is determined, by a computer processor, that no cache coherence action is necessary for the store operation. A store-without-coherence-action instruction is generated for the store operation, responsive to determining that no cache coherence action is necessary. The store-without-coherence-action instruction specifies that the store operation is to be performed without a cache coherence action, and cache coherence is maintained upon execution of the store-without-coherence-action instruction.

  15. Coherence-vortex lattice formed via Mie scattering of partially coherent light by several dielectric nanospheres.

    Science.gov (United States)

    Marasinghe, Madara L; Paganin, David M; Premaratne, Malin

    2011-03-15

    We previously demonstrated that Mie scattering of stationary partially coherent light by dielectric spheres generates coherence vortices. In this Letter, we demonstrate that a lattice of coherence vortices can be generated by Mie scattering of partially coherent electromagnetic waves by a system of three coplanar dielectric spheres. Spontaneous coherence-vortex creation and destruction is observed in our computer modeling of this system.

  16. Experimental generation of optical coherence lattices

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yahong; Cai, Yangjian, E-mail: serpo@dal.ca, E-mail: yangjiancai@suda.edu.cn [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006 (China); Ponomarenko, Sergey A., E-mail: serpo@dal.ca, E-mail: yangjiancai@suda.edu.cn [Department of Electrical and Computer Engineering, Dalhousie University, Halifax, Nova Scotia B3J 2X4 (Canada)

    2016-08-08

    We report experimental generation and measurement of recently introduced optical coherence lattices. The presented optical coherence lattice realization technique hinges on a superposition of mutually uncorrelated partially coherent Schell-model beams with tailored coherence properties. We show theoretically that information can be encoded into and, in principle, recovered from the lattice degree of coherence. Our results can find applications to image transmission and optical encryption.

  17. WEB COHERENCE LEARNING

    Directory of Open Access Journals (Sweden)

    Peter Karlsudd

    2008-09-01

    Full Text Available This article describes a learning system constructed to facilitate teaching and learning by creating a functional web-based contact between schools and organisations which in cooperation with the school contribute to pupils’/students’ cognitive development. Examples of such organisations include science centres, museums, art and music workshops and teacher education internships. With the support of the “Web Coherence Learning” IT application (abbreviated in Swedish to Webbhang developed by the University of Kalmar, the aim is to reinforce learning processes in the encounter with organisations outside school. In close cooperation with potential users a system was developed which can be described as consisting of three modules. The first module, “the organisation page” supports the organisation in simply setting up a homepage, where overarching information on organisation operations can be published and where functions like calendar, guestbook, registration and newsletter can be included. In the second module, “the activity page” the activities offered by the organisation are described. Here pictures and information may prepare and inspire pupils/students to their own activities before future visits. The third part, “the participant page” is a communication module linked to the activity page enabling school classes to introduce themselves and their work as well as documenting the work and communicating with the educators responsible for external activities. When the project is finished, the work will be available to further school classes, parents and other interested parties. System development and testing have been performed in a small pilot study where two creativity educators at an art museum have worked together with pupils and teachers from a compulsory school class. The system was used to establish, prior to the visit of the class, a deeper contact and to maintain a more qualitative continuous dialogue during and after

  18. Experimental study of coherence vortices: Local properties of phase singularities in a spatial coherence function

    DEFF Research Database (Denmark)

    Wang, W.; Duan, Z.H.; Hanson, Steen Grüner

    2006-01-01

    By controlling the irradiance of an extended quasimonochromatic, spatially incoherent source, an optical field is generated that exhibits spatial coherence with phase singularities, called coherence vortices. A simple optical geometry for direct visualization of coherence vortices is proposed, an...

  19. Coherent states on Hilbert modules

    Energy Technology Data Exchange (ETDEWEB)

    Ali, S Twareque [Department of Mathematics and Statistics, Concordia University, 1455 De Maisonneuve Blvd West, Montreal, Quebec H3G 1M8 (Canada); Bhattacharyya, T [Department of Mathematics, Indian Institute of Science, Bengaluru 560012, Karnataka (India); Roy, S S, E-mail: stali@math.concordia.ca, E-mail: tirtha@member.ams.org [Department of Mathematics and Statistics, Indian Institute of Science Education and Research, Kolkata, Mohanpur 741252, West Bengal (India)

    2011-07-08

    We generalize the concept of coherent states, traditionally defined as special families of vectors on Hilbert spaces, to Hilbert modules. We show that Hilbert modules over C*-algebras are the natural settings for a generalization of coherent states defined on Hilbert spaces. We consider those Hilbert C*-modules which have a natural left action from another C*-algebra, say A. The coherent states are well defined in this case and they behave well with respect to the left action by A. Certain classical objects like the Cuntz algebra are related to specific examples of coherent states. Finally we show that coherent states on modules give rise to a completely positive definite kernel between two C*-algebras, in complete analogy to the Hilbert space situation. Related to this, there is a dilation result for positive operator-valued measures, in the sense of Naimark. A number of examples are worked out to illustrate the theory. Some possible physical applications are also mentioned.

  20. Coherent laser scanning diffraction microscopy

    International Nuclear Information System (INIS)

    Dierolf, Martin; Thibault, Pierre; Kewish, Cameron M; Menzel, Andreas; Bunk, Oliver; Pfeiffer, Franz

    2009-01-01

    Coherent diffractive imaging (CDI) is a promising approach to high-resolution x-ray microscopy. While CDI typically has a rather limited field of view, this problem can be solved by ptychography, a technique for which an extended object is raster scanned by a compact coherent illumination probe. Significant overlap of illumination for adjacent scan points allows then a self-consistent reconstruction from the entirety of collected coherent diffraction patterns. However, current reconstruction schemes require accurate a priori knowledge of the probe. Our recently developed new algorithm for ptychographic data sets allows us to simultaneously reconstruct both object and illuminating probe. We demonstrate the application of the new method in a test experiment with visible laser light showing that intricate illumination functions can be retrieved reliably.

  1. The FERMI @ Elettra Technical Optimization Study: General Layoutand Parameters and Physics Studies of Longitudinal Space Charge, theSpreader, the Injector, and Preliminary FEL Performance

    Energy Technology Data Exchange (ETDEWEB)

    Byrd, John; Corlett, John; Doolittle, Larry; Fawley, William; Lidia, Steven; Penn, Gregory; Ratti, Alex; Staples, John; Wilcox,Russell; Wurtele, Jonathan; Zholents, Alexander

    2005-09-01

    The FERMI {at} Elettra facility will make use of the existing GeV linac at Sincrotrone Elettra, which will become available for dedicated FEL applications following the completion of construction of a new injector booster complex for the storage ring. With a new rf photocathode injector, and some additional accelerating sections, this linac will be capable of providing high brightness bunches at 1.2 GeV and up to 50 Hz repetition rates.

  2. The FERMI (at) Elettra Technical Optimization Study: General Layout and Parameters and Physics Studies of Longitudinal Space Charge, the Spreader, the Injector, and Preliminary FEL Performance

    International Nuclear Information System (INIS)

    Byrd, John; Corlett, John; Doolittle, Larry; Fawley, William; Lidia, Steven; Penn, Gregory; Ratti, Alex; Staples, John; Wilcox, Russell; Wurtele, Jonathan; Zholents, Alexander

    2005-01-01

    The FERMI (at) Elettra facility will make use of the existing GeV linac at Sincrotrone Elettra, which will become available for dedicated FEL applications following the completion of construction of a new injector booster complex for the storage ring. With a new rf photocathode injector, and some additional accelerating sections, this linac will be capable of providing high brightness bunches at 1.2 GeV and up to 50 Hz repetition rates

  3. Coherence effects in Mie scattering.

    Science.gov (United States)

    Fischer, David G; van Dijk, Thomas; Visser, Taco D; Wolf, Emil

    2012-01-01

    The scattering of a partially coherent beam by a deterministic, spherical scatterer is studied. In particular, the Mie scattering by a Gaussian Schell-model beam is analyzed. Expressions are derived for (a) the extinguished power, (b) the radiant intensity of the scattered field, and (c) the encircled energy in the far field. It is found that the radiant intensity and the encircled energy in the far field depend on the degree of coherence of the incident beam, whereas the extinguished power does not.

  4. Incoherent and coherent tune shifts

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S.Y. [Brookhaven National Lab., Upton, NY (United States). AGS Dept.

    1995-12-31

    The longitudinal and transverse microwave instabilities are the two important limiting factors for the performance of an accelerator. Comparing with the fairly unified approach for the longitudinal microwave instabilities, different approaches have been used to define the transverse microwave instabilities. One reason of this is related to the role played by the space charge incoherent and coherent tune shifts. In this article, the transverse microwave instabilities will be discussed by defining separately the roles of the space charge incoherent and coherent tunes, which are represented by the space charge transverse impedances. Preliminary results for the AGS as proton driver are presented by using this approach.

  5. Development of a Pump-Probe System using a Non-Coated ZnSe Beam Splitter Cube for an MIR-FEL

    CERN Document Server

    Heya, Manabu; Horiike, Hiroshi; Ishii, Katsonuri; Suzuki, Sachiko

    2004-01-01

    A pump-probe technique is essential for a proper understanding of laser interaction with tissue and material. Our pump-probe system divides the incident mid-infrared Free Electron Laser (MIR-FEL) into two beams with equal intensity, and crosses simultaneously the two incoming beams at the same position. One is for a pump beam, another is for a probe beam. Time-resolved absorption spectroscopy involving this technique gives us information on the vibrational dynamics of molecules. We have developed this system for an MIR-FEL using a non-coating ZnSe beam splitter cube. The beam splitter cube is composed of two ZnSe prisms in the shape like a trapezoid. The two pulses with equal intensity are generated due to Fresnel reflection and transmission at the boundary between two prisms, then are reflected due to total reflection at other side boundaries between each prism and air, and illuminate simultaneously the same spot. We have conducted a proof-of-concept of experiment of this system using an MIR-FEL. We showed t...

  6. Potential applications of a dual-sweep streak camera system for characterizing particle and photon beams of VUV, XUV, and x-ray FELS

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A. [Argonne National Lab., IL (United States)

    1995-12-31

    The success of time-resolved imaging techniques in the Characterization of particle beams and photon beams of the recent generation of L-band linac-driven or storage ring FELs in the infrared, visible, and ultraviolet wavelength regions can be extended to the VUV, XUV, and x-ray FELs. Tests and initial data have been obtained with the Hamamatsu C5680 dual-sweep streak camera system which includes a demountable photocathode (thin Au) assembly and a flange that allows windowless operation with the transport vacuum system. This system can be employed at wavelengths shorter than 100 nm and down to 1 {Angstrom}. First tests on such a system at 248-nm wavelengths have been performed oil the Argonne Wakefield Accelerator (AWA) drive laser source. A quartz window was used at the tube entrance aperture. A preliminary test using a Be window mounted on a different front flange of the streak tube to look at an x-ray bremsstrahlung source at the AWA was limited by photon statistics. This system`s limiting resolution of {sigma}{approximately}1.1 ps observed at 248 nm would increase with higher incoming photon energies to the photocathode. This effect is related to the fundamental spread in energies of the photoelectrons released from the photocathodes. Possible uses of the synchrotron radiation sources at the Advanced Photon Source and emerging short wavelength FELs to test the system will be presented.

  7. Coherence vortices in Mie scattering of statistically stationary partially coherent fields.

    Science.gov (United States)

    Marasinghe, Madara L; Premaratne, Malin; Paganin, David M

    2010-03-29

    Points within a fully coherent complex scalar optical field, where the amplitude is identically zero but the optical phase has a jump discontinuity, have been widely investigated by the singular-optics community. More recent researches have extended the domain of singular optics to include partially coherent fields. For example, in coherence vortices the phase of the two-point spectral degree of coherence of a partially coherent field exhibits vortex structure around a point where the magnitude of the spectral degree of coherence vanishes. We show that the spectral degree of coherence of Mie scattered partially coherent statistically stationary electromagnetic fields exhibits a rich set of coherence vortices in both the internal and external fields. Specifically, we look at Mie scattering of a stationary beam from a dielectric sphere and study the formation of coherence vortices and their evolution with both the properties of the scattering sphere, and of the incident partially coherent beam.

  8. Interference due to coherence swapping

    Indian Academy of Sciences (India)

    pinhole arrangement in a diaphragm behind the crystal and/or with the use of filters. 4.2 Proposed observation of coherence swapping. We take two separate down conversion crystals, A, B, however pumped by the same pulsed laser (see figure 2). The pump beam is beam-split in such a way that the pulses enter both. 398.

  9. Optical coherent control in semiconductors

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Vadim, Lyssenko; Hvam, Jørn Märcher

    2001-01-01

    of quantum control including the recent applications to semiconductors and nanostructures. We study the influence of inhomogeneous broadening in semiconductors on CC results. Photoluminescence (PL) and the coherent emission in four-wave mixing (FWM) is recorded after resonant excitation with phase...

  10. Interference due to coherence swapping

    Indian Academy of Sciences (India)

    Quantum Optics and Information Groups, School of Informatics, Dean Street, University of Wales,. Bangor LL 57 1UT, UK ... has come from a single source and made to pass through a double slit or through a suit- able device such as a .... This is a method to swap coherence from the primary pairs of possible paths to another ...

  11. Coherence effects in Mie scattering

    NARCIS (Netherlands)

    Fischer, D.G.; van Dijk, T.; Visser, T.D.; Wolf, E.

    2012-01-01

    The scattering of a partially coherent beam by a deterministic, spherical scatterer is studied. In particular, the Mie scattering by a Gaussian Schell-model beam is analyzed. Expressions are derived for (a) the extinguished power, (b) the radiant intensity of the scattered field, and (c) the

  12. Coherent state quantization of quaternions

    Energy Technology Data Exchange (ETDEWEB)

    Muraleetharan, B., E-mail: bbmuraleetharan@jfn.ac.lk, E-mail: santhar@gmail.com [Department of Mathematics and Statistics, University of Jaffna, Thirunelveli (Sri Lanka); Thirulogasanthar, K., E-mail: bbmuraleetharan@jfn.ac.lk, E-mail: santhar@gmail.com [Department of Computer Science and Software Engineering, Concordia University, 1455 De Maisonneuve Blvd. West, Montreal, Quebec H3G 1M8 (Canada)

    2015-08-15

    Parallel to the quantization of the complex plane, using the canonical coherent states of a right quaternionic Hilbert space, quaternion field of quaternionic quantum mechanics is quantized. Associated upper symbols, lower symbols, and related quantities are analyzed. Quaternionic version of the harmonic oscillator and Weyl-Heisenberg algebra are also obtained.

  13. Laser-Limited Signatures of Quantum Coherence

    NARCIS (Netherlands)

    Tempelaar, Roel; Halpin, Alexei; Johnson, Philip J. M.; Cai, Jianxin; Murphy, R. Scott; Knoester, Jasper; Miller, R. J. Dwayne; Jansen, Thomas L. C.

    2016-01-01

    Quantum coherence is proclaimed to promote efficient energy collection by light-harvesting complexes and prototype organic photovoltaics. However, supporting spectroscopic studies are hindered by the problem of distinguishing between the excited state and ground state origin of coherent spectral

  14. Coherent states, wavelets, and their generalizations

    CERN Document Server

    Ali, Syed Twareque; Gazeau, Jean-Pierre

    2014-01-01

    This second edition is fully updated, covering in particular new types of coherent states (the so-called Gazeau-Klauder coherent states, nonlinear coherent states, squeezed states, as used now routinely in quantum optics) and various generalizations of wavelets (wavelets on manifolds, curvelets, shearlets, etc.). In addition, it contains a new chapter on coherent state quantization and the related probabilistic aspects. As a survey of the theory of coherent states, wavelets, and some of their generalizations, it emphasizes mathematical principles, subsuming the theories of both wavelets and coherent states into a single analytic structure. The approach allows the user to take a classical-like view of quantum states in physics.   Starting from the standard theory of coherent states over Lie groups, the authors generalize the formalism by associating coherent states to group representations that are square integrable over a homogeneous space; a further step allows one to dispense with the group context altoget...

  15. Spatial coherence in reverberant sound fields

    DEFF Research Database (Denmark)

    Jacobsen, Finn; Roisin, Thibaut

    1999-01-01

    A new method of measuring spatial correlation functions in reverberant sound fields is presented. It is shown that coherence functions determined with appropriate spectral resolution contain the same information as the corresponding correlation functions, and that measuring such coherence functio...

  16. Generalized coherence concurrence and path distinguishability

    International Nuclear Information System (INIS)

    Chin, Seungbeom

    2017-01-01

    We propose a new family of coherence monotones, named the generalized coherence concurrence (or coherence k -concurrence), which is an analogous concept to the generalized entanglement concurrence. The coherence k -concurrence of a state is nonzero if and only if the coherence number (a recently introduced discrete coherence monotone) of the state is not smaller than k , and a state can be converted to a state with nonzero entanglement k -concurrence via incoherent operations if and only if the state has nonzero coherence k -concurrence. We apply the coherence concurrence family to the problem of wave-particle duality in multi-path interference phenomena. We obtain a sharper equation for path distinguishability (which witnesses the duality) than the known one and show that the amount of each concurrence for the quanton state determines the number of slits which are identified unambiguously. (paper)

  17. Generalized coherence concurrence and path distinguishability

    Science.gov (United States)

    Chin, Seungbeom

    2017-11-01

    We propose a new family of coherence monotones, named the generalized coherence concurrence (or coherence k-concurrence), which is an analogous concept to the generalized entanglement concurrence. The coherence k-concurrence of a state is nonzero if and only if the coherence number (a recently introduced discrete coherence monotone) of the state is not smaller than k, and a state can be converted to a state with nonzero entanglement k-concurrence via incoherent operations if and only if the state has nonzero coherence k-concurrence. We apply the coherence concurrence family to the problem of wave-particle duality in multi-path interference phenomena. We obtain a sharper equation for path distinguishability (which witnesses the duality) than the known one and show that the amount of each concurrence for the quanton state determines the number of slits which are identified unambiguously.

  18. Theoretical estimation and experimental design of high-intensity far-infrared to MM-wave coherent synchrotron radiation generated by short electron bunches at BFEL

    International Nuclear Information System (INIS)

    Zhu Junbiao; Li Yonggui; Xie Jialin

    2000-01-01

    Broadband continuous and high-intensity coherent synchrotron radiation (CSR) emitted from 4 ps electron bunches provided by the 30 MeV RF linac of Beijing FEL is analyzed and numerically calculated using an exact series expansion for the infinite integral of fractional modified Bessel function. CSR in the mm-wave and far-IR to mm-wave regions can be respectively generated by directly using these bunches and by applying those ones compressed to ≤=1 ps. The CSR powers, approximately as 10 8 -10 9 times as the SR ones, in the range from several hundred microwatts to milliwatts are dependent on chosen electron density distribution, wavelength range, and gathering angle. The power produced by rectangular bunches is greater than that generated by Gaussian ones. The shorter the bunch, the stronger the produced CSR, the greater the energy concentrated to the far-IR end. Experiments to generate CSR and measure the bunch length are designed

  19. Electron beam instrumentation techniques using coherent radiation

    International Nuclear Information System (INIS)

    Wang, D.X.

    1997-01-01

    Much progress has been made on coherent radiation research since coherent synchrotron radiation was first observed in 1989. The use of coherent radiation as a bunch length diagnostic tool has been studied by several groups. In this paper, brief introductions to coherent radiation and far-infrared measurement are given, the progress and status of their beam diagnostic application are reviewed, different techniques are described, and their advantages and limitations are discussed

  20. On P-coherent endomorphism rings

    Indian Academy of Sciences (India)

    A ring is called right -coherent if every principal right ideal is finitely presented. Let M R be a right -module. We study the -coherence of the endomorphism ring of M R . It is shown that is a right -coherent ring if and only if every endomorphism of M R has a pseudokernel in add M R ; S is a left -coherent ring if and ...