Science.gov

Sample records for proposed visible fel

  1. A proposed visible FEL Facility at Boeing

    SciTech Connect

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

    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.

  2. Nonlinear harmonic generation and proposed experimental verification in SASE FELs.

    SciTech Connect

    Biedron, S. G.; Freund, H. P.; Milton, S. V.

    1999-08-24

    Recently, a 3D, polychromatic, nonlinear simulation code was developed to study the growth of nonlinear harmonics in self-amplified spontaneous emission (SASE) free-electron lasers (FELs). The simulation was applied to the parameters for each stage of the Advanced Photon Source (APS) SASE FEL, intended for operation in the visible, UV, and short UV wavelength regimes, respectively, to study the presence of nonlinear harmonic generation. Significant nonlinear harmonic growth is seen. Here, a discussion of the code development, the APS SASE FEL, the simulations and results, and, finally, the proposed experimental procedure for verification of such nonlinear harmonic generation at the APS SASE FEL will be given.

  3. Proposed uv-FEL user facility at BNL

    SciTech Connect

    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.

  4. Beam quality and wavelength limitation in visible and UV FEL oscillations

    SciTech Connect

    Tomimasu, T.

    1995-12-31

    The FELI linac beam has succeeded in visible-FEL oscillation on the third harmonics at 0.64 {mu}m using a 3-m undulator and a 6.72-m optical cavity with two Au-coated mirrors in Feb. 28, 1995. The beam is a 68-MeV, 40-A electron beam with a normalized emittance of 26 {pi}mm{center_dot}mrad and a relative energy spread of 1%. In 1993, an ultraviolet (UV) FEL oscillation was already achieved on the third harmonics at 0.37{mu} m using a 46-MeV, 130-A electron beam with a normalized emittance of 3{pi}mm{center_dot}mrad and a relative energy spread of 0.24% from the APEX L-band linac with an rf photocathode electron gun. However, we are now trying to achieve an FEL oscillation in the UV range using the FELI linac with the thermionic gun because of long-life, easy-operation, and low-cost of the thermionic gun, as the FELI ring with 9.8-m long straight sections capable of storing a long lived 1-A beam is in the design stage. Recent experimental and theoretical results on relations between beam quality and short wavelength FEL oscillations have been also reviewed and wavelength limitations due to normalized emittance and relative energy spread are discussed.

  5. Performance of an undulator for visible and UV FELs at FELI

    SciTech Connect

    Miyauchi, Y.; Zako, A.; Koga, A.

    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.

  6. The FEL and IFEL design study for the proposed NTHU photon-electron dynamics laboratory

    NASA Astrophysics Data System (ADS)

    Huang, Y. C.; Hsue, C. S.; Pantell, R. H.; Smith, T. I.

    1999-06-01

    A photon-electron dynamics laboratory is being proposed at National Tsinghua University, Taiwan. The mission of the proposed laboratory is to conduct advanced research on free-electron laser, inverse free-electron laser, and laser-driven particle acceleration. We discuss in this paper the design study of the Stanford high efficiency FEL and the reconfigured Stanford/TRW wiggler in the proposed laboratory. The Stanford high efficiency FEL is to demonstrate a 19% beam-to-laser efficiency. The reconfigured, 1-m Stanford/TRW wiggler may serve as an inverse FEL that provides 1.5-μm bunched electrons for various kinds of laser-driven acceleration experiments.

  7. On use of time-dependent microwave fields to increase an FEL oscillator efficiency

    SciTech Connect

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

    1995-12-31

    Various schemes of a high efficiency FEL oscillator with time-dependent accelerating (or decelerating) microwave field in interaction region are proposed. All the, schemes are based on standard accelerating structure and undulator technology. Feasibility of the proposed schemes is confirmed by results of numerical simulations. Realistic examples of FEL oscillators of infrared and visible wavelength ranges with efficiency about 20 % are presented.

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

    SciTech Connect

    Benson, S. V.; Douglas, D. R.; Evtushenko, P.; Hannon, F. E.; Hernandez-Garcia, C.; Klopf, J. M.; Legg, R. A.; Neil, G. R.; Shinn, M. D.; Tennant, C. D.; Zhang, S.; Williams, G. P.

    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.

  9. Briefing paper for the proposed ultraviolet free-electron laser (UV- FEL) facility at Brookhaven National Laboratory

    SciTech Connect

    Johnson, E.D.

    1992-07-15

    The proposed Brookhaven National Laboratory ultraviolet free-electron laser (UV-FEL) user facility will provide picosecond and sub-picosecond pulses of coherent ultraviolet radiation for wavelengths from 300 to 75 nm. Pulse width will be variable from about 7 ps to {approx} 200 fs, with repetition rates as high as l0{sup 4}Hz, single pulse energies > 1 NJ and hence peak pulse power > 200 MW and average beam power > 10 W. The facility will be capable of ``pump-probe`` experiments utilizing the FEL radiation with: (1) synchronized auxiliary lasers, (2) a second, independently tunable FEL beam, or (3) broad-spectrum, high-intensity x-rays from an insertion device in the x-ray ring of the adjacent National Synchrotron Light Source. The UV-FEL consists of a high repetition rate recirculating superconducting linear accelerator which feeds pulses of electrons to two magnetic wigglers. Within these two devices, photons from tunable ``conventional`` lasers are frequency multiplied and amplified. By synchronously tuning the seed laser and modulating the energy of the electron beam, tuning of as much as 60% in wavelength is possible between alternating pulses supplied to different experimental stations, with Fourier transform limited resolution. Thus, up to four independent experiments may operate at one time, each with independent control of the wavelength and pulse duration. A total of eight experimental stations are planned, with two currently assigned to general users, two each for solid state and chemical physics, and one each for atomic physics and biology. This document provides a few representative examples of experiments in these fields, as well as an introduction to the facility, its limitations, and its potential for future growth.

  10. Briefing paper for the proposed ultraviolet free-electron laser (UV- FEL) facility at Brookhaven National Laboratory

    SciTech Connect

    Johnson, E.D.

    1992-07-15

    The proposed Brookhaven National Laboratory ultraviolet free-electron laser (UV-FEL) user facility will provide picosecond and sub-picosecond pulses of coherent ultraviolet radiation for wavelengths from 300 to 75 nm. Pulse width will be variable from about 7 ps to {approx} 200 fs, with repetition rates as high as l0{sup 4}Hz, single pulse energies > 1 NJ and hence peak pulse power > 200 MW and average beam power > 10 W. The facility will be capable of pump-probe'' experiments utilizing the FEL radiation with: (1) synchronized auxiliary lasers, (2) a second, independently tunable FEL beam, or (3) broad-spectrum, high-intensity x-rays from an insertion device in the x-ray ring of the adjacent National Synchrotron Light Source. The UV-FEL consists of a high repetition rate recirculating superconducting linear accelerator which feeds pulses of electrons to two magnetic wigglers. Within these two devices, photons from tunable conventional'' lasers are frequency multiplied and amplified. By synchronously tuning the seed laser and modulating the energy of the electron beam, tuning of as much as 60% in wavelength is possible between alternating pulses supplied to different experimental stations, with Fourier transform limited resolution. Thus, up to four independent experiments may operate at one time, each with independent control of the wavelength and pulse duration. A total of eight experimental stations are planned, with two currently assigned to general users, two each for solid state and chemical physics, and one each for atomic physics and biology. This document provides a few representative examples of experiments in these fields, as well as an introduction to the facility, its limitations, and its potential for future growth.

  11. 78 FR 68089 - Proposed Information Collection; Visibility Valuation Survey

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-13

    ... National Park Service Proposed Information Collection; Visibility Valuation Survey AGENCY: National Park... conduct a nationwide stated preference survey to estimate the value of visibility changes in national parks and wilderness areas. Survey development and pre-testing have already been conducted under...

  12. Tapered undulators for SASE FELs

    NASA Astrophysics Data System (ADS)

    Fawley, William M.; Huang, Zhirong; Kim, Kwang-Je; Vinokurov, Nikolai A.

    2002-05-01

    We discuss the use of tapered undulators to enhance the performance of free-electron lasers (FELs) based upon self-amplified spontaneous emission, where the radiation tends to have a relatively broad bandwidth and limited temporal coherence. Using the polychromatic FEL simulation code GINGER, we numerically demonstrate the effectiveness of tapered undulators for parameters corresponding to the Argonne low-energy undulator test line FEL and the proposed linac coherent light source.

  13. Tapered undulator for SASE FELs

    SciTech Connect

    Fawley, William M.; Huang, Zhirong; Kim, Kwang-Je; Vinokurov, Nikolai A.

    2001-09-14

    We discuss the use of tapered undulators to enhance the performance of free-electron lasers (FELs) based upon self-amplified spontaneous emission (SASE), where the radiation tends to have a relatively broad bandwidth, limited temporal phase coherence, and large amplitude fluctuations. Using the polychromatic FEL simulation code GINGER, we numerically demonstrate the effectiveness of a tapered undulator for parameters corresponding to the existing Argonne low-energy undulator test line (LEUTL) FEL. We also study possible tapering options for proposed x-ray FELs such as the Linac Coherent Light Source (LCLS).

  14. Two FEL`s in one

    SciTech Connect

    Epp, V.; Nikitin, M.

    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.

  15. 77 FR 63340 - Agency Information Collection Activities; Proposed Collection; Comments Requested: FEL Out-of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-16

    ... of Alcohol, Tobacco, Firearms and Explosives Agency Information Collection Activities; Proposed... (DOJ), Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), will be submitting the following... collection: Form Number: None. Bureau of Alcohol, Tobacco, Firearms and Explosives. (4) Affected public...

  16. FEL Oscillators

    SciTech Connect

    George Neil

    2003-05-12

    FEL Oscillators have been around since 1977 providing not only a test bed for the physics of Free Electron Lasers and electron/photon interactions but as a workhorse of scientific research. More than 30 FEL oscillators are presently operating around the world spanning a wavelength range from the mm region to the ultraviolet using DC and rf linear accelerators and storage rings as electron sources. The characteristics that have driven the development of these sources are the desire for high peak and average power, high micropulse energies, wavelength tunability, timing flexibility, and wavelengths that are unavailable from more conventional laser sources. Substantial user programs have been performed using such sources encompassing medicine, biology, solid state research, atomic and molecular physics, effects of non-linear fields, surface science, polymer science, pulsed laser vapor deposition, to name just a few.

  17. Measuring FEL Radiation Properties at VISA-FEL

    SciTech Connect

    Cornacchia, Massimo

    2002-08-21

    The VISA (Visible to Infrared SASE Amplifier) SASE free electron laser has been successfully operated at the Accelerator Test Facility (ATF) at BNL. High gain and saturation were observed at 840 nm. We describe here the diagnostic system, experimental procedures and data reduction algorithms, as the FEL performance was measured along the length of the undulator. We also discuss selected spectral radiation measurements.

  18. Simulation studies of a XUV/soft X-ray harmonic-cascade FEL for the proposed LBNL recirculating linac*

    SciTech Connect

    Fawley, W.M.; Barletta, W.A.; Corlett, J.N.; Zholents, A.

    2003-06-02

    Presently there is significant interest at LBNL in designing and building a facility for ultrafast (i.e. femtosecond time scale) x-ray science based upon a superconducting, recirculating RF linac (see Corlett et al. for more details). In addition to producing synchrotron radiation pulses in the 1-15 keV energy range, we are also considering adding one or more free-electron laser (FEL) beamlines using a harmonic cascade approach to produce coherent XUV soft X-ray emission beginning with a strong input seed at {approx}200 nm wavelength obtained from a ''conventional'' laser. Each cascade 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, which together then undergo FEL action in the modulator. We present various results obtained with the GINGER simulation code examining final output sensitivity to initial electron beam parameters. We also discuss the effects of spontaneous emission and shot noise upon this particular cascade approach which can limit the final output coherence.

  19. Short wavelength FELS

    SciTech Connect

    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.

  20. Lightning control system using high power microwave FEL

    SciTech Connect

    Shiho, M.; Watanbe, A.; Kawasaki, S.

    1995-12-31

    A research project for developing a thunder lightning control system using an induction linac based high power microwave free electron laser (FEL) started at JAERI The system will produce 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 MW/cm{sup 2} power density is enough for the atmospheric breakdown in the microwave region, and which means high power microwave FEL with GW level output power is feasible for atmospheric breakdown, and accordingly is feasible for thunder lightning control tool with making a conductive plasma channel in the atmosphere. From the microwave attenuation consideration in the atmosphere, FEL of 35GHz(0.13dB/km), 90GHz(0.35dB/km), 140GHz(1.7dB/km), and of 270 GHz(4.5dB/km) are the best candidates for the system. Comparing with other proposed lightning control system using visible or ultraviolet laser, the system using microwave has an advantage that microwave suffers smaller attenuation by rain or snow which always exist in the real atmospheric circumstances when lightning occurs.

  1. 76 FR 12367 - Proposed Information Collection; Visibility Valuation Survey Pilot Study

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-07

    ... National Park Service Proposed Information Collection; Visibility Valuation Survey Pilot Study AGENCY... Control Number 1024-0255). The purpose of this IC is to conduct a pilot study to test the survey... collection. Title: Visibility Valuation Survey Pilot Study. Type of Request: New. Affected Public...

  2. Computing visible areas from proposed recreation developments...a case study

    Treesearch

    Gary H. Elsner

    1971-01-01

    A new computerized technique called VIEWIT for measuring the terrain visible from a given point was applied in a study on the Black Hills National Forest, South Dakota. The seen area from 12 heavily visited scenic points and along three proposed routes for a scenic tramway were delineated. The computer produced overlay maps that show the maximum area visible from each...

  3. Photon Beam Diagnostics for VISA FEL

    SciTech Connect

    Murokh, A.; Pellegrini, C.; Rosenzweig, J.; Frigola, P.; Musumeci, P.; Tremaine, A.; Babzien, M.; Ben-Zvi, I.; Doyuran, A.; Johnson, E.; Skaritka, J.; Wang, X.J.; Van Bibber, K.; Hill, J.M.; LeSage, G.P.; Nguyen, D.; Cornacchia, M.

    1999-11-05

    The VISA (Visible to Infrared SASE Amplifier) project is designed to be a SASE-FEL driven to saturation in the sub-micron wavelength region. Its goal is to test various aspects of the existing theory of Self-Amplified Spontaneous Emission, as well as numerical codes. Measurements include: angular and spectral distribution of the FEL light at the exit and inside of the undulator; electron beam micro-bunching using CTR; single-shot time resolved measurements of the pulse profile, using auto-correlation technique and FROG algorithm. The diagnostics are designed to provide maximum information on the physics of the SASE-FEL process, to ensure a close comparison of the experimental results with theory and simulations.

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

    SciTech Connect

    Huang, Z.; Fawley, W.M.

    2001-07-01

    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.

  5. Boosting laser power - the FEL's research potential ranges from fusion energy to cancer

    SciTech Connect

    Yarris, L.

    1986-11-01

    The status of FEL research at Lawrence Berkeley Laboratories is reviewed, and some potential applications are examined. The history of laser development is traced; the operating principles of FELs are outlined; and the importance of tapered undulators in extending FEL output beyond 200 MW and increasing energy-extraction efficiency from 5 to 40 percent is stressed. The use of such FELs to heat plasma in nuclear fusion reactors or as the microwave source for a proposed two-beam accelerator is considered.

  6. Optical tailoring of xFEL beams

    SciTech Connect

    West, Gavin; Coffee, R.

    2015-08-20

    There is an inherent exibility unique to free electron lasers (FELs) that lends well to experimental approaches normally too difficult for other light sources to accomplish. This includes the ability to optically shape the electron bunch prior to final its acceleration for the final FEL process. Optical pulse shaping of the electron bunch can enable both femtosecond and attosecond level FEL pulse control. Pulse shaping is currently implemented, not optically but mechanically, in LCLS-I with an adjustable foil slit that physically spoils the momentum phase of the electron bunch. This selectively suppresses the downstream FEL process ofspoiled electrons. Such a mechanical spoiling method fails for both the soft x-ray regime as well as the high repetition rates that are planned in LCLS-II. Our proposed optical spoiling method circumvents this limitation by making use of the existing ultrafast laser beam that is typically used for adjusting the energy spread for the initial electron bunch. Using Fourier domain shaping we can nearly arbitrarily shape the laser pulses to affect the electron bunch. This can selectively spoil electrons within each bunch. Here we demonstrate the viability of this approach with a programmable acousto-optic dispersive filter. This method is not only well suited for LCLS-II but also has several advantages over mechanical spoiling, including lack of radiation concerns, experiment specific FEL pulse shapes, and real-time adjustment for applications that require high duty-cycle variation such as lock-in amplification of small signals.

  7. Users program for storage-ring based FEL and synchrotron sources of the Duke FEL Laboratory

    SciTech Connect

    Straub, K.D.; Barnett, G.; Burnham, B.

    1995-12-31

    The storage ring at the Duke FEL Laboratory was first operated with a stored e-beam in November, 1994. It has now achieved operation energies in excess 1 GeV with more than 100 mA current at 280 MeV. The ring has several ports for FEL and synchrotron light source research. The circulating ring current can be synchronized with the seperate Mark III FEL operating in the 2-9.5 {mu}m IR region. This allows low optical jitter (10-20 ps) between the two sources and thus pump-probe operation. The ring has been configured to drive a number of light sources including the OK-4 FEL system capable of FEL operation between 400 and 65 nm, an inverse Compton scattering source using this undulator which will yield 4-200 MeV gammas, an undulator source at approximately 40 {angstrom} (not an FEL), a mm FEL with inverse compton scattering providing 1-100 keV x-rays and two synchrotron ports from the bend magnets for which the {lambda}{sub c} = 11-12 {angstrom} for 1 GeV. The broadly tunable FEL sources and their associated inverse compton scattering are extremely bright. The initial research proposals, submitted to the Laboratory emphasizes photoelectron spectroscopy, PEEM, high resolution vacuum UV of gases, solid spectroscopy and photochemistry in the UV, X-ray microprobe studies, X-ray microscopy, X-ray holography, X-ray crystallography, Mossbauer spectroscopy, nuclear spectroscopy, neutron production, photon activation therapy and broadband synchrotron as a probe of fast reaction in the IR and near IR.

  8. Transverse effects in UV FELs

    SciTech Connect

    Small, D.W.; Wong, R.K.; Colson, W.B.

    1995-12-31

    In an ultraviolet Free Electron Laser (UV FEL), the electron beam size can be approximately the same as the optical mode size. The performance of a UV FEL is studied including the effect of emittance, betatron focusing, and external focusing of the electron beam on the transverse optical mode. The results are applied to the Industrial Laser Consortium`s UV FEL.

  9. Small-signal gain in a gas-loaded FEL

    SciTech Connect

    Goloviznin, V.V.; Amersfoort, P.W. van

    1995-12-31

    At present, existing FEL facilities operate in the infrared and visible ranges of wavelengths. Generation of shorter waves (in the VUV and X-ray region) is of great scientific interest, but this would require a very expensive accelerator which could provide a high-current electron beam in the GeV-range of energies. A promising way to relax requirements on electron energy by introduction of a gas into the optical cavity was proposed nearly ten years ago. For small deviations from the vacuum wavelength, the idea was confirmed in experiments performed in Stanford; however, a detailed theory of such a device is still not developed. We present an analysis of the small-signal gain in a gas-loaded free-electron laser. Multiple scattering of electrons by the atoms of the gas inside the optical cavity is shown to lead to two additional effects, as compared to the case of a vacuum FEL: a loss of coherence between different parts of the electron trajectory and an enhancement of the phase {open_quotes}jitter{close_quotes}. Both effects become increasingly important at short wavelengths and significantly reduce the small-signal gain per pass. In 1D approximation analytical expressions are obtained and numerical calculations are made to estimate beam and undulator parameters necessary for lasing in the vacuum ultraviolet. Hydrogen-filled FELs are shown to have good prospects for this at today`s technological level. To operate in the range of wavelengths 125-140 nm, an electron beam should have an energy above 50 MeV and a good quality: a normalised emittance of the order of 5{pi} mm-mrad and an energy spread below 10{sup -3}. All these parameters are achieveable with modern linacs and photoinjectors.

  10. FEL-accelerator related diagnostics

    SciTech Connect

    Kevin Jordan; David Douglas; Stephen V. Benson; Pavel Evtuschenko

    2007-08-02

    Free Electron Lasers (FEL) present a unique set of beam parameters to the diagnostics suite. The FEL requires characterization of the full six dimensional phase space of the electron beam at the wiggler and accurate alignment of the electron beam to the optical mode of the laser. In addition to the FEL requirements on the diagnostics suite, the Jefferson Lab FEL is operated as an Energy Recovered Linac (ERL) which imposes additional requirements on the diagnostics. The ERL aspect of the Jefferson Lab FEL requires that diagnostics operate over a unique dynamic range and operate with simultaneous transport of the accelerated and energy recovered beams. This talk will present how these challenges are addressed at the Jefferson Lab FEL.

  11. Picosecond pump-probe using an FEL and a synchrotron source

    SciTech Connect

    Denbeaux, G.; Straub, K.D.; Madey, J.M.J.

    1995-12-31

    Two color pump-probe experiments using both the Duke Storage Ring as a synchrotron light source for visible light the Mark III FEL as a tunable, high peak power IR source are possible. The visible synchrotron source can be used as a probe of vibrational excitation from the FEL in an experiment using vibrationally-assisted fluorescence as an indicator of overlap of the IR and the visible pulses. An optical delay line in the FEL beam will allow adjustment of the arrival time of the IR pulse relative to the visible probe. The storage ring RF booster and the Mark III FEL RF sources will be both driven by the same master oscillator with a timing jitter between sources of less than 20 psec. Exploration of coupling between electronic excitation and lifetimes of vibrational excitation of fluorescent compounds in solution can be carried out with this configuration.

  12. Power beaming with FEL lasers

    NASA Astrophysics Data System (ADS)

    Lampel, Michael C.; Curtin, Mark S.; Burke, Robert J.; Cover, Ralph A.; Rakowsky, George; Bennett, Glenn T.

    1993-06-01

    FEL power beaming has broad application to space operations. The Rocketdyne Division of Rockwell International Corporation has examined the commercial applications of beamed power from Earth to space using the Radio Frequency LINAC Free Electron Laser (RF FEL) and has determined that there is a substantial addressable market. Rocketdyne's experience in developing and demonstrating FEL technologies, optics and atmospheric compensation and advanced power and power distribution systems ideally positions the Division to conduct the initial demonstration to prove the feasibility of using a FEL to beam power to space platforms.

  13. Saturation and pulsed FEL dynamics

    SciTech Connect

    Giannessi, L.; Mezi, L.

    1995-12-31

    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.

  14. FEL potential of eRHIC

    SciTech Connect

    Litvinenko, V.N.; Ben-Zvi, I.; Hao, Y.; Kao, C-C.; Kayran, D.; Murphy, J.B.; Ptitsyn, V.; Trbojevic, D.; Tsoupas, N.

    2010-08-23

    Brookhaven National Laboratory plans to build a 5-to-30 GeV energy-recovery linac (ERL) for its future electron-ion collider, eRHIC. In past few months, the Laboratory turned its attention to the potential of this unique machine for free electron lasers (FELS), which we initially assessed earlier. In this paper, we present our current vision of a possible FEL farm, and of narrow-band FEL-oscillators driven by this accelerator. eRHIC, the proposed electron-ion collider at BNL, takes advantage of the existing Relativistic Heavy Ion Collider (RHIC) complex. Plans call for adding a six-pass super-conducting (SRF) ERL to this complex to collide polarized- and unpolarized- electron beams with heavy ions (with energies up to 130 GeV per nucleon) and with polarized protons (with energies up to 325 GeV). RHIC, with a circumference of 3.834 km, has three-fold symmetry and six straight sections each {approx} 250 m long. Two of these straight sections will accommodate 703-MHz SRF linacs. The maximum energy of the electron beam in eRHIC will be reached in stages, from 5 GeV to 30 GeV, by increasing the lengths of its SRF linacs. We plan to install at the start the six-pass magnetic system with small gap magnets. The structure of the eRHIC's electron beam will be identical with that of its hadron beam, viz., 166 bunches will be filled, reserving about a one-microsecond gap for the abort kicker. With modest modifications, we can assure that eRHIC's ERL will become an excellent driver for continuous wave (CW) FELs (see Fig.1). The eRHIC's beam structure will support the operation of several such FELs in parasitic mode.

  15. Water-cooled, in-cavity apertures for high power operation of FEL oscillators

    NASA Astrophysics Data System (ADS)

    Huang, S.; Li, J.; Wu, Y. K.

    2009-07-01

    In an oscillator FEL, higher-order harmonic radiation from wigglers can cause serious damage to the downstream FEL resonator mirror and limit the maximum electron beam current for FEL operation due to thermal overload. These problems can be effectively dealt with for FELs driven by helical wigglers using a system to block off-axis wiggler harmonic radiation. In this paper, we report a new scheme to block the off-axis radiation from helical wigglers using a set of motorized, water-cooled, in-cavity apertures. These apertures can reduce the wiggler harmonic radiation power load on the downstream FEL resonator mirror by two orders of magnitude or more. With these apertures, we were able to operate the Duke FEL with record high intracavity power in infrared and visible wavelengths and extend FEL operation into ultraviolet wavelengths with a large electron beam current. The technique for limiting wiggler harmonic radiation using in-cavity apertures is expected to be useful for other types of FEL oscillators including high average power FEL oscillators driven by superconducting linacs.

  16. Rocketdyne FEL for power beaming using a regenerative amplifier

    NASA Astrophysics Data System (ADS)

    Cover, R. A.; Bennett, G. T.; Burke, R. J.; Curtin, M. S.; Lampel, M. C.; Rakowsky, G.; Stone, J. P.

    1993-08-01

    The Rocketdyne free-electron laser (FEL) being presently developed for operation in the visible to one-micron regime is described, with particular attention given to some of the principal optics and atmospheric propagation issues. The paper describes the system assembly and discusses the performance requirements for power beaming, the resonator design, and the basic ideas and calculations involved in the beam propagating through the atmosphere and tilt corrections. This FEL will be capable of an average output of greater than 1 kW in the near infrared. The laser system has an ability of scaling to power levels required for beaming power to space platforms.

  17. Towards short wavelengths FELs workshop

    SciTech Connect

    Ben-Zvi, I.; Winick, H.

    1993-12-01

    This workshop was caged because of the growing perception in the FEL source community that recent advances have made it possible to extend FEL operation to wavelengths about two orders of magnitude shorter than the 240 nm that has been achieved to date. In addition short wavelength FELs offer the possibilities of extremely high peak power (several gigawatts) and very short pulses (of the order of 100 fs). Several groups in the USA are developing plans for such short wavelength FEL facilities. However, reviewers of these plans have pointed out that it would be highly desirable to first carry out proof-of-principle experiments at longer wavelengths to increase confidence that the shorter wavelength devices will indeed perform as calculated. The need for such experiments has now been broadly accepted by the FEL community. Such experiments were the main focus of this workshop as described in the following objectives distributed to attendees: (1) Define measurements needed to gain confidence that short wavelength FELs will perform as calculated. (2) List possible hardware that could be used to carry out these measurements in the near term. (3) Define a prioritized FEL physics experimental program and suggested timetable. (4) Form collaborative teams to carry out this program.

  18. The Stanford Picosecond FEL Center

    SciTech Connect

    Schwettman, H.A.; Smith, T.I.; Swent, R.L.

    1995-12-31

    In the past two years, FELs have decisively passed the threshold of scientific productivity. There are now six FEL facilities in the United States and Europe, each delivering more than 2000 hours of FEL beam time per year. at the present time approximately 100 papers are published each in referred journals describing optics experiments performed with FELs. Despite the recent success there are important challenges the FEL facilities must address. At Stanford these challenges include: (1) Providing sufficient experimental time at reasonable cost: At Stanford we provide 2000 hours of experimental time per year at a cost of approximately $500 per hour: We are now studying options for markedly increasing experimental time and decreasing cost per hour. (2) Competing effectively with conventional lasers in the mid-IR: Despite the NRC report we do not intend to concede the mid-IR to conventional lasers. FELs are capable of providing optical beams of exceptional quality and stability, and they can also be remarkable flexible devices. Improvements in our superconducting linac driver and our optical beam conditioning systems will dramatically enhance our FEL experimental capabilities. (3) making the transition from first generation to second generation experiments: Important pump-probe and photon echo experiments have been performed at Stanford and others are feasible using present capabilities. None-the-less we are now investing substantial experimental time to improving signal-to-noise and developing other optical cababilities. (4) Extending operation to the far-infrared where the FEL is unique inits capabilities: {open_quotes}FIREFLY{close_quotes} will extend our FEL capabilities to 100 microns. We are now seeking funds for optical instrumentation. (5) Creating and maintaining a good environment for graduate students.

  19. Nonlinear harmonic generation in the STARS FEL

    NASA Astrophysics Data System (ADS)

    Abo-Bakr, M.; Goldammer, K.; Kamps, T.; Knobloch, J.; Kuske, B.; Leitner, T.; Meseck, A.

    2008-08-01

    BESSY proposes to build STARS, an FEL to demonstrate cascaded High Gain Harmonic Generation (HGHG). In two HGHG stages, a laser source of 700-900 nm is converted down to a wavelength of 40-70 nm. The STARS facility consists of a normal-conducting RF photoinjector, three superconducting TESLA-type acceleration modules, a magnetic bunch compressor and two stages of HGHG, each consisting of a modulator, dispersive chicane and a radiator. At the entrance of the undulator section, the beam energy is 325 MeV and the peak current is about 500 A. With these parameters, the STARS FEL reaches saturation with a peak power of 100-350 MW. A superradiant mode is also foreseen which boosts the radiation power to the GW-level. Due to nonlinear harmonic generation (NHG), free electron lasers also radiate coherently at higher harmonics of the FEL resonant frequency. STARS can hence extend its output range to even shorter wavelengths. This paper presents studies of the STARS harmonic content in the wavelength range of 6-20 nm. Seeding with high harmonic generation pulses at 32 nm is also discussed.

  20. FEL on slow cyclotron wave

    SciTech Connect

    Silivra, A.

    1995-12-31

    A physical mechanism of interaction of fast electromagnetic wave with slow cyclotron wave of relativistic electron beam in a FEL with helical wiggler field is described. It is shown that: (1) interaction is possible for both group of steady state electron trajectories (2) positive gain is achieved within certain interval of guide field strength (3) operation wavelength for group 1 trajectories ({Omega}{sub 0}/{gamma} < k{omega}{upsilon}{parallel}) is shorter than for the conventional FEL synchronism. A nonlinear analysis shows that efficiency of slow cyclotron FEL is restricted mainly by a breakdown of a single electron synchronism due to dependence of (modified) electron cyclotron frequency on an energy of electron. Nevertheless, as numerical simulation shows, typical efficiency of 15 % order is achieved in millimeter wavelength band for the midrelativistic ({gamma}= 3 {divided_by} 4) slow cyclotron wave FEL. Tapering of magnetic field results in a substantial increase of efficiency.

  1. Review of High Gain FELs

    SciTech Connect

    Shintake, Tsumoru

    2007-01-19

    For understanding on basic radiation mechanism of the high-gain FEL based on SASE, the author presents electron-crystal interpretation of FEL radiation. In the electron-crystal, electrons are localized at regularly spaced multi-layers, which represents micro-bunching, whose spacing is equal to the radiation wavelength, and the multi-layers are perpendicular to beam axis, thus, diffracted wave creates Bragg's spots in forward and backward directions. Due to the Doppler's effect, frequency of the back-scattered wave is up-converted, generates forwardly focused X-ray. The Bragg's effect contributes focusing the X-ray beam into a spot, thus peak power becomes extremely higher by factor of typically 107. This is the FEL radiation. As well known, the total numbers of scattered photons in Bragg's spots is equal to the total elastic scattering photons from the atoms contained in the crystal. Therefore, total power in the FEL laser is same as the spontaneous radiation power from the undulator for the same beam parameter. The FEL radiation phenomenon is simple interference effect. In today's presentations, we use the laser pointer, and we frequently experience difficulty in pointing precisely or steadily in one place on the screen, since the laser spot is very small and does not spread. Exactly same to this, X-ray FEL is a highly focused beam, and pointing stability dominates productivity of experiment, thus we need special care on beam stability from linear accelerator.

  2. SYNCHROTRON RADIATION, FREE ELECTRON LASER, APPLICATION OF NUCLEAR TECHNOLOGY, ETC.: Operating the SDUV-FEL with the echo-enabled harmonic generation scheme

    NASA Astrophysics Data System (ADS)

    Chen, Jian-Hui; Deng, Hai-Xiao; Gu, Qiang; Li, Dong-Guo; Wang, Dong; Zhang, Meng; Zhao, Zhen-Tang

    2009-08-01

    Using the recently proposed echo-enabled harmonic generation (EEHG) free-electron laser (FEL) scheme, it is shown that operating the Shanghai deep ultraviolet FEL (SDUV-FEL) with single-stage to higher harmonics is very promising, with higher frequency up-conversion efficiency, higher harmonic selectivity and lower power requirement of the seed laser. The considerations on a proof-of-principle experiment and expected performance in SDUV-FEL are given.

  3. UV FEL light source for industrial processing

    NASA Astrophysics Data System (ADS)

    Kelley, Michael J.; Dylla, H. Frederick; Neil, George R.; Brillson, Leonard J.; Henkel, Daniel P.; Helvajian, Henry

    1996-04-01

    Short-wavelength UV light is strongly absorbed by most materials, creating the opportunity to drive near-surface thermal or chemical processes. The resulting modifications have a wide range of prospective applications, but few have been developed because of the low capacity and high unit cost of light from present sources. We analyze the light source requirements for large-scale applications to polymers and metals. We describe meeting them with free electron laser whose design is described in a companion paper in this session. This machine will deliver 1.0 to 2.5 kW between 190 nm and 350 nm with options in the visible and IR, and serve to further develop FEL technology for much higher powered machines. We gratefully acknowledge support for this work from the Commonwealth of Virginia Center for Innovative Technologies and The U.S. Department of Energy.

  4. Electron beam effects in a UV FEL

    SciTech Connect

    Wong, R.K.; Blau, J.; Colson, W.B.

    1995-12-31

    At the Continuous Electron Beam Accelerator Facility (CEBAF), a free electron laser (FEL) is designed to produce ultraviolet (UV) light. A four-dimensional FEL simulation studies the effects of betatron oscillations, external focusing, and longitudinal pulse compression of the electron beam on the FEL performance.

  5. HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS.

    SciTech Connect

    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.

  6. Resonance hard radiation in a gas-loaded FEL

    SciTech Connect

    Gevorgian, L.A.

    1995-12-31

    The process of induced radiation under the condition when the relativistic beam oscillation frequency coincides with the plasma frequency of the FEL filling gas, is investigated. Such a resonance results in a giant enhancement of interaction between electrons and photons providing high gain in the hard FEL frequency region. Meanwhile the spectralwidth of the spontaneous radiation is broadened significantly. A method is proposed for maintaining the synchronism between the electron oscillation frequency and the medium plasma frequency, enabling to transform the electron energy into hard radiation with high efficiency.

  7. A Test of Superradiance in an FEL Experiment

    SciTech Connect

    Boyce, R

    2004-12-14

    We describe the design of an FEL Amplifier Test Experiment (FATE)1 to demonstrate the superradiant short bunch regime of a Free Electron Laser in the 1-3 {micro}m wavelength range starting from noise. The relevance to the LCLS X-ray FEL [1] proposal is discussed and numerical simulations are shown. It is numerically demonstrated for the first time with the 2-D code GINGER, that clean-up of noise in the superradiant regime occurs even at low power levels.

  8. Energy stability in a high average power FEL

    SciTech Connect

    Merminga, L.; Bisognano, J.J.

    1995-12-31

    Recirculating, energy-recovering linacs can be used as driver accelerators for high power FELs. Instabilities which arise from fluctuations of the cavity fields are investigated. Energy changes can cause beam loss on apertures, or, when coupled to M{sub 56}, phase oscillations. Both effects change the beam induced voltage in the cavities and can lead to unstable variations of the accelerating field. Stability analysis for small perturbations from equilibrium is performed and threshold currents determined. Design strategies to increase the instability threshold are discussed and the high average power FEL proposed for construction at CEBAF is used as an example.

  9. STARS A Two Stage High Gain Harmonic Generation FEL Demonstrator

    SciTech Connect

    M. Abo-Bakr; W. Anders; J. Bahrdt; P. Budz; K.B. Buerkmann-Gehrlein; O. Dressler; H.A. Duerr; V. Duerr; W. Eberhardt; S. Eisebitt; J. Feikes; R. Follath; A. Gaupp; R. Goergen; K. Goldammer; S.C. Hessler; K. Holldack; E. Jaeschke; Thorsten Kamps; S. Klauke; J. Knobloch; O. Kugeler; B.C. Kuske; P. Kuske; A. Meseck; R. Mitzner; R. Mueller; M. Neeb; A. Neumann; K. Ott; D. Pfluckhahn; T. Quast; M. Scheer; Th. Schroeter; M. Schuster; F. Senf; G. Wuestefeld; D. Kramer; Frank Marhauser

    2007-08-01

    BESSY is proposing a demonstration facility, called STARS, for a two-stage high-gain harmonic generation free electron laser (HGHG FEL). STARS is planned for lasing in the wavelength range 40 to 70 nm, requiring a beam energy of 325 MeV. The facility consists of a normal conducting gun, three superconducting TESLA-type acceleration modules modified for CW operation, a single stage bunch compressor and finally a two-stage HGHG cascaded FEL. This paper describes the faciliy layout and the rationale behind the operation parameters.

  10. R&D Requirements, RF Gun Mode Studies, FEL-2 Steady-StateStudies, Preliminary FEL-1 Time-Dependent Studies, and Preliminary LayoutOption Investigation

    SciTech Connect

    Byrd, John; Corlett, John; Doolittle, Larry; Fawley, William; Lidia, Steven; Penn, Gregory; Ratti, Alex; Staples, John; Wilcox Russell; Wurtele, Jonathan; Zholents, Alexander

    2005-10-01

    This report constitutes the third deliverable of LBNLs contracted role in the FERMI {at} Elettra Technical Optimization study. It describes proposed R&D activities for the baseline design of the Technical Optimization Study, initial studies of the RF gun mode-coupling and potential effects on beam dynamics, steady-state studies of FEL-2 performance to 10 nm, preliminary studies of time-dependent FEL-1 performance using electron bunch distribution from the start-to-end studies, and a preliminary investigation of a configuration with FEL sinclined at a small angle from the line of the linac.

  11. Optimisation of An HHG-Seeded Harmonic Cascade FEL Design for the NLS Project

    SciTech Connect

    Dunning, David; Thompson, Neil; Bartolini, Riccardo; Geng, Huiping; Huang, Zhirong; McNeil, Brian; /Strathclyde U.

    2012-06-25

    Optimization studies of an HHG-seeded harmonic cascade FEL design for the UK's proposed New Light Source (NLS) facility are presented. Three separate FELs are planned to meet the requirements for continuous coverage of the photon energy range 50-1000 eV with variable polarization, 20 fs pulse widths and good temporal coherence. The design uses an HHG seed source tuneable from 50-100 eV to provide direct FEL seeding in this range, and one or two stage harmonic cascades to reach the higher photon energies. Studies have been carried out to optimize a harmonic cascade FEL operating at 1 keV; topics investigated include modulator configuration, seed power level and ef- fects of the HHG seed structure. FEL simulations using realistic electron beam distributions are presented and tolerance to increased emittance has been considered.

  12. A beam trajectory monitor for the TTF-FEL

    SciTech Connect

    Ng, Johnny S. T.

    1997-06-01

    A method to determine the electron beam trajectory inside a long undulator module is described. Three-dimensional information is obtained by imaging the spontaneous radiation off-axis using pinholes and high resolution position sensors. The proposal for such a monitor for the SASE-FEL at the TESLA Test Facility is discussed.

  13. Operation of FERMI FELs for users

    NASA Astrophysics Data System (ADS)

    Svandrlik, M.

    2015-05-01

    The FERMI seeded free electron laser facility, located at the Elettra laboratory in Trieste (Italy), has been operated for user experiments in the past years using the first FEL line, FEL-1, covering the VUV - EVU spectral range (100 - 20 nm). After the conclusion of the commissioning for the soft-X ray FEL line, FEL-2, the facility is now ready to provide the scientific community with intense FEL pulses (<10 μJ) characterized by a high degree of coherence and spectral stability in the whole range from 100 nm down to 4 nm. We report about the recent achievement of FERMI FELs and our experience with operations for user requiring specific FEL configurations.

  14. Technical report of biota, FEL Site 1, Lawrence Livermore National Laboratory: Final report

    SciTech Connect

    Taylor, D.W.; Davilla, W.; Orloff, S.

    1986-09-26

    Lawrence Livermore National Laboratory is considering an expansion of laser test facilities adjacent to its existing LLNL Site 300 test location. Construction of a free-electron laser, known as the FEL Project, is being considered on approximately 3900 hectates (10,500 acres) of land. We will refer to this proposed site as FEL Site 1. Knowledge of the flora and vegetation resources of the proposed FEL Site 1 is necessary in order to plan for construction, operation, and possible future expansion of the FEL facility. The purpose of botanical sections of this report is to quantitatively describe the variation of vegetation on FEL Site 1, and to relate the vegetation to potential environmental impacts associated with present operation and possible expansion of site facilities. The primary purpose of the wildlife studies was to determine the presence and status of any endangered, threatened, fully protected, or otherwise sensitive species on FEL Site 1 that might be affected by the proposed FEL project. We directed our studies mainly toward the federally endangered San Joaquin kit fox (Vulpes macrotis mutica), but also toward another 14 special status species that potentially occur on site, including the state threatened Alameda striped racer (Masticophis lateralis euryxanthus).

  15. SUPERSTRUCTURES FOR HIGH CURRENT FEL APPLICATION

    SciTech Connect

    Jacek Sekutowicz; Kevin Beard; Peter Kneisel; Genfa Wu; Catherine Thomas; Zheng

    2003-05-01

    The next generations of FELs at TJNAF will produce coherent light at power levels of 10 kW and 100 kW, respectively [1]. To achieve these power levels, 200 MeV electron beams of 10 mA and 100 mA have to be accelerated in the linear accelerators of the devices. The accelerators will be based on superconducting technology. Stable operation of these machines is only possible if the cavity Higher Order Modes (HOM) excited by the beams can sufficiently be damped. One of the possible accelerating structures which can fulfill this requirement, is a superstructure (SST) made of two weakly coupled subunits and equipped with appropriate HOM couplers. Based on the positive experience at DESY with 1.3 GHz superstructures, we are investigating for possible use similar structures in the linacs for the FEL upgrades. We have built a copper model of the proposed superstructure, based on two copper models of the 5-cell CEBAF cavities. This contribution presents measured results on this model. We are now in the process of fabrication a Nb prototype and hope to perform its cold test by the end of this year.

  16. X-band prebunched FEL amplifier

    SciTech Connect

    Saito, Kazuyoshi; Takayama, Ken; Ozaki, Toshiyuki

    1995-12-31

    Following the successful results of the ion-channel-guiding FEL experiments, we began a new experiment {open_quotes}prebunched FEL{close_quotes}. It is an FEL driven by prebunched beams, whose configuration is a normal FEL system with a prebuncher like the bunching section of a klystron. There are two purposes in this prebunched FEL system; (1) Demonstration of a compact/efficient FEL. Attaining the saturation power level with a short wiggler length (compact wiggler) and enhancing the power through the remaining wiggler length by wiggler tapering (high efficiency FEL). (2) Experimental simulation of multi-stage FELs in the FEL-TBA. Examination of FEL interactions with prebunched injection beams, especially, about the controllability of the output RF phase by changing the RF phase of the input seed power to the wiggler. Recent experimental results show: (1) The saturation power of 120MW has been attained at the wiggler length of 1.1m by 1.5MeV prebunched beams with a 45%-modulated 750A current. However, enhanced power has not been observed yet by wiggler tapering. (2) The current modulation of the injection beam (1.5MeV-500A) becoming higher than 30%, the adjustable range of the output RF phase was limitted less than 40 degrees by the input power of 60kW only. Detail explanations of design concept, theoretical and experimental results will be presented at the conference.

  17. RF FEL for power beaming

    NASA Astrophysics Data System (ADS)

    Burke, Robert

    The laser device components associated with operating a radio frequency-free electron laser (RF-FEL) for beaming power from Earth were designed and tested. Analysis of the power beaming system requirements reveals that the FEL, identified by NASA as the laser of choice, is the major subsystem requiring demonstration before proceeding further in proving the efficacy of laser power beaming. Rocketdyne has identified a series of low cost, low risk demonstrations which proceed sequentially, as follows: (1) a 1 kW proof-of-principle demonstration; (2) a 150 kW demonstration of beaming power to a satellite; and (3) a MW class demonstration of Earth to lunar surface power transmission. This sequence of events can be completed in 5.5 years at a cost of $188M, with key milestones each year.

  18. Prospects for the FEL (Free Electron Laser)

    SciTech Connect

    Sessler, A.M.

    1989-04-01

    The future for FELs depends upon the very large number of applications which is envisioned for them. These grow out of the FEL extensive range of wavelengths, tunability, and high power capability. High power requires demonstration of optical guiding. Tunability has already been demonstrated. And the effort to extend the range of wavelengths is ever ongoing. The future will also bring more work on gas-loaded FELs, on electromagnetic wigglers, and on harmonic generation. We can, also, look forward to observation of various new effects, a few of which will be described. Finally, a list of various FEL projects around the world will be given. 12 refs., 5 figs., 8 tabs.

  19. A concept for Z-dependent microbunching measurements with coherent X-ray transition radiation in a sase FEL

    SciTech Connect

    Lumpkin, A.H.; Fawley, W.M.; Rule, D.W.

    2004-09-10

    We present an adaptation of the measurements performed in the visible-to-VUV regime of the z-dependent microbunching in a self-amplified spontaneous emission (SASE) free-electron laser (FEL). In these experiments a thin metal foil was used to block the more intense SASE radiation and to generate coherent optical transition radiation (COTR) as one source in a two-foil interferometer. However, for the proposed x-ray SASE FELs, the intense SASE emission is either too strongly transmitted at 1.5 Angstrom or the needed foil thickness for blocking scatters the electron beam too much. Since x-ray transition radiation (XTR) is emitted in an annulus with opening angle 1/g = 36 mrad for 14.09-GeV electrons, we propose using a thin foil or foil stack to generate the XTR and coherent XTR (CXTR) and an annular crystal to wavelength sort the radiation. The combined selectivity in angle and wavelength will favor the CXTR over SASE by about eight orders of magnitude. Time-dependent GINGER simulations support the z-dependent gain evaluation plan.

  20. Simulations of the LANL regenerative amplifier FEL

    SciTech Connect

    Kesselring, M.; Colson, W.B.; Wong, R.K.; Sheffield, R.L.

    1997-08-01

    The LANL regenerative amplifier FEL is designed to produce an average output power of 1 kW. Simulations study the transverse effects due to guiding by the intense electron beam and feedback. These simulations coupled with experimental measurements can be used to improve future high-power FEL designs.

  1. Compact FEL`s based on slow wave wigglers

    SciTech Connect

    Riyopoulos, S.

    1995-12-31

    Slow waves excited in magnetron-type cavities are attractive canditates as wigglers for compact Free Electron Lasers. Because of group velocities much below the speed of light, slow waves offer an order of magnitude increase in FEL gain under given circulating power in the wiggler resonator, compared to fast wave wigglers of similar period. In addition, they offer the versatility of operation either at modest beam energy via upshifing of the fundamental wavelength, or at low beam energy benefiting from the submillimeter wiggler harmonics. Because the main electron undulation is in the transverse direction for all spatial harmonics, the radiated power is increased by a factor {gamma}{sup 2} relative to the Smith-Purcell approach that relies on axial electron undulation. Technical advantages offered by magnetron-type wiggles are: the generation of the wiggler microwaves and the FEL interaction take place inside the same cavity, avoiding the issue of high power coupling between cavities; the excitation of wiggler microwaves relies on distributed electron emission from the cavity wall and does not require separate beam injection.

  2. Recent developments in CrystFEL 1

    PubMed Central

    White, Thomas A.; Mariani, Valerio; Brehm, Wolfgang; Yefanov, Oleksandr; Barty, Anton; Beyerlein, Kenneth R.; Chervinskii, Fedor; Galli, Lorenzo; Gati, Cornelius; Nakane, Takanori; Tolstikova, Alexandra; Yamashita, Keitaro; Yoon, Chun Hong; Diederichs, Kay; Chapman, Henry N.

    2016-01-01

    CrystFEL is a suite of programs for processing data from ‘serial crystallography’ experiments, which are usually performed using X-ray free-electron lasers (FELs) but also increasingly with other X-ray sources. The CrystFEL software suite has been under development since 2009, just before the first hard FEL experiments were performed, and has been significantly updated and improved since then. This article describes the most important improvements which have been made to CrystFEL since the first release version. These changes include the addition of new programs to the suite, the ability to resolve ‘indexing ambiguities’ and several ways to improve the quality of the integrated data by more accurately modelling the underlying diffraction physics. PMID:27047311

  3. Integrated computer simulation on FIR FEL dynamics

    SciTech Connect

    Furukawa, H.; Kuruma, S.; Imasaki, K.

    1995-12-31

    An integrated computer simulation code has been developed to analyze the RF-Linac FEL dynamics. First, the simulation code on the electron beam acceleration and transport processes in RF-Linac: (LUNA) has been developed to analyze the characteristics of the electron beam in RF-Linac and to optimize the parameters of RF-Linac. Second, a space-time dependent 3D FEL simulation code (Shipout) has been developed. The RF-Linac FEL total simulations have been performed by using the electron beam data from LUNA in Shipout. The number of particles using in a RF-Linac FEL total simulation is approximately 1000. The CPU time for the simulation of 1 round trip is about 1.5 minutes. At ILT/ILE, Osaka, a 8.5MeV RF-Linac with a photo-cathode RF-gun is used for FEL oscillation experiments. By using 2 cm wiggler, the FEL oscillation in the wavelength approximately 46 {mu}m are investigated. By the simulations using LUNA with the parameters of an ILT/ILE experiment, the pulse shape and the energy spectra of the electron beam at the end of the linac are estimated. The pulse shape of the electron beam at the end of the linac has sharp rise-up and it slowly decays as a function of time. By the RF-linac FEL total simulations with the parameters of an ILT/ILE experiment, the dependencies of the start up of the FEL oscillations on the pulse shape of the electron beam at the end of the linac are estimated. The coherent spontaneous emission effects and the quick start up of FEL oscillations have been observed by the RF-Linac FEL total simulations.

  4. Energy stability in a high average power FEL

    SciTech Connect

    Mermings, L.; Bisognano, J.; Delayen, J.

    1995-12-31

    Recirculating, energy-recovering linacs can be used as driver accelerators for high power FELs. Instabilities which arise from fluctuations of the cavity fields or beam current are investigated. Energy changes can cause beam loss on apertures, or, when coupled to M, phase oscillations. Both effects change the beam induced voltage in the cavities and can lead to unstable variations of the accelerating field. Stability analysis for small perturbations from equilibrium is performed and threshold currents are determined. Furthermore, the analytical model is extended to include feedback. Comparison with simulation results derived from direct integration of the equations of motion is presented. Design strategies to increase the instability threshold are discussed and the UV Demo FEL, proposed for construction at CEBAF, and the INP Recuperatron at Novosibirsk are used as examples.

  5. Progress at the Jefferson Laboratory FEL

    SciTech Connect

    Tennant, Christopher

    2009-01-01

    As the only currently operating free electron laser (FEL) based on a CW superconducting energy recovering linac (ERL), the Jefferson Laboratory FEL Upgrade remains unique as an FEL driver. The present system represents the culmination of years of effort in the areas of SRF technology, ERL operation, lattice design, high power optics and DC photocathode gun technology. In 2001 the FEL Demo generated 2.1 kW of laser power. Following extensive upgrades, in 2006 the FEL Upgrade generated 14.3 kW of laser power breaking the previous world record. The FEL Upgrade remains a valuable testbed for studying a variety of collective effects, such as the beam breakup instability, longitudinal space charge and coherent synchrotron radiation. Additionally, there has been exploration of operation with lower injection energy and higher bunch charge. Recent progress and achievements in these areas will be presented, and two recent milestones â installation of a UV FEL and establishment of a DC gun test s

  6. Laser-Pumped Coherent X-Ray FEL

    DTIC Science & Technology

    2008-11-14

    laser field replaces the magnetic wiggler field of a conventional FEL. Depending on the intensity and quality of both the electron beam and pump laser...and Line Width 16 IV. Comparison of Theory with Simulations 17 a) Wiggler based X-Ray FEL 17 b) Laser Pumped X-Ray FEL 18 V. Conclusions 19...FEL) an intense laser field replaces the magnetic wiggler field of a conventional FEL. Depending on the intensity and quality of both the electron

  7. SASE FEL Polarization Control Using Crossed Undulator

    SciTech Connect

    Ding, Yuantao; Huang, Zhirong; /SLAC

    2008-09-30

    There is a growing interest in producing intense, coherent x-ray radiation with an adjustable and arbitrary polarization state. In this paper, we study the crossed undulator scheme for rapid polarization control in a self-amplified spontaneous emission (SASE) free electron laser (FEL). Because a SASE source is a temporally chaotic light, we perform a statistical analysis on the state of polarization using FEL theory and simulations. We show that by adding a small phase shifter and a short (about 1.3 times the FEL power gain length), 90{sup o} rotated planar undulator after the main SASE planar undulator, one can obtain circularly polarized light--with over 80% polarization--near the FEL saturation.

  8. Temporal characteristics of a SASE FEL.

    SciTech Connect

    Li, Y,; Huang, Z.; Kim, K.-J.; Lewellen, J.; Milton, S. V.; Sajaev, V.

    2003-01-01

    We have performed a single-shot, time-resolved measurement of the output field of a SASE FEL using the frequency-resolved optical gating (FROG) technique. The measurement reveals the phase and the amplitude of the SASE output as functions of time and frequency, hence enables us to perform a full characterization of the SASE FEL output. We examined both the single-shot field evolution as well as the statistics over multiple shots on the phase and intensity evolution.

  9. Ther FERMI FEL project at TRIESTE

    SciTech Connect

    Walker, R.P.; Bulfone, D.; Cargnello, F.

    1995-12-31

    The goal of the FERMI project - Free Electron Radiation and Matching Instrumentation - is to construct a new user facility for FEL radiation beams covering a broad spectral range (2-250 {mu}m) to complement the high brightness VUV/Soft-Xray radiation available from the ELETTRA synchrotron radiation facility at Trieste. A unique feature of the project will be the possibility of carrying out {open_quote}pump-probe{close_quote} experiments using synchronized radiation beams from FERMI and ELETTRA on the same sample. The project was launched at a meeting with Italian FEL experts held in Trieste on the 18th November 1994, chaired by C. Rubbia, as a collaboration between Sincrotrone Trieste, ENEA (Frascati), INFN (Frascati) and the University of Naples (Department of Electronic Engineering). The facility will make use of an existing linac, that forms part of the ELETTRA injection system, and a hall into which the beam can be extracted. In addition, for the first phase of the project equipment will be used from the suspended INFN/ENEA {open_quote}SURF{close_quote} FEL experiment, including the undulator, beam transport magnets and optical cavity. In this first International FEL Conference report on the project, we summarize the main features of the project, concentrating in particular on the most recent activities, including: results of measurements of the linac beam in the FEL mode of operation, further studies of the electron beam transport system including possibilities for bunch length manipulations, and further numerical calculations of the FEL performance.

  10. Predicted performance of a multi-section VUV FEL with the Amsterdam pulse stretcher and storage ring AmPS

    SciTech Connect

    Bazylev, V.A.; Pitatelev, M.I.; Tulupov, A.V.

    1995-12-31

    A design is proposed to realize a VUV FEL with the Amsterdam Pulse Stretcher and Storage Ring (AmPS). The FEL is based on 4 identical undulator sections and 3 dispersive sections. The total magnetic system has a length of 12 m. 3 D simulations with the actual electron beam parameters of AmPS have been done with a version of TDA code modified for multi-sectional FELs. The spectral range between 50 and 100 nm has been considered. The simulations show that an amplification as large as 1*E5 - 1*E7 can be achieved. The amplification can be enhanced by a further optimisation procedure.

  11. Optical beam transport system at FEL-SUT

    NASA Astrophysics Data System (ADS)

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

    2000-05-01

    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.

  12. Towards attosecond X-ray pulses from the FEL

    SciTech Connect

    Zholents, Alexander A.; Fawley, William M.

    2004-07-01

    The ability to study ultrafast phenomena has been recently advanced by the demonstrated production and measurement of a single, 650-attosecond (10{sup 18} sec), VUV x-ray pulse[1] and, latter, a 250-attosecond pulse[2]. The next frontier is a production of the x-ray pulses with shorter wavelengths and in a broader spectral range. Several techniques for a generation of an isolated, attosecond duration, short-wavelength x-ray pulse based upon the ponderomotive laser acceleration [3], SASE and harmonic cascade FELs ([4] - [6]) had been already proposed. In this paper we briefly review a technique proposed in [5] and present some new results.

  13. Wavelength dependent delay in the onset of FEL tissue ablation

    SciTech Connect

    Tribble, J.A.; Edwards, G.S.; Lamb, J.A.

    1995-12-31

    We are investigating the wavelength dependence of the onset of laser tissue ablation in the IR Visible and UV ranges. Toward this end, we have made simultaneous measurements of the ejected material (using a HeNe probe beam tangential to the front surface) and the residual stress transient in the tissue (using traditional piezoelectric detection behind the thin samples). For the IR studies we have used the Vanderbilt FEL and for the UV and Vis range we have used a Q-switched ND:Yag with frequency doubling and quadrupling. To satisfy the conditions of the near field limit for the detection of the stress transient, the duration of the IR FEL macropulse must be as short as possible. We have obtained macropulses as short as 100 ns using Pockels Cell technology. The recording of the signals from both the photodiode monitoring the HeNe probe beam and the acoustic detector are synchronized with the arrival of the 100 ns macropulse. With subablative intensities, the resulting stress transient is bipolar with its positive peak separated from its negative peak by 100 ns in agreement with theory. Of particular interest is the comparison of ablative results using 3 {mu}m and 6.45 {mu}m pulses. Both the stress transient and the ejection of material suffer a greater delay (with respect to the arrival of the 100 ns pulse) when the FEL is tuned to 3 {mu}m as compared to 6.45 {mu}m. A comparison of IR Vis and UV data will be discussed in terms of microscopic mechanisms governing the laser ablation process.

  14. FEL options for power beaming

    SciTech Connect

    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{sub L} = 200kW. The wavelength is chosen to be {lambda} = 0.84 {micro}m, 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.

  15. Summary of the working group on FEL theory

    SciTech Connect

    Pellegrini, C.

    1984-01-01

    The working group on FEL theory dedicated most of its discussions to topics relevant to the high gain regime in a free electron laser. In addition the area of interest was mainly restricted to FELs for the production of XUV radiation (<1000 A). A list of the topics that were felt to be relevant is: (1) characterization of the FEL high gain regime; (2) the amplified spontaneous emission mode of operation (ASE); (3) superradiance in FELs; (4) diffraction effects for high gain FELs; (5) noise and start-up; (6) coherence properties of the radiation for the ASE and superradiant FELS. 9 references.

  16. Assessment of the visibility impairment caused by the emissions from the proposed power plant at Boron, California

    NASA Technical Reports Server (NTRS)

    Bergstrom, R. W.; Doyle, J. R.; Johnson, C. D.; Holman, H. Y.; Wojcik, M. A.

    1980-01-01

    The current atmospheric conditions and visibility were modeled, and the effect of the power plant effluent was then added to determine its influence upon the prevailing visibility; the actual reduction in visibility being a function of meteorological conditions and observer-plume-target geometry. In the cases investigated, the perceptibility of a target was reduced by a minimum of 10 percent and a maximum of 100 percent. This significant visual impact would occur 40 days per year in the Edwards area with meteorological conditions such as to cause some visual impact 80 days per year.

  17. Polarization control in X-ray FELs by reverse undulator tapering

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    Baseline design of a typical X-ray FEL undulator assumes a planar configuration which results in a linear polarization of the FEL radiation. However, many experiments at X-ray FEL user facilities would profit from using a circularly polarized radiation. As a cheap upgrade one can consider an installation of a short helical (or cross-planar) afterburner, but then one should have an efficient method to suppress powerful linearly polarized background from the main undulator. In this paper we propose a new method for such a suppression: an application of the reverse taper in the main undulator. We discover that in a certain range of the taper strength, the density modulation (bunching) at saturation is practically the same as in the case of non-tapered undulator while the power of linearly polarized radiation is suppressed by orders of magnitude. Then strongly modulated electron beam radiates at full power in the afterburner. Considering SASE3 undulator of the European XFEL as a practical example, we demonstrate that soft X-ray radiation pulses with peak power in excess of 100 GW and an ultimately high degree of circular polarization can be produced. The proposed method is rather universal, i.e. it can be used at SASE FELs and seeded (self-seeded) FELs, with any wavelength of interest, in a wide range of electron beam parameters, and with any repetition rate.

  18. Multi-stage FEL amplifier with diaphragm focusing line as direct energy driver for inertial confinement fusion

    SciTech Connect

    Saldin, E.L.; Schneidmiller, E.A.; Ulyanov, Yu.N.

    1995-12-31

    An FEL based energy driver for Inertial Confinement Fusion (ICF) is proposed. The key element of the scheme is free electron laser system. Novel technical solutions, namely, using of multichannel, multi-stage FEL amplifier with diaphragm focusing line, reveal a possibility to construct the FEL system operating at radiation wavelength {lambda} = 0.5 {mu}m and providing flush energy E = 1 MJ and brightness 4 x 10{sup 22} W cm{sup -2} sr{sup -1} within steering pulse duration {tau} {approximately} 0.1-2 ns. Total energy efficiency of the proposed ICF energy driver is about of 11% and repetition rate is 40 Hz. It is shown that the FEL based ICF energy driver may be constructed at the present level of accelerator technique R& D.

  19. High quality electron beams for high quality FEL

    NASA Astrophysics Data System (ADS)

    Allaria, E.

    2017-05-01

    Thanks to the use of seeding, modern high gain FELs can now produce high power pulses with a longitudinal coherence much higher than normally available from SASE FELs. This possibility of fully coherent FEL pulses in the X-ray spectral range has several benefits for user's experiment and also it opens the door to new experimental possibilities such as coherent control experiments. The achievement of a full coherence in the FEL pulses does not only requires a coherent seed but also needs an electron beam whose properties does not change over the length of the final FEL pulse. For this reason, requirements for electron beam quality in seeded FELs are significantly higher than for SASE FEL. Starting from the FERMI experience we report in the talk examples of small electron beam perturbations that have a large impact on FEL properties.

  20. Design study of a longer wavelength FEL for FELIX

    SciTech Connect

    Lin, L.; Oepts, D.; Meer, A.F.G. van der

    1995-12-31

    We present a design study of FEL3, which will extend the FELIX spectral range towards a few hundred microns. A rectangular waveguide will be used to reduce diffraction losses. Calculations show that with a waveguide gap of 1 cm, only one sinusoidal mode along the guided direction can exist within the FEL gain bandwidth, thus excluding group velocity dispersion and lengthening of short radiation pulses. To incorporate FEL3 in the existing FELIX facility, two options are being considered: to combine FEL3 with FEL1 by insertion of a waveguide into FEL1, and to build a dedicated third beam line for FEL3 after the two linacs. Expected FEL performance: gain, spectrum, power, pulse shape, etc., will be presented based on numerical simulations.

  1. X-ray FEL Simulation with the MPP version of the GINGER Code

    NASA Astrophysics Data System (ADS)

    Fawley, William

    2001-06-01

    GINGER is a polychromatic, 2D (r-z) PIC code originally developed in the 1980's to examine sideband growth in FEL amplifiers. In the last decade, GINGER simulations have examined various aspects of x-ray and XUV FEL's based upon initiation by self-amplified spontaneous emission (SASE). Recently, GINGER's source code has been substantially updated to exploit many modern features of the Fortran90 language and extended to exploit multiprocessor hardware with the result that the code now runs effectively on platforms ranging from single processor workstations in serial mode to MPP hardware at NERSC such as the Cray-T3E and IBM-SP in full parallel mode. This poster discusses some of the numerical algorithms and structural details of GINGER which permitted relatively painless porting to parallel architectures. Examples of some recent SASE FEL modeling with GINGER will be given including both existing experiments such as the LEUTL UV FEL at Argonne and proposed projects such as the LCLS x-ray FEL at SLAC.

  2. On a theory of an FEL amplifier with circular waveguide and guiding magnetic field

    SciTech Connect

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

    1995-12-31

    We consider an FEL amplifier with an axisymmetric electron beam, circular waveguide, helical undulator and guiding magnetic field. The presented nonlinear theory of the FEL amplifier is based on Hamiltonian description of particle motion and radiation field representation with Green function method. The space charge fields, energy spread and diffraction effects are taken into consideration. Such an FEL amplifier configuration possesses some peculiarities when it operates in a regime with the negative longitudinal mass (i.e. when{mu}{sup -1}{proportional_to}dv{sub z}/dE < 0). It is shown that in the presence of strong space charge fields, the so-called {open_quotes}negative mass{close_quotes} instability may influence significantly on the FEL amplifier operation resulting in a significant increase in the FEL amplifier efficiency. It is proposed in the presented paper to use the effect of the {open_quotes}negative mass instability{close_quotes} to achieve an effective bunching of the CERN Linear Collider (LIC) driving beam.

  3. The Jefferson Lab 1 KW IR FEL

    SciTech Connect

    D. Douglas for the Jefferson Lab IR Demo FEL Team

    2000-08-01

    The Jefferson Lab (JLab) IR Demo Free Electron Laser (FEL) has completed commissioning and is initiating user service. The FEL - a high repetition rate, low extraction efficiency wiggler-driven optical cavity resonator - produces over 1 kW of tuneable light on intervals in a 3-6 lim wavelength range. It is driven by a 35-48 MeV, 5 mA superconducting RF (SRF) based energy-recovering continuous wave (CW) electron linac. The driver accelerator meets requirements imposed by low energy, high current, and a demand for stringent beam control at the wiggler and during energy recovery. These constraints are driven by the need for six-dimensional phase space management, the existence of deleterious collective phenomena (space charge, wake-fields, beam break-up, and coherent synchrotron radiation), and interactions between the FEL and the accelerator RF. The authors detail the system design, relate commissioning highlights, and discuss present performance.

  4. The Calcium Goes Meow: Effects of Ions and Glycosylation on Fel d 1, the Major Cat Allergen.

    PubMed

    Ligabue-Braun, Rodrigo; Sachett, Liana Guimarães; Pol-Fachin, Laércio; Verli, Hugo

    2015-01-01

    The major cat allergen, Fel d 1, is a structurally complex protein with two N-glycosylation sites that may be filled by different glycoforms. In addition, the protein contains three putative Ca2+ binding sites. Since the impact of these Fel d 1 structure modifications on the protein dynamics, physiology and pathology are not well established, the present work employed computational biology techniques to tackle these issues. While conformational effects brought upon by glycosylation were identified, potentially involved in cavity volume regulation, our results indicate that only the central Ca2+ ion remains coordinated to Fel d 1 in biological solutions, impairing its proposed role in modulating phospholipase A2 activity. As these results increase our understanding of Fel d 1 structural biology, they may offer new support for understanding its physiological role and impact into cat-promoted allergy.

  5. Multidimensional simulation studies of the SELENE FEL oscillator/buncher followed by a radiator/amplifier output scheme

    SciTech Connect

    Hahn, S.J.; Fawley, W.M.

    1995-02-01

    We analyze and present numerical simulations of the so-called electron output scheme [G. I. Erg et al., 15th Int. FEL Conf., The Hague, The Netherlands, 1993, Book of Abstracts p. 50; Preprint Budker INP 93-75] applied to the SELENE proposal of using a high power FEL to illuminate satellite solar cells. In this scheme, a first stage FEL oscillator bunches the electron beam while a second stage ``radiator`` extracts high power radiation. Our analysis suggests only in the case where the radiator employs a long, tapered undulator will the electron output scheme produce a significant increase in extraction efficiency over what is obtainable from a simple, single-stage oscillator. 1- and 2-D numerical simulations of a 1.7{mu}m FEL employing the electron output scheme show reasonably large bunching fractions ({approximately} 0.3--0.4) at the output of the oscillator stage but only {le}2% extraction efficiency from the radiator stage.

  6. The Calcium Goes Meow: Effects of Ions and Glycosylation on Fel d 1, the Major Cat Allergen

    PubMed Central

    Pol-Fachin, Laércio; Verli, Hugo

    2015-01-01

    The major cat allergen, Fel d 1, is a structurally complex protein with two N-glycosylation sites that may be filled by different glycoforms. In addition, the protein contains three putative Ca2+ binding sites. Since the impact of these Fel d 1 structure modifications on the protein dynamics, physiology and pathology are not well established, the present work employed computational biology techniques to tackle these issues. While conformational effects brought upon by glycosylation were identified, potentially involved in cavity volume regulation, our results indicate that only the central Ca2+ ion remains coordinated to Fel d 1 in biological solutions, impairing its proposed role in modulating phospholipase A2 activity. As these results increase our understanding of Fel d 1 structural biology, they may offer new support for understanding its physiological role and impact into cat-promoted allergy. PMID:26134118

  7. The APS SASE FEL : modeling and code comparison.

    SciTech Connect

    Biedron, S. G.

    1999-04-20

    A self-amplified spontaneous emission (SASE) free-electron laser (FEL) is under construction at the Advanced Photon Source (APS). Five FEL simulation codes were used in the design phase: GENESIS, GINGER, MEDUSA, RON, and TDA3D. Initial comparisons between each of these independent formulations show good agreement for the parameters of the APS SASE FEL.

  8. Scaling formulae for FEL operating in linear and non linear regime

    SciTech Connect

    Dattoli, G.; Mezi, L.; Segreto, A.

    1995-12-31

    Scaling relations for the FEL gain, including the e-beam quality effects, have been usefully exploited to design FEL devices. We propose further extension of the above formulae including high gain, inhomogeneous broadening and saturation effects. A crucial role to get these relations is the use of approximant methods generalizing the Pade procedure. We derive gain equations containing the corrections due to energy spread, emittances and field intensity. It is shown that these equations can be exploited to {open_quotes}simulate{close_quotes} the FEL evolution with an almost negligible computational effort. Comments on the role of the saturation intensity and its dependence on the e-beam quality, high gain corrections etc. are also presented.

  9. Analysis of slippage in THz-FEL with a parallel plate waveguide

    NASA Astrophysics Data System (ADS)

    Deng, L. Z.; Tan, P.; Qin, B.; Xiong, Y. Q.

    2014-03-01

    An approach is proposed to analyze the slippage of waveguide FEL. Based on what we find that the derivative of the detuning parameter with respect to the axial wavenumber is proportional to the slippage, several expressions of slippage are derived for analyzing slippage. The analysis results show that both zero-slippage and maximal slippage can be obtained at specific conditions. Especially for the given parameters of THz-FEL oscillator which is under development at Huazhong University of Science and Technology (HUST), the maximal slippage occurs when the parameter Δ approximately equals to 0.5. Then by analyzing the slippage in HUST THz-FEL oscillator, the parallel plate waveguide with the dimension of 4-6 mm is considered for optimum design.

  10. Optimization of the lattice function in the planar undulator applied for terahertz FEL oscillators

    NASA Astrophysics Data System (ADS)

    Yang, Lei; Qin, Bin; Yang, Jun; Liu, Xia-Ling; Tan, Ping; Hu, Tong-Ning

    2014-03-01

    Since the beta function of the electron beam within the undulator has a great influence on the power gain of the free electron laser (FEL), optimization of the undulator lattice becomes important. In this paper, the transfer matrix of the planar undulator is obtained from differential equations of the electron motion. Based on this, the lattice function of the planar undulator in a terahertz FEL oscillator proposed by Huazhong University of Science and Technology (HUST-FEL) is optimized and the expressions of the average beta function are derived. The accuracy of the optimization result was confirmed well by the numerical method. The application range of this analytical method is given as well. At last, the emittance growth in the horizontal direction due to the attenuation of the magnetic field is discussed.

  11. Physical design of FEL injector based on the performance-enhanced EC-ITC RF gun

    NASA Astrophysics Data System (ADS)

    Hu, Tong-Ning; Chen, Qu-Shan; Pei, Yuan-Ji; Li, Ji; Qin, Bin

    2014-01-01

    To meet the requirements of high performance THz-FEL (Free Electron Laser), a compact scheme of FEL injector was proposed. A thermionic cathode was chosen to emit electrons instead of a photo-cathode with its complex structure and high cost. The effective bunch charge was improved to ~200 pC by adopting an enhanced EC-ITC (External Cathode Independently Tunable Cells) RF gun to extract micro-bunches; back bombardment effects were almost eliminated as well. Constant gradient accelerator structures were designed to improve energy to ~14 MeV, while the focusing system was applied for emittance suppressing and bunch state maintenance. The physical design and beam dynamics of the key components for the FEL injector were analyzed. Furthermore, start-to-end simulations with multi-pulses were performed using homemade MATLAB and Parmela. The results show that continual high brightness electron bunches with a low energy spread and emittance could be obtained stably.

  12. Powerful electrostatic FEL: Regime of operation, recovery of the spent electron beam and high voltage generator

    SciTech Connect

    Boscolo, I.; Gong, J.

    1995-02-01

    FEL, driven by a Cockcroft-Walton electrostatic accelerator with the recovery of the spent electron beam, is proposed as powerful radiation source for plasma heating. The low gain and high gain regimes are compared in view of the recovery problem and the high gain regime is shown to be much more favourable. A new design of the onion Cockcroft-Walton is presented.

  13. Studies for a beam trajectory monitor for TTF-FEL at DESY

    SciTech Connect

    Mueller, Ute Carina

    1997-06-01

    A beam trajectory monitor for the FEL at the TESLA test facility at DESY has been proposed for the reconstruction of the electron beam trajectory by observing the spontaneous undulator radiation along the beam using the pinhole camera principle. Simulations for this concept have been performed and results are presented here.

  14. A high-power compact regenerative amplifier FEL

    SciTech Connect

    Nguyen, D.C.; Sheffield, R.L.; Fortgang, C.M.; Kinross-Wright, J.M.; Ebrahim, N.A.; Goldstein, J.C.

    1997-08-01

    The Regenerative Amplifier FEL (RAFEL) is a new FEL approach aimed at achieving the highest optical power from a compact rf-linac FEL. The key idea is to feed back a small fraction (< 10%) of the optical power into a high-gain ({approximately}10{sup 5} in single pass) wiggler to enable the FEL to reach saturation in a few passes. This paper summarizes the design of a high-power compact regenerative amplifier FEL and describes the first experimental demonstration of the RAFEL concept.

  15. Some novel features of an FEL oscillator with tapered undulator

    SciTech Connect

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

    1995-12-31

    A one-dimensional analysis of an FEL oscillator with a linear undulator tapering is presented. Some principally novel results have been obtained. The origin of these results is in principal difference between the FEL oscillator and an FEL amplifier. In the case of the FEL amplifier the frequency of the amplified wave and all the other parameters are defined by an experimenter. Contrary to this, the case of the FEL oscillator with tapered undulator is more complicated. The lasing frequency is defined by the maximum of the small-signal gain and depends on the tapering depth in some complex way.

  16. A compact FEL upconverter of coherent radiation

    SciTech Connect

    Liu, Y.; Marshall, T.C.

    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.

  17. Grating-based pulse compressor for applications to FEL sources

    NASA Astrophysics Data System (ADS)

    Poletto, Luca; Frassetto, Fabio; Miotti, Paolo; Gauthier, David; Fajardo, Marta; Mahieu, Benoit; Svetina, Cristian; Zangrando, Marco; Zeitoun, Philippe; De Ninno, Giovanni

    2015-05-01

    We present the optical layout of a reflective grating compressor specifically designed for extreme-ultraviolet FEL sources. The working principle is based on the use of a couple of constant-line-spaced gratings used at grazing incidence and illuminated in divergent light. The two possible grating configurations, namely the on-plane and off-plane, are analyzed and compared. The Group Delay Dispersion (GDD) introduced by the compressor is analytically analyzed and quantified. The spatial chirp also is considered, and its effect analyzed. The deviation from the ideal case in which the instrument is feed with a collimated beam is considered. The effect of the beam divergence on the compressor response is quantified and the attenuation of this effect by a "de-tuning" of the compressor is proposed. This solution avoids the use of a pre-collimating optics, therefore incrementing the total instrumental throughput. Finally, it is shown the optical design of an actual compressor for the FERMI FEL, that can be inserted in the optical path without any deviation or translation of the photon beam with respect to the nominal path.

  18. Design and simulations of CAEP THz FEL resonator

    NASA Astrophysics Data System (ADS)

    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%.

  19. On a theory of an FEL oscillator with multicomponent undulator

    SciTech Connect

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

    1995-12-31

    Some novel results of a theory of an FEL oscillator with multicomponent undulator are presented. Two popular FEL oscillator configuration are under consideration: optical klystron and FEL oscillator with a prebuncher and tapered main undulator. Using similarity techniques, universal formulae and plots are obtained which allow one to calculate the FEL oscillator lasing conditions an output parameters at saturation. A one-dimensional analysis of an FEL oscillator with a linear undulator tapering is presented. Some principally novel results have been obtained. The origin of these results is in principal difference between the FEL oscillator and an FEL amplifier. In the case of the FEL amplifier the frequency of the amplified wave and all the other parameters are defined by an experimenter. Contrary to this, the case of the FEL oscillator with tapered undulator is more complicated. The lasing frequency is defined by the maximum of the small-signal gain and depends on the tapering depth in some complex way. In particular, at smooth increasing of the tapering depth, the lasing frequency may change by a leap and lasing occurs at another local maximum of the gain curve. This effect influences significantly on the FEL oscillator operation at saturation. As a result, generally accepted method of undulator tapering (for instance, by decreasing undulator field at fixed period) provides an efficiency increase only in a narrow range of the parameters of tapering. We show that in some cases, so called {open_quotes}negative tapering{close_quotes} (for instance, by increasing undulator field at fixed period) has a benefit against traditional tapering method. Ignoring of these basic features of the FEL oscillator with the tapered undulator have led many FEL research groups to nonoptimal design of the FEL experiments and incorrect interpretation of the obtained results.

  20. New RF gun for Novosibirsk ERL FEL

    NASA Astrophysics Data System (ADS)

    Volkov, Vladimir N.; Arbusov, Vladimir S.; Kenzhebulatov, Ermek K.; Kolobanov, Evgeniy I.; Kondakov, Aleksey A.; Kozyrev, Evgeniy V.; Krutikhin, Sergey A.; Kurkin, Grigoriy Ya.; Kuptsov, Igor V.; Motygin, Sergey V.; Ovchar, Vladimir K.; Petrov, Victor M.; Pilan, Andrey M.; Rotov, Evgeniy A.; Sedlyarov, Igor K.; Serednykov, Stanislav S.; Shevchenko, Oleg A.; Scheglov, Mikhail A.; Tribendis, Aleksey G.; Vinokurov, Nikolay A.

    The new radiofrequency (RF) gun making an intensive high-quality electron beam for injecting in Novosibirsk microtron recuperator (ERL) and driving Free Electron Laser (FEL) is made in Budker INP SB RAS. Bench tests of RF gun demonstrated good results in strict accordance with the calculations predicting average current of a bunch of 100 iA, energy of particles of 400 keV and normalized emittance less than 15 microns. The RF gun stand testing showed reliable work, unpretentious for vacuum conditions and stable in long-term operation. The additional injection beamline built-in to the existing system of the NovoFEL injector with the static gun is developed and designed.

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

    SciTech Connect

    Litvinenko, V.N.; Burnham, B.; Madey, J.M.J.

    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.

  2. Optical Klystron Enhancement to SASE X-ray FELs

    SciTech Connect

    Ding, Yuantao; Emma, Paul; Huang, Zhirong; Kumar, Vinit

    2006-04-07

    The optical klystron enhancement to self-amplified spontaneous emission (SASE) free electron lasers (FELs) is studied in theory and in simulations. In contrast to a seeded FEL, the optical klystron gain in a SASE FEL is not sensitive to any phase mismatch between the radiation and the microbunched electron beam. The FEL performance with the addition of four optical klystrons located at the undulator long breaks in the Linac Coherent Light Source (LCLS) shows significant improvement if the uncorrelated energy spread at the undulator entrance can be controlled to a very small level. In addition, FEL saturation at shorter x-ray wavelengths (around 1.0 A) within the LCLS undulator length becomes possible. We also discuss the application of the optical klystron in a compact x-ray FEL design that employs relatively low electron beam energy together with a shorter-period undulator.

  3. High-power, high-efficiency FELs

    SciTech Connect

    Sessler, A.M.

    1989-04-01

    High power, high efficiency FELs require tapering, as the particles loose energy, so as to maintain resonance between the electromagnetic wave and the particles. They also require focusing of the particles (usually done with curved pole faces) and focusing of the electromagnetic wave (i.e. optical guiding). In addition, one must avoid transverse beam instabilities (primarily resistive wall) and longitudinal instabilities (i.e sidebands). 18 refs., 7 figs., 3 tabs.

  4. Energy recovery transport design for PKU FEL

    SciTech Connect

    Guimei Wang; Yu-Chiu Chao; KUI Zhao; Xiangyang Lu; Jiejia Zhuang; Chuyu Liu; Zhenchao Liu; Jiaer Chen

    2007-06-25

    A free-electron laser based on superconducting linac is under construction in Peking University(PKU). To increase FEL output power, energy recovery is chosen as one of the most potential and popular way. The design of beam transport system for energy recovery is presented, which is suitable for Peking University construction area. Especially, a chicane structure is chosen to change path length at +/-18 degree and R56 in the arc is adjusted for fully bunch compression.

  5. FEL for the polymer processing industries

    NASA Astrophysics Data System (ADS)

    Kelley, Michael J.

    1997-05-01

    Polymers are everywhere in modern life because of their unique combination of end-use functionalities, ease of processing, recycling potential and modest cost. The physical and economic scope of the infrastructure committed to present polymers makes the introduction of entirely new chemistry unlikely. Rather, the breadth of commercial offerings more likely to shrink in the face of the widening mandate for recycling, especially of packaging. Improved performance and new functionality must therefore come by routes such as surface modification. However they must come with little environmental impact and at painfully low cost. Processing with strongly absorbed light offers unique advantages. The journal and patent literatures disclose a number of examples of benefits that can be achieved, principally by use of excimer lasers or special UV lamps. Examples of commercialization are few, however, because of the unit cost and maximum scale of existing light sources. A FEL, however, offers unique advantages: tunability to the optimum wavelength, potential for scale up to high average power, and a path to attractively low unit cost of light. A business analysis of prospective applications defines the technical and economic requirements a FEL for polymer surface processing must meet. These are compared to FEL technology as it now stands and as it is envisioned.

  6. Harmonic cascade FEL designs for LUX

    SciTech Connect

    Penn, G.; Reinsch, M.; Wurtele, J.; Corlett, J.N.; Fawley, W.M.; Zholents, A.; Wan, W.

    2004-07-16

    LUX is a design concept for an ultrafast X-ray science facility, based on an electron beam accelerated to GeV energies in are circulating linac. Included in the design are short duration (200 fs or shorter FWHM) light sources using multiple stages of higher harmonic generation, seeded by a 200-250 nm laser of similar duration. This laser modulates the energy of a group of electrons within the electron bunch; this section of the electron bunch then produces radiation at a higher harmonic after entering a second, differently tuned undulator. Repeated stages in a cascade yield increasing photon energies up to 1 keV. Most of the undulators in the cascade operate in the low-gain FEL regime. Harmonic cascades have been designed for each pass of the recirculating linac up to a final electron beam energy of 3.1 GeV. For a given cascade, the photon energy can be selected over a wide range by varying the seed laser frequency and the field strength in the undulators. We present simulation results using the codes GENESIS and GINGER, as well as the results of analytical models which predict FEL performance. We discuss lattice considerations pertinent for harmonic cascade FELs, as well as sensitivity studies and requirements on the electron beam.

  7. Future metrology needs for FEL reflective optics.

    SciTech Connect

    Assoufid, L.

    2000-09-21

    An International Workshop on Metrology for X-ray and Neutron Optics has been held March 16-17, 2000, at the Advanced Photon Source, Argonne National Laboratory, near Chicago, Illinois (USA). The workshop gathered engineers and scientists from both the U.S. and around the world to evaluate metrology instrumentation and methods used to characterize surface figure and finish for long grazing incidence optics used in beamlines at synchrotrons radiation sources. This two-day workshop was motivated by the rapid evolution in the performance of x-ray and neutron sources along with requirements in optics figure and finish. More specifically, the performance of future light sources, such as free-electron laser (FEL)-based x-ray sources, is being pushed to new limits in term of both brilliance and coherence. As a consequence, tolerances on surface figure and finish of the next generation of optics are expected to become tighter. The timing of the workshop provided an excellent opportunity to study the problem, evaluate the state of the art in metrology instrumentation, and stimulate innovation on future metrology instruments and techniques to be used to characterize these optics. This paper focuses on FEL optics and metrology needs. (A more comprehensive summary of the workshop can be found elsewhere.) The performance and limitations of current metrology instrumentation will be discussed and recommendations from the workshop on future metrology development to meet the FEL challenges will be detailed.

  8. Staged energy cascades for the LUX FEL

    SciTech Connect

    Penn, G.

    2004-07-27

    Designs and simulation studies for harmonic cascades, consisting of multiple stages of harmonic generation in free electron lasers (FELs), are presented as part of the LUX R&D project to design ultrafast, high photon energy light sources for basic science. Beam energies of 1.1, 2.1, and 3.1 GeV, corresponding to each pass through a recirculating linac, have independent designs for the harmonic cascade. Simulations were performed using the GENESIS FEL code, to obtain predictions for the performance of these cascades over a wide range of photon energies in terms of the peak power and laser profile. The output laser beam consists of photon energies of up to 1 keV, with durations of the order of 200 fs or shorter. The contribution of shot noise to the laser output is minimal, however fluctuations in the laser and electron beam properties can lead to variations in the FEL output. The sensitivity of the cascade to electron beam properties and misalignments is studied, taking advantage of the fact that GENESIS is a fully 3-dimensional code.

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

    SciTech Connect

    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.

  10. Oscillator Seeding of a High Gain Harmonic Generation FEL in a Radiator-First Configuration

    SciTech Connect

    Gandhi, P.; Wurtele, J.; Penn, G.; Reinsch, M.

    2012-05-20

    A longitudinally coherent X-ray pulse from a high repetition rate free electron laser (FEL) is desired for a wide variety of experimental applications. However, generating such a pulse with a repetition rate greater than 1 MHz is a significant challenge. The desired high repetition rate sources, primarily high harmonic generation with intense lasers in gases or plasmas, do not exist now, and, for the multi-MHz bunch trains that superconducting accelerators can potentially produce, are likely not feasible with current technology. In this paper, we propose to place an oscillator downstream of a radiator. The oscillator generates radiation that is used as a seed for a high gain harmonic generation (HGHG) FEL which is upstream of the oscillator. For the first few pulses the oscillator builds up power and, until power is built up, the radiator has no HGHG seed. As power in the oscillator saturates, the HGHG is seeded and power is produced. The dynamics and stability of this radiator-first scheme is explored analytically and numerically. A single-pass map is derived using a semi-analytic model for FEL gain and saturation. Iteration of the map is shown to be in good agreement with simulations. A numerical example is presented for a soft X-ray FEL.

  11. Strong focusing influence on high gain FEL characteristics

    SciTech Connect

    Smirnov, A.; Varfolomeev, A.

    1995-12-31

    The use of intrinsic alternating focusing in a linac-driven FEL with planar undulator is considered numerically. The analysis is done on the basis of TDA code for soft X-ray FEL with FD lattice implementing focusing of quadrupole and periodic sextupole type. The influence of the focusing (type and phase advance) on FEL performance and the reasons of difference in FEL performance for focusing of two kinds are analyzed. A possibility of some kind of beam conditioning for intrinsic focusing is discussed.

  12. Innovative FEL schemes using variable-gap undulators

    NASA Astrophysics Data System (ADS)

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

    2017-06-01

    We discuss theoretical background and experimental verification of advanced schemes for X-ray FELs using variable gap undulators (harmonic lasing self-seeded FEL, reverse taper etc.) Harmonic lasing in XFELs is an opportunity to extend operating range of existing and planned X-ray FEL user facilities. Contrary to nonlinear harmonic generation, harmonic lasing can provide much more intense, stable, and narrow-band FEL beam which is easier to handle due to the suppressed fundamental. Another interesting application of harmonic lasing is Harmonic Lasing Self-Seeded (HLSS) FEL that allows to improve longitudinal coherence and spectral power of a SASE FEL. Recently this concept was successfully tested at the soft X-ray FEL user facility FLASH in the wavelength range between 4.5 nm and 15 nm. That was also the first experimental demonstration of harmonic lasing in a high-gain FEL and at a short wavelength (before it worked only in infrared FEL oscillators). Another innovative scheme that was tested at FLASH2 is the reverse tapering that can be used to produce circularly polarized radiation from a dedicated afterburner with strongly suppressed linearly polarized radiation from the main undulator. This scheme can also be used for an efficient background-free production of harmonics in an afterburner. Experiments on the frequency doubling that allowed to reach the shortest wavelength at FLASH as well as on post-saturation tapering to produce a record intencity in XUV regime are also discussed.

  13. Start-Up of FEL Oscillator from Shot Noise

    SciTech Connect

    Kumar, V.; Krishnagopal, S.; Fawley, W.M.

    2007-01-25

    In free-electron laser (FEL) oscillators, as inself-amplified spontaneous emission (SASE) FELs, the buildup of cavitypower starts from shot noise resulting from the discreteness ofelectronic charge. It is important to do the start-up analysis for thebuild-up of cavity power in order to fix the macropulse width from theelectron accelerator such that the system reaches saturation. In thispaper, we use the time-dependent simulation code GINGER [1]toperformthis analysis. We present results of this analysis for theparameters of the Compact Ultrafast TErahertz FEL (CUTE-FEL) [2]beingbuilt atRRCAT.

  14. Design of High Power FELS and the Effects of Diffraction on Detuning in an FEL Oscillator

    DTIC Science & Technology

    2015-12-01

    DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) In experiments going back to the first free electron laser (FEL) oscillator at Stanford, the measured...Advisor Keith Cohn Second Reader Kevin Smith Chair, Department of Physics iii THIS PAGE INTENTIONALLY LEFT BLANK iv ABSTRACT In experiments going back to

  15. Where Would Economics Education Be without Rendigs Fels?

    ERIC Educational Resources Information Center

    Siegfried, John J.; And Others

    1994-01-01

    Discusses the career of Rendigs Fels from his first academic appointment in 1948 until the present. Concludes that Fels is one of a small number of respected economists who have made interest, involvement, and research in the teaching of economics an important and respectable part of the profession. (CFR)

  16. Feedback Requirements for SASE-FELs

    SciTech Connect

    Loos, Henrik; /SLAC

    2012-07-06

    The operation of a Self Amplified Spontaneous Emission (SASE) Free Electron Lasers (FEL) at soft and hard X-ray wavelengths driven by a high brightness electron beam imposes strong requirements on the stability of the accelerator and feedback systems are necessary to both guarantee saturation of the SASE process as well as a stable photon beam for user experiments. Diagnostics for the relevant transverse and longitudinal beam parameters are presented and various examples of feedback systems for bunches with low repetition rate as well as systems for intra bunch train feedbacks are discussed.

  17. Gain results for low voltage FEL

    SciTech Connect

    Shaw, A.; Stuart, R.A.; Al-Shamma`a, A.

    1995-12-31

    We have designed and constructed a low voltage (130 kV) FEL system capable of operating in the microwave frequency range for which the electron beam current is cw (rather than pulsed) in time at a level of {approximately} 12 mA. The gain of this system has been measured as a function of the electron beam accelerating voltage and current level, and the input microwave frequency (8-10 GHz). The results are compared with the predictions of a simple theoretical model.

  18. Diagnostic technique applied for FEL electron bunches

    NASA Astrophysics Data System (ADS)

    Brovko, O.; Grebentsov, A.; Morozov, N.; Syresin, E.; Yurkov, M.

    2016-05-01

    Diagnostic technique applied for FEL ultrashort electron bunches is developed at JINR-DESY collaboration within the framework of the FLASH and XFEL projects. Photon diagnostics are based on calorimetric measurements and detection of undulator radiation. The infrared undulator constructed at JINR and installed at FLASH is used for longitudinal bunch shape measurements and for two-color lasing provided by the FIR and VUV undulators. The pump probe experiments with VUV and FIR undulators provide the bunch profile measurements with resolution of several femtosecond. The new three microchannel plates (MCP) detectors operated in X-ray range are under development now in JINR for SASE1-SASE 3 European XFEL.

  19. Analysis of the eigenvalue equation of the FEL amplifier with axisymmetric electron beam and diaphragm focusing line

    SciTech Connect

    Saldin, E.L.; Schneidmiller, E.A.; Ulyanov, Yu.N.

    1995-12-31

    The paper presents analysis of the eigenvalue problem of the FEL amplifier with axisymmetric electron beam and diaphragm focusing line. An FEL model is discussed wherein diffraction effects, space charge fields and energy spread of electrons in the beam are taken into account. To take into account diffraction effects at the diaphragms we apply the rigorous impedance boundary conditions proposed by Veinstein. The rigorous solutions of the eigenvalue problem leave been found for the stepped and bounded parabolic electron beam profiles. Analytical expressions for eigenfunctions of active open waveguide and formulae of their expansion in eigenfunctions of passive open waveguide, are derived, too. Asymptotic behaviour of the obtained solutions is studied in details. The multilayer approximation method has been used to solve the eigenvalue problem for the beams with an arbitrary gradient profile of current density. This novel type of an FEL amplifier has perspective to be used for applications where high average and peak radiation power is required.

  20. Generation of a few femtoseconds pulses in seeded FELs using a seed laser with small transverse size

    NASA Astrophysics Data System (ADS)

    Li, Heting; Jia, Qika

    2016-09-01

    We propose a simple method to generate a few femtosecond pulses in seeded FELs. We use a longitudinal energy-chirped electron beam passing through a dogleg where transverse dispersion will generate a horizontal energy chirp, then in the modulator, a seed laser with narrow beam radius will only modulate the center portion of the electron beam and then short pulses at high harmonics will be generated in the radiator. Using a representative realistic set of parameters, we show that 30 nm XUV pulse based on the HGHG scheme and 9 nm soft x-ray pulse based on the EEHG scheme with duration of about 8 fs (FWHM) and peak power of GW level can be generated from a 180 nm UV seed laser with beam waist of 75 μm. This new scheme can provide an optional operation mode for the existing seeded FEL facilities to meet the requirement of short-pulse FEL.

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

    SciTech Connect

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

    2009-08-14

    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.

  2. Seeded FEL Microbunching Experiments at the UCLA Neptune Laboratory

    SciTech Connect

    Tochitsky, S. Ya.; Musumeci, P.; Rosenzweig, J. B.; Joshi, C.; Gottschalk, S. C.

    2010-11-04

    Seeded high-gain FELs, which can generate very powerful radiation pulses in a relatively compact undulator and simultaneously modulate the electron beam longitudinally at the seed wavelength, are important tools for advanced accelerator development. A single-pass 0.5-9 THz FEL amplifier-buncher driven by a regular photoinjector is being built at the UCLA Neptune Laboratory. FEL interactions at 340 {mu}m (1 THz) are considered for the first experiment, since time-resolved measurements of longitudinal current distribution of the bunched beam using the RF deflecting cavity are possible. A design of a 0.2-2.0 {mu}m FEL using the same undulators is presented. In this case the FEL is driven by a high-peak current beam from the laser-plasma accelerator tunable in the 100-300 MeV range.

  3. Method for separating FEL output beams from long wavelength radiation

    DOEpatents

    Neil, George; Shinn, Michelle D.; Gubeli, Joseph

    2016-04-26

    A method for improving the output beam quality of a free electron laser (FEL) by reducing the amount of emission at wavelengths longer than the electron pulse length and reducing the amount of edge radiation. A mirror constructed of thermally conductive material and having an aperture therein is placed at an oblique angle with respect to the beam downstream of the bending magnet but before any sensitive use of the FEL beam. The aperture in the mirror is sized to deflect emission longer than the wavelength of the FEL output while having a minor impact on the FEL output beam. A properly sized aperture will enable the FEL radiation, which is coherent and generally at a much shorter wavelength than the bending radiations, to pass through the aperture mirror. The much higher divergence bending radiations will subsequently strike the aperture mirror and be reflected safely out of the way.

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

    SciTech Connect

    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.

  5. Dielectric Wakefield Accelerator to drive the future FEL Light Source.

    SciTech Connect

    Jing, C.; Power, J.; Zholents, A. )

    2011-04-20

    X-ray free-electron lasers (FELs) are expensive instruments and a large part of the cost of the entire facility is driven by the accelerator. Using a high-energy gain dielectric wake-field accelerator (DWA) instead of the conventional accelerator may provide a significant cost saving and reduction of the facility size. In this article, we investigate using a collinear dielectric wakefield accelerator to provide a high repetition rate, high current, high energy beam to drive a future FEL x-ray light source. As an initial case study, a {approx}100 MV/m loaded gradient, 850 GHz quartz dielectric based 2-stage, wakefield accelerator is proposed to generate a main electron beam of 8 GeV, 50 pC/bunch, {approx}1.2 kA of peak current, 10 x 10 kHz (10 beamlines) in just 100 meters with the fill factor and beam loading considered. This scheme provides 10 parallel main beams with one 100 kHz drive beam. A drive-to-main beam efficiency {approx}38.5% can be achieved with an advanced transformer ratio enhancement technique. rf power dissipation in the structure is only 5 W/cm{sup 2} in the high repetition rate, high gradient operation mode, which is in the range of advanced water cooling capability. Details of study presented in the article include the overall layout, the transform ratio enhancement scheme used to increase the drive to main beam efficiency, main wakefield linac design, cooling of the structure, etc.

  6. Transverse-coherence properties of the FEL at the LCLS

    SciTech Connect

    Ding, Yuantao; Huang, Zhirong; Ocko, Samuel A.; /MIT, Cambridge, Dept. Phys.

    2010-09-02

    The recently commissioned Linac Coherent Light Source is an x-ray free-electron laser at the SLAC National Accelerator Laboratory, which is now operating at x-ray wavelengths of 20-1.2 Angstrom with peak brightness nearly ten orders of magnitude beyond conventional synchrotron sources. Understanding of coherence properties of the radiation from SASE FELs at LCLS is of great practical importance for some user experiments. We present the numerical analysis of the coherence properties at different wavelengths based on a fast algorithmusing ideal and start-end simulated FEL fields. The sucessful commissioning and operation of the linac coherent light source (LCLS) [1] has demonstrated that the x-ray free-electron laser (FEL) has come of age; these types of x-ray sources are poised to revolutionize the ultra-fast x-ray sciences. The LCLS and other hard x-ray FELs under construction are based on the principle of self-amplified spontaneous emission (SASE) [2, 3], where the amplification process starts from the shot noise in the electron beam. A large number of transverse radiation modes are also excited when the electron beam enters the undulator. The FEL collective instability in the electron beam causes the modulation of the electron density to increase exponentially, and after sufficient undulator distances, a single transverse mode starts to dominate. As a result, SASE FEL is almost fully coherent in the transverse dimension. Understanding of transverse coherence properties of the radiation from SASE FELs is of great practical importance. The longitudinal coherence properties of SASE FELs have been studied before [4]. Some studies on the transverse coherence can be found in previous papers, for example, in ref. [5, 6, 7, 8, 9]. In this paper, we first discuss a new numerical algorithm based on Markov chain Monte Carlo techniques to calculate the FEL transverse coherence. Then we focus on the numerical analysis of the LCLS FEL transverse coherence.

  7. Discovering and annotating fish early life-stage (FELS) adverse outcome pathways: Putting the research strategy into practice

    EPA Science Inventory

    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 ...

  8. Discovering and annotating fish early life-stage (FELS) adverse outcome pathways: Putting the research strategy into practice

    EPA Science Inventory

    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 ...

  9. FEL gain optimisation and spontaneous radiation

    SciTech Connect

    Bali, L.M.; Srivastava, A.; Pandya, T.P.

    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.

  10. The GALAXIE all-optical FEL project

    SciTech Connect

    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.; 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.

  11. Non equilibrium studies on FEL facilities

    NASA Astrophysics Data System (ADS)

    Harmand, Marion

    2013-06-01

    The recent development of Free Electron Lasers (FEL), giving ultrafast, high intensity pulses in the X-ray and XUV energy range is opening new opportunities for WDM studies. Development of X-ray diagnostics such as X-ray absorption spectroscopy and X-ray scattering, has received much attention for the in situ measurement of the structure and physical properties of matter at extreme conditions. Coupled to ultrafast pump - probe schemas, such diagnostics are giving new insights into out-of-equilibrium processes and thus validate current models. We report recent developments to perform few fs time resolved pump - probe experiments, giving access to ultrafast transient WDM states. We also present collective Thomson Scattering with soft x-ray Free Electron Laser radiation (at FLASH) as a method to track the evolution of highly transient warm dense hydrogen with around 100 fs time resolution. In addition, recent experiments at LCLS are suggesting the possibility to perform X-ray absorption spectroscopy (XANES) on FEL facilities to provide simultaneously information on the valence electrons and on the atomic local arrangement within sub-ps time scales.

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

    NASA Astrophysics Data System (ADS)

    Cee, R.; Krassilnikov, M.; Setzer, S.; Weiland, T.; Novokhatski, A.

    2002-05-01

    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, Büdinger 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

  14. A non-conventional ERL configuration for high-power EUV FELs

    NASA Astrophysics Data System (ADS)

    Venturini, M.; Penn, G.

    2015-09-01

    We show that a standard Linac configuration (consisting of accelerating sections, linearizing section, and magnetic chicane compressor) currently used in drivers for single-pass EUV/x-ray FELs is compatible with energy recovery, provided that certain timing constraints are met. By circulating the spent, rather than the fresh beam as in a conventional high-power ERL FEL design, the beam brightness can be more easily preserved thus facilitating lasing at short wavelength. As in a conventional ERL, the proposed design allows for energy-spread compression, enabling low-energy beam dumping and high energy-recovery efficiency. Results from numerical simulations presented in this paper show that this configuration could, in principle, support the generation of multi-kW average radiation power required for high-volume production EUV lithography.

  15. Performance Achievements and Challenges for FELs based on Energy Recovered Linacs

    SciTech Connect

    Geoffrey Krafft

    2006-08-27

    During the past decade several groups have assembled free electron lasers based on energy recovered linacs (ERLs). Such arrangements have been built to obtain high average power electron and photon beams, by using high repetition rate beam pulses driving FEL oscillators. In this paper the performance of many existing and several proposed facilities from around the world are reviewed. Going forward, many questions must be addressed to achieve still better performance including: higher average current injectors, better optimized accelerating cavities, higher energy acceptance and lower loss beam recirculation systems, and better optical cavity designs for dealing with the optical beam power circulating in the ERL FELs. This paper presents some of the current thinking on each of these issues.

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

    SciTech Connect

    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.

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

    SciTech Connect

    Smetanin, I.V.; Grigor`ev, S.V.

    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.

  18. Optics-free x-ray FEL oscillator

    SciTech Connect

    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.

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

    SciTech Connect

    Litvinenko, V.N.; Madey, J.M.J.; O`Shea, P.G.

    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.

  20. CEBAF UV/IR FEL subsystem testing and validation program

    SciTech Connect

    G.R. Neil; S.V. Benson; H.F. Dylla; H. Liu

    1995-01-01

    A design has been established for IR and UV FELs within the Laser Processing Consortium's (LPC) program for development and application of high-average-power FELs for materials processing. Hardware prototyping and testing for the IR portion of the system are underway. The driver portion has been designed based on the superconducting radio-frequency (SRF) technology now seeing large-scale application in the commissioning of CEBAF, the Continuous Electron Beam Accelerator Facility, where LPC activities are centered. As of July 1994, measurements of beam performance confirm SRF's benefits in beam quality and stability, which are applicable to high-average-power FELs.

  1. First Observations and Suppression of Multipass, Multibunch Beam Breakup in the Jefferson Laboratory FEL Upgrade

    SciTech Connect

    Christopher D. Tennant; David R. Douglas; Kevin C. Jordan; Nikolitsa Merminga; Eduard G. Pozdeyev; Kevin B. Beard; Todd I. Smith

    2005-01-01

    It is well known that the multipass, multibunch beam breakup (BBU) instability imposes a potentially severe limitation to the average current that can be accelerated in an energy recovery linac (ERL). Simulation results for Jefferson Lab's FEL Upgrade Driver are presented which predict the occurrence of BBU below the nominal operating current of the machine. In agreement with simulation, BBU was observed and preliminary measurements to identify the higher-order mode (HOM) causing the instability are shown. In addition, measurements performed to experimentally determine the threshold current are described. Using a newly developed two-dimensional BBU simulation code, we study the effect of optical suppression techniques, first proposed by Rand and Smith in 1980 [1], on the threshold current of the FEL. Specifically we consider the effect of (1) reflecting the betatron planes about 45 degrees and (2) rotating the betatron planes by 90 degrees. In two pass recirculators, a 90 degrees rotation significantly increases the threshold current of BBU. The successful installation of a five skew-quadrupole reflector in the backleg of the FEL has been shown to be effective at suppressing the instability and comments on preliminary operational experience will be given.

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

    SciTech Connect

    Saeki, K.; Okuma, S.; Oshita, E.

    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.

  3. The FERMI seeded-FEL facility: Status and perspectives

    SciTech Connect

    Allaria, Enrico; Badano, Laura; Bencivenga, Filippo; Callegari, Carlo Capotondi, Flavio; Castronovo, Davide; Cinquegrana, Paolo; Coreno, Marcello; Cucini, Riccardo; Cudin, Ivan; Danailov, Miltcho B.; D’Auria, Gerardo; De Monte, Raffaele; De Ninno, Giovanni; Delgiusto, Paolo; Demidovich, Alexander; Di Mitri, Simone; Diviacco, Bruno; Fabris, Alessandro; Fabris, Riccardo; and others

    2016-07-27

    The FERMI Free Electron Laser (FEL) in Trieste, Italy operates in the extreme ultraviolet and soft x rays (EUV-SXR) wavelength range delivering high-fluence, stable, ultra-short pulses. Its unique design based on a seeded scheme and on tunable undulators allows unprecedented control of pulse parameters such as wavelength, phase, polarization, synchronization, pulse duration and implementation of multi-color FEL schemes. Both FEL-1 and FEL-2 lines with nominal wavelength range 100–20 nm and 20–4 nm, respectively, are open to users. We report on the unique features of FERMI, in particular those that have evolved beyond the original design, and on their application to pioneering experiments. We also present the upgrades that are planned to further expand the capabilities of this unique light source.

  4. Electro-Magnetic Quadrupole Magnets in the LCLS FEL Undulator

    SciTech Connect

    Emma, P.

    2005-01-31

    We discuss various aspects of electro-magnetic quadrupole (EMQ) magnets for the LCLS FEL undulator, including their utility in beam-based alignment (BBA), magnet design issues, and impact on tunnel environment, reliability, and cost.

  5. Intrabeam Scattering in an X-ray FEL Driver

    SciTech Connect

    Huang, Z.

    2005-01-31

    Intrabeam scattering (IBS) of a high-brightness electron beam in an x-ray free-electron laser (FEL) driver is studied. Such a beam is much ''colder'' in the longitudinal direction than in transverse ones. As a result, the beam energy spread is increased with negligible change of transverse emittances. We estimate the IBS induced energy spread in the Linac Coherent Light Source and evaluate its effects on FEL and CSR microbunching instabilities.

  6. Recent Progress in High-Gain FEL Theory

    SciTech Connect

    Huang, Z.; /SLAC

    2005-09-30

    High-gain free electron lasers (FEL) are being developed as extremely bright x-ray sources of a next-generation radiation facility. In this paper, we review the basic theory and the recent progress in understanding the startup, the exponential growth and the saturation of the high-gain process, emphasizing the self-amplified spontaneous emission (SASE). We will also discuss how the FEL performance may be affected by various errors and wakefield effects in the undulator.

  7. The performance of the Duke FEL storage ring

    SciTech Connect

    Wu, Y.; Burnham, B.; Litvinenko, V.N.

    1995-12-31

    The commissioning of the Duke FEL storage ring has been completed. During commissioning, we have conducted a series of performance measurements on the storage ring lattice and the electron beam parameters. In this paper, we will discuss the techniques used in the measurements, present measurement results, and compare the measured parameters with the design specifications. In addition, we will present the expected OK-4 FEL performance based on the measured beam parameters.

  8. Study of waveguide resonators for FEL operating at submillimeter wavelengths

    SciTech Connect

    Yakover, I.M.; Pinhasi, Y.; Gover, A.

    1995-12-31

    This paper presents theoretical results of waveguide resonator study for FEL operating at the submillimeter wavelength region. Because of increased ohmic losses it is harder to obtain high Q waveguide cavities at these wavelengths. The following unconventional multimode waveguides: metal-dielectric, corrugated and curved parallel plates, were considered. The type and structure of the operating modes were determined and their attenuation constant, effective mode area and wave impedance were calculated. On the basis of this analysis small-signal gain simulations were made. We have performed a parametric study of the various FEL oscillator cavity designs based on the parameters of the Israeli Tandem FEL experiment. It was found that an FEL utilizing unconventional waveguides has much better performance in comparison to an FEL based on conventional multimode rectangular and circular waveguides. In particular, promising design parameters for a sub-mm wavelength FEL utilizing a metal-dielectric waveguide were identified: gain of 45%/Amp and ohmic losses of 2% at frequency 300 GHz, and gain of 20%/Amp and ohmic losses 1% at frequency 675 GHz.

  9. Photon Source Capabilities of the Jefferson Lab FEL

    SciTech Connect

    Benson, S. V.; Douglas, D. R.; Evtushenko, P.; Hannon, F. E.; Hernandez-Garcia, C.; Klopf, J. M.; Legg, R. A.; Neil, G. R.; Shinn, M. D.; Tennant, C. D.; Zhang, S.; Williams, G. P.

    2013-03-22

    Jefferson Lab operates a superconducting energy recovered linac which is operated with CW RF and which powers oscillator-based IR and UV Free Electron Lasers (FELs) with diffraction limited sub-picosecond pulses with >10{sup 13} photons per pulse (1.0%BW) at pulse repetition frequencies up to 75 MHz. Useful harmonics extend into the vacuum ultraviolet (VUV). Based on FEL model calculations validated using this facility, we have designed both an oscillator-based VUV-FEL that would produce 6 10{sup12} coherent (0.5% BW) 100 eV photons per pulse at multi-MHz repetition rates in the fundamental, and a dual FEL configuration that would allow simultaneous lasing lasing at THz and UV wavelengths. The VUV-FEL would utilize a novel high gain, low Q cavity, while the THz source would be an FEL oscillator with a short wiggler providing diffraction limited pulses with pulse energy exceeding 50 microJoules. The THz source would use the exhaust beam from a UVFEL. Such multiphoton capabilities would provide unique opportunities for out of equilibrium dynamical studies at time-scales down to 50 fs. The fully coherent nature of all these sources results in peak and average brightness values that are many orders of magnitude higher than storage rings. We acknowledge support from the Commonwealth of Virginia. Jefferson Lab is supported by the U.S. DOE under Contract No. DE-AC05-84-ER40150.

  10. FEL Design Studies at LBNL: Activities and Plans

    SciTech Connect

    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.

  11. Generation of doublet spectral lines at self-seeded X-ray FELs

    NASA Astrophysics Data System (ADS)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2011-06-01

    Self-seeding schemes, consisting of two undulators with a monochromator in between, aim to reduce 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. The obvious and technically possible extension is to use such kind of monochromator setup with two (or more) crystals arranged in a series to spectrally filter the SASE radiation at two (or more) closely-spaced wavelengths within the FEL gain band. This allows for the production of doublet (or multiplet) spectral lines. Exploitations of such mode of operation involve any situation where there is a large change in cross-section over a narrow wavelength range. In this paper we consider the simultaneous operation of the LCLS hard X-ray FEL at two closely spaced wavelengths. We present simulation results for the LCLS baseline, and we show that this method can produce fully coherent radiation shared between two longitudinal modes. Mode spacing can be easily tuned within the FEL gain band, i.e. within 10 eV. An interesting aspect of the proposed scheme is a way of modulating the electron bunch at optical frequencies without a seed quantum laser. In fact, the XFEL output intensity contains an oscillating "mode-beat" component whose frequency is related to the frequency difference between the pair of longitudinal modes considered. Thus, at saturation one obtains FEL-induced modulations of energy loss and energy spread in the electron bunch at optical frequency. These modulations can be converted into density modulation at the same optical frequency with the help of a weak chicane installed behind the baseline undulator. Powerful coherent radiation can then be generated with the help of an optical transition radiation (OTR) station, which have important applications. In this paper we briefly consider how the doublet structure of the XFEL generation spectra can be monitored by an

  12. Current status of the Novosibirsk infrared FEL and the third stage lasing

    NASA Astrophysics Data System (ADS)

    Shevchenko, O. A.; Arbuzov, V. S.; Chernov, K. N.; Davidyuk, I. V.; Dementyev, E. N.; Dovzhenko, B. A.; Getmanov, Ya. V.; Knyazev, B. A.; Kolobanov, E. I.; Kondakov, A. A.; Kozak, V. R.; Kozyrev, E. V.; Kubarev, V. V.; Kulipanov, G. N.; Kuper, E. A.; Kuptsov, I. V.; Kurkin, G. Ya.; Motygin, S. V.; Osipov, V. N.; Petrov, V. M.; Medvedev, L. E.; Ovchar, V. K.; Pilan, A. M.; Popik, V. M.; Repkov, V. V.; Salikova, T. V.; Scheglov, M. A.; Sedlyarov, I. K.; Serdobintsev, G. V.; Serednyakov, S. S.; Skrinsky, A. N.; Tararyshkin, S. V.; Tcheskidov, V. G.; Tribendis, A. G.; Vinokurov, N. A.; Vobly, P. D.

    2016-12-01

    Novosibirsk FEL facility is based on the first in the world multi-turn energy recovery linac (ERL). It comprises three FELs (stages). FELs on the first and the second tracks were commissioned in 2004 and 2009 respectively and operate for users now. The third stage FEL is installed on the fourth track of the ERL. It includes three undulator sections and 40-meters-long optical cavity. The design tuning range of this FEL is from 5 to 20 microns and the design average power at bunch repetition rate 3.74 MHz is about 1 kW. Recent results of the third stage FEL commissioning are reported.

  13. Time-delay-compensated grating monochromator for FEL beamlines

    NASA Astrophysics Data System (ADS)

    Frassetto, Fabio; Ploenjes, Elke; Kuhlmann, Marion; Poletto, Luca

    2014-09-01

    We present the design of a time-delay-compensated monochromator explicitly designed for extreme-ultraviolet FEL sources, in particular the upcoming FLASH II at DESY (Hamburg). The design originates from the variable-line-spaced (VLS) grating monochromator by adding a second grating to compensate for the pulse-front tilt given by the first grating after the diffraction. The covered spectral range is 6-60 nm, the spectral resolution is in the range 1000-2000, while the residual temporal broadening is lower than 15 fs. Accounting for typical FLASH II divergences, the grazing angles on the different optics have been chosen so that the mirrors and gratings are respectively shorter than 500 mm and 300 mm. The proposed design: 1) minimizes the number of optical elements, since just one grating is added with respect to a standard VLS monochromator B-L; 2) guarantees high focusing properties in the whole spectral range of operation; 3) requires simple mechanical movements, since only rotations are needed to perform the spectral scan.

  14. Dark Matter Searches using a Free-Electron Laser (FEL)

    NASA Astrophysics Data System (ADS)

    Boyce, James R.; Afanasev, A.; Baker, O. K.; Beard, K. B.; Biallas, G.; Minarni, M.; Ramdon, R.; Shinn, M.; Slocum, P.

    2009-05-01

    Photon coupling to light neutral bosons in the meV mass range has been predicted and searched for by several international collaborations. Using the ``light shining through a wall'' technique, light from Jefferson Lab's high average power Free-Electron Laser (FEL) was passed through a strong magnetic field upstream of an optical beam dump; regenerated photons were then searched for downstream of a second magnetic field region optically shielded from the former. While our initial results show no evidence for scalar coupling in this region of parameter space, the results establish new coupling boundaries. New constraints on the hypothetical para-photon particles were also obtained. We describe the experimental setup, the initial scalar boson results, and proposed experiments that include searching for para-photons and chameleon particles. Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

  15. An induction linac developed for FEL application

    NASA Astrophysics Data System (ADS)

    de Mascureau, J.; Anthouard, Ph.; Bardy, J.; Eyharts, Ph.; Eyl, P.; Launspach, J.; Thevenot, M.; Villate, D.

    1992-07-01

    An induction linac is being studied and built at CESTA for FEL application. At first we studied the induction technology and namely the high-voltage (HV) generators and the induction cells. A HV generator designed to feed the cells with calibrated pulses (150 kV, 50 ns, δV/V < 1%) has been built using a resonant charging system and magnetic switches. This generator is planned for kHz repetition-rate operation. A prototype induction cell has also been built and tested with a cable generator. An electron injector (1.5 MeV, 1.5kA) has been designed and is now under test: it uses ten induction cells and a thermionic dispenser cathode. Numerical codes have been developed and simulations have been compared with experimental results for HV generators, induction cells, and the injector. An induction accelerating module has been studied and we plan to have the accelerator working at 3 MeV in 1992.

  16. Gain narrowing of temporal and spectral widths in the UVSOR-FEL

    SciTech Connect

    Kimura, K.; Yamazaki, J.; Kinoshita, T.

    1995-12-31

    Storage ring free electron laser (SR-FEL) dynamics on the UVSOR-FEL in the visible region has been studied with measurements of the temporal and the spectral widths of the laser micropulse. The micro- and the macro-temporal structures were measured using a dual sweep streak camera. We have also investigated spectral evolution of the laser with a Fabry-Perot etalon. Only a slow sweep function of the streak camera has been used for a fringe pattern formed by the air gap etalon to derive time-dependent variations of the spectral shape. We have measured the time-averaged pulsewidths and linewidths as a function of the ring current. We observed that every macropulse contains internal substructures in both the temporal and the spectral distributions. The internal substructure, however, disappeared when the spectra of more than fifty macropulses were superimposed, and the envelope of the distribution became close to a Gaussian. We have found that the pulsewidth and the linewidth become narrower as the ring current decays. In the gain-switching mode, the micropulse duration and the linewidth at the maximum ring current were 80 ps(FWHM) and 0.3 nm(FWHM), respectively, and decreased down to 20 ps and 0.1 nm just above the threshold current. The temporal and the spectral widths seem to follow the gain behavior. Assuming that the pulsewidth and the linewidth depend on the laser gain, the bandwidth in weakly saturated situation such as SR-FEL is determined by the gain narrowing of the laser amplifier. Because the gain evolution is able to be deduced from the macropulse shape, we can obtain the relation between the bandwidth and an effective gain above the mirror loss. The temporal and the spectral evolutions of the UVSOR-FEL were well explained by the gain narrowing related to a gain integrated from the oscillation build-up to the gain saturation. Detail of the experiment and the analysis will be presented.

  17. Ultrafast laser synchronization at the FERMI@Elettra FEL

    NASA Astrophysics Data System (ADS)

    Sigalotti, P.; Cinquegrana, P.; Demidovich, A.; Ivanov, R.; Nikolov, I.; Kurdi, G.; Danailov, M. B.

    2013-05-01

    Modern VUV and X-ray Free Electron Laser (FEL) facilities contain a number of ultrafast lasers (like photoinjector, seed and pump-probe lasers) whose performance is crucial for the generated FEL light quality as well as for the accuracy of the time resolved measurements performed using the FEL pulses. One of the very important laser related aspects, especially at seeded FELs, is the ability to precisely lock the ultrafast laser systems to the master clock signal, keeping the timing jitter and drifts of the generated pulses with respect to the machine timing as low as possible. The aim of this work is to review the main sources of timing jitter and drifts and present the schemes and solutions developed at FERMI for their characterization and compensation. The paper will first introduce a general scheme showing the architecture of the laser locking system developed for FERMI. Both the radio-frequency (RF) locking and the advanced balanced optical cross correlator electronics and optical setup design are described, together with data on the laser oscillator locking performance obtained in different modalities. Cross correlation measurements indicating the contribution of the ultrafast regenerative amplifier and optical beam transport part to the overall temporal jitter of the amplified ultrashort pulses arriving at destination are presented. The paper also includes examples of the influence of improved laser timing jitter and drifts on the seeded FEL performance and discusses foreseen future developments.

  18. Infrared FEL photochemistry: Multiple-photon dissociation of Freon gas

    SciTech Connect

    Newnam, B.E.; Early, J.W.; Lyman, J.L.

    1993-10-01

    Wavelength tunability, synchrotron sidebands, and picosecond pulse structure are inherent FEL characteristics that should be advantageous for photochemistry involving infrared multiple-photon photodissociation. Tuned to an absorption resonance, the FEL sideband structure will overlap the broad, excited-state spectral absorption and should lead to enhanced dissociation. The Los Alamos APEX FEL was operated with and without sidebands to test this hypothesis on CFCl{sub 3} (Freon 11), an inert chlorofluorocarbon widely used in refrigeration systems and one of the gases implicated as depleting the ozone in the Earth`s stratospheric layer. The FEL wavelength was set at the C-Cl stretch absorption resonance at 11.8-{mu}m, the oscillator cavity length was detuned first to minimize and then to maximize the spectral bandwidth, and the beam was focused through a pair of test cells (1.0 Torr Freon+1.7 Torr air). Comparison of final and initial absorbance spectra indicated the CFCl{sub 3} photodissociation yield was 1.2% for the cell exposed with sideband spectra (3% FWHM) and 9-ns micropulse separation. Negligible effect was seen without sidebands, albeit at lower total beam fluence. Although the result of this single experiment is not large enough to be conclusive, it does provide a basis for optimizing the FEL temporal and spectral parameters to attain higher photodissociation yield in future tests.

  19. Infrared FEL photochemistry: Multiple-photon dissociation of freon gas

    NASA Astrophysics Data System (ADS)

    Newnam, B. E.; Early, J. W.; Lyman, J. L.

    Wavelength tunability, synchrotron sidebands, and picosecond pulse structure are inherent FEL characteristics that should be advantageous for photochemistry involving infrared multiple-photon photodissociation. Tuned to an absorption resonance, the FEL sideband structure will overlap the broad, excited-state spectral absorption and should lead to enhanced dissociation. The Los Alamos APEX FEL was operated with and without sidebands to test this hypothesis on CFCl3 (Freon 11), an inert chlorofluorocarbon widely used in refrigeration systems and one of the gases implicated as depleting the ozone in the Earth's stratospheric layer. The FEL wavelength was set at the C-Cl stretch absorption resonance at 11.8-microns, the oscillator cavity length was detuned first to minimize and then to maximize the spectral bandwidth, and the beam was focused through a pair of test cells (1.0 Torr Freon + 1.7 Torr air). Comparison of final and initial absorbance spectra indicated the CFCl3 photodissociation yield was 1.2% for the cell exposed with sideband spectra (3% FWHM) and 9-ns micropulse separation. Negligible effect was seen without sidebands, albeit at lower total beam fluence. Although the result of this single experiment is not large enough to be conclusive, it does provide a basis for optimizing the FEL temporal and spectral parameters to attain higher photodissociation yield in future tests.

  20. Electron Beam Diagnostics Of The JLAB UV FEL

    SciTech Connect

    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.

  1. Temporal characterization of the Stanford Mid-IR FEL by frequency-resolved optical gating

    SciTech Connect

    Richman, B.A.; DeLong, K.W.; Trebino, R.

    1995-02-01

    We measure the time-dependent intensity and phase of laser pulses from the Stanford Mid-IR FEL. We present the first measurements of near-transform-limited, linearly chirped, and sideband modulated FEL pulses.

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

    SciTech Connect

    Qing-Xiang Liu |; Yong Xu

    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.

  3. Gain measurements on a waveguide FEL amplifier with pre-bunched electron beam

    SciTech Connect

    Dearden, G.; Mayhew, S.E.; Lucas, J.

    1995-12-31

    A theory proposed by Doria et al. suggests that a synchronous pre-bunched electron beam should amplify radiation with a power gain which is inversely proportional to the square root of the input power. We have measured the power gain experimentally for a waveguide FEL system using a low-voltage (55kV) pre-bunched electron beam produced by a waveguide cavity buncher. The gain has been observed as a function of the electron beam current and energy; the results are compared with theory.

  4. Evidence for transverse dependencies in COTR and microbunching in a SASE FEL.

    SciTech Connect

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

    2002-09-24

    Using coherent optical transition radiation (COTR) techniques, we have observed transverse dependencies, which in some aspects relate to the electron beam microbunching in a visible wavelength (540 nm) self-amplified spontaneous emission (SASE) free-electron laser (FEL). The experimental COTR observations include the z-dependent e-beam sizes, the z-dependent angular distributions, and the z-dependent spectra (which show an x-dependence). A 30-40% narrowing of the observed beam size using COTR is explainable by the mechanism's dependence on the square of the number of microbunched particles. However, additional effects are needed to explain beam size reductions by factors of 2-3 at different z locations. Localized e-beam structure in the gun or induced in the bunch compression process may result in microbunching transverse dependence, and hence the observed COTR effects.

  5. Fast synchrotron and FEL beam monitors based on single-crystal diamond detectors and InGaAs/InAlAs quantum well devices

    NASA Astrophysics Data System (ADS)

    Antonelli, M.; Di Fraia, M.; Carrato, S.; Cautero, G.; Menk, R. H.; Jark, W. H.; Ganbold, T.; Biasiol, G.; Callegari, C.; Coreno, M.; De Sio, A.; Pace, E.

    2013-12-01

    Simultaneous photon-beam position and intensity monitoring is becoming of increasing importance for new-generation synchrotron radiation sources and free-electron lasers (FEL). Thus, novel concepts of beam diagnostics are required in order to keep such beams under control. From this perspective diamond is a promising material for the production of semitransparent in situ photon beam monitors, which can withstand the high dose rates occurring in such radiation facilities. Here, we report on the development of freestanding, single-crystal chemical-vapor-deposited diamond detectors with segmented electrodes. Due to their direct, low-energy band gap, InGaAs quantum well devices operated at room temperature may also be used as fast detectors for photons ranging from visible to X-ray. These features are valuable in low-energy and time-resolved FEL applications. In particular, a novel segmented InGaAs/InAlAs device has been developed and will be discussed. Dedicated measurements carried out on both these devices at the Elettra Synchrotron show their capability to monitor the position and the intensity of the photon beam with bunch-by-bunch temporal performances. Furthermore, preliminary tests have been performed on diamond detectors at the Fermi FEL, extracting quantitative intensity and position information for 100-fs-wide FEL pulses with a photon energy of 28.8 eV.

  6. FERMI@Elettra FEL Design Technical Optimization Final Report

    SciTech Connect

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

    2006-07-31

    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.

  7. Analysis of FEL optical systems with grazing incidence mirrors

    SciTech Connect

    Knapp, C.E.; Viswanathan, V.K.; Bender, S.C.; Appert, Q.D.; Lawrence, G.; Barnard, C.

    1986-01-01

    The use of grazing incidence optics in resonators alleviates the problem of damage to the optical elements and permits higher powers in cavities of reasonable dimensions for a free electron laser (FEL). The design and manufacture of a grazing incidence beam expander for the Los Alamos FEL mock-up has been completed. In this paper, we describe the analysis of a bare cavity, grazing incidence optical beam expander for an FEL system. Since the existing geometrical and physical optics codes were inadequate for such an analysis, the GLAD code was modified to include global coordinates, exact conic representation, raytracing, and exact aberration features to determine the alignment sensitivities of laser resonators. A resonator cavity has been manufactured and experimentally setup in the Optical Evaluation Laboratory at Los Alamos. Calculated performance is compared with the laboratory measurements obtained so far.

  8. Seeded quantum FEL at 478 keV

    SciTech Connect

    Guenther, M. M.; Jentschel, M.; Thirolf, P. G.; Seggebrock, T.; Habs, D.

    2012-07-09

    We present for the first time the concept of a seeded {gamma} quantum Free-Electron-Laser (QFEL) at 478 keV, which has very different properties compared to a classical. The basic concept is to produce a highly brilliant {gamma} beam via SASE. To produce highly intense and coherent {gamma} beam, we intend to use a seeded FEL scheme. Important for the production of such a {gamma} beam are novel refractive {gamma}-lenses for focusing and an efficient monochromator, allowing to generate a very intense and coherent seed beam. The energy of the {gamma} beam is 478 keV, corresponding to a wavelength in the sub-Angstrom regime (1/38 A). To realize a coherent {gamma} beam at 478 keV, it is necessary to use a quantum FEL design. At such high radiation energies a classical description of the {gamma}-FEL becomes wrong.

  9. High-precision x-ray FEL pulse arrival time measurements at SACLA by a THz streak camera with Xe clusters.

    PubMed

    Juranić, P N; Stepanov, A; Ischebeck, R; Schlott, V; Pradervand, C; Patthey, L; Radović, M; Gorgisyan, I; Rivkin, L; Hauri, C P; Monoszlai, B; Ivanov, R; Peier, P; Liu, J; Togashi, T; Owada, S; Ogawa, K; Katayama, T; Yabashi, M; Abela, R

    2014-12-01

    The accurate measurement of the arrival time of a hard X-ray free electron laser (FEL) pulse with respect to a laser is of utmost importance for pump-probe experiments proposed or carried out at FEL facilities around the world. This manuscript presents the latest device to meet this challenge, a THz streak camera using Xe gas clusters, capable of pulse arrival time measurements with an estimated accuracy of several femtoseconds. An experiment performed at SACLA demonstrates the performance of the device at photon energies between 5 and 10 keV with variable photon beam parameters.

  10. Quasi-isochronous storage ring for enhanced FEL performance

    NASA Astrophysics Data System (ADS)

    Ohgaki, H.; Robin, D.; Yamazaki, T.

    1996-02-01

    A compact storage ring is designed to be used as driver for a free electron laser (FEL). This ring can be operated very close to zero momentum compaction factor (α) to increase the electron density and thus the gain of the FEL. In order to control α with zero dispersion in the straight sections we use an inverted dipole located between the bending magnets and 4 families of quadrupoles. By using 3 families of sextupoles we can control the 2 transverse chromaticities and 2nd order momentum compaction. We find that the ring has sufficient dynamic aperture for good performance.

  11. A Parameter Optimization for a National SASE FEL Facility

    SciTech Connect

    Yavas, O.; Yigit, S.

    2007-04-23

    The parameter optimization for a national SASE FEL facility was studied. Turkish State Planing Organization (DPT) gave financial support as an inter-universities project to begin technical design studies and test facility of National Accelerator Complex starting from 2006. In addition to a particle factory, the complex will contain a linac based free electron laser, positron ring based synchrotron radiation facilities and a proton accelerator. In this paper, we have given some results of main parameters of SASE FEL facility based on 130 MeV linac, application potential in basic and applied research.

  12. Progress in the injector for FEL at CIAE

    SciTech Connect

    Tianlu Yang; Wenzhen Zhou; Shinian Fu

    1995-12-31

    An intense current RF-linac for the far-infrared FEL is now under construction at CIAE. The normalized brightness of 3.4 x 10{sup 9} A/(m-rad) was obtained from the injector of the linac. An acceleration section with 9 cells will be connected with the injector to provide an electron beam for the 200 {mu}m FEL oscillator. In this paper, the late results from the injector beam test will be reported. The physical design and research progress in the acceleration section, beam transport, undulator as well as optical cavity will be introduced respectively.

  13. The bunch compression system at the TESLA test facility FEL

    NASA Astrophysics Data System (ADS)

    Limberg, T.; Weise, H.; Molodozhentsev, A.; Petrov, V.

    1996-02-01

    A SASE-FEL [A.M. Kontradenko and E.L. Saldin, Particle Accelerators 10 (1980) 207; R. Bonifacio, C. Pellegrini and I.M. Narducci, Opt. Commun. 50 (1884) 373] requires extremely high peak currents which cannot be achieved by electron guns. The bunch length therefore has to be reduced along the accelerating linac, the bunch has to be compressed. In the TTF-FEL this is done with the help of bending magnet chicanes in three stages. We present the lay-out of the scheme as well as first beam dynamics calculations.

  14. FEL GAIN LENGTH AND TAPER MEASUREMENTS AT LCLS

    SciTech Connect

    Ratner, D.; Fawley, W. M.; Brachmann, A.; Decker, F.J.; Ding, Y.; Dowell, D.; Emma, P.; Frisch, J.; Gilevich, S.; Hays, G.; Hering, P.; Huang, Z.; Loos, H.; Miahnahri, A.; Nuhn, H.D.; Turner, J.; Welch, J.; White, W.; Wu, J.; Xiang, D.; Yocky, G.; Fawley, W. M.

    2009-08-14

    We present experimental studies of the gain length and saturation power level from 1.5 nm to 1.5 Angstroms at the Linac Coherent Light Source (LCLS). By disrupting theFEL process with an orbit kick, we are able to measure the X-ray intensity as a function of undulator length. This kick method is cross-checked with the method of removing undulator sections. We also study the FEL-induced electron energy loss after saturation to determine the optimal taper of the undulator K values. The experimental results are compared to theory and simulations.

  15. FEL Gain Length and Taper Measurements at LCLS

    SciTech Connect

    Ratner, Daniel; Brachmann, A.; Decker, F.J.; Ding, Y.; Dowell, D.; Emma, P.; Frisch, J.; Gilevich, S.; Hays, G.; Hering, P.; Huang, Z.; Iverson, R.; Loos, H.; Miahnahri, A.; Nuhn, H.D.; Turner, J.; Welch, J.; White, W.; Wu, J.; Xiang, D.; Yocky, G.; /SLAC /LBL, Berkeley

    2010-07-30

    We present experimental studies of the gain length and saturation power level from 1.5 nm to 1.5 {angstrom} at the Linac Coherent Light Source (LCLS). By disrupting the FEL process with an orbit kick, we are able to measure the X-ray intensity as a function of undulator length. This kick method is cross-checked with the method of removing undulator sections. We also study the FEL-induced electron energy loss after saturation to determine the optimal taper of the undulator K values. The experimental results are compared to theory and simulations.

  16. Undulators for the BESSY SASE-FEL Project

    NASA Astrophysics Data System (ADS)

    Bahrdt, J.; Frentrup, W.; Gaupp, A.; Kuske, B.; Meseck, A.; Scheer, M.

    2004-05-01

    BESSY plans to build a SASE-FEL facility for the energy range from 20 eV to 1000 eV. The energy range will be covered by three APPLE II type undulators with a magnetic length of about 60 m each. This paper summarizes the basic parameters of the FEL-undulators. The magnetic design will be presented. A modified APPLE II design will be discussed which provides higher fields at the expense of reduced horizontal access. GENESIS simulations give an estimate on the tolerances for the beam wander and for gap errors.

  17. The Mark III IR FEL: Improvements in performance and operation

    SciTech Connect

    Barnett, G.A.; Madey, J.M.J.; Straub, K.D.

    1995-12-31

    The Mark III IR FEL has been upgraded by the installation of a new thermionic microwave gun. The new gun yields a reduced emittance and allows operation at a higher repetition rate and an increased electron macropulse length. The RF system of the Mark III has also been phase-locked to the RF systemof the adjacent storage ring driver for the laboratory`s short-wavelength FEL sources, making possible two-color UV-IR pump probe experiments. In this paper, the design and performance of the new gun are presented and the implications of the improvements investigated.

  18. Undulators for the BESSY SASE-FEL Project

    SciTech Connect

    Bahrdt, J.; Frentrup, W.; Gaupp, A.; Kuske, B.; Meseck, A.; Scheer, M.

    2004-05-12

    BESSY plans to build a SASE-FEL facility for the energy range from 20 eV to 1000 eV. The energy range will be covered by three APPLE II type undulators with a magnetic length of about 60 m each. This paper summarizes the basic parameters of the FEL-undulators. The magnetic design will be presented. A modified APPLE II design will be discussed which provides higher fields at the expense of reduced horizontal access. GENESIS simulations give an estimate on the tolerances for the beam wander and for gap errors.

  19. The PixFEL project: Progress towards a fine pitch X-ray imaging camera for next generation FEL facilities

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    The INFN PixFEL project is developing the fundamental building blocks for a large area X-ray imaging camera to be deployed at next generation free electron laser (FEL) facilities with unprecedented intensity. Improvement in performance beyond the state of art in imaging instrumentation will be explored adopting advanced technologies like active edge sensors, a 65 nm node CMOS process and vertical integration. These are the key ingredients of the PixFEL project to realize a seamless large area focal plane instrument composed by a matrix of multilayer four-side buttable tiles. In order to minimize the dead area and reduce ambiguities in image reconstruction, a fine pitch active edge thick sensor is being optimized to cope with very high intensity photon flux, up to 104 photons per pixel, in the range from 1 to 10 keV. A low noise analog front-end channel with this wide dynamic range and a novel dynamic compression feature, together with a low power 10 bit analog to digital conversion up to 5 MHz, has been realized in a 110 μm pitch with a 65 nm CMOS process. Vertical interconnection of two CMOS tiers will be also explored in the future to build a four-side buttable readout chip with high density memories. In the long run the objective of the PixFEL project is to build a flexible X-ray imaging camera for operation both in burst mode, like at the European X-FEL, or in continuous mode with the high frame rates anticipated for future FEL facilities.

  20. Visibles Revisited

    ERIC Educational Resources Information Center

    Bridger, Mark; Zelevinsky, Andrei

    2005-01-01

    Within the set of points in the plane with integer coordinates, one point is said to be visible from another if no other point in the set lies between them. This study of visibility draws in topics from a wide variety of mathematical areas, including geometry, number theory, probability, and combinatorics.

  1. VISIBLE SPEECH.

    ERIC Educational Resources Information Center

    POTTER, RALPH K.; AND OTHERS

    A CORRECTED REPUBLICATION OF THE 1947 EDITION, THE BOOK DESCRIBES A FORM OF VISIBLE SPEECH OBTAINED BY THE RECORDING OF AN ANALYSIS OF SPEECH SOMEWHAT SIMILAR TO THE ANALYSIS PERFORMED BY THE EAR. ORIGINALLY INTENDED TO PRESENT AN EXPERIMENTAL TRAINING PROGRAM IN THE READING OF VISIBLE SPEECH AND EXPANDED TO INCLUDE MATERIAL OF INTEREST TO VARIOUS…

  2. An Overview of the MaRIE X-FEL and Electron Radiography LINAC RF Systems

    SciTech Connect

    Bradley, Joseph Thomas III; Rees, Daniel Earl; Scheinker, Alexander; Sheffield, Richard L.

    2015-05-04

    The purpose of the Matter-Radiation Interactions in Extremes (MaRIE) facility at Los Alamos National Laboratory is to investigate the performance limits of materials in extreme environments. The MaRIE facility will utilize a 12 GeV linac to drive an X-ray Free-Electron Laser (FEL). Most of the same linac will also be used to perform electron radiography. The main linac is driven by two shorter linacs; one short linac optimized for X-FEL pulses and one for electron radiography. The RF systems have historically been the one of the largest single component costs of a linac. We will describe the details of the different types of RF systems required by each part of the linacs. Starting with the High Power RF system, we will present our methodology for the choice of RF system peak power and pulselength with respect to klystron parameters, modulator parameters, performance requirements and relative costs. We will also present an overview of the Low Level RF systems that are proposed for MaRIE and briefly describe their use with some proposed control schemes.

  3. Numerical simulations of x-ray generation in miltisectional FELs

    SciTech Connect

    Pitatelev, M.M.

    1995-12-31

    The process of x-ray generation in milticomponent FELs with alternate undulator and dispersion sections is investigate. The coptuter simulation was fulfilled for the ultrarelativistic electron beams. It was shown that the use of much number of dispersion sections allows to increase the gain considerably and to use more short magnetic systems.

  4. Status of the project of Novosibirsk high power FEL

    SciTech Connect

    Pinayev, I.V.; Erg, G.I.; Gavrilov, N.G.

    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.

  5. Optimization Studies of the FERMI at ELETTRA FEL Design

    SciTech Connect

    De Ninno, Giovanni; Fawley, William M.; Penn, Gregory E.; Graves,William

    2005-08-25

    The FERMI at ELETTRA project at Sincotrone Trieste involves two FEL's, each based upon the principle of seeded harmonic generation and using the existing ELETTRA injection linac at 1.2 GeV beam energy. Scheduled to be completed in 2008, FEL-1 will operate in 40-100 nm wavelength range and will involve one stage of harmonic up-conversion. The second undulator line, FEL-2, will begin operation two years later in the 10-40 nm wavelength range and use two harmonic stages operating as a cascade. The FEL design assumes continuous wavelength tunability over the full wavelength range, and polarization tunability of the output radiation including vertical or horizontal linear as well as helical polarization. The design considers focusing properties and segmentation of realizable undulators and available input seed lasers. We review the studies that have led to our current design. We present results of simulations using GENESIS and GINGER simulation codes including studies of various shot-to-shot fluctuations and undulator errors. Findings for the expected output radiation in terms of the power, transverse and longitudinal coherence are reported.

  6. Infrared FEL photochemistry: multiple-photon dissociation of Freon gas

    NASA Astrophysics Data System (ADS)

    Newnam, Brian E.; Early, James W.; Lyman, John L.

    1994-03-01

    Wavelength tunability, synchrotron sidebands, and picosecond pulse structure are inherent characteristics of free-electron lasers (FELs) that should be advantageous for photochemistry involving infrared multiple-photon photodissociation. Tuned to an absorption resonance, the FEL sideband structure will overlap the broad, red-shifted, quasi-continuous excited-state absorption spectra and should lead to enhanced dissociation. The Los Alamos APEX FEL was operated with and without sidebands to test this hypothesis on CFCl 3 (Freon 11), one of the gases implicated as depleting the ozone in the Earth's stratospheric layer. The FEL wavelength was set at the CCl stretch absorption resonance at 11.8 μm, the oscillator cavity length was detuned first to minimize and then to maximize the spectral bandwidth, and the beam was focused through a pair of test cells. Comparison of final and initial absorbance spectra indicated the CFCl 3 photodissociation yield was 1.2% for the cell exposed with sideband spectra (3% FWHM) and 9-ns micropulse separation. Negligible effect was seen without sidebands, albeit at lower total beam fluence.

  7. TESLA FEL Gun simulations with PARMELA and MAFIA

    SciTech Connect

    Zhang Min; Schuett, Petra

    1997-02-01

    The most recent simulation results of the DESY TESLA FEL gun are presented. Two codes are used: PARMELA and MAFIA. Since the two use different schemes in particle simulations, we will address their differences and try to give an explanation for them.

  8. TESLA FEL Gun simulations with PARMELA and MAFIA

    SciTech Connect

    Zhang, M.; Schuett, P.

    1997-02-01

    The most recent simulation results of the DESY TESLA FEL gun are presented. Two codes are used: PARMELA and MAFIA. Since the two use different schemes in particle simulations, we will address their differences and try to give an explanation for them. {copyright} {ital 1997 American Institute of Physics.}

  9. A Comparison of Short Rayleigh Range FEL Performance with Simulations

    SciTech Connect

    Benson, Stephen; Evtushenko, Pavel; Michelle D. Shinn; Neil, George; Blau, Joe; Burggraff, D.; Colson, William; Crooker, P.P.; Sans Aguilar, J.

    2007-08-01

    One approach to attaining very high power in a free-electron laser (FEL) is to operate with a Rayleigh range much smaller than the wiggler length. Previously, 3D simulations of Free-electron laser (FEL) oscillators showed that FEL gain doesn't fall off with Rayleigh range as predicted by one-dimensional simulations*. They also predict that the angular tolerance for the mirrors is much large than simplistic theory predicts. Using the IR Upgrade laser at Jefferson Lab lasing at 935 nm we have studied the performance of an FEL with very short Rayleigh range. We also looked at the angular sensitivity for several different Rayleigh ranges. We find very good agreement between simulations and measured gain and angular sensitivities. Surprisingly the gain continues to rise as the Rayleigh range is shortened and continues to grow even when the resonator becomes geometrically unstable. The same behavior is seen in both the experiment and simulations. We also find that, even for large Rayleigh r

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

    SciTech Connect

    Ogasawara, Hirohito; Nordlund, Dennis a Nilsson, Anders; /SLAC, SSRL

    2005-09-30

    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.

  11. Second floor order perturbation calculation in energy exchange of FEL

    SciTech Connect

    Wei, J.; Lee, S. Y.

    1987-06-01

    Perturbation expansion of standard FEL equations is performed up to second nontrivial order in the Vlasov's equation. We found that the perturbation expansion can be characterized by a single parameter, Ωτ, the number of sychrotron oscillations in the wiggler. The validity of perturbation theory is discussed in this paper.

  12. Efficiency optimization in a FEL with fields` nonadiabatic tapering

    SciTech Connect

    Goncharov, I.A.; Belyavskiy, E.D.; Silivra, A.A.

    1995-12-31

    Amplification of an electromagnetic wave in free electron lasers with a reversed guide field and right-hand polarized wiggler field is investigated both analytically and numerically. An effect of electron bunch trapping by the high frequency electromagnetic field is used for efficiency optimization. On the basis of motion stability criteria a possibility of bunches trapping by FEL parameters nonadiabatic (experimentally realizable) tapering is shown. The stability analysis of electron motion is based on Lyapunov theory for autonomy systems. A particle simulation is carried out for FEL parameters close to the experimental ones (relativistic factor {gamma}=4.75, wiggler field strength B{sub w}= 2.8 kG, guide field strength B{sub o}= -1.4 kG, operation wavelength {lambda}=6.2 mm) for the case of wiggler field tapering. Theoretically predicted rule of wiggler field tapering corresponding to FEL efficiency of 55% is approximated by stepped functions. For the experimentally realizable tapering it is found that FEL efficiency can be over 40%.

  13. The physics of FEL in an infinite electron beam

    SciTech Connect

    Wang, G.; Litvinenko, V.N.; Webb, S.

    2010-10-07

    We solve linearized Vlasov-Maxwell FEL equations for a 3-D perturbation in the infinite electron beam with Lorentzian energy distributions using paraxial approximation. We present analytical solutions for various initial perturbations and discuss the effect of optical guiding in such system.

  14. Harmonic millimeter radiation from a microwave FEL amplifier

    NASA Astrophysics Data System (ADS)

    Liu, Y.-H.; Marshall, T. C.

    1997-02-01

    In this project, an electron beam is bunched at a microwave frequency and the harmonics of this bunching drive radiation at millimeter wavelengths, using a FEL, configured as a single-pass travelling wave amplifier. A 10 kW 24 GHz microwave input signal grows to ˜200 kW level using the lower-frequency unstable root of the waveguide FEL dispersion relation. The Columbia FEL facility operates at this frequency in the TE11 mode, using a helical undulator (1.85 cm period) and a 3 mm diameter 600 kV electron beam contained in a 8.7 mm ID cylindrical waveguide. The harmonic currents set up by the microwave are found to cause growth of harmonic power under two conditions. First, we choose the parameters of the device so that the upper frequency root corresponds to the third harmonic, in which case we observe a small amount of third-harmonic emission in the TE11 mode, accompanied by comparable second harmonic. The millimeter harmonic radiation produced is coherent and phase-related to the microwave source. Second, we have found substantial emission at the seventh harmonic, most likely from the TE72 mode — which, in cylindrical waveguide geometry, travels at very nearly the same wave speed as the 24 GHz TE11 power. In order to excite the seventh-harmonic radiation, the electron beam must be displaced from the system axis — ˜2 mm in this device. The seventh-harmonic output is potentially an attractive choice for a CW FEL which must generate appreciable power at ˜2 mm wavelength for plasma electron cyclotron heating since we can produce this radiation for electron beam energy as low as 400 kV. We present a theoretical model of the experiment which predicts that if the microwave signal is strong enough to drive the FEL into saturation, the harmonic emission becomes powerful.

  15. Numerical study of the 3-D effect on FEL performance and its application to the APS LEUTL FEL

    SciTech Connect

    Chae, Y.C.

    1998-09-01

    A Low-Energy Undulator Test Line (LEUTL) is under construction at the Advanced Photon Source (APS). In LEUTL periodic focusing is provided by external quadrupoles. This results in an elliptical beam with its betatron oscillation envelope varying along the undulators. The free-electron laser (FEL) interaction with such a beam will exhibit truly 3-D effects. Thus the investigation of 3-D effects is important in optimizing the FEL performance. The programs GINGER and TDA3D, coupled with theoretically known facts, have been used for this purpose. Both programs are fully 3-D in moving the particle, but model the interaction between particles and axially symmetric electromagnetic waves. Even though TDA3D can include a few azimuthal modes in the interaction, it is still not a fully 3-D FEL code. However, they show that these 2-D programs can still be used for an elliptical beam whose aspect ratio is within certain limits. The author presents numerical results of FEL performance for the circular beam, the elliptical beam, and finally for the beam in the realistic LEUTL lattice.

  16. Optical alignment and tuning system for the HUST THz-FEL

    NASA Astrophysics Data System (ADS)

    Liu, Xu; Liu, Kaifeng; Qin, Bin; Tan, Ping; Fu, Qiang; Wang, Wei; Pei, Yuanji

    2016-11-01

    A compact FEL oscillator with a radiation wavelength of 30 - 100 μm is proposed by HUST and NSRL. The optical cavity is very sensitive to misalignment errors of the mirror, due to its near-concentric and symmetric structure. The magnetic axis of the undulator, the optical axis of the resonator, and the electron beam propagation axis must all be aligned with high precision for achieving saturated lasing. This paper introduces a high-precision, multi-degree-of-freedom controlled optical alignment system, which has the ability to align in the transverse and longitudinal directions. The alignment tolerances are given by theoretical analysis and numerical simulations with three-dimensional FEL code GENESIS and optical propagation code (OPC). To accomplish optical alignment, two auxiliary HeNe laser systems were introduced. By adjusting the HeNe laser beam spot on the wedge, the optical axis can be aligned to the magnetic axis, and the estimated errors meet the tolerances. Finally, the electron beam will be guided through the hole in the central wedge to complete the transverse alignment. The longitudinal alignment and tuning methods are also described.

  17. THz wiggler applied for measurements of electron bunch longitudinal structure in FEL

    NASA Astrophysics Data System (ADS)

    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.

  18. Output characteristics of SASE-driven short wavelength FEL`s

    SciTech Connect

    Fawley, W.M.

    1997-02-01

    This paper investigates various properties of the ``microspikes`` associated with self-amplified spontaneous emission (SASE) in a short wavelength free-electron laser (FEL). Using results from the 2-D numerical simulation code GINGER, we confirm theoretical predictions such as the convective group velocity in the exponential gain regime. In the saturated gain regime beyond the initial saturation, we find that the average radiation power continues to grow with an approximately linearly dependence upon undulator length. Moreover, the spectrum significantly broadens and shifts in wavelength to the redward direction, with{ital P(w)} approaching a constant, asymptotic value. This is in marked contrast to the exponential gain regime where the spectrum steadily narrows, {ital P(w)} grows, and the central wavelength remains constant with {ital z}. Via use of a spectrogram diagnostic {ital S(w,t)}, it appears that the radiation pattern in the saturated gain regime is composed of an ensemble of distinct ``sinews`` whose widths AA remain approximately constant but whose central wavelengths can ``chirp`` by varying a small extent with {ital t}.

  19. Analysis of the eigenvalue equation of the FEL amplifier with axisymmetric electron beam and diaphragm focusing line

    NASA Astrophysics Data System (ADS)

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

    1996-02-01

    The paper presents analysis of the eigenvalue problem of the FEL amplifier with axisymmetric electron beam and diaphragm focusing line. This novel type of an FEL amplifier has perspective to be used for applications where high average and peak radiation power is required [E.L. Saldin et al., Nucl. Instr. and meth. A 361 (1995) 317; these Proceedings, Nucl. Instr. and Meth. 375 (1996) 389; Nucl. Instr. and Meth. A 361 (1995) 101]. An FEL model is discussed wherein diffraction effects, space charge fields and energy spread of electrons in the beam are taken into account. To take into account diffraction effects at the diaphragms we apply the rigorous impedance boundary conditions proposed by Veinstein. The rigorous solutions of the eigenvalue problem have been found for the stepped electron beam profile. Analytical expressions for eigenfunctions of active open waveguide and formulae of their expansion in the eigenfunctions of passive open waveguide, are derived, too. Asymptotic behaviour of the obtained solutions is studied in details.

  20. Design of an XUV FEL Driven by the Laser-Plasma Accelerator at theLBNL LOASIS Facility

    SciTech Connect

    Schroeder, Carl B.; Fawley, W.M.; Esarey, Eric; Leemans, W.P.

    2006-09-01

    We present a design for a compact FEL source of ultrafast, high-peak flux, soft x-ray pulses employing a high-current, GeV-energy electron beam from the existing laser-plasma accelerator at the LBNL LOASIS laser facility. The proposed ultra-fast source would be intrinsically temporally synchronized to the drive laser pulse, enabling pump-probe studies in ultra-fast science with pulse lengths of tens of fs. Owing both to the high current ({approx} 10 kA) and reasonable charge/pulse ({approx} 0.1-0.5 nC) of the laser-plasma-accelerated electron beams, saturated output fluxes are potentially 10{sup 13}--10{sup 14} photons/pulse. We examine devices based both on SASE and high-harmonic generated input seeds to give improved coherence and reduced undulator length, presenting both analytic scalings and numerical simulation results for expected FEL performance. A successful source would result in a new class of compact laser-driven FELs in which a conventional RF accelerator is replaced by a GeV-class laser-plasma accelerator whose active acceleration region is only a few cm in length.

  1. Field Encapsulation Library The FEL 2.2 User Guide

    NASA Technical Reports Server (NTRS)

    Moran, Patrick J.; Henze, Chris; Ellsworth, David

    1999-01-01

    This document describes version 2.2 of the Field Encapsulation Library (FEL), a library of mesh and field classes. FEL is a library for programmers - it is a "building block" enabling the rapid development of applications by a user. Since FEL is a library intended for code development, it is essential that enough technical detail be provided so that one can make full use of the code. Providing such detail requires some assumptions with respect to the reader's familiarity with the library implementation language, C++, particularly C++ with templates. We have done our best to make the explanations accessible to those who may not be completely C++ literate. Nevertheless, familiarity with the language will certainly help one's understanding of how and why things work the way they do. One consolation is that the level of understanding essential for using the library is significantly less than the level that one should have in order to modify or extend the library. One more remark on C++ templates: Templates have been a source of both joy and frustration for us. The frustration stems from the lack of mature or complete implementations that one has to work with. Template problems rear their ugly head particularly when porting. When porting C code, successfully compiling to a set of object files typically means that one is almost done. With templated C++ and the current state of the compilers and linkers, generating the object files is often only the beginning of the fun. On the other hand, templates are quite powerful. Used judiciously, templates enable more succinct designs and more efficient code. Templates also help with code maintenance. Designers can avoid creating objects that are the same in many respects, but not exactly the same. For example, FEL fields are templated by node type, thus the code for scalar fields and vector fields is shared. Furthermore, node type templating allows the library user to instantiate fields with data types not provided by the FEL

  2. Two-color FEL amplifier for femtosecond-resolution pump-probe experiments with GW-scale X-ray and optical pulses

    NASA Astrophysics Data System (ADS)

    Feldhaus, J.; Körfer, M.; Möller, T.; Pflüger, J.; Saldin, E. L.; Schneidmiller, E. A.; Schreiber, S.; Yurkov, M. V.

    2004-08-01

    The paper describes a scheme for pump-probe experiments that could be performed at the soft X-ray SASE FEL at the TESLA Test Facility (TTF) at DESY and determines what additional hardware developments will be required to bring these experiments to fruition. Pump-probe experiments combining pulses from a XFEL and optical femtosecond laser are very attractive for sub-picosecond time-resolved studies. Since the synchronization between the two light sources to an accuracy of 100 fs is not yet solved, it is proposed to derive both femtosecond radiation pulses from the same electron bunch but from two insertion devices. This eliminates the need for synchronization and developing tunable, high power femtosecond quantum laser. In the proposed scheme for pump-probe experiments, GW-level soft X-ray pulse is naturally synchronized with his GW-level optical pulse and cancel jitter. The concept is based on generation of the optical radiation in the master oscillator-power FEL amplifier configuration. An attractive feature of the FEL amplifier scheme is the absence of limitation which would prevent operation in the femtosecond regime in a wide (200- 900 nm) wavelength range. The problem of tunable quantum seed laser can be solved with commercially available long pulse dye laser. An important feature of the proposed scheme is that optical radiator uses the spent electron beam. As a result, saturation mode of operation of the optical FEL does not interfere with the main mode of the soft X-ray SASE FEL operation.

  3. A wiggler magnet for FEL low voltage operation

    SciTech Connect

    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.

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

    SciTech Connect

    Yamada, K.; Yamazaki, T.; Sei, N.

    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.

  5. Locking Lasers to RF in an Ultra Fast FEL

    SciTech Connect

    Wilcox, R.; Huang, G.; Doolittle, L.; White, W.; Frisch, J.; Coffee, R.

    2010-01-02

    Using a novel, phase-stabilized RF-over-fiber scheme, they transmit 3GHz over 300m with 27fs RMS error in 250kHz bandwidth over 12 hours, and phase lock a laser to enable ultrafast pump-probe experiments. Free-electron lasers (FELs) are capable of producing short-duration (< 10fs), high-energy X-ray pulses for a range of scientific applications. The recently activated Linac Coherent Light Source (LCLS) FEL facility at SLAC will support experiments which require synchronized light pulses for pump-probe schemes. They developed and operated a fiber optic RF transmission system to synchronize lasers to the emitted X-ray pulses, which was used to enable the first pump-probe experiments at the LCLS.

  6. Studies of Resistive Wall Heating at JLAB FEL

    SciTech Connect

    Li, Rui; Benson, Stephen V.

    2013-06-01

    When the JLAB FEL is under CW operation, it had been observed that temperature rises over the wiggler vacuum chamber, presumably as the result of the power deposition on the resistive wall of the wiggler chamber. Previous analyses have been done on the resistive wall impedance for various cases, such as DC, AC, and anomalous skin effects*. Here we report an investigation on the beam kinetic energy losses for each of these cases. This study includes the non-ultrarelativistic effect on resistive wall loss, for both round pipe and parallel plates. We will present the comparison of our results with the measured data obtained during CW operation of the JLAB FEL. Other possible factors contributing to the measured heating will also be discussed.

  7. Beam transport for an SRF recirculating-linac FEL

    SciTech Connect

    Neuffer, D.; Douglas, D.; Li, Z.

    1995-12-31

    The beam transport system for the CEBAF UV Demo FEL includes a two-pan transport of the beam with acceleration from injector to wiggler, followed by energy recovery transport from wiggler to dump. From that contact we discuss the general problem of multi-pass energy-recovery beam transport for FELs. Tuneable, nearly-isochronous, large-momentum-acceptance import 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. Issues such as injection and final energies, number of passes, linac focusing effects, beam separation, chronicity management, and stability constraints are critical. Various possible designs are discussed. Particle tracking results exploring the design options are also reported.

  8. Physical optics simulations with PHASE for SwissFEL beamlines

    SciTech Connect

    Flechsig, U.; Follath, R.; Reiche, S.; Bahrdt, J.

    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.

  9. First lasing of the IR upgrade FEL at Jefferson lab

    SciTech Connect

    Christopher Behre; Stephen Benson; George Biallas; James Boyce; Christopher Curtis; David Douglas; H. Dylla; L. Dillon-townes; Richard Evans; Albert Grippo; Joseph Gubeli; David Hardy; John Heckman; Carlos Hernandez-Garcia; Tommy Hiatt; Kevin Jordan; Nikolitsa Merminga; George Neil; Joseph Preble; Harvey Rutt; Michelle D. Shinn; Timothy Siggins; Hiroyuki Toyokawa; David W. Waldman; Richard Walker; Neil Wilson; Byung Yunn; Shukui Zhang

    2004-08-01

    We report initial lasing results from the IR Upgrade FEL at Jefferson Lab[1]. The electron accelerator was operated with low average current beam at 80 MeV. The time structure of the beam was 120 pC bunches at 4.678 MHz with up to 750 {micro}sec pulses at 2Hz. Lasing was established over the entire wavelength range of the mirrors (5.5-6.6 {micro}m). The detuning curve length, turn-on time, and power were in agreement with modeling results assuming a 1 psec FWHM micropulse. The same model predicts over 10 kW of power output with 10 mA of beam and 10% output coupling, which is the ultimate design goal of the IR Upgrade FEL. The behavior of the laser while the dispersion section strength was varied was found to qualitatively match predictions. Initial CW lasing results also will be presented.

  10. Polarization properties of FEL lamps as applied to radiometric calibration.

    PubMed

    Voss, Kenneth J; Belmar da Costa, Leonardo

    2016-11-01

    The polarization of the irradiance from several 1000 W FEL lamps was measured between 450 and 900 nm. These lamps are universally used as irradiance calibration standards in radiometric laboratories. The irradiance was polarized between 2.3% and 3.2%, with the polarization axis aligned with the coiled filament, nearly perpendicular to the lamp axis. We have presented a simple model of the filament that explains the degree of polarization and the plane of polarization, based on the polarized emissivity of tungsten, and gives an approximate value for this polarization. While the irradiance is polarized, this polarization does not significantly effect the polarization of the light when reflected from a Spectralon plaque (Labsphere, Inc.). The polarization of these lamps should be considered when these FEL lamps are used to characterize optical instruments, particularly grating spectrometers without polarization scrambling devices.

  11. Oscillation in FEL Self-Amplified Spontaneous Emission

    NASA Astrophysics Data System (ADS)

    Bakhtyari, Arash; Walsh, John E.; Brownell, J. Hayden

    2002-04-01

    An electron beam traveling perpendicular to the groves of a metallic grating produces radiation with a wavelength depending on the beam velocity and the observation angle. Named the Smith-Purcell effect after its discoverers, this process is the basis of a compact THz free electron laser (SP-FEL). Currently, a modified scanning electron microscope serves as an electron beam source and provides precise control of the operating parameters. Superradiant emission in this device was achieved in 1997. The output power just below threshold oscillates with beam current, exhibiting distinct features attributable to the beating of three co-propagating waves, as predicted by the Pierce theory for traveling-wave tubes. Observation of this behavior confirms the gain mechanism underlying the SP-FEL.

  12. Israeli tandem FEL: first-lasing results and future plans

    NASA Astrophysics Data System (ADS)

    Abramovich, A.; Arensburg, A.; Chairman, D.; Eichenbaum, A.; Draznin, M.; Gover, Abraham; Kleinman, H.; Merhasin, I.; Pinhasi, Yosef; Sokolowski, J. S.; Yakover, Y. M.; Cohen, Moshe; Levin, L. A.; Shahal, O.; Rosenberg, Avner; Schnitzer, Itzhak; Shiloh, J.

    1997-11-01

    Results of first operation of the Israeli Electrostatic- Accelerator Tandem Free-Electron Laser (EA-FEL) are reported. This EA-FEL utilizes a 1.4 Amp electron beam obtained from a parallel flow Pierce-type electron gun. The e-beam is transported through a resonator located inside a plane Halbach configuration wiggler, both located at the high voltage terminal of the van de graaf accelerator. The high voltage terminal is charge to a positive plates waveguide and two Talbot effect quasioptical reflectors. It exhibited a quality factor of Q approximately equals 30,000. Millimeter wave radiation pulses of 2 microsecond(s) ec duration were obtained at a frequency of 100.5 GHz, as predicted, at a power level above 1 kW.

  13. Measurement of single-pulse spectra of an infrared FEL

    NASA Astrophysics Data System (ADS)

    Leemans, W. P.; Edighoffer, J. A.; Swent, R. L.

    1994-03-01

    A novel diagnostic system [W.P. Leemans et al., Nucl. Instr. and Meth. A 331 (1993) 615] has been used to measure the micropulse spectra of infrared pulses generated by the free electron laser (FEL) at Stanford University. The diagnostic system makes use of a high resolution 1 m spectrometer, and an imaging system based on an image dissector [H.A. Baldis et al., Rev. Sci. Instr. 48 (1977) 173] and a single element HgCdTe-high speed detector with integrating sphere. Spectra of single and multiple consecutive micropulses at a repetition rate of 11.8 MHz have been obtained for the FEL operating at 5 μm.

  14. Serial snapshot crystallography for materials science with SwissFEL

    SciTech Connect

    Dejoie, Catherine; Smeets, Stef; Baerlocher, Christian; Tamura, Nobumichi; Pattison, Philip; Abela, Rafael; McCusker, Lynne B.

    2015-04-21

    New opportunities for studying (sub)microcrystalline materials with small unit cells, both organic and inorganic, will open up when the X-ray free electron laser (XFEL) presently being constructed in Switzerland (SwissFEL) comes online in 2017. Our synchrotron-based experiments mimicking the 4%-energy-bandpass mode of the SwissFEL beam show that it will be possible to record a diffraction pattern of up to 10 randomly oriented crystals in a single snapshot, to index the resulting reflections, and to extract their intensities reliably. The crystals are destroyed with each XFEL pulse, but by combining snapshots from several sets of crystals, a complete set of data can be assembled, and crystal structures of materials that are difficult to analyze otherwise will become accessible. Even with a single shot, at least a partial analysis of the crystal structure will be possible, and with 10–50 femtosecond pulses, this offers tantalizing possibilities for time-resolved studies.

  15. AN EXPERIMENTAL TEST OF SUPERRADIANCE IN A SINGLE PASS SEEDED FEL.

    SciTech Connect

    WATANABE, T.; LIU, D.; MURPHY, J.B.; ROSE, J.; SHAFTAN, T.; TSANG, T.; WANG, X.J.; YU, L.H.

    2005-08-21

    Superradiance and nonlinear evolution of a FEL pulse in a single-pass FEL were experimentally demonstrated at the National Synchrotron Light Source (NSLS) Source Development Laboratory (SDL). The experiment was performed using a 1.5 ps high-brightness electron beam and a 100fs Ti:Sapphire seed laser. The seed laser and electron beam interact in the 10 meter long NISUS undulator with a period of 3.89 cm. The FEL spectrum, energy and pulse length along the undulator were measured. FEL saturation was observed, and gain of more the 200 (relative to seed laser) was measured. Both FEL spectrum widening and pulse length shortening were observed; FEL pulses as short as 65 fs FWHM were measured. The superradiance and nonlinear evolution were also simulated using the numerical code GENESIS1.3 yielding good agreement with the experimental results.

  16. Possible enhancement of SASE FEL output field intensity induced by local phase jump

    NASA Astrophysics Data System (ADS)

    Varfolomeev, A. A.; Yarovoi, T. V.; Bousine, P. V.

    1998-02-01

    A possible influence on the FEL dynamics of a locally induced phase jump between the FEL radiation and electron beam is considered. A numerical study has been made for the SASE mode FEL supposing that the phase jumps are introduced at different depths inside the undulator. The FEL evolution starting from a small input signal was studied in 1D high gain approach. It was shown that the FEL radiation output is sensitive to the phase jump value if it is introduced at the depth where saturation of output power takes places. In the steady state regime, the phase displacement of order ˜π provides enhancement of the peak output power up to 50%. Some kind of optical tapering is also possible giving further FEL efficiency enhancement.

  17. 140 GHz microwave FEL experiments using ELF-II

    SciTech Connect

    Throop, A.L.; Jong, R.A.; Atkinson, D.P.; Clark, J.C.; Felker, B.; Ferguson, S.W.; Makowski, M.A.; Nexsen, W.E.; Stallard, B.W.; Stever, R.D.; Turner, W.C.

    1989-09-01

    We describe the modeling, the experimental facility, and the initial operating results for ELF-II, an induction-linac based free-electron laser designed to produce up to 2 GW of peak power at 140 GHz. ELF-II is the initial configuration of an FEL system which will eventually produce up to 2 MW of average power at a frequency of 250 GHz, for use in plasma heating experiments in the Microwave Tokamak Experiment. 6 refs., 9 figs.

  18. Evolution of longitudinal modes in low voltage FEL

    SciTech Connect

    Stuart, R.A.; Al-Shamma`a, A.; Shaw, A.

    1995-12-31

    A low voltage FEL operating at 130 kV which can be run cw with a continuous electron beam current level up to 12 mA has been constructed for the X-Band microwave range (8-12 GHz). In this poster, we will report on the dependence on time, after the electron beam is switched on, of the growth and competition of those longitudinal modes in the cavity having nett gain.

  19. Energy Recovery Transport Design for Peking University FEL

    SciTech Connect

    G. M. Wang; Y.-C. Chao; J.-E. Chen; C. Liu; Z. C. Liu; X. Y. Lu; K. Zhao; J. Zhuang

    2007-08-01

    A free-electron laser based on a superconducting linac is under construction in Peking University. To increase FEL output power, energy recovery is chosen as one of the most potential and popular ways. The design of a beam transport system for energy recovery is presented, which is suitable for the Peking University construction area. Especially, a chicane structure is chosen to change path length at ±20 degree and M56 in the arc is adjusted for fully bunch compression.

  20. Simulation of waveguide FEL oscillator using RF linac

    SciTech Connect

    Kuruma, S.; Asakawa, M.; Imasaki, K.

    1995-12-31

    One dimensional multifrequency simulation code for waveguide mode FEL has been developed. Using this simulation code, we analyzed the spontaneous emission from electron micropulse from RF Linac. It is found that some parameters both high and low frequency waveguide modes are growing simultaneously, so the two radiation pulses are generated and amplified. And the experimental data for cavity length detuning of the radiation power are analyzed.

  1. Commissioning the FELI linac and UV-FEL facility

    SciTech Connect

    Tomimasu, T.; Saeki, K.; Miyauchi, Y.

    1995-12-31

    The FELI 165-MeV linac and UV-FEL facility are in the commissioning, stage. A thermionic triode gun of the 6-MeV injector emits 500-ps pulses of 2.3A at 22.3125MHz. These pulses are compressed to 60AX 7ps by a 714-MHz prebuncher and a 2856-MHz buncher and seven ETL type accelerating waveguides with a length of 2.93m. The length of the linac including bending sections of two S-type BT systems for two undulators used for IR-FEL oscillations is 46m. The buncher and these accelerating waveguides are powered by two klystrons (E3729, 2856MHz, total 48MW, 24-{mu}s flat top long pulses). The flatness of our klystron modulator pulses is 0.067% at 24-{mu}s duration. An rf-ageing for new four accelerating waveguides will be started in May. An S-type BT line for 165-MeV beam from the linac will be installed in the end of April. A 2.68-m undulator ({lambda}u=4.0cm, N=67, Kmax gap length {ge}16mm) and an optical cavity (Lc=6.72m) will be installed early in July. The beam conditionings for UV-FEL experiments will be started in July.

  2. Electron bunch length measurement at the Vanderbilt FEL

    SciTech Connect

    Amirmadhi, F.; Brau, C.A.; Mendenhall, M.

    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.

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

    SciTech Connect

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

    1995-12-31

    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.

  4. Parameter design considerations for an oscillator IR-FEL

    NASA Astrophysics Data System (ADS)

    Jia, Qi-Ka

    2017-01-01

    An infrared oscillator FEL user facility will be built at the National Synchrotron Radiation Laboratory at in Hefei, China. In this paper, the parameter design of the oscillator FEL is discussed, and some original relevant approaches and expressions are presented. Analytic formulae are used to estimate the optical field gain and saturation power for the preliminary design. By considering both physical and technical constraints, the relation of the deflection parameter K to the undulator period is analyzed. This helps us to determine the ranges of the magnetic pole gap, the electron energy and the radiation wavelength. The relations and design of the optical resonator parameters are analyzed. Using dimensionless quantities, the interdependences between the radii of curvature of the resonator mirror and the various parameters of the optical resonator are clearly demonstrated. The effect of the parallel-plate waveguide is analyzed for the far-infrared oscillator FEL. The condition of the necessity of using a waveguide and the modified filling factor in the case of the waveguide are given, respectively. Supported by National Nature Science Foundation of China (21327901, 11375199)

  5. Monoclonal antibodies to the major feline allergen Fel d I. II. Single step affinity purification of Fel d I, N-terminal sequence analysis, and development of a sensitive two-site immunoassay to assess Fel d I exposure.

    PubMed

    Chapman, M D; Aalberse, R C; Brown, M J; Platts-Mills, T A

    1988-02-01

    Two mAb were used to develop new techniques for the purification and quantitation of the major feline salivary allergen, Felis domesticus allergen I (Fel d I). The allergen was purified from aqueous house dust extract with a high Fel d I content by affinity chromatography over a monoclonal immunosorbent and elution with 4 mM HCl, pH 2.5. This single step procedure gave 40 to 50% recovery of 90% pure allergen which, following final purification by size exclusion HPLC, showed a single line on immunodiffusion and crossed immunoelectrophoresis against monospecific anti-Fel d I and polyclonal anti-cat dander antibodies. The m.w. of native Fel d I was 39,000 on size exclusion HPLC, and 17,000 under nonreducing conditions on gel electrophoresis. The N-terminal amino acid sequence (33 residues) showed no homology with other known protein sequences. The combination of the SDS-PAGE and N-terminal sequence data suggests that Fel d I is a non-covalently linked homodimer. A two-site RIA was developed using mAb directed against different epitopes on Fel d I. This assay was species-specific, highly sensitive (0.0004 U/ml), and showed an excellent correlation with a polyclonal inhibition RIA (n = 27, r = 0.93, p less than 0.001). Cat allergen extracts used for immediate skin tests showed marked differences in Fel d I content (from 0.1 to 30 U/ml). Consistently high Fel d I levels were found at monthly intervals in six dust samples from four houses with cats (10 to 100 U/g of dust). Comparisons of Fel d I and mite and pollen allergen levels showed that house dust can contain greater than 100 micrograms/g of either of these allergens and is a potent source of foreign environmental antigens. Monoclonal affinity chromatography provides a major breakthrough in the purification of Fel d I, from a source material that would otherwise have been considered impossible (house dust). The mAb assay for Fel d I is both more sensitive and more easily standardized than existing techniques. These

  6. Residential characteristics predict changes in Der p 1, Fel d 1 and ergosterol but not fungi over time.

    PubMed

    Matheson, M C; Dharmage, S C; Forbes, A B; Raven, J M; Woods, R K; Thien, F C K; Guest, D I; Rolland, J M; Haydn Walters, E; Abramson, M J

    2003-09-01

    Allergen and fungal exposures are important risk factors for asthma. We conducted a longitudinal analysis of allergen levels in Melbourne homes between 1996 and 1998 to examine the effects of changing residential characteristics on allergen and fungal levels. We also examined the changes in levels of indoor allergens. The subjects were participants in the European Community Respiratory Health Survey (ECRHS) in Melbourne. In 1996, 485 subjects participated in a follow-up study, which involved both home and laboratory visits. Dust and air samples were collected from participants' bedrooms and a validated residential questionnaire was administered. In 1998, 360 participants underwent further follow-up. House dust mite (Der p 1) and cat allergens (Fel d 1) and ergosterol were measured in dust. We observed moderate within home correlations between 1996 and 1998 in floor Der p 1 (intraclass correlation ICC=0.48), bed Der p 1 (ICC=0.61), Fel d 1 (kappa=0.53) and ergosterol (ICC=0.28) levels. We found that the floor Der p 1 levels decreased from 1996 to 1998 in the homes of participants who moved to an attached home, moved their bedrooms to the first floor, removed fitted carpet or central heating. Replacing or vacuuming the mattress more than twice per year reduced levels of Der p 1 in the bed. Ergosterol levels were reduced by removing visible mould and fitted carpet. These findings provide evidence to support current advice with regard to allergen avoidance in patients with dust mite and fungal allergies.

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

    NASA Astrophysics Data System (ADS)

    Lumpkin, A. H.; Dejus, R.; Lewellen, J. W.; Berg, W.; Biedron, S.; Borland, M.; Chae, Y.; Erdmann, M.; Huang, Z.; Kim, K.-J.; Li, Y.; Milton, S. V.; Moog, E.; Rule, D. W.; Sajaev, V.; Yang, B. X.

    2002-05-01

    We report the initial, comprehensive set of z-dependent measurements of electron-beam microbunching using coherent optical transition radiation (COTR) 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 the microbunching. The results will be compared to relevant calculations using GENESIS and/or GINGER.

  8. Potential applications of a dual-sweep streak camera system for characterizing particle and photon beams of VUV, XUV, and x-ray FELS

    SciTech Connect

    Lumpkin, A.

    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.

  9. What Have We Learned from the kilowatt IR-FEL at Jefferson Lab?

    SciTech Connect

    Stephen V. Benson

    2002-05-01

    Recent work at Jefferson Lab has demonstrated the concept of same cell energy recovery to attain high average power in a free-electron laser (FEL)[1]. Since this device was the first of its kind, we learned a great deal about how to design such systems as we learned to operate the prototype. We are in the process of building a laser with an average power in excess of 10 kW in the infrared and have point designs for even higher power. This talk will summarize the problems which were thought to exist before the IR Demo lased and what we have learned since the laser operated successfully. The upgrade has its own challenges and these will be described and the proposed solutions will be described. The changes required in the electron beam transport [2] will be summarized. A new optical cavity has been designed which allows much higher power than the IR Demo. The design details will be covered.

  10. Circular polarization with crossed-planar undulators in high gain FELs.

    SciTech Connect

    Kim, K.-J.

    1999-08-31

    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.

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

    NASA Astrophysics Data System (ADS)

    Zhang, Kaiqing; Qi, Zheng; Feng, Chao; Deng, Haixiao; Wang, Dong; Zhao, Zhentang

    2017-05-01

    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.

  12. Shot noise startup of the 6 nm SASE FEL at the TESLA test facility

    NASA Astrophysics Data System (ADS)

    Pierini, P.; Fawley, W. M.

    1996-02-01

    We present here the results of an extensive simulation activity for the TESLA SASE FEL. We have used the program GINGER to determine the FEL saturation length and the power fluctuations from shot to shot. The spectral properties of the output power and the correlation functions are investigated and compared with available theoretical models.

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

    SciTech Connect

    Kulipanov, G.N.; Sokolov, A.S.; Vinokurov, N.A.

    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.

  14. FEL beam sharing systems for eight user`s stations of the FELI

    SciTech Connect

    Okuma, S.; Saeki, K.; Kobayashi, A.

    1995-12-31

    Two infrared free electron lasers (FELs) of the FELI are now operating in the wavelength range of 1-20 {mu}m. Two kinds of FEL beam are sent from the exits of the optical cavities to the diagnostics room through the evacuated optical pipelines whose inner diameter is about 150 mm. From the diagnostic room to user`s stations, FEL beams are delivered through FEL beam sharing systems. Au-coated mirrors with fan-shaped holes are used instead of half mirrors such as ZnSe to share FEL beams to the diagnostics room and the following user`s stations, since maximum diameter of FEL beams is 50 mm in the wavelength range of 1-20 {mu}m and an opening angle of the fan-shaped holes can change a sharing ratio of delivering FEL average power for user`s stations; for instance, 10% to the diagnostics room and 90% to eight user`s stations. Each system enables us to use the same FEL beam simultaneously at the user`s stations. The two beam sharing systems will be installed in the user`s facility early in August.

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

    SciTech Connect

    Balfour, C.; Shaw, A.; Mayhew, S.E.

    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.

  16. Development of a high average power, CW, MM-wave FEL

    SciTech Connect

    Ramian, G.

    1995-12-31

    Important operational attributes of FELs remain to be demonstrated including high average power and single-frequency, extremely narrow-linewidth lasing. An FEL specifically designed to achieve these goals for scientific research applications is currently under construction. Its most salient feature is operation in a continuous-wave (CW) mode with an electrostatically generated, high-current, recirculating, DC electron beam.

  17. Plasma switch as a temporal overlap tool for pump-probe experiments at FEL facilities

    NASA Astrophysics Data System (ADS)

    Harmand, M.; Murphy, C. D.; Brown, C. R. D.; Cammarata, M.; Döppner, T.; Düsterer, S.; Fritz, D.; Förster, E.; Galtier, E.; Gaudin, J.; Glenzer, S. H.; Göde, S.; Gregori, G.; Hilbert, V.; Hochhaus, D.; Laarmann, T.; Lee, H. J.; Lemke, H.; Meiwes-Broer, K.-H.; Moinard, A.; Neumayer, P.; Przystawik, A.; Redlin, H.; Schulz, M.; Skruszewicz, S.; Tavella, F.; Tschentscher, T.; White, T.; Zastrau, U.; Toleikis, S.

    2012-08-01

    We have developed an easy-to-use and reliable timing tool to determine the arrival time of an optical laser and a free electron laser (FEL) pulses within the jitter limitation. This timing tool can be used from XUV to X-rays and exploits high FELs intensities. It uses a shadowgraph technique where we optically (at 800 nm) image a plasma created by an intense XUV or X-ray FEL pulse on a transparent sample (glass slide) directly placed at the pump - probe sample position. It is based on the physical principle that the optical properties of the material are drastically changed when its free electron density reaches the critical density. At this point the excited glass sample becomes opaque to the optical laser pulse. The ultra-short and intense XUV or X-ray FEL pulse ensures that a critical electron density can be reached via photoionization and subsequent collisional ionization within the XUV or X-ray FEL pulse duration or even faster. This technique allows to determine the relative arrival time between the optical laser and the FEL pulses in only few single shots with an accuracy mainly limited by the optical laser pulse duration and the jitter between the FEL and the optical laser. Considering the major interest in pump-probe experiments at FEL facilities in general, such a femtosecond resolution timing tool is of utmost importance.

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

    SciTech Connect

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

    1995-12-31

    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{sup 2}-10{sup 4} times up to 10{sup 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. Lattice Design for a High-Power Infrared FEL

    NASA Astrophysics Data System (ADS)

    Douglas, D. R.

    1997-05-01

    A 1 kW infrared FEL, funded by the U.S. Navy, is under construction at Jefferson Lab. This device will be driven by a compact, 42 MeV, 5 mA, energy-recovering, CW SRF-based linear accelerator to produce light in the 3-6.6 μm range. The machine concept comprises a 10 MeV injector, a linac based on a single high-gradient Jefferson Lab accelerator cryomodule, a wiggler and optical cavity, and an energy-recovery recirculation arc. Energy recovery limits cost and technical risk by reducing the RF power requirements in the driver accelerator. Following deceleration to 10 MeV, the beam is dumped. Stringent phase space requirements at the wiggler, low beam energy, and high beam current subject the accelerator lattice to numerous constraints. Principal considerations include: transport and delivery to the FEL of a high-quality, high-current beam; the impact of coherent synchrotron radiation (CSR) during beam recirculation transport; beam optics aberration control, to provide low-loss energy-recovery transport of a 5% relative momentum spread, high-current beam; attention to possible beam breakup (BBU) instabilities in the recirculating accelerator; and longitudinal phase space management during beam transport, to optimize RF drive system control during energy recovery and FEL operation. The presentation will address the design process and design solution for an accelerator transport lattice that meets the requirements imposed by these physical phenomena and operational necessities.

  20. Scientific Applications of a Hard-X-Ray FEL

    NASA Astrophysics Data System (ADS)

    Arthur, John

    1998-04-01

    Free electron lasers are now being designed which will operate at wavelengths down to about 1 angstrom. Due to the physics of the high-gain, single pass FEL process that these sources will exploit, the radiation produced will have unique properties. In particular: -- The FEL peak intensity and peak brightness will be many orders of magnitude higher than can be produced by any other source. -- The pulse length will be less than 1 picosecond, orders of magnitude shorter than can be achieved with any other bright source such as a synchrotron. -- The FEL radiation will have full transverse coherence and a degeneracy parameter (photons/coherence volume) equal to 10^9 or more. No other source can produce hard x-radiation with a degeneracy parameter significantly greater than 1. These properties offer the chance to study chemical, biological, and condensed matter dynamical processes with sub-picosecond time resolution and angstrom spatial resolution. X-ray crystallography could be used to determine the structures of very-short-lived states of photosynthetic reaction centers. X-ray photon correlation spectroscopy could be used to study fluctuations in materials such as gels and glass-forming liquids, on a time scale complementary to that probed by neutron spin echo and dynamic light scattering techniques, but with better spatial resolution. Snap-shot x-ray scattering experiments could be performed on samples in extreme conditions such as ultra-high pulsed magnetic fields. Furthermore, the high peak power of the FEL radiation could be used to create precisely-controlled chemical and structural modifications inside samples. There is also the possibility that nonlinear x-ray interactions could be used to give increased resolution for spectroscopic studies, to greatly expand the parameter space for atomic physics studies, and to permit new fundamental tests of quantum mechanics. For example, the study of nonlinear photon interactions with core atomic electrons would test and

  1. A cost estimation model for high power FELs

    SciTech Connect

    Neil, G.R.

    1995-12-31

    A cost estimation model for scaling high-power free-electron lasers has been developed for estimating the impact of system-level design choices in scaling high-average-power superconducting-accelerator-based FELs. The model consists of a number of modules which develop subsystem costs and derive as an economic criterion the cost per kilojoule of light produced. The model does not include design engineering or development costs, but represents the 2nd through nth device. Presented in the paper is the relative sensitivity of designs to power and linac frequency while allowing the operating temperature of the superconducting cavities to optimize.

  2. Self-seeded injection-locked FEL amplifer

    DOEpatents

    Sheffield, Richard L.

    1999-01-01

    A self-seeded free electron laser (FEL) provides a high gain and extraction efficiency for the emitted light. An accelerator outputs a beam of electron pulses to a permanent magnet wiggler having an input end for receiving the electron pulses and an output end for outputting light and the electron pulses. An optical feedback loop collects low power light in a small signal gain regime at the output end of said wiggler and returns the low power light to the input end of the wiggler while outputting high power light in a high signal gain regime.

  3. High acceleration rates obtained in plasma-loaded FEL

    NASA Astrophysics Data System (ADS)

    Gevorgian, Lekdar A.

    2005-08-01

    The problem of acceleration of electron bunches interacting with powerful laser beam in a plasma-loaded inverse free electron laser (IFEL) is considered. It is shown that the presence of plasma in a free electron laser (FEL) results in a new mechanism of interaction between relativistic electrons and laser soft photons. This interaction maintains the synchronism during the induced absorption of laser photons by electrons. This method can provide high acceleration rates. It is also shown that the efficiency of this interaction increases essentially due to coherent effects in case of truncated dense electron bunches. As a result one obtains high acceleration rates in a wide energy region.

  4. Using the X-FEL to photo-pump X-ray laser transitions in He-like Ne

    SciTech Connect

    Nilsen, J; Rohringer, N

    2011-08-30

    Nearly four decades ago H-like and He-like resonantly photo-pumped laser schemes were proposed for producing X-ray lasers. However, demonstrating these schemes in the laboratory has proved to be elusive because of the difficulty of finding a strong resonant pump line. With the advent of the X-ray free electron laser (X-FEL) at the SLAC Linac Coherent Light Source (LCLS) we now have a tunable X-ray laser source that can be used to replace the pump line in previously proposed laser schemes and allow researchers to study the physics and feasibility of resonantly photo-pumped laser schemes. In this paper we use the X-FEL at 1174 eV to photo-pump the singly excited 1s2p state of He-like Ne to the doubly excited 2p3p state and model gain on the 2p3p-2p2s transition at 175 eV and the 2p3p-1s3p transition at 1017 eV. One motivation for studying this scheme is to explore possible quenching of the gain due to strong non-linear coupling effects from the intense X-FEL beam We compare this scheme with photo-pumping the He-like Ne ground state to the 1s3p singly excited state followed by lasing on the 3p-2s and 3d-2p transitions at 158 and 151 eV. Experiments are being planned at LCLS to study these laser processes and coherent quantum effects.

  5. Performance of hole coupling resonator in the presence of asymmetric modes and FEL gain

    SciTech Connect

    Xie, Ming; Kim, Kwang-Je.

    1991-08-01

    We continue the study of the hole coupling resonator for free electron laser (FEL) application. The previous resonator code is further developed to include the effects of the azimutally asymmetric modes and the FEL gain. The implication of the additional higher order modes is that there are more degeneracies to be avoided in tuning the FEL wavelengths. The FEL interaction is modeled by constructing a transfer map in the small signal regime and incorporating it into the resonator code. The FEL gain is found to be very effective in selecting a dominant mode from the azimuthally symmetric class of modes. Schemes for broad wavelength tuning based on passive mode control via adjustable apertures are discussed. 12 refs., 7 figs., 1 tab.

  6. Steady State Analysis of Short-wavelength, High-gainFELs in a Large Storage Ring

    SciTech Connect

    Huang, Z.; Bane, K.; Cai, Y.; Chao, A.; Hettel, R.; Pellegrini, C.; /UCLA

    2007-10-15

    Storage ring FELs have operated successfully in the low-gain regime using optical cavities. Discussions of a high-gain FEL in a storage ring typically involve a special bypass to decouple the FEL interaction from the storage ring dynamics. In this paper, we investigate the coupled dynamics of a high-gain FEL in a large storage ring such as PEP and analyze the equilibrium solution. We show that an FEL in the EUV and soft x-ray regimes can be integrated into a very bright storage ring and potentially provides three orders of magnitude improvement in the average brightness at these radiation wavelengths. We also discuss possibilities of seeding with HHG sources to obtain ultra-short, high-peak power EUV and soft x-ray pulses.

  7. Synchrotron Radiation and X-ray FEL Projects in Korea

    NASA Astrophysics Data System (ADS)

    Cho, M. H.

    2012-03-01

    There are two on-going major projects in Pohang Accelerator Laboratory (PAL), the PLS-II light source upgrade and the construction of PAL-XFEL facility. PLS-II is a new light source upgraded from PLS(Pohang Light Source) which had been operated for 16 years from 1995 and shut down in Dec. 2010. The performance will be improved from ``18.9 nm-rad, 2.5 GeV, and 200 mA'' to ``5.8 nm-rad, 3 GeV, and 400 mA'' using three superconducting RF cavities. The old storage ring has been completely dismantled and new DBA ring has been re-installed in the same tunnel within 6 months, and is under commissioning now. The unique feature of PLS-II is the compact employment of 20 insertion-devices including 14 in-vacuum undulators. The PALXFEL is a 0.1-nm hard X-ray FEL construction project started in 2011 and to compete in 2014 with a total budget of 400 M. The PAL-XFEL is designed to have hard X-ray undulator lines at the end of 10-GeV linac, and a dog-leg branch line at 2.65 GeV point for a soft X-ray undulator line simultaneously and independently from hard X-ray FEL undulator line. The overview of two projects with current status is presented.

  8. Design Principles for a Compact High Average Power IR FEL

    SciTech Connect

    Lia Merminga; Steve Benson

    2001-08-01

    Progress in superconducting rf (srf) technology has led to dramatic changes in cryogenic losses, cavity gradients, and microphonic levels. Design principles for a compact high average power Energy Recovery FEL at IR wavelengths, consistent with the state of the art in srf, are outlined, High accelerating gradients, of order 20 MV/m at Q{sub 0}{approx}1x10{sup 10} possible at rf frequencies of 1300 MHz and 1500 MHz, allow for a single-cryomodule linac, with minimum cryogenic losses. Filling every rf bucket, at these high frequencies, results in high average current at relatively low charge per bunch, thereby greatly ameliorating all single bunch phenomena, such as wakefields and coherent synchrotron radiation. These principles are applied to derive self-consistent sets of parameters for 100 kW and 1 MW average power IR FELs and are compared with low frequency solutions. This work supported by U.S. DOE Contract No. DE-AC05-84ER40150, the Commonwealth of Virginia and the Laser Processing Consortium.

  9. ETHERNET BASED EMBEDDED SYSTEM FOR FEL DIAGNOSTICS AND CONTROLS

    SciTech Connect

    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.

  10. Serial snapshot crystallography for materials science with SwissFEL

    DOE PAGES

    Dejoie, Catherine; Smeets, Stef; Baerlocher, Christian; ...

    2015-04-21

    New opportunities for studying (sub)microcrystalline materials with small unit cells, both organic and inorganic, will open up when the X-ray free electron laser (XFEL) presently being constructed in Switzerland (SwissFEL) comes online in 2017. Our synchrotron-based experiments mimicking the 4%-energy-bandpass mode of the SwissFEL beam show that it will be possible to record a diffraction pattern of up to 10 randomly oriented crystals in a single snapshot, to index the resulting reflections, and to extract their intensities reliably. The crystals are destroyed with each XFEL pulse, but by combining snapshots from several sets of crystals, a complete set of datamore » can be assembled, and crystal structures of materials that are difficult to analyze otherwise will become accessible. Even with a single shot, at least a partial analysis of the crystal structure will be possible, and with 10–50 femtosecond pulses, this offers tantalizing possibilities for time-resolved studies.« less

  11. The FERMI-Elettra FEL Photon Transport System

    SciTech Connect

    Zangrando, M.; Cudin, I.; Fava, C.; Godnig, R.; Kiskinova, M.; Masciovecchio, C.; Parmigiani, F.; Rumiz, L.; Svetina, C.; Turchet, A.; Cocco, D.

    2010-06-23

    The FERMI-Elettra free electron laser (FEL) user facility is under construction at Sincrotrone Trieste (Italy), and it will be operative in late 2010. It is based on a seeded scheme providing an almost perfect transform-limited and fully spatially coherent photon beam. FERMI-Elettra will cover the wavelength range 100 to 3 nm with the fundamental harmonics, and down to 1 nm with higher harmonics. We present the layout of the photon beam transport system that includes: the first common part providing on-line and shot-to-shot beam diagnostics, called PADReS (Photon Analysis Delivery and Reduction System), and 3 independent beamlines feeding the experimental stations. Particular emphasis is given to the solutions adopted to preserve the wavefront, and to avoid damage on the different optical elements. Peculiar FEL devices, not common in the Synchrotron Radiation facilities, are described in more detail, e.g. the online photon energy spectrometer measuring shot-by-shot the spectrum of the emitted radiation, the beam splitting and delay line system dedicated to cross/auto correlation and pump-probe experiments, and the wavefront preserving active optics adapting the shape and size of the focused spot to meet the needs of the different experiments.

  12. High power induction linac for FEL applications at CESTA

    NASA Astrophysics Data System (ADS)

    Launspach, J.; Angles, J. M.; Angles, M.; Anthouard, P.; Bardy, J.; Bonnafond, C.; Bottollier-Curtet, H.; Devin, A.; Eyharts, P.; Eyl, P.; Gardelle, J.; Germain, G.; Grua, P.; Labrouche, J.; de Mascureau, J.; Le Taillandier, P.; Stadnikoff, W.; Thevenot, M.

    1991-07-01

    The purpose of the LELIA program developed at CESTA is to acquire the knowledge on induction accelerator technology for high peak power FEL applications. In a first step we study basic technology: (1) A high voltage pulse generator (150 kV, 60 ns, 2 ω) has been designed to drive the induction injector and the accelerating cells. It is able to work at high repetition rate (typically 1 kHz) by the use of magnetic switches. A flat top of 130 kV with {ΔV}/{V} = ±0.8% has been obtained for about 50 ns. (2) An induction cell prototype has been built in order to check technological choices (vacuum, mechanics, magnetic guiding, voltage supply, etc.) for injector and accelerating modules. (3) The injector geometry is being studied using Euphrosyne (a classical intense relativistic electron beam device) which consists of a concave thermo-ionic oxide cathode, an intermediate electrode and a hollow anode with a magnetic guiding channel. This diode delivers an electron beam between 1 and 3 MV, about 1 kA and a flat top pulse during 20 ns. We will carry on the injector studies with our induction injector LELIA I (1.5 MV, 1.5 kA, 1 kHz) which will be available at the end of 1990. An accelerating module is also being designed, taking into account guiding and stability problems. All these points are described in more detail in a poster paper [J. Bardy et al., these Proceedings (12th Int. FEL Conf., Paris, France, 1990) Nucl. Instr. and Meth. A304 (1991) 311]. The main goal is to build a 10 MV, 1-3 kA, 1 kHz induction accelerator and to have it running at CESTA in 1993. On the other hand, we want to use the electron beam provided by Euphrosyne then in LELIA I to perform FEL experiments at 35 GHz using a bifilar helical wiggler [H. Bottollier-Curtet et al., these Proceedings, p. 197].

  13. Analysis of FEL-based CeC amplification at high gain limit

    SciTech Connect

    Wang, G.; Litvinenko, V.; Jing, Y.

    2015-05-03

    An analysis of Coherent electron Cooling (CeC) amplifier based on 1D Free Electron Laser (FEL) theory was previously performed with exact solution of the dispersion relation, assuming electrons having Lorentzian energy distribution. At high gain limit, the asymptotic behavior of the FEL amplifier can be better understood by Taylor expanding the exact solution of the dispersion relation with respect to the detuning parameter. In this work, we make quadratic expansion of the dispersion relation for Lorentzian energy distribution and investigate how longitudinal space charge and electrons’ energy spread affect the FEL amplification process.

  14. Performance study of a soft X-ray harmonic generation FEL seededwith an EUV laser pulse

    SciTech Connect

    Gullans, M.; Wurtele, J.S.; Penn, G.; Zholents, A.A.

    2007-02-01

    The performance of a free electron laser (FEL) using alow-power extreme ultraviolet (EUV) pulse as an input seed isinvestigated. The parameters are appropriate for 30 nm seeds producedfrom high-power Ti:Sa pulses using high harmonic generation schemes. Itis found that, for reasonable beam parameters, robust FEL performance canbe obtained. Both time-independent and time-dependent simulations areperformed for varying system parameters using the GENESIS simulationcode. A comparison is made with a two-stage harmonic FEL that is seededby a high-power Ti:Sa pulse.

  15. Polarization Analysis for Seeded FELs in a Crossed-Planar Undulator

    SciTech Connect

    Geng, Huiping; Ding, Yuantao; Huang, Zhirong; Bartolini, Riccardo; Dunning, David; Thompson, Neil; /Daresbury

    2012-06-25

    The crossed-planar undulator is a promising scheme for full polarization control in x-ray FELs. For SASE FELs, it has been shown a maximum degree of circular polarization of about 80% is achievable at fundamental wavelength just before saturation. In this paper, we study the effectiveness of a crossed undulator for a seeded x-ray FEL. The degree of circular polarization for both the fundamental and the harmonic radiation are considered. Simulations with realistic beam distributions show that a degree of circular polarization of over 90% and 80% is obtainable at the fundamental and 2nd harmonic frequencies, respectively.

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

    SciTech Connect

    Nassiri, A.; Kustom, R.L.; Kang, Y.W.

    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.

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

    SciTech Connect

    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.

  18. Study of CSR Effects in the Jefferson Laboratory FEL Driver

    SciTech Connect

    Hall, C. C.; Biedron, S.; Burleson, Theodore A.; Milton, Stephen V.; Morin, Auralee L.; Benson, Stephen V.; Douglas, David R.; Evtushenko, Pavel E.; Hannon, Fay E.; Li, Rui; Tennant, Christopher D.; Zhang, Shukui; Carlsten, Bruce E.; Lewellen, John W.

    2013-08-01

    In a recent experiment conducted on the Jefferson Laboratory IR FEL driver the effects of Coherent Synchrotron Radiation (CSR) on beam quality were studied. The primary goal of this work was to explore CSR output and effect on the beam with variation of the bunch compression in the IR chicane. This experiment also provides a valuable opportunity to benchmark existing CSR models in a system that may not be fully represented by a 1-D CSR model. Here we present results from this experiment and compare to initial simulations of CSR in the magnetic compression chicane of the machine. Finally, we touch upon the possibility for CSR induced microbunching gain in the magnetic compression chicane, and show that parameters in the machine are such that it should be thoroughly damped.

  19. EMITTANCE GROWTH IN THE FEL RF-GUN

    SciTech Connect

    Novokhatski, Alexander

    2002-08-20

    A high brightness and low emittance is of crucial importance for the SASE-FEL at the TESLA Test Facility. Therefore a Photo-RF-Gun has been installed as particle source. Numerical simulations with codes like ASTRA [1] and MAFIA [2] show that the space charge dominated processes inside the RF-Gun contribute significantly to the emittance. In this paper we present the results of detailed studies with MAFIA TS2 which clarify the effects resulting in emittance growth for space charge dominated beams. It is shown that the resulting emittance can be minimized by changing the laser parameters like pulse length and spot size on the cathode. Additionally we present the concept of slice emittances which allows a more precise prediction of the real transverse emittance achievable with an emittance compensation scheme.

  20. Ethernet Based Embedded IOC for FEL Control Systems

    SciTech Connect

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

    2008-01-01

    An Ethernet based embedded Input Output Controller (IOC) has been developed as part of an upgrade to the control system for the Free Electron Laser Project at Jefferson Lab. Currently most of the FEL systems are controlled, configured and monitored using a central VME bus-based configuration. These crate based systems are limited in growth and usually interleave multiple systems. In order to accommodate incremental system growth and lower channel costs, we developed a stand-alone system, an Ethernet based embedded controller called the Single Board IOC (SBIOC). The SBIOC is a module which integrates an Altera FPGA and the Arcturus uCdimm Coldfire 5282 Microcontroller daughter card into one module, which can be easily configured for different kinds of I/O devices. The microcontroller is a complete System-on-Module, including three highly integrated functional blocks, the core processor, memory, and Ethernet communication. A real-time operating system, RTEMS is cross compiled with

  1. An analysis of the saturation of a high gain FEL

    SciTech Connect

    Gluckstern, R.L.; Okamoto, Hiromi . Dept. of Physics); Krinsky, S. )

    1992-12-01

    We study the saturated state of an untapered free electron laser in the Compton regime, arising after exponential amplification of an initial low level of radiation by an initially monoenergetic, unbunched electron beam. The saturated state of the FEL is described by oscillations about an equilibrium state. Using the two invariants of the motion, and certain assumptions motivated by computer simulations, we provide approximate analytic descriptions of the radiation field and electron distribution in the saturation regime. We first consider a one-dimensional approximation, and later extend our approach to treat an electron beam of finite radial extent. Of note is a result on the radiated power in the case of an electron beam with small radius.

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

    SciTech Connect

    Attwood, David

    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.

  3. Effects of Beamtube Roughness on X-Ray FEL Performance

    SciTech Connect

    Stupakov, Gennady

    1999-04-05

    In an X-Ray FEL like the Linear Coherent Light Source (LCLS) being designed at SLAC, electron bunches about 70 {micro}m FWHM long are sent into a beam tube only 5 mm in internal diameter and more than 100 m in length. Due to the surface roughness of the beam tube, wakefields can be generated that catch up to the bunch and interact with it, causing energy spread and emittance growth. The strength of this effect depends on the details of the roughness of the surface. We present here a study in which the roughness of the beam tube was measured, and the longitudinal impedance of the tube was calculated. Our result shows that commercially available beam tube can be made smooth enough so the resulting wakefield effects are within the tolerance determined by the requirement that the induced relative energy spread of the beam be less then 5 x 10{sup {minus}4}.

  4. Recent Results from the IR Upgrade FEL at Jefferson Lab

    SciTech Connect

    K. Beard; C. Behre; S. Benson; G. Biallas; J. Boyce; D. Douglas; H. F. Dylla; R. Evans; A. Grippo; J. Gubeli; D. Hardy; C. Hernandez-Garcia; K. Jordan; L. Merminga; N. Nishimori; G. Neil; J. Preble; Michelle D. Shinn; T. Siggins; R. Walker; G. Williams; S. Zhang

    2005-08-21

    After demonstrating 10 kW operation with 1 second pulses, the Jefferson Lab program switched to demonstrating high power operation at short wavelengths using a new 8 cm period wiggler and a THz suppression chicane. We report here on the lasing results to date using this new configuration. We have demonstrated a large reduction in THz heating on the mirrors. We have also eliminated heating in the mirror steering assemblies, making operation at high power much more stable. Finally, we have greatly reduced astigmatism in the optical cavity, allowing operation with a very short Rayleigh range. The laser has been tuned from 0.9 to 3.1 microns using the new wiggler. User experiments commenced in April of 2005 with the FEL Upgrade operating over the 1-3 micron range. We are in the process of installing a 5.5 cm permanent magnet wiggler that will give us even larger tuning range and higher power.

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

    SciTech Connect

    Jaroszynski, D.A.; Prazeres, R.; Glotin, F.

    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.

  6. Ultrahigh harmonics generation in a FEL with a seed laser

    SciTech Connect

    Goloviznin, V.V.; Amersfoort, P.W. van

    1995-12-31

    One of the most challenging problems in modern FEL technology is to operate in the X-ray region, especially in the {open_quotes}water window{close_quotes}. Because of the absence of optical resonators in this range of wavelengths, only a single-pass device may be suitable for this task. The Self-Amplified Spontaneous Emission (SASE) mechanism is now under active discussion as a realistic way to provide high-power coherent emission in the X-ray range. Both the undulator parameters and the electron beam parameters required for the lasing are achieveable at today`s technological level. On the other hand, the SASE approach implies a very long and expensive periodic magnetic structure, typically several tens of meters long. This is mainly because of the rather long build-up time necessary to establish a coherent mode from incoherent noise. A mechanism of shortening this time would be therefore highly desirable. In the present paper we consider a scheme using two undulators and a seed-laser to produce coherent X-ray emission. The first undulator and the seed-laser provide a pre-modulation of the beam while the second undulator serves as a source of coherent spontaneous radiation at a very high harmonic of the seed-laser frequency; the whole scheme may then be considered to be an FEL-based frequency upconvertor. The total length of the periodic magnetic structure is shown to be of the order of several meters, nearly an order of magnitude shorter than in the SASE case. For the same beam quality as in the SASE scheme and with realistic seed-laser parameters, the efficiency of the beam pre-modulation at the 50-th (!) harmonic is shown to be as high as 15%. The output radiation is tunable between discrete harmonics of the seed-frequency.

  7. Parameter study of the VUV-FEL at the Tesla Test Facility

    SciTech Connect

    Brefeld, W.; Faatz, B.

    1995-12-31

    In this contribution we present a detailed study of the influence of the electron beam and machine parameters on the performance of the TTF VUV FEL, which is in its design stage at DESY. The TTF FEL will be a 6 nm SASE device operating with the beam provided by the Tesla Test Facility superconducting linac, driven by an rf photcathode gun. The FEL output power and saturation length have been assessed with the use of different 2D3-D steady state simulation codes. The parameter range over which the FEL would reach saturation within the specified undulator length of 25 to 30 m have been determined and checked against semi-analytical expressions.

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

    NASA Astrophysics Data System (ADS)

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

    SciTech Connect

    Kabanov, V.S.; Dzergach, A.I.

    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.

  10. Statistical Analysis of Crossed Undulator for Polarization Control in a SASE FEL

    SciTech Connect

    Ding, Yuantao; Huang, Zhirong; /SLAC

    2008-02-01

    There is a growing interest in producing intense, coherent x-ray radiation with an adjustable and arbitrary polarization state. In this paper, we study the crossed undulator scheme (K.-J. Kim, Nucl. Instrum. Methods A 445, 329 (2000)) for rapid polarization control in a self-amplified spontaneous emission (SASE) free electron laser (FEL). Because a SASE source is a temporally chaotic light, we perform a statistical analysis on the state of polarization using FEL theory and simulations. We show that by adding a small phase shifter and a short (about 1.3 times the FEL power gain length), 90{sup o} rotated planar undulator after the main SASE planar undulator, one can obtain circularly polarized light--with over 80% polarization--near the FEL saturation.

  11. Diffraction and pulse slippage in the Boeing 1 kW FEL oscillator

    SciTech Connect

    Blau, J.; Wong, R.K.; Colson, W.B.

    1995-12-31

    A four-dimensional simulation in x, y, z, and t, including betatron motion of the electrons, is used to study the combined effects of diffraction, pulse slippage and desynchronism in the Boeing 1 kW FEL oscillator.

  12. Generation of XUV light by resonant frequency tripling in a two-wiggler FEL amplifier

    SciTech Connect

    Bonifacio, R.; de Salvo Souza, L.; Pierini, P. . Dipt. di Fisica Istituto Nazionale di Fisica Nucleare, Milan ); Scharlemann, E.T. )

    1989-01-01

    FEL operation at short wavelength is limited by electron beam quality, by the availability of mirrors for oscillators, and by the availability of input sources for FEL amplifiers. It is possible to use and FEL amplifier as a resonant frequency tripling device, generating light and strong bunching at the 3rd harmonic of a conventional input source in an initial section of wiggler, then using a second section of wiggler resonant at the tripled frequency to amplify the short wavelength light. Neither mirrors nor a short-wavelength input source are required, and some relaxation of electron beam quality appears to be possible. We illustrate the scheme with a one-dimensional model and then with NUTMEG simulations of an 80 nm FEL amplifier initiated by a 240 nm input signal, in which an efficiency of conversion of electron beam power to 80 nm light of nearly 10{sup -4} was obtained. 3 refs., 6 figs., 1 tab.

  13. Generation of XUV light by resonant frequency tripling in a two-wiggler FEL amplifier

    NASA Astrophysics Data System (ADS)

    Bonifacio, R.; De Salvo Souza, L.; Pierini, P.; Scharlemann, E. T.

    1990-10-01

    FEL operation at short wavelengths is limited by electron-beam quality, by the availability of mirrors for oscillators and by the availability of input sources for FEL amplifiers. It is possible to use an FEL amplifier as a resonant-frequency tripling device, generating light and strong bunching at the third harmonic of a conventional input source in an initial wiggler section, then using a second wiggler section resonant at the tripled frequency to amplify the short-wavelength light. Neither mirrors nor a short-wavelength input source are required, and some relaxation of the electron-beam quality appears to be possible. We illustrate the scheme with a one-dimensional model and then with NUTMEG simulations of an 80 nm FEL amplifier initiated by a 240 nm input signal, in which an efficiency of the electron-beam power conversion to 80 nm light of nearly 10-4 was obtained.

  14. Generation of XUV light by resonant frequency tripling in a two-wiggler FEL amplifier

    NASA Astrophysics Data System (ADS)

    Bonifacio, R.; Desalvosouza, L.; Pierini, P.; Scharlemann, E. T.

    FEL operation at short wavelength is limited by electron beam quality, by the availability of mirrors for oscillators, and by the availability of input sources for FEL amplifiers. It is possible to use and FEL amplifier as a resonant frequency tripling device, generating light and strong bunching at the 3rd harmonic of a conventional input source in an initial section of wiggler, then using a second section of wiggler resonant at the tripled frequency to amplify the short wavelength light. Neither mirrors nor a short-wavelength input source are required, and some relaxation of electron beam quality appears to be possible. We illustrate the scheme with a one-dimensional model and then with NUTMEG simulations of an 80 nm FEL amplifier initiated by a 240 nm input signal, in which an efficiency of conversion of electron beam power to 80 nm light of nearly 10(exp -4) was obtained.

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

    SciTech Connect

    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.

  16. Optical properties of mid-infrared FELs from the FELI Facility I

    SciTech Connect

    Kobayashi, A.; Okuma, S.; Oshita, E.

    1995-12-31

    The FELI Facility I has succeeded in mid-infrared FEL oscillation at 6 {mu} m using a 30-MeV, 42-A electron beam from the FELI S-band linac in October 31, 1994. The FELI Facility I is composed of a 2-m vertical type undulator ({lambda}u=3.4cm, N=58, K m a x = 55, gap length{ge}14mm) and a 6.72-m optical cavity. It can cover the wavelength range of 5-20{mu}m. The FELs can be delivered from the optical cavity to the diagnostics room through a 50-m evacuated optical pipeline. Wavelength and cavity length dependences of optical properties such as peak power, average power, spectrum width, subpulses in FEL macropulse, FEL transverse profile are reported.

  17. Wakefield computations for a corrugated pipe as a beam dechirper for FEL applications

    SciTech Connect

    Ng, C. K.; Bane, K. L.F.

    2015-06-09

    A beam “dechirper” based on a corrugated, metallic vacuum chamber has been proposed recently to cancel residual energy chirp in a beam before it enters the undulator in a linac-based X-ray FEL. Rather than the round geometry that was originally proposed, we consider a pipe composed of two parallel plates with corrugations. The advantage is that the strength of the wake effect can be tuned by adjusting the separation of the plates. The separation of the plates is on the order of millimeters, and the corrugations are fractions of a millimeter in size. The dechirper needs to be meters long in order to provide sufficient longitudinal wakefield to cancel the beam chirp. Considerable computation resources are required to determine accurately the wakefield for such a long structure with small corrugation gaps. Combining the moving window technique and parallel computing using multiple processors, the time domain module in the parallel finite-element electromagnetic suite ACE3P allows efficient determination of the wakefield through convergence studies. In this paper, we will calculate the longitudinal, dipole and quadrupole wakefields for the dechirper and compare the results with those of analytical and field matching approaches.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Gain enhancement plasma-loaded FEL in the presence of beat waves

    SciTech Connect

    Shamamian, A.H.; Gevorgian, L.A.

    1995-12-31

    An expression for the dielectric permittivity of underdense plasma interacting with laser beat waves is derived. It is shown that the presence of beat waves in plasma results in an effective growth of the plasma frequency. The FEL Gain is investigated in the case when the frequency of soft photons weakly depending on the electron beam energy and the synchronism condition is maintained. It is shown that the plasma beat waves lead to the essential increase in FEL gain.

  20. Reflection Matrix for Optical Resonators in FEL (Free Electron Lasers) Oscillators

    DTIC Science & Technology

    1988-09-22

    is the dominant factor determining the reflction coefficient. The effects of deflecting tho’ light beam enter as small corrections, of first order in...RESONATORS IN FEL OSCILLATORS I. INTRODUCTION 1-7 Free Electron Lasers (FEL) operating as oscillators require the 8-10 trapping of light pulses between...The simplest oscillator configuration is that of an open resonator with two opposed identical mirrors. The radiation vector potential for this

  1. Optical design of the ARAMIS-beamlines at SwissFEL

    SciTech Connect

    Follath, R.; Flechsig, U.; Milne, C.; Szlachetko, J.; Ingold, G.; Patterson, B.; Patthey, L.; Abela, R.

    2016-07-27

    SwissFEL is a free electron laser facility for hard and soft X-rays at the Paul Scherrer Institut in Switzerland. The first hard X-ray FEL named ARAMIS will deliver photons in the wavelength range from 1 Å to 7 Å in up to three beamlines alternatively. The beamlines are equipped with crystal monochromators, cover the full wavelength range and offer a variety of operational modes.

  2. Scaling of gain with energy spread and energy in the PEP FEL

    SciTech Connect

    Fisher, A.S.

    1992-07-13

    The Sag Harbor paper on the PEP FEL discusses the scaling of various FEL parameters with energy spread {sigma}{sub {var epsilon}}. I will repeat some of this material here and then examine the benefit of increasing the energy spread. How much energy spread can be achieved with damping wigglers is the next topic. Finally, I consider the dependence of gain and saturation length on beam energy and undulator field.

  3. Scaling of gain with energy spread and energy in the PEP FEL

    SciTech Connect

    Fisher, A.S.

    1992-07-13

    The Sag Harbor paper on the PEP FEL discusses the scaling of various FEL parameters with energy spread {sigma}{sub {var_epsilon}}. I will repeat some of this material here and then examine the benefit of increasing the energy spread. How much energy spread can be achieved with damping wigglers is the next topic. Finally, I consider the dependence of gain and saturation length on beam energy and undulator field.

  4. Interferometric visibility and coherence

    NASA Astrophysics Data System (ADS)

    Biswas, Tanmoy; García Díaz, María; Winter, Andreas

    2017-07-01

    Recently, the basic concept of quantum coherence (or superposition) has gained a lot of renewed attention, after Baumgratz et al. (Phys. Rev. Lett. 113, 140401. (doi:10.1103/PhysRevLett.113.140401)), following Åberg (http://arxiv.org/abs/quant-ph/0612146), have proposed a resource theoretic approach to quantify it. This has resulted in a large number of papers and preprints exploring various coherence monotones, and debating possible forms for the resource theory. Here, we take the view that the operational foundation of coherence in a state, be it quantum or otherwise wave mechanical, lies in the observation of interference effects. Our approach here is to consider an idealized multi-path interferometer, with a suitable detector, in such a way that the visibility of the interference pattern provides a quantitative expression of the amount of coherence in a given probe state. We present a general framework of deriving coherence measures from visibility, and demonstrate it by analysing several concrete visibility parameters, recovering some known coherence measures and obtaining some new ones.

  5. Acute optic nerve sheath fenestration in humans using the free electron laser (FEL): a case report

    NASA Astrophysics Data System (ADS)

    Joos, Karen M.; Mawn, Louise A.; Shen, Jin-Hui; Jansen, E. Duco; Casagrande, Vivien A.

    2002-06-01

    Our previous studies using rabbits and monkeys showed that the Amide II wavelength (6.45 micrometers ) produced by the FEL could efficiently produce an optic nerve sheath fenestration with minimal damage. In order to determine if the technology safely could be applied to human surgery, we used 2 blind human eyes during enucleation to compare the results of producing fenestrations with the FEL or a scissors. FDA and Vanderbilt IRB approvals, and individual patient consents were obtained. The FEL energy was transmitted to a human operating room. After disinsertion of the medial rectus muscle, an optic nerve sheath fenestration (2 mm diameter) was made with either the FEL (6.45 micrometers , 325 micrometers spot size, 30 Hz, 3 mJ) through a hollow waveguide surgical probe or with a scissors. The enucleation was then completed. The optic nerve was dissected from the globe and fixed. Specimens were examined histologically. Dural incisions were effective with both methods. FEL energy at 6.45 micrometers can be transmitted to an operating room and delivered to human ocular tissue through a hollow waveguide surgical probe. This FEL wavelength can produce an optic nerve sheath fenestration without acute direct damage to the nerve in this case report.

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

    SciTech Connect

    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.

    2007-06-24

    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.

  7. Removal of cat major allergen (Fel d I) from futon (Japanese bedding) with a home washing machine.

    PubMed

    Hashimoto, M; Nigi, H; Sakaguchi, M; Inouye, S; Miyazawa, H; Watanabe, M; Mitsuseki, M; Yasueda, H; Nitta, H

    1994-06-01

    We evaluated the removal of a cat major allergen (Fel d I) from futons (Japanese bedding) with the use of a large-sized home washing machine. Before and after washing a futon that had been used in a home with a cat, a small amount of cotton was collected from the futon and Fel d I was extracted from the cotton. The levels of Fel d I were assayed by a sandwich enzyme-linked immunosorbent assay (ELISA). We found that washing reduced the Fel d I level in futons by more than 95%. In conclusion, washing of futons is an effective method for elimination of their cat allergens.

  8. Transport studies of LPA electron beam towards the FEL amplification at COXINEL

    NASA Astrophysics Data System (ADS)

    Khojoyan, M.; Briquez, F.; Labat, M.; Loulergue, A.; Marcouillé, O.; Marteau, F.; Sharma, G.; Couprie, M. E.

    2016-09-01

    Laser Plasma Acceleration (LPA) [1] is an emerging concept enabling to generate electron beams with high energy, high peak current and small transverse emittance within a very short distance. The use of LPA can be applied to the Free Electron Laser (FEL) [2] case in order to investigate whether it is suitable for the light amplification in the undulator. However, capturing and guiding of such beams to the undulator is very challenging, because of the large divergence and high energy spread of the electron beams at the plasma exit, leading to large chromatic emittances. A specific beam manipulation scheme was recently proposed for the COXINEL (Coherent X-ray source inferred from electrons accelerated by laser) setup, which makes an advantage from the intrinsically large chromatic emittance of such beams [3]. The electron beam transport is studied using two simulation codes: a SOLEIL in-house one and ASTRA [4]. The influence of the collective effects on the electron beam performance is also examined.

  9. Visible-infrared self-amplified spontaneous emission amplifier free electron laser undulator

    NASA Astrophysics Data System (ADS)

    Carr, Roger; Cornacchia, Max; Emma, Paul; Nuhn, Heinz-Dieter; Poling, Ben; Ruland, Robert; Johnson, Erik; Rakowsky, George; Skaritka, John; Lidia, Steve; Duffy, Pat; Libkind, Marcus; Frigola, Pedro; Murokh, Alex; Pellegrini, Claudio; Rosenzweig, James; Tremaine, Aaron

    2001-12-01

    The visible-infrared self-amplified spontaneous emission amplifier (VISA) free electron laser (FEL) is an experimental device designed to show self-amplified spontaneous emission (SASE) to saturation in the near infrared to visible light energy range. It generates a resonant wavelength output from 800-600 nm, so that silicon detectors may be used to characterize the optical properties of the FEL radiation. VISA is designed to show how SASE FEL theory corresponds with experiment in this wavelength range, using an electron beam with emittance close to that planned for the future Linear Coherent Light Source at SLAC. VISA comprises a 4 m pure permanent magnet undulator with four 99 cm segments, each of 55 periods, 18 mm long. The undulator has distributed focusing built into it, to reduce the average beta function of the 70-85 MeV electron beam to about 30 cm. There are four FODO cells per segment. The permanent magnet focusing lattice consists of blocks mounted on either side of the electron beam, in the undulator gap. The most important undulator error parameter for a free electron laser is the trajectory walk-off, or lack of overlap of the photon and electron beams. Using pulsed wire magnet measurements and magnet shimming, we were able to control trajectory walk-off to less than +/-50 μm per field gain length.

  10. COMPARISON OF TWO DIFFERENT WAVELENGTH TUNING SCHEMES IN A SEEDED HIGH-GAIN FEL.

    SciTech Connect

    SHAFTAN,T.; YU,L.H.

    2004-08-04

    In the following text we analyze and compare results of the two publications ([1], [2]), dedicated to development of the tunable high-gain Free Electron laser (FEL), seeded by an external source. As a conclusion we summarize similarities and differences between these concepts. This note is initiated by the polemics on the similarity of two different schemes of the wavelength tuning in a seeded high-gain FEL. Below we will be calling the scheme, presented by S. Biedron, S, Milton and H. Freund in Nuclear Instruments and Methods of 2001 ([1]), as the first (1st) scheme. The scheme that we developed and presented in the BNL preprint ([2]) will be called as the second (2nd) scheme. The following analysis provides important information on similarities and differences between both techniques. We start by considering the first approach. As we understand, the goal of the Modular Approach is to make X-ray FEL design more flexible [1]. Usual linac-based FELs begin from a long linac with bunch compressor(s) followed by an FEL magnetic system. The essence of the Modular Approach is to break a machine into modules and then recombine these modules in a more efficient way (from the point of view of monetary and/or time constraints). The chapter 3.5 of [1] presents some basic example of Modular Approach. We have studied the scheme, discussed in [1] and illustrated in Fig. 2. Even though very few details of the scheme were presented, it was still sufficient to obtain a complete qualitative picture. Let us begin with the usual phase space of the microbunched beam, which enters a radiator in a prebunched FEL (Fig. 1). The sharp spike (in blue) represents the longitudinal density bunching, which will be the main subject of interest in this discussion. The key principle of a seeded high-gain FEL optimization is to establish this kind of the electron beam phase space at the entrance of the radiator.

  11. A Low-Charge, Hard X-Ray FEL Driven with an X-band Injector and Accelerator

    SciTech Connect

    Sun, Yipeng; Adolphsen, Chris; Limborg-Deprey, Cecile; Raubenheimer, Tor; Wu, Juhao; /SLAC

    2012-02-17

    After the successful operation of FLASH (Free-Electron Laser in Hamburg) and LCLS (Linac Coherent Light Source), soft and hard X-ray Free Electron Lasers (FELs) are being built, designed or proposed at many accelerator laboratories. Acceleration employing lower frequency RF cavities, ranging from L-band to C-band, is usually adopted in these designs. In the first stage bunch compression, higher-frequency harmonic RF system is employed to linearize the beam's longitudinal phase space, which is nonlinearly chirped during the lower frequency RF acceleration process. In this paper, a hard X-ray FEL design using an all X-band accelerator at 11.424 GHz (from photo-cathode RF gun to linac end) is presented, without the assistance of any harmonic RF linearization. It achieves LCLS-like performance at low charge using X-band linac drivers, which is more versatile, efficient and compact than ones using S-band or C-band rf technology. It employs initially 42 microns long (RMS), low charge (10 pC) electron bunches from an X-band photoinjector. An overall bunch compression ratio of roughly 100 times is proposed in a two stage bunch compressor system. The start-to-end macro-particle 3-D simulation employing several computer codes is presented in this paper, where space charge, wakefields, incoherent and coherent synchrotron radiation (ISR and CSR) effects are included. Employing an undulator with a short period of 1.5 cm, a Genesis FEL simulation shows successful lasing at a wavelength of 0.15 nm with a pulse length of 2 fs and a power saturation length as short as 20 meters, which is equivalent to LCLS low charge mode. Its overall length of both accelerators and undulators is 180 meters (much shorter than the effective LCLS overall length of 1230 meters, including an accelerator length of 1100 meters and an undulator length of 130 meters), which makes it possible to be built in places where only limited space is available.

  12. Output characteristics of SASE-driven short-wavelength FELs

    NASA Astrophysics Data System (ADS)

    Fawley, William M.

    1997-05-01

    This paper investigates various properties of the 'microspikes' associated with self-amplified spontaneous emission (SASE) in a short wavelength free-electron laser (FEL). Using results from the 2-D numerical simulation code GINGER, we confirm theoretical predictions such as the convective group velocity in the exponential gain regime. In the saturated gain regime beyond the initial saturation, we find that the average radiation power continues to grow with an approximately linearly dependence upon undulator length. Moreover, the spectrum significantly broadens and shifts in wavelength to the redward direction, with P(omega) approaching a constant, asymptotic value. This is in marked contrast to the exponential gain regime where the spectrum steadily narrows, P(omega) grows, and the central wavelength remains constant with z. Via use of a spectrogram diagnostic S(omega, t), it appears that the radiation pattern in the saturated gain regime is composed of an ensemble of distinct 'sinews' whose widths (Delta) (lambda) remain approximately constant but whose central wavelengths can 'chirp' by varying a small extent with t.

  13. Extension of the spectral range of the CLIO FEL

    SciTech Connect

    Marcouille, O.; Boyer, J.C.; Corlier, M.

    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.

  14. Validation of Maturity Offset in the Fels Longitudinal Study.

    PubMed

    Malina, Robert M; Choh, Audrey C; Czerwinski, Stefan A; Chumlea, Wm Cameron

    2016-08-01

    Sex-specific equations for predicting maturity offset, time before or after peak height velocity (PHV), were evaluated in 63 girls and 74 boys from the Fels Longitudinal Study. Serially measured heights (0.1 cm), sitting heights (0.1 cm), weights (0.1 kg), and estimated leg lengths (0.1 cm) from 8 to 18 years were used. Predicted age at PHV (years) was calculated as the difference between chronological age (CA) and maturity offset. Actual age at PHV for each child was derived with a triple logistic model (Bock-Thissen-du Toit). Mean predicted maturity offset was negative and lowest at 8 years and increased linearly with increasing CA. Predicted ages at PHV increased linearly with CA from 8 to 18 years in girls and from 8 to 13 years in boys; predictions varied within relatively narrow limits from 12 to 15 years and then increased to 18 years in boys. Differences between predicted and actual ages at PHV among youth of contrasting maturity status were significant across the age range in both sexes. Dependence of predicted age at PHV upon CA at prediction and on actual age at PHV limits its utility as an indicator of maturity timing and in sport talent programs.

  15. Optical modeling of the Jefferson Lab IR Demo FEL

    SciTech Connect

    G. Neil; S. Benson; Michelle D. Shinn; P. Davidson; P. Kloppel

    1997-01-01

    The Thomas Jefferson National Accelerator Facility (formerly known as CEBAF) has embarked on the construction of a 1 kW free-electron laser operating initially at 3 microns that is designed for laser-material interaction experiments and to explore the feasibility of scaling the system in power and wavelength for industrial and Navy defense applications. The superconducting radio-frequency linac, and single-pass transport which accelerates the beam from injector to wiggler, followed by energy-recovery deceleration to a dump. The electron and optical beam time structure in the design consists of a train of pecosecond pulses at a 37.425 MHz pulse repetition rate. The initial optical configuration is a conventional near-concentric resonator with transmissive outcoupling. Future upgrades of the system will increase the power and shorten the operating wavelength, and utilize a more advanced resonator system capable of scaling to high powers. The optical system of the laser has been mode led using the GLAD code by using a Beer's-law region to mimic the FEL interaction. Effects such as mirror heating have been calculated and compared with analytical treatments. The magnitude of the distorium for several materials and wavelengths has been estimated. The advantages as well as the limitations of this approach are discussed.

  16. Design and test of SX-FEL cavity BPM

    NASA Astrophysics Data System (ADS)

    Yuan, Ren-Xian; Zhou, Wei-Min; Chen, Zhi-Chu; Yu, Lu-Yang; Wang, Bao-Pen; Leng, Yong-Bin

    2013-11-01

    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 TM010 mode in the output signal. The isolation of TM010 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 TM110 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.

  17. RF coupler for high-power CW FEL photoinjector

    SciTech Connect

    Kurennoy, S.; Young, L. M.

    2003-01-01

    A high-current emittance-compensated RF photoinjector is a key enabling technology for a high-power CW FEL. The design presently under way is a 100-mA 2.5-cell {pi}-mode, 700-MHz, normal conducting demonstration CW RF photoinjector. This photoinjector will be capable of accelerating 3 nC per bunch with an emittance at the wiggler less than 10 mm-mrad. The paper presents results for the RF coupling from ridged wave guides to hte photoinjector RF cavity. The LEDA and SNS couplers inspired this 'dog-bone' design. Electromagnetic modeling of the coupler-cavity system has been performed using both 2-D and 3-D frequency-domain calculations, and a novel time-domain approach with MicroWave Studio. These simulations were used to adjust the coupling coefficient and calculate the power-loss distribution on the coupling slot. The cooling of this slot is a rather challenging thermal management project.

  18. Addressing Physics Grand Challenges Using the Jefferson Lab FEL

    NASA Astrophysics Data System (ADS)

    Williams, Gwyn P.

    2006-11-01

    The Jefferson Lab Free Electron Laser[1] is the first of the so-called 4^th generation light sources to go operational. Capable of delivering extraordinarily bright, tunable light in ultrafast pulses from THz[2] through infrared to UV, the facility extends the experimental reach of accelerator-based light-sources by many orders of magnitude. This allows new opportunities to study many of the ``Grand Challenges'' recently defined by the Office of Science, Basic Energy Sciences Division, most of which are concerned with understandings of equilibrium and non-equilibrium behavior of materials in physics, chemistry and biology using precise pump and probe techniques. Specifically, in condensed matter physics, the JLab FEL permits new studies which go beyond earlier studies of reductionist behavior to those which examine emergent behavior. Thus, the understanding of high Tc superconductivity, colossal magneto-resistance, and observations of the breakdown of the Born-Oppenheimer approximation, are examples of collective behavior which is now treated theoretically via the concept of quasiparticles. In this presentation we will describe the dual pathways of light source development and physics challenges, and then show how they are combined in experiments that allow new insights to be developed to understand material function. We will illustrate this with details of the evolution of accelerator-based light sources, and with examples of work performed to date. References: [1] Neil et al. Phys. Rev.Letts 84, 662 (2000). [2] Carr, Martin, McKinney, Neil, Jordan & Williams, Nature 420, 153 (2002).

  19. Optical modeling of the Jefferson Laboratory IR demo FEL

    NASA Astrophysics Data System (ADS)

    Neil, George R.; Benson, Stephen V.; Shinn, Michelle D.; Davidson, Paul C.; Kloeppel, Peter K.

    1997-05-01

    The Thomas Jefferson National Accelerator Facility (formerly known as CEBAF) has embarked on the construction of a 1 kW free-electron laser operating initially at 3 microns that is designed for laser-material interaction experiments and to explore the feasibility of scaling the system in power and wavelength for industrial and Navy defense applications. The accelerator system for this IR demo includes a 10 MeV photocathode-based injector, a 32 MeV CEBAF-style superconducting radio-frequency linac, and single-pass transport which accelerates the beam from injector to wiggler, followed by energy-recovery deceleration to a dump. The electron and optical beam time structure in the design consists of a train of picosecond pulses at 37.425 MHz pulse repetition rate. The initial optical configuration is a conventional near-concentric resonator with transmissive outcoupling. Future upgrades of the system will increase the power and shorten the operating wavelength, and utilize a more advanced resonator system capable of scaling to high powers. The optical system of the laser has been modeled using the GLADR code by using a Beer's-law region to mimic the FEL interaction. Effects such as mirror heating have been calculated and compared with analytical treatments. The magnitude of the distortion for several materials and wavelengths has been estimated. The advantages as well as the limitations of this approach are discussed.

  20. Spherical Focusing Mirror for the VUV-FEL

    SciTech Connect

    Chapman, H N

    2005-09-20

    Based on analysis and ray-tracing that he did, Jacek Krzywinski has suggested that it should be possible to focus the 32 nmVUV-FEL beam down below 0.2 {micro}m spot size with a normal-incidence multilayer-coated spherical mirror. There are advantages to a spherical mirror over an ellipsoid (or near-paraboloid) which are ease of manufacture and alignment. Off-axis aberrations are generally small, since for a beam that underfills the sphere's aperture, the beam itself defines the axis (rather than the optic). The dominant aberration for a sphere is spherical aberration, which decreases with increasing sphere radius of curvature. However, as the radius of curvature increases, so too does the focal length and f-number, and the diffraction-limited spot increases. Hence, as Jacek has pointed out, there is an optimum radius of curvature, to achieve the smallest possible spot, given a beam diameter. This optimum is determined by balancing the spread of the beam due to spherical aberration and the spread due to diffraction.

  1. A photocathode RF gun for x-ray FEL

    SciTech Connect

    Wang, X.J.; Batchelor, K.; Ben-Zvi, I.

    1995-12-31

    A 1.6 cell photocathode RF gun was developed by a BNL/SLAC/UCLA collaboration for X-ray FEL and other applications. The objective of the collaboration is to develop a cost effective and more reliable photocathode RF gun based on the operational experience of the original BNL gun. The new photocathode RF gun is cable of producing 1 mm-mrad normalized rms emittance photocurrent with a peak current of 100 A. The half-cell length of the new RF gun was lengthened to reduce the peak field on the cavity surface, the side-coupled scheme for cavity and waveguide coupling was replaced by a symmetrized coupling to the full-cell. The cavity aperture was increased to improve the coupling between two cells and for flat beam application. The experimental results of cold testing the RF gun will be presented. We will also present an injector design based on the new photocathode RF gun and emittance compensation technique.

  2. 77 FR 75660 - Agency Information Collection Activities; Proposed Collection; Comments Requested: FEL Out-of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-21

    ... notification of the discontinuance or succession and submit his license or permit and any copies furnished with... and Planning Staff, Justice Management Division, Department of Justice, Two Constitution Square,...

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

    SciTech Connect

    Benson, S.; Bohn, C.; Dylla, H.F.

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Evidence for a Fel d I-like molecule in the "big cats" (Felidae species).

    PubMed

    de Groot, H; van Swieten, P; Aalberse, R C

    1990-07-01

    In this study, we investigated the cross-reactivity pattern of IgE and IgG4 antibodies to the major feline allergen, Fel d I. We studied the IgE and IgG4 response of 11 cat-allergic patients against Fel d I-like structures in eight members of the Felidae family: ocelot, puma, serval, siberian tiger, lion, jaguar, snow leopard, and caracal. Hair from these "big cats" was collected, extracted, and used in a RAST system and histamine-release test. By means of a RAST-inhibition assay with affinity-purified Fel d I from cat dander, it was established that, in the Felidae species, a Fel d I equivalent is present that reacts with IgE and IgG4 antibodies. We found that all patients had cross-reacting IgE antibodies to seven of the Felidae tested; no IgE antibodies reactive with the caracal were found. Eight of 10 patients with IgG4 antibodies directed to cat dander also had IgG4 antibodies directed to several Felidae species, including the caracal. However, the correlation between the IgE and the IgG4 antibody specificity was low, indicating that, in the case of Fel d I IgE and IgG4, antibodies do not necessarily have the same specificity.

  6. FULL ELECTROMAGNETIC FEL SIMULATION VIA THE LORENTZ-BOOSTED FRAME TRANSFORMATION

    SciTech Connect

    Fawley, William; Vay, Jean-Luc

    2010-08-16

    Numerical electromagnetic simulation of some systems containing charged particles with highly relativistic directed motion can by speeded up by orders of magnitude by choice of the proper Lorentz-boosted frame. A particularly good application for calculation in a boosted frame isthat of short wavelength free-electron lasers (FELs) where a high energy electron beam with small fractional energy spread interacts with a static magnetic undulator. In the optimal boost frame (i.e., the ponderomotive rest frame), the red-shifted FEL radiation and blue-shifted undulator field have identical wavelengths and the number of required longitudinal grid cells and time-steps for fully electromagnetic simulation (relative to the laboratory frame) decrease by factors of gamma^2 each. In theory, boosted frame EM codes permit direct study of FEL problems for which the eikonal approximation for propagation of the radiation field and wiggler-period-averaging for the particle-field interaction may be suspect. We have adapted the WARP code to apply this method to several electromagnetic FEL problems including spontaneous emission, strong exponential gain in a seeded, single pass amplifier configuration, and emission from e-beams in undulators with multiple harmonic components. WARP has a standard relativistic macroparticle mover and a fully 3-D electromagnetic field solver. We discuss our boosted frame results and compare with those obtained using the ?standard? eikonal FEL simulation approach.

  7. Validation of the dissemination of spectral irradiance values using FEL lamps

    NASA Astrophysics Data System (ADS)

    Johnson, B. C.; Graham, Gary D.; Saunders, Robert D.; Yoon, Howard W.; Shirley, Eric L.

    2012-09-01

    Scales of spectral irradiance are disseminated by NIST using assignment of values to FEL lamp standards for defined conditions. These lamp standards can be used for absolute calibrations of irradiance radiometers, or more typically, be used in conjunction with a diffuse reflectance standard to establish a scale of spectral radiance and for subsequent absolute calibrations of radiance radiometers. The NIST FEL standards are valuable artifacts requiring special care. Many users optimize resources by in-house transfer of their primary standard to working standards. There are a number of sources of uncertainty in utilizing FEL lamps, e.g., lamp current, alignment, distance setting, instrument aperture size, drift, scattered light, and interpolation in the wavelength grid for the specified irradiance values. In this work, we validated the transfer activity by ITT of their primary, NIST-traceable FEL lamp standards. A portable irradiance bench that had kinematic mounts for an FEL lamp, on-axis baffle, and three different irradiance radiometers was built, tested, and deployed to ITT in Rochester, NY. We report the results of this comparison activity. An uncertainty budget was developed and it was found that the results agreed well within the combined uncertainties of 1.5% to 1.6% (k = 2).

  8. Visibility in California

    SciTech Connect

    Trijonis, J.

    1982-02-01

    A comprehensive study is conducted of visibility in California using prevailing visibility measurements at 67 weather stations in conjunction with data on particulate concentrations and meteorology. The weather station visibility data, when handled with special techniques that account for the nature of visibility reporting practices, prove to be of very good quality for the purposes of most of the analyses that are attempted. It is found that the most important meteorological parameters with respect to visibility are relative humidity, temperature, and special weather events (especially fog). A detailed isopleth map of visibility within California, when compared with earlier work on nationwide visibility, reveals that California experiences far more severe and complex spatial gradients in visibility than those observed anywhere else in the U.S. Two major pockets of heavy man-made visibility impact in California are the Los Angeles basin and the San Joaquin Valley. The spatial, seasonal, and diurnal patterns of visibility are found to be readily explainable in terms of corresponding patterns in emissions, air quality, and meteorology. Regression analyses relating visibility to relative humidity and aerosol concentrations produce high levels of correlation and physically reasonable regression coefficients; these analyses indicate that secondary aerosols are major contributors to visibility reduction in California. An analysis of long-term visibility trends from 1949 to 1976 reveals several interesting features in historical visibility changes for California.

  9. Critical review of high gain x-ray FEL experiments

    SciTech Connect

    Kim, Kwang-Je

    1996-08-01

    There is a renewed interest at the present time to develop x-ray free electron lasers (FELs). The interest is driven by the scientific opportunities with coherent x-rays glimpsed at the third generation light sources. With the recent development in linac technology in producing high-energy, high-brightness electron beams, it is now possible to design intense coherent x-ray source for wavelengths as short as one Angstrom based on the self- amplified spontaneous emission (SASE) principle. Major linac laboratories such as SLAC and DESY are therefore actively pursuing detailed design studies for the x-ray SASE facilities. The x-rays from these facilities will provide a peak brightness more than ten orders of magnitude higher than that of the current synchrotron radiation sources. Short wavelength coherent radiation could also be generated with harmonic generation techniques in linacs or storage rings. However, these schemes are not expected to be effective for 1 {Angstrom} wavelengths. This review will therefore concentrate on the linac based SASE scheme. The critical components of the SASE are: an electron source consisting of an RF photocathode gun with the emittance corrector producing high brightness electron beam; the beam bunching and acceleration; and a long undulator in which the radiation develops from initially incoherent radiation to intense, coherent radiation. We discuss the critical experimental issues in these components highlighting some relevant recent experiments. We also discuss issues related to the SASE experiment which are distinct from the usual free electron lasers. We give a brief survey of the world-wide SASE experiments. We conclude with a summary and outlook.

  10. X-band photoinjector for a chirped-pulse FEL

    SciTech Connect

    Luhmann, Jr., N. C.; Alvis, R. M.; Baldis, H. A.; Hartemann, F. V; Heritage, J. P.; Ho, C. H.; Landahl, E. C.; Li, K.; Troha,A. L.; White, W. E.

    1998-12-15

    The phase noise and jitter characteristics of the laser and rf systems of a high gradient X-band photoinjector have been measured experimentally. When > 100 coherently phased 5 MeV electron bunches are produced in bursts, the photoinjector should be an ideal electron source for a pulsed, pre-bunched free-electron laser (FEL) operating at 100 GHz. The laser oscillator is a self-modelocked Titanium:Sapphire system operating at the 108th subharmonic of the rf gun. The X-band signal is produced from the laser by a phase-locked dielectric resonance oscillator, and amplified by a pulsed TWT and klystron. A comparison between the klystron and TWT amplifier phase noise and the fields excited in the rf gun demonstrates the filtering effect of the high Q structure, thus indicating that the rf gun can be used as a master oscillator, and could be energized by either a rf oscillator such as a magnetron or a compact source such as a cross-field amplifier. In particular, the rf gun can play the role of a pulsed rf clock to synchronize the photocathode laser system: direct drive of a synchronously mode-locked AlGaAs quantum well laser has been achieved using the X0-band gun rf fields. This novel, GHz repetition rate, sub-picosecond laser system is being developed to replace the more conventional femtosecond Ti: Al2O3 system. Some advantages include pumping this laser with a stabilized current source instead of a costly, low efficiency pump laser. Finally, dark current measurements and initial photoelectron measurements are reported.

  11. X-ray FEL induced multiphton ionization and molecular dissociation

    NASA Astrophysics Data System (ADS)

    Fang, Li

    2014-05-01

    X-ray Free electron lasers (FELs) enable multiphoton absorption at the core levels which is not possible with conventional light sources. Multiphoton ionization and the subsequent core-hole states relaxation lead to dramatic dynamics of the molecules. We present our experimental as well as theoretical results on multiphoton ionization and molecular fragmentation dynamics with the Linac Coherent Light Source (LCLS) at SLAC National Laboratory. We investigated simple diatomic system, N2 molecules, where we used multiphoton ionization as an internal clock for imaging the dynamics in time and the internuclear separation domain. We observed the modification of the ionization dynamic by varying the x-ray beam parameters and the effect of the spatial distribution on the ionization. We also investigated a complex system, C60, where we developed a full model to simulate the multiphoton ionization that results in various molecular ions and atomic carbon ions up to charge 6+. The calculation agrees well with our experimental results in ion kinetic energy distribution and charge state distribution. Moreover, our model provides further insights into the photoionization and dissociation dynamics as a function of time and molecular size. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. Thank T. Osipov, B. Murphy, Z. Jurek, S.-K. Son, R. Santra, and N. Berrah, M. Hoener, O. Gessner, F. Tarantelli, S.T. Pratt, O. Kornilov, C. Buth, M. Güehr, E. Kanter, C. Bostedt, J. D. Bozek, P. H. Bucksbaum, M. Chen, R. Coffee, J. Cryan, L. DiMauro, M. Glownia, E. Kukk, S.R. Leone, L. Avaldi, P. Bolognesi, J. Eland, J. Farrell, R. Feifel, L. Frasinski, D.T. Ha, K. Hoffmann, B. McFarland, C. Miron, M. Mucke, R. Squibb, K. Ueda for their contributions to this work.

  12. Design of compressors for FEL pulses using deformable gratings

    NASA Astrophysics Data System (ADS)

    Bonora, Stefano; Fabris, Nicola; Frassetto, Fabio; Giovine, Ennio; Miotti, Paolo; Quintavalla, Martino; Poletto, Luca

    2017-06-01

    We present the optical layout of soft X-rays compressors using reflective grating specifically designed to give both positive or negative group-delay dispersion (GDD). They are tailored for chirped-pulse-amplification experiments with FEL sources. The optical design originates from an existing compressor with plane gratings already realized and tested at FERMI, that has been demonstrated capable to introduce tunable negative GDD. Here, we discuss two novel designs for compressors using deformable gratings capable to give both negative and positive GDD. Two novel designs are discussed: 1) a design with two deformable gratings and an intermediate focus between the twos, that is demonstrated capable to introduce positive GDD; 2) a design with one deformable grating giving an intermediate focus, followed by a concave mirror and a plane grating, that is capable to give both positive and negative GDD depending on the distance between the second mirror and the second grating. Both the designs are tunable in wavelength and GDD, by acting on the deformable gratings, that are rotated to tune the wavelength and the GDD and deformed to introduce the radius required to keep the spectral focus. The deformable gratings have a laminar profile and are ruled on a thin silicon plane substrate. A piezoelectric actuator is glued on the back of the substrate and is actuated to give a radius of curvature that is varying from infinite (plane) to few meters. The ruling procedure, the piezoelectric actuator and the efficiency measurements in the soft X-rays will be presented. Some test cases are discussed for wavelengths shorter than 12 nm.

  13. The DarkLight Experiment at the JLab FEL

    NASA Astrophysics Data System (ADS)

    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.

  14. Immunological differences in the global release of the major cat allergen Fel d 1 are influenced by sex and behaviour.

    PubMed

    Bienboire-Frosini, Cécile; Cozzi, Alessandro; Lafont-Lecuelle, Céline; Vervloet, Daniel; Ronin, Catherine; Pageat, Patrick

    2012-07-01

    The biological function of Fel d 1, the major cat allergen released in the environment, is still unclear despite studies suggesting a putative role in chemical communication. Structural and immunological polymorphisms of Fel d 1 have been described. This study examined how Fel d 1 immunological polymorphism may have a physiological origin by estimating a potential relationship with the sex of cats and cat-human interactions. Samples from bath washes of 21 cats were screened to study antibody binding to Fel d 1 using an ELISA. Personality and Tolerance Handling scores were used to assess the behaviour of the cats. In the washes, Fel d 1 concentrations were significantly lower in females than in males (P<0.05). Slopes from the ELISA dose-dependent curves varied among the cats: males secreted Fel d 1 variants with higher antibody recognition than females (P<0.01). Females that were aggressive and difficult to handle displayed a diminished slope value, and therefore a weaker Fel d 1 immunoreactivity in global washes, compared to females that were sociable (P=0.09) and easy to handle (P=0.07). This study shows a variable immunological polymorphism of Fel d 1 within a cat population, particularly between males and females, and this polymorphism appears to be related to cat-human interactions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Development of an alternative testing strategy for the fish early life-stage (FELS) test using the AOP framework

    EPA Science Inventory

    Currently, the fish early life-stage (FELS) test (OECD 210) is the primary guideline used to estimate chronic toxicity of regulated chemicals. Although already more cost-efficient than adult fish tests, the FELS test has some important drawbacks. Both industry and regulatory inst...

  16. VisibilityCluster: average directional visibility for many-light rendering.

    PubMed

    Wu, Yu-Ting; Chuang, Yung-Yu

    2013-09-01

    This paper proposes the VisibilityCluster algorithm for efficient visibility approximation and representation in many-light rendering. By carefully clustering lights and shading points, we can construct a visibility matrix that exhibits good local structures due to visibility coherence of nearby lights and shading points. Average visibility can be efficiently estimated by exploiting the sparse structure of the matrix and shooting only few shadow rays between clusters. Moreover, we can use the estimated average visibility as a quality measure for visibility estimation, enabling us to locally refine VisibilityClusters with large visibility variance for improving accuracy. We demonstrate that, with the proposed method, visibility can be incorporated into importance sampling at a reasonable cost for the many-light problem, significantly reducing variance in Monte Carlo rendering. In addition, the proposed method can be used to increase realism of local shading by adding directional occlusion effects. Experiments show that the proposed technique outperforms state-of-the-art importance sampling algorithms, and successfully enhances the preview quality for lighting design.

  17. The research facilities of the Duke FEL Laboratory - uniqueness and challenges

    SciTech Connect

    Madey, J.M.J.; Barnett, G.; Burnham, B.

    1995-12-31

    FEL light sources offer unique promise as broadly tuneable, high brightness sources of radiation throughout the electromagnetic spectrum. But the effective utilization of these new light sources also raises a series of unprecedented issues and challenges arising, in general, from the limited number of beamlines which can be supported by a single source. The cost effective utilization of this technology therefore requires emphasis on (1) the realization of one or more truly unique research capabilities, (2) the optimization of access to the research beamlines which are available, and (3) the management and support services required by users to maximize their productivity. The experience we have acquired in the development and operation of the facilities of the Duke FEL Lab provide a point of reference which may prove useful to other research-oriented FEL facilities.

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

    SciTech Connect

    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.

  19. A Dynamic Feedback Model for High Repetition Rate LINAC-Driven FELS

    SciTech Connect

    Mellado Munoz, M.; Doolittle, L.; Emma, P.; Huang, G.; Ratti, A.; Serrano, C.; Byrd, J. M.

    2012-05-20

    One of the concepts for the next generation of linacdriven FELs is a CW superconducting linac driving an electron beam with MHz repetition rates. One of the challenges for next generation FELs is improve the stability of the xray pulses by improving the shot-to-shot stability of the energy, charge, peak current, and timing jitter of the electron beam. A high repetition rate FEL with a CW linac presents an opportunity to use a variety of broadband feedbacks to stabilize the beam parameters. To understand the performance of such a feedback system, we are developing a dynamic model of the machine with a focus on the longitudinal beam properties. The model is being developed as an extension of the LITrack code and includes the dynamics of the beam-cavity interaction, RF feedback, beam-based feedback, and multibunch effects. In this paper, we present a detailed description of this model.

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

    SciTech Connect

    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.

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

    NASA Astrophysics Data System (ADS)

    Awazu, Kunio; Kinpara, Takeshi; Tamiya, Eiichi

    2002-05-01

    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 2. FEL irradiation at a wavelength of 5.75 and 6.1 μm, 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 μm. The maximum transfer efficiency was about 0.5%.

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

    PubMed Central

    Engel, Robin; Düsterer, Stefan; Brenner, Günter; Teubner, Ulrich

    2016-01-01

    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. PMID:26698053

  3. Start-to-end Simulation for the LCLS Xray-FEL

    SciTech Connect

    Emma, Paul J

    2002-08-23

    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.

  4. Future of ePix detectors for high repetition rate FELs

    SciTech Connect

    Blaj, G. Caragiulo, P.; Carini, G.; Dragone, A.; Haller, G.; Hart, P.; Hasi, J.; Herbst, R.; Kenney, C.; Markovic, B.; Pines, J.; Segal, J.; Tamma, C.; Tomada, A.; Nishimura, K.

    2016-07-27

    Free-electron lasers (FELs) made the imaging of atoms and molecules in motion possible, opening new science opportunities with high brilliance, ultra-short x-ray laser pulses at up to 120 Hz. Some new or upgraded FEL facilities will operate at greatly increased pulse rates (kHz to MHz), presenting additional requirements on detection. We will present the ePix platform for x-ray detectors and the current status of the ePix detectors: ePix100 for low noise applications, ePix10k for high dynamic range applications, and ePixS for spectroscopic applications. Then we will introduce the plans to match the ePix detectors with the requirements of currently planned high repetition rate FELs (mainly readout speed and energy range).

  5. Visibility and Haze

    EPA Pesticide Factsheets

    Haze forms when sunlight encounters particle pollution. It reduces visibility in cities and scenic areas. This web area provides regulatory information and progress towards improving visibility through EPA’s regional haze program.

  6. Cat (Fel d 1) and dog (Can f 1) allergen levels in cars, dwellings and schools.

    PubMed

    Niesler, A; Ścigała, G; Łudzeń-Izbińska, B

    Pets are an important source of indoor allergens. The aim of the study was to compare cat and dog allergen levels in cars, schools and homes. The study was carried out in 17 cars, 14 classrooms and 19 dwellings located in the highly industrialized and urbanized region of Poland. Dust and air samples were analyzed for Fel d 1 and Can f 1 using a double monoclonal ELISA assay. The highest amounts of cat and dog allergens (Fel d 1: 1169 μg/g; Can f 1: 277 μg/g) were found in dwellings with pets. Allergen concentrations were correlated with the number of animals kept at home. Although concentrations on automobile seats were lower, Fel d 1 levels exceeded 8 μg/g in 23.5 % of cars and high levels of Can f 1 (>10 μg/g) were found in 17.6 % of cars. The study revealed that cars of pet owners may be reservoirs of cat and dog allergens even when animals are not transported in them. In schools, concentrations of pet allergens did not reach high levels, but the moderate levels of Fel d 1 (≥1-8 μg/g) and Can f 1 (≥2-10 μg/g) were detected in 42.9 and 7.1 % of the investigated classrooms. Concentrations of cat and dog allergen in schools were higher than in homes without pets. While airborne Fel d 1 and Can f 1 levels were found low, residential allergen concentrations in settled dust and air were correlated. The study results suggest that classrooms and cars of pet owners may be important sites of exposure to cat and dog allergens, though the highest concentrations of Fel d 1 and Can f 1 are found in homes of pet owners.

  7. SOFT X-RAY FEL BY CASCADING STAGES OF HIGH GAIN HARMONIC GENERATION.

    SciTech Connect

    YU,L.H.

    2003-04-17

    Short wavelength Free-Electron Lasers are perceived as the next generation of synchrotron light sources. 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 VUV FELs and make x-ray FELs possible. Self-Amplified Spontaneous Emission (SASE) and High Gain Harmonic Generation (HGHG)[17-19] are the two leading candidates for x-ray FELs. The first lasing of HGHG proof-of-principle experiment succeeded in August, 1999 in Brookhaven National Laboratory. The experimental results agree with the theory prediction. Compared with SASE FEL, the following advantages of HGHG FEL were confirmed; (1) Better longitudinal coherence, and hence, much narrower bandwidth than SASE. (2) More stable central wavelength, (3) More stable output energy. In this introduction, we will first briefly describe the principle of HGHG in Section A. Then in Section B, we give a general description about how to produce soft x-ray by cascading HGHG scheme. In section 2, we give a detailed description of the system design. Then, in section 3, we give a description of an analytical estimate for the HGHG process, and the calculation of the parameters of different parts of the system. The estimate is found to agree with simulation within about a factor 2 for most cases we studied. The stability issue, the sensitivity to parameter variation, the harmonic contents of the final output, and the noise degradation issue of such HGHG scheme are discussed in Section 4. The results are presented in Section 4. Finally, in Section 5, we will give some discussion of the challenges in development of the system. The conclusion is given in Section 6.

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

    SciTech Connect

    Pflueger, J.; Pierini, P.

    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.

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

    SciTech Connect

    Stanley, R.J.; Haar, P.; Boxer, S.G.

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

    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.

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

    SciTech Connect

    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; Zhang, Shukui

    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.

  12. An Analysis of Shot Noise Propagation and Amplificationin Harmonic Cascade FELs

    SciTech Connect

    Huang, Z.; /SLAC

    2006-12-11

    The harmonic generation process in a harmonic cascade (HC) FEL is subject to noise degradation which is proportional to the square of the total harmonic order. In this paper, we study the shot noise evolution in the first-stage modulator and radiator of a HC FEL that produces the dominant noise contributions. We derive the effective input noise for a modulator operating in the low-gain regime, and analyze the radiator noise for a density-modulated beam. The significance of these noise sources in different harmonic cascade designs is also discussed.

  13. Strategies for minimizing emittance growth in high charge CW FEL injectors

    SciTech Connect

    Liu, H.

    1995-12-31

    This paper is concerned with the best strategies for designing low emittance, high charge CW FEL injectors. This issue has become more and more critical as today`s interest in FELs is toward UV wavelength high average power operation. The challenge of obtaining the smallest possible emittance is discussed from both the practical point of view and the beam physics point of view. Various mechanisms responsible for beam emittance growth are addressed in detail. Finally, the design of a high charge injector test stand at CEBAF is chosen to help illustrate the design strategies and emittance growth mechanisms discussed in this paper.

  14. The use of an external cavity with the SCA/FEL

    NASA Astrophysics Data System (ADS)

    Haar, P.; Fishman, I. M.; Smith, T. I.; Schwettman, H. A.

    1992-07-01

    We have investigated the possibility of coupling the FEL optical beam into an external cavity. The resulting buildup of optical energy in the cavity offers several advantages. First, the sensitivity of the stored energy to source instabilities makes the external cavity a powerful FEL diagnostic. The dependence of the stored energy on several important instabilities will be discussed, as will plans for actually quantifying these instabilities with the external cavity. Second, a large amount of energy can be accumulated in the external cavity. Outcoupling this energy can significantly increase the micropulse energy delivered. Three possible outcoupling schemes will be discussed: "enhanced" outcoupling, photo-activated cavity dumping, and electro-optic cavity dumping.

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

    SciTech Connect

    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.

  16. Strong coupling operation of a FEL amplifier with an axial magnetic field

    NASA Astrophysics Data System (ADS)

    Rullier, J. L.; Gardelle, J.; Labrouche, J.; Le Taillandier, P.

    1995-04-01

    This paper presents the results of a FEL experiment at 35 GHz, using a highly relativistic electron beam (T = 1.75 MeV). The electron pulse length is 30 ns FWHM with a peak current of 400 A. The FEL is designed to operate in the high-gain Compton regime, with a negative coupling parameter (Φ < 0) leading to a stong growth rate. More than 50 MW of RF power in the TE11 mode (43 dB gain) has been obtained with good reproducibility. The experimental results are in good agreement with predictions made using the 3D stationary simulation code SOLITUDE.

  17. Measurement of nonlinear coefficients of crystals at terahertz frequencies via High Field THzat the FELIX FEL

    DTIC Science & Technology

    2017-04-03

    plane. As the sample moves along the z-axis, the intensity of the incident radiation increases in a known fashion, and, at high intensities , a...AFRL-AFOSR-UK-TR-2017-0027 Measurement of nonlinear coefficients of crystals at terahertz frequencies via High - Field THz at the FELIX FEL Mira...coefficients of crystals at terahertz frequencies via High - Field THz at the FELIX FEL 5a.  CONTRACT NUMBER FA9550-15-C-0068 5b.  GRANT NUMBER 5c.  PROGRAM

  18. Benchmark and comparisons of FEL simulation programs TDA3D and GENESIS.

    SciTech Connect

    Chae, Y.-C.; Milton, S.V.

    1999-09-11

    A low-energy undulator test line (LEUTL) is under construction at the Advanced Photon Source (APS). This line will initially be used to demonstrate a free-electron laser (FEL) based on the self-amplified spontaneous-emission (SASE) process. The FEL simulation programs, TDA3D and GENESIS, together with several other codes have been used for the LEUTL project. In order to increase the confidence on the simulation results, we attempted to benchmark two programs TDA3D and GENESIS. The results are reported here.

  19. High gain FEL amplification of charge modulation caused by a hadron

    SciTech Connect

    Litvinenko,V.; Ben-Zvi, I.; Hao, Y.; Kayran, D.; Pozdeyev, E.; Wang, G.; Reiche, S.; Shevchenko, O.; Vinokurov, N. A.

    2008-08-24

    In scheme of coherent electron cooling (CeC) [1,2], a modulation of electron beam density induced by a copropagation hadron is amplified in high gain FEL. The resulting amplified modulation of electron beam, its shape, form and its lethargy determine number of important properties of the coherent electron cooling. In this talk we present both analytical and numerical (using codes RON [3] and Genesis [4]) evaluations of the corresponding Green functions. We also discuss influence of electron beam parameters on the FEL response.

  20. A review of environment-dependent processes within FEL excited matter

    NASA Astrophysics Data System (ADS)

    Ziaja, B.; Jurek, Z.; Medvedev, N.; Thiele, R.; Toleikis, S.

    2013-09-01

    In this review we discuss four examples of environment-dependent processes triggered by free-electron laser radiation within systems of various complexity. Those are: (i) non-thermal structural changes within irradiated solids, (ii) inverse bremsstrahlung during VUV irradiation of atomic clusters, (iii) shifts of ionic potentials due to a charged ion environment within a plasma, and (iv) fast thermalization of the electrons created after FEL irradiation. We show that FEL excitation enables access to a unique class of environment-influenced processes, depending on the radiation wavelength, pulse fluence and the structure of sample.

  1. A novel self-seeding scheme for hard X-ray FELs

    NASA Astrophysics Data System (ADS)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2011-09-01

    Typical SASE XFEL pulses exhibit poor longitudinal coherence, a characteristic inherited from the start-up from shot noise. Self-seeding schemes are an answer to the call for improved longitudinal coherence. If applied to already working or designed XFELs, these schemes are subject to constraints, including minimal change to the baseline design, and possibility to recover the baseline mode of operation. In this work we propose a novel single-bunch self-seeding method, based on a particular kind of monochromator that satisfies these constraints. We will limit ourselves to the analysis of the simplest possible configuration, consisting of an input undulator and an output undulator, separated by our novel monochromatization stage. Such a stage consists of a weak few-meter long chicane, acting as a tunable delay stage, washing out the electron beam microbunching, and creating a transverse offset for the monochromator. In essence, the monochromator consists of a single crystal in Bragg-transmission geometry, which operates as a bandstop filter for the transmitted X-ray SASE radiation pulse. When the incident angle and the spectral contents of the incoming beam satisfy the Bragg diffraction condition, the temporal waveform of the transmitted radiation pulse shows a long monochromatic tail, whose duration is inversely proportional to the bandwidth of the absorption line in the transmittance spectrum. The magnetic chicane is tuned to shift the electron bunch on top of the monochromatic wake created by the bandstop filter thus selecting (temporal windowing) a part of the wake. By this, the electron bunch is seeded with a radiation pulse characterized by a bandwidth much narrower than the natural FEL bandwidth. The output power from our setup can be further increased by tapering the magnetic field of the undulator, yielding a tremendous increase in peak brightness with respect to the baseline mode of operation. In this work we present a feasibility study and exemplifications

  2. Effects of undulator interruptions on the performance of high-gain FEL amplifiers

    SciTech Connect

    Kim, K.J.; Xie, M.; Pelligrini, C.

    1995-12-31

    The high-gain amplifiers for short wavelength free electron lasers (FELs) such as the LCLS project require a long undulator. The construction of the undulator as well as the FEL operation would become easier if the undulator could be interrupted with drift sections every few gain lengths. We have investigated the influence of such interruption on the FEL performances. Three effects are considered: (i) the diffraction loss, (ii) the phase mismatch and, (iii) the phase smearing due to velocity spread and to dispersion errors. The effect (i) is the loss during the process in which the optical mode in a section of the undulator leaves the undulator, propagates through the free space and then re-enters and re-adjusts in the next section. The effect (ii) is the fact that the phase of the optical beam is displaced with respect to the electrons density modulation for optical FEL interaction due to the slippage of the electron beam in the interruption region. The effect (iii) is the fact that electrons velocity spread, emittance, and dispersion due to misalignment of the quadrupoles used for additional focusing lead to a reduction of the bunching factor. We present an approximate analysis of these effects. When applied to the LCLS parameters, we find that the effect (i) is negligible, the effect (ii) gives a condition on the length of the drift section, and the effects (iii) are small, but could be non-negligible if there are sufficient number of interruptions.

  3. Bunch Length Measurements at the JLab FEL Using Coherent Transition and Synchrotron Radiation

    SciTech Connect

    Pavel Evtushenko; James Coleman; Kevin Jordan; J. Michael Klopf; George Neil; Gwyn Williams

    2006-05-01

    The JLab FEL is routinely operated with sub-picosecond bunches. The short bunch length is important for high gain of the FEL. Coherent transition radiation has been used for the bunch length measurements for many years [1]. This diagnostic can be used only in the pulsed beam mode. It is our goal to run the FEL with CW beam and a 74.85 MHz micropulse repetition rate, which, with the 135 pC nominal bunch charge corresponds to the beam average current of 10 mA. Hence it is very desirable to have the possibility of making bunch length measurements when running CW beam with any micropulse frequency. We use a Fourier transform infrared (FTIR) interferometer, which is essentially a Michelson interferometer, to measure the spectrum of the coherent synchrotron radiation generated in the last dipole of the magnetic bunch compressor upstream of the FEL wiggler. This noninvasive diagnostic provides bunch length measurements for CW beam operation at any micropulse frequency. We also compare the measurements made with the help of the FTIR interferometer with data obtained using the Martin-Puplett interferometer [1]. Results of the two diagnostics agree within 15 %. Here we present a description of the experimental setup, data evaluation procedure and results of the beam measurements.

  4. Microbunching Instability Effect Studies and Laser Heater Optimization for the SPARX FEL Accelerator

    SciTech Connect

    Vaccarezza, C.; Chiadroni, E.; Ferrario, M.; Giannessi, L.; Quattromini, M.; Ronsivalle, C.; Venturini, C.; Migliorati, M.; Dattoli, G.

    2010-05-23

    The effects of microbunching instability for the SPARX accelerator have been analyzed by means of numerical simulations. The laser heater counteracting action has been addressed in order to optimize the parameters of the compression system, either hybrid RF plus magnetic chicane or only magnetic, and possibly enhance the FEL performance.

  5. Experimental setups for FEL-based four-wave mixing experiments at FERMI

    SciTech Connect

    Bencivenga, Filippo; Zangrando, Marco; Svetina, Cristian; Abrami, Alessandro; Battistoni, Andrea; Borghes, Roberto; Capotondi, Flavio; Cucini, Riccardo; Dallari, Francesco; Danailov, Miltcho; Demidovich, Alexander; Fava, Claudio; Gaio, Giulio; Gerusina, Simone; Gessini, Alessandro; Giacuzzo, Fabio; Gobessi, Riccardo; Godnig, Roberto; Grisonich, Riccardo; Kiskinova, Maya; Kurdi, Gabor; Loda, Giorgio; Lonza, Marco; Mahne, Nicola; Manfredda, Michele; Mincigrucci, Riccardo; Pangon, Gianpiero; Parisse, Pietro; Passuello, Roberto; Pedersoli, Emanuele; Pivetta, Lorenzo; Prica, Milan; Principi, Emiliano; Rago, Ilaria; Raimondi, Lorenzo; Sauro, Roberto; Scarcia, Martin; Sigalotti, Paolo; Zaccaria, Maurizio; Masciovecchio, Claudio

    2016-01-01

    The recent advent of free-electron laser (FEL) sources is driving the scientific community to extend table-top laser research to shorter wavelengths adding elemental selectivity and chemical state specificity. Both a compact setup (mini-TIMER) and a separate instrument (EIS-TIMER) dedicated to four-wave-mixing (FWM) experiments has been designed and constructed, to be operated as a branch of the Elastic and Inelastic Scattering beamline: EIS. The FWM experiments that are planned at EIS-TIMER are based on the transient grating approach, where two crossed FEL pulses create a controlled modulation of the sample excitations while a third time-delayed pulse is used to monitor the dynamics of the excited state. This manuscript describes such experimental facilities, showing the preliminary results of the commissioning of the EIS-TIMER beamline, and discusses original experimental strategies being developed to study the dynamics of matter at the fs–nm time–length scales. In the near future such experimental tools will allow more sophisticated FEL-based FWM applications, that also include the use of multiple and multi-color FEL pulses.

  6. Transient absorption spectroscopy using the super-ACO storage ring FEL

    NASA Astrophysics Data System (ADS)

    Renault, Eric; Nahon, Laurent; Nutarelli, Daniele; Garzella, David; Merola, F.; Couprie, Marie-Emmanuelle

    2000-04-01

    The Super-ACO storage ring FEL is operating with a high average power in the UV range (300 mW at 350 nm), and recently at wavelengths down to 300 nm. In addition this source exhibits high stability and long lifetime which makes it a unique tool for user applications. The coupling of the FEL with other synchrotron based sources (bending magnet and undulator) opens many unexplored possibilities for various types of two-color time-resolved spectroscopies. Presently, we are developing a two-color experiment where we study the sub-nanosecond time-resolved absorption of different chromophoric compounds. In this type of pump-probe experiments, 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 ranging from UV to IR, which is naturally synchronized with the FEL pulses and can be used to probe the photochemical subsequent events and the transient species. With a dye molecule (POPOP), we have obtained a two-color effect which demonstrates the feasibility of the experiment in terms of flux. Applications on various chromophores of biological interest are planned.

  7. FLOYDS Classification of ATLAS17iig/AT 2017fel as a Young Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Hosseinzadeh, G.; Arcavi, I.; Valenti, S.; Howell, D. A.; McCully, C.

    2017-07-01

    We obtained a spectrum of ATLAS17iig/AT 2017fel (Tonry et al. 2017, TNSTR, 12396) on 2017 July 8.6 UT with the robotic FLOYDS instrument mounted on the Las Cumbres Observatory 2-meter telescope on Haleakala, Hawai'i.

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

    NASA Astrophysics Data System (ADS)

    Agapov, I.; Geloni, G.; Tomin, S.; Zagorodnov, I.

    2014-12-01

    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.

  9. Inverse Cherenkov and inverse FEL accelerator experiments at the Brookhaven Accelerator Test Facility

    SciTech Connect

    Pogorelsky, I.V.; vanSteenbergen, A.; Babzien, M.

    1995-12-31

    Status update on the ongoing inverse Cherenkov acceleration experiment and prospects to its 100 MeV short-term upgrade. The first report on 1 MeV electron acceleration with the 0.5 GW CO{sub 2} laser used in the inverse FEL scheme. (author). 22 refs., 8 figs., 1 tab.

  10. First operation of an FEL in same-cell energy recovery mode

    SciTech Connect

    G.R. Neil; S. Benson; G. Biallas; C.L. Bohn; D. Douglas; H.F. Dylla; R. Evans; J. Fugitt; J. Gubeli; R. Hill; K. Jordan; G. Krafft; R. Li; L. Merminga; D. Oepts; P. Piot; J. Preble; Michelle D. Shinn; T. Siggins; R. Walker; B. Yunn

    1999-09-01

    The driver for Jefferson Lab's kW-level infrared free-electron laser (FEL) is a superconducting, recirculating accelerator that recovers 75% of the electron-beam power and converts it to radio frequency power. As reported in FEL'98, the accelerator operated ''straight-ahead'' to deliver 38 MeV, 1.1 mA cw current for lasing at wavelengths in the vicinity of 5 microns. The waste beam was sent directly to a dump, bypassing the recirculation loop. Stable operation at up to 311 W cw was achieved in this mode. The machine has now recirculated cw average current up to 4.6 mA and has lased cw with energy recovery up to 1,720 W output at 3.1 microns. This is the first FEL to ever operate in the ''same-cell'' energy recovery mode. Energy recovery offers several advantages (reduced RF power and dramatically reduced radio-nuclide production at the dump) and several challenges will be described. The authors have observed heating effects in the mirrors which will be described. They will also report on the additional performance measurements of the FEL that have been performed and connect those measurements to standard models.

  11. Availability Performance and Considerations for LCLS X-Ray FEL at SLAC

    SciTech Connect

    Allen, W.B.; Brachmann, A.; Colocho, W.; Stanek, M.; Warren, J.; /SLAC

    2011-08-16

    The Linac Coherent Light Source (LCLS) is an X-ray Free Electron Laser (FEL) facility located at the SLAC National Accelerator Laboratory. LCLS has been in operation since spring 2009, and it has completed its 3rd user run. LCLS is the first in its class of X-ray FEL user facilities, and presents different availability challenges compared to storage ring light sources. This paper presents recent availability performance of the FEL as well as factors to consider when defining the operational availability figure of merit for user runs. During LCLS [1] user runs, an availability of 95% has been set as a goal. In run III, LCLS photon and electron beam systems achieved availabilities of 94.8% and 96.7%, respectively. The total availability goal can be distributed among subsystems to track performance and identify areas that need attention in order to maintain and improve hardware reliability and operational availability. Careful beam time accounting is needed to understand the distribution of down time. The LCLS complex includes multiple experimental hutches for X-ray science, and each user program has different requirements of a set of parameters that the FEL can be configured to deliver. Since each user may have different criteria for what is considered 'acceptable beam', the quality of the beam must be considered to determine the X-ray beam availability.

  12. First operation of an FEL in same-cell energy recovery mode

    NASA Astrophysics Data System (ADS)

    Neil, G. R.; Benson, S.; Biallas, G.; Bohn, C. L.; Douglas, H. F. Dylla, D.; Evans, R.; Fugitt, J.; Gubeli, J.; Hill, R.; Jordan, K.; Krafft, G.; Li, R.; Merminga, L.; Oepts, D.; Piot, P.; Preble, J.; Shinn, M.; Siggins, T.; Walker, R.; Yunn, B.

    2000-05-01

    The driver for Jefferson Lab's kW-level infrared free-electron laser (FEL) is a superconducting, recirculating accelerator that recovers 75% of the electron-beam power and converts it to radio frequency power. As reported in FEL'98, the accelerator operated "straight-ahead" to deliver 38 MeV, 1.1 mA cw current for lasing at wavelengths in the vicinity of 5 μm. The waste beam was sent directly to a dump, bypassing the recirculation loop. Stable operation at up to 311 W cw was achieved in this mode. The machine has now recirculated cw average current up to 4.7 mA, and has lased cw with energy recovery up to 1720 W output at 3.1 μm. This is the first FEL to ever operate in the "same-cell" energy recovery mode. Energy recovery offers several advantages (reduced RF power and dramatically reduced radio-nuclide production at the dump) and several challenges (potential for instabilities and difficult beam transport due to large energy spreads). Solutions to these challenges will be described. We have observed heating effects in the mirrors which will be described. We will also report on the additional performance measurements of the FEL that have been performed and connect those measurements to standard models.

  13. Influence of cat characteristics on Fel d 1 levels in the home.

    PubMed

    Nicholas, Charlotte; Wegienka, Ganesa; Havstad, Suzanne; Ownby, Dennis; Johnson, Christine Cole

    2008-07-01

    Previous studies investigating cat characteristics and cat allergen production focused on clinical experiments that quantified allergen from either the shaved skin or the fur of the animal; however, these studies did not address these experimental relationships in the home. To determine the relationships between cat characteristics and cat allergen isolated from household dust. Fel d 1 allergen levels in dust from homes participating in a population-based study of environmental effect on allergy development were analyzed using a standard monoclonal antibody-based assay. Cat characteristics were based on interviews conducted during home visits by study personnel. Households with any cats had higher geometric mean Fel d 1 levels than households without cats (32.88 vs 0.43; P < .01), and cat allergen levels increased with increasing numbers of cats in the home (P < .01). Length of cat hair, cat sex, reproductive status, and time spent indoors were analyzed; the only characteristic associated with higher levels of Fel d 1 was whether the cat had been neutered or spayed. Having cats in the home is significantly associated with increased Fel d 1 levels, and having more cats in the home is correlated with more cat allergen. Cat reproductive characteristics may be associated with measurable differences in cat allergen levels.

  14. Optical design and performance of an XUV FEL (free-electron laser) oscillator

    SciTech Connect

    Goldstein, J.C.; McVey, B.D.; Newnam, B.E.

    1989-01-01

    A study of numerical simulation of the performance of a multifacet metal mirror ring resonator FEL is presented for several XUV wavelengths. Laser performance in the presence of mirror aberrations and thermal distortion is calculated for two different output coupling methods, a scraper mirror and a hole. 11 refs., 1 fig.

  15. Numerical modeling of thermal loading of diamond crystal in X-ray FEL oscillators

    NASA Astrophysics Data System (ADS)

    Song, Mei-Qi; Zhang, Qing-Min; Guo, Yu-Hang; Li, Kai; Deng, Hai-Xiao

    2016-04-01

    Due to high reflectivity and high resolution of X-ray pulses, diamond is one of the most popular Bragg crystals serving as the reflecting mirror and mono-chromator in the next generation of free electron lasers (FELs). The energy deposition of X-rays will result in thermal heating, and thus lattice expansion of the diamond crystal, which may degrade the performance of X-ray FELs. In this paper, the thermal loading effect of diamond crystal for X-ray FEL oscillators has been systematically studied by combined simulation with Geant4 and ANSYS, and its dependence on the environmental temperature, crystal size, X-ray pulse repetition rate and pulse energy are presented. Our results show that taking the thermal loading effects into account, X-ray FEL oscillators are still robust and promising with an optimized design. Supported by National Natural Science Foundation of China (11175240, 11205234, 11322550) and Program for Changjiang Scholars and Innovative Research Team in University (IRT1280)

  16. Progress of the commissioning of the DELTA storage ring FEL facility

    SciTech Connect

    Noelle, D.; Geisler, A.; Ridder, M.

    1995-12-31

    This paper will present the status of the ongoing commissioning of the DELTA storage-ring FEL facility. The commissioning of the LINAC started in autumn `94. The operation of the booster started in spring `95, the first stored beam was achieved end of march `95. During the summer of `95 the commissioning of the main storage ring will be started. Simultaneously, the first FEL FELICTA I was built. All FEL hardware is in house, the undulator is already mounted in the storage-ring. Thus first operation of the undulator with electron beam, will take place immediately after the first stored beam in DELTA. Therefore, first spontanous photons are to be expected in late summer `95. As soon as DELTA provides stable and rather reliable operation the experiments on FELICITA I will start. 16 mA total average current in DELTA at 500 MeV should be sufficient to reach the laser threshold in the FEL mode of FELICITA I. Operating the device as an optical klystron should result in lasing at substantial less currents.

  17. The cat lipocalin Fel d 7 and its cross-reactivity with the dog lipocalin Can f 1.

    PubMed

    Apostolovic, D; Sánchez-Vidaurre, S; Waden, K; Curin, M; Grundström, J; Gafvelin, G; Cirkovic Velickovic, T; Grönlund, H; Thomas, W R; Valenta, R; Hamsten, C; van Hage, M

    2016-10-01

    We investigated the prevalence of sensitization to the cat lipocalin Fel d 7 among 140 cat-sensitized Swedish patients and elucidated its allergenic activity and cross-reactivity with the dog lipocalin Can f 1. Sixty-five of 140 patients had IgE to rFel d 7 whereof 60 also had IgE to rCan f 1. A moderate correlation between IgE levels to rFel d 7 and rCan f 1 was found. rFel d 7 activated basophils in vitro and inhibited IgE binding to rCan f 1 in 4 of 13 patients, whereas rCan f 1 inhibited IgE binding to rFel d 7 in 7 of 13 patients. Fel d 7 and Can f 1 showed high similarities in protein structure and epitopes in common were found using cross-reactive antisera. Fel d 7 is a common allergen in a Swedish cat-sensitized population that cross-reacts with Can f 1, and may contribute to symptoms in cat- but also in dog-allergic patients. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  18. Precision timing and interlocks systems for FEL (free-electron laser) heating experiments on MTX (Microwave Tokamak Experiment)

    SciTech Connect

    Petersen, D.E. )

    1989-09-20

    A new precision timing system has been installed on the Microwave Tokamak Experiment (MTX) at Lawrence Livermore National Laboratory (LLNL). The purpose of the system is to synchronize the tokamak's plasma discharge with a 140-GHz, 2-GW microwave pulse generated by a free-electron laser (FEL). The installation involved modifying the existing sequencer system and adding Digital delay generators, three in-house-designed CAMAC modules and other components. The system controls placement of the 30-ns FEL pulse during the MTX plasma discharge. It also provides precision triggers for the microwave plasma diagnostics. These triggers are distributed over 100-Mbit/s fiber-optic links. The MTX interlock system has been expanded to provide personnel safety during FEL experiments, to protect the FEL and related equipment, and to control the path of the FEL beam starting from the FEL's output, through the beam transport system, and into the tokamak. This paper describes how the existing MTX timing and interlocks systems were upgraded to accommodate these new FEL experiments. 4 refs., 4 figs.

  19. Design of micropulse-picking system with acoustic-optic modulators in mid-infrared region FEL

    NASA Astrophysics Data System (ADS)

    Heya, Manabu; Fukami, Yuko; Nagata, Hiroyuki; Nunoyama, Hiroaki; Awazu, Kunio

    2001-05-01

    A micropulse-picking system attached to a free electron laser (FEL) opens a broad range of potential applications of ultrafast phenomena in medicine and biology. This paper reports the micropulse-picking system of a mid-infrared (IR) FEL at iFEL, Osaka University. We have designed the system with a germanium acousto-optic modulator (Ge-AOM), which can effectively deflect the direction of the FEL propagation due to Bragg diffraction of the FEL and radio frequency (RF) waves. The system includes a reducing optics for the FEL beam, a focusing optics onto the Ge- AOM and a micropulse-picking device (including the Ge-AOM and the RF driver). The system, which is independent on wavelength in the mid-IR region, can be realized by using the following technique: the RF frequency is carefully controlled to satisfy the Bragg angle matching over the mid-IR region. As a result, the micropulse-picking system can supply single and/or some FEL micropulses at an arbitrary repetition rate over the mid-IR region (equals 2 - 12 micrometers ) and can control the resulting peak power and average power in the ranges of approximately 1 - 2 MW and approximately 50 (mu) W - 20 mW, respectively.

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

    SciTech Connect

    Hama, Hiroyuki

    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.

  1. ECH by FEL and gyrotron sources on the Microwave Tokamak Experiment (MTX) tokamak

    SciTech Connect

    Stallard, B.W.; Turner, W.C.; Allen, S.L.; Byers, J.A.; Felker, B.; Fenstermacher, M.E.; Ferguson, S.W.; Hooper, E.G.; Thomassen, K.I.; Throop, A.L. ); Makowski, M.A. )

    1990-08-09

    The Microwave Tokamak Experiment (MTX) at LLNL is studying the physics of intense pulse ECH is a high-density tokamak plasma using a microwave FEL. Related technology development includes the FEL, a windowless quasi-optical transmission system, and other microwave components. Initial plasma experiments have been carried out at 140 GHz with single rf pulses generated using the ETA-II accelerator and the ELF wiggler. Peak power levels up to 0.2 GW and pulse durations up to 10 ns were achieved for injection into the plasma using as untapered wiggler. FEL pulses were transmitted over 33 m from the FEL to MTX using six mirrors mounted in a 50-cm-diam evacuated pipe. Measurements of the microwave beam and transmission through the plasma were carried out. For future rapid pulse experiments at high average power (4 GW peak power, 5kHz pulse rate, and {bar P} > 0.5 MW) using the IMP wiggler with tapered magnetic field, a gyrotron (140 GHz, 400 kW cw or up to 1 MW short pulse) is being installed to drive the FEL input or to directly heat the tokamak plasma at full gyrotron power. Quasi-optic techniques will be used to couple the gyrotron power. For direct plasma heating, the gyrotron will couple into the existing mirror transport system. Using both sources of rf generation, experiments are planned to investigate intense pulse absorption and tokamak physics, such as the ECH of a pellet-fueled plasma and plasma control using localized heating. 12 refs., 9 figs.

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

    SciTech Connect

    Kimel, I.; Elias, L.R.

    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.

  3. Inverse Compton gamma-ray source for nuclear physics and related applications at the Duke FEL

    SciTech Connect

    O`Shea, P.G.; Litvinenko, V.N.; Madey, J.M.J.

    1995-12-31

    In recent years the development of intense, short-wavelength FEL light sources has opened opportunities for the development new applications of high-energy Compton-backscattered photons. These applications range from medical imaging with X-ray photons to high-energy physics with {gamma}{gamma} colliders. In this paper we discuss the possibilities for nuclear physics studies using polarized Compton backscattered {gamma}-rays from the Duke storage-ring-driven UV-FEL. There are currently a number of projects that produce polarized {gamma}-rays for nuclear physics studies. All of these facilities operate by scattering conventional laser-light against electrons circulating in a storage ring. In our scheme, intra-cavity scattering of the UV-FEL light will produce a {gamma}-flux enhancement of approximately 10{sup 3} over existing sources. The Duke ring can operate at energies up to 1.2 GeV and can produce FEL photons up to 12.5 eV. We plan to generate {gamma}-rays up to 200 MeV in energy with an average flux in excess of 10{sup 7} /s/MeV, using a modest scattering beam of 10-mA average stored current. The {gamma}-ray energy may be tuned by varying the FEL wavelength or by adjusting the stored electron beam energy. Because of the intense flux, we can eliminate the need for photon energy tagging by collimating of the {gamma}-ray beam. We will discuss the characteristics of the device and its research opportunities.

  4. Amplification of current density modulation in a FEL with an infinite electron beam

    SciTech Connect

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

    2011-03-28

    We show that the paraxial field equation for a free electron laser (FEL) in an infinitely wide electron beam with {kappa}-2 energy distribution can be reduced to a fourth ordinary differential equation (ODE). Its solution for arbitrary initial phase space density modulation has been derived in the wave-vector domain. For initial current modulation with Gaussian profile, close form solutions are obtained in space-time domain. In developing an analytical model for a FEL-based coherent electron cooling system, an infinite electron beam has been assumed for the modulation and correction processes. While the assumption has its limitation, it allows for an analytical close form solution to be obtained, which is essential for investigating the underlying scaling law, benchmarking the simulation codes and understanding the fundamental physics. 1D theory was previously applied to model a CeC FEL amplifier. However, the theory ignores diffraction effects and does not provide the transverse profile of the amplified electron density modulation. On the other hand, 3D theories developed for a finite electron beam usually have solutions expanded over infinite number of modes determined by the specific transverse boundary conditions. Unless the mode with the largest growth rate substantially dominates other modes, both evaluation and extracting scaling laws can be complicated. Furthermore, it is also preferable to have an analytical FEL model with assumptions consistent with the other two sections of a CeC system. Recently, we developed the FEL theory in an infinitely wide electron beam with {kappa}-1 (Lorentzian) energy distribution. Close form solutions have been obtained for the amplified current modulation initiated by an external electric field with various spatial-profiles. In this work, we extend the theory into {kappa}-2 energy distribution and study the evolution of current density induced by an initial density modulation.

  5. ECH by FEL and gyrotron sources on the Microwave Tokamak Experiment (MTX) tokamak

    NASA Astrophysics Data System (ADS)

    Stallard, B. W.; Turner, W. C.; Allen, S. L.; Byers, J. A.; Felker, B.; Fenstermacher, M. E.; Ferguson, S. W.; Hooper, E. G.; Thomassen, K. I.; Throop, A. L.

    1990-08-01

    The Microwave Tokamak Experiment (MTX) at LLNL is studying the physics of intense pulse ECH is a high-density tokamak plasma using a microwave FEL. Related technology development includes the FEL, a windowless quasi-optical transmission system, and other microwave components. Initial plasma experiments have been carried out at 140 GHz with single RF pulses generated using the ETA-2 accelerator and the ELF wiggler. Peak power levels up to 0.2 GW and pulse durations up to 10 ns were achieved for injection into the plasma using as untapered wiggler. FEL pulses were transmitted over 33 m from the FEL to MTX using six mirrors mounted in a 50 cm diam evacuated pipe. Measurements of the microwave beam and transmission through the plasma were carried out. For future rapid pulse experiments at high average power (4 GW peak power, 5 kHz pulse rate, and bar P is greater than 0.5 MW) using the IMP wiggler with tapered magnetic field, a gyrotron (140 GHz, 400 kW CW or up to 1 MW short pulse) is being installed to drive the FEL input or to directly heat the tokamak plasma at full gyrotron power. Quasi-optic techniques will be used to couple the gyrotron power. For direct plasma heating, the gyrotron will couple into the existing mirror transport system. Using both sources of RF generation, experiments are planned to investigate intense pulse absorption and tokamak physics, such as the ECH of a pellet-fueled plasma and plasma control using localized heating.

  6. In-pixel conversion with a 10 bit SAR ADC for next generation X-ray FELs

    NASA Astrophysics Data System (ADS)

    Lodola, L.; Batignani, G.; Benkechkache, M. A.; Bettarini, S.; Casarosa, G.; Comotti, D.; Dalla Betta, G. F.; Fabris, L.; Forti, F.; Grassi, M.; Latreche, S.; Malcovati, P.; Manghisoni, M.; Mendicino, R.; Morsani, F.; Paladino, A.; Pancheri, L.; Paoloni, E.; Ratti, L.; Re, V.; Rizzo, G.; Traversi, G.; Vacchi, C.; Verzellesi, G.; Xu, H.

    2016-07-01

    This work presents the design of an interleaved Successive Approximation Register (SAR) ADC, part of the readout channel for the PixFEL detector. The PixFEL project aims at substantially advancing the state-of-the-art in the field of 2D X-ray imaging for applications at the next generation Free Electron Laser (FEL) facilities. For this purpose, the collaboration is developing the fundamental microelectronic building blocks for the readout channel. This work focuses on the design of the ADC carried out in a 65 nm CMOS technology. To obtain a good tradeoff between power consumption, conversion speed and area occupation, an interleaved SAR ADC architecture was adopted.

  7. Design Features of a Planar Hybrid/Permanent Magnet Strong Focusing Undulator for Free Electron Laser (FEL) And Synchrotron Radiation (SR) Applications

    SciTech Connect

    Tatchyn, Roman; /SLAC

    2011-09-09

    Insertion devices for Angstrom-wavelength Free Electron Laser (FEL) amplifiers driven by multi-GeV electron beams generally require distributed focusing substantially stronger than their own natural focusing fields. 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 to permanent magnet (PM) lattices inserted into the insertion device gap. In this paper we present design studies of a flexible high-field hybrid/PM undulator with strong superimposed planar PM focusing proposed for a 1.5 Angstrom Linac Coherent Light Source (LCLS) driven by an electron beam with a 1 mm-mr normalized emittance. Attainable field parameters, tuning modes, and potential applications of the proposed structure are discussed.

  8. Assessing human responses to impairments of atmospheric visibility

    SciTech Connect

    Flachsbart, P.G.

    1980-01-01

    Solving the problems of visibility impairments in Class I (pristine) areas will require both strategic and tactical measures. A proposed framework for assessing impairments to visibility is described. A method for predicting human response to visibility impairments must consider behavioral, psychophysiological, and psychological aspects of human response to the environment. Human perceptual thresholds corresponding to objective measurements of visibility impairment must be determined. The ability of humans to distinguish between natural and anthropogenic visibility impairments occurring simultaneously at a given setting must be considered. Economic, social, and psychological costs and benefits of protecting visibility on Class I lands must be identified. (2 diagrams, 17 references)

  9. Visibility and Citation Impact

    ERIC Educational Resources Information Center

    Ebrahim, Nader Ale; Salehi, Hadi; Embi, Mohamed Amin; Tanha, Farid Habibi; Gholizadeh, Hossein; Motahar, Seyed Mohammad

    2014-01-01

    The number of publications is the first criteria for assessing a researcher output. However, the main measurement for author productivity is the number of citations, and citations are typically related to the paper's visibility. In this paper, the relationship between article visibility and the number of citations is investigated. A case study of…

  10. Viewer Makes Radioactivity "Visible"

    NASA Technical Reports Server (NTRS)

    Yin, L. I.

    1983-01-01

    Battery operated viewer demonstrates feasibility of generating threedimensional visible light simulations of objects that emit X-ray or gamma rays. Ray paths are traced for two pinhold positions to show location of reconstructed image. Images formed by pinholes are converted to intensified visible-light images. Applications range from radioactivity contamination surveys to monitoring radioisotope absorption in tumors.

  11. Enhancement of Permeation in Transdermal Drug Delivery System by 6μm Wavelength Area Using an MIR-FEL

    NASA Astrophysics Data System (ADS)

    Uchizono, T.; Ishii, K.; Iwao, Y.; Itou, Y.; Maruo, H.; Hori, M.; Awazu, K.

    2005-03-01

    Ablation of the stratum corneum (SC) by pulsed-laser irradiation is one method of enhancing transdermal drug delivery (TD). For non-invasive laser TD treatment, we have tried to enhance TD without ablation of the SC using an MIR-FEL (6-μm wavelength) (FEL : free electron laser). Lidocaine was used as the drug in this study. The enhancement of TD was measured by HPLC. It was found that the lidocaine TD of the sample irradiated by MIR-FEL was enhanced 10 fold faster than the non-irradiated sample with a flux at 0.5 μg/cm2/h, measured by HPLC. We have demonstrated the effectiveness of TD enhancement by an MIR-FEL (6-μm wavelength) irradiation.

  12. S2E simulation of an ERL-based high-power EUV-FEL source for lithography

    NASA Astrophysics Data System (ADS)

    Nakamura, N.; Kato, R.; Miyajima, T.; Shimada, M.; Hotei, T.; Hajima, R.

    2017-07-01

    Energy recovery linac (ERL) based extreme ultraviolet (EUV) free electron lasers (FELs) are candidates of a next-generation high-power EUV source for lithography. An ERL-based EUV FEL source has been designed in order to demonstrate the feasibility of generating a 10-kW class EUV power. Start-to-End (S2E) simulation including the injection beam optimization, bunch compression, FEL lasing and bunch decompression is performed for the designed EUV source. As a result it is demonstrated that the EUV FEL can produce high power more than 10 kW at 10 mA and that the electron beam can be well transported throughout the EUV source without beam loss.

  13. A high-average power tapered FEL amplifier at submillimeter frequencies using sheet electron beams and short-period wigglers

    SciTech Connect

    Bidwell, S.W.; Radack, D.J.; Antonsen, T.M. Jr.; Booske, J.H.; Carmel, Y.; Destler, W.W.; Granatstein, V.L.; Levush, B.; Latham, P.E.; Zhang, Z.X.

    1990-01-01

    A high-average-power FEL amplifier operating at submillimeter frequencies is under development at the University of Maryland. Program goals are to produce a CW, {approximately}1 MW, FEL amplifier source at frequencies between 280 GHz and 560 GHz. To this end, a high-gain, high-efficiency, tapered FEL amplifier using a sheet electron beam and a short-period (superconducting) wiggler has been chosen. Development of this amplifier is progressing in three stages: (1) beam propagation through a long length ({approximately}1 m) of short period ({lambda}{sub {omega}} = 1 cm) wiggler, (2) demonstration of a proof-of-principle amplifier experiment at 98 GHz, and (3) designs of a superconducting tapered FEL amplifier meeting the ultimate design goal specifications. 17 refs., 1 fig., 1 tab.

  14. CASTNet visibility implementation and status

    SciTech Connect

    Evans, E.G.

    1994-01-01

    The Clean Air Status and Trends Network (CASTNet) is an integrated monitoring network combining different long-term monitoring projects and their data collection activities under one umbrella for the purpose of performing integrated assessments. Current monitoring projects include the CASTNet Dry Deposition Network, the CASTNet Visibility Network, and the CASTNet Urban Air Toxics Network. The data collected by these networks include wet and dry deposition and their constituents, ground based O3, fine particle aerosol and its components, light scattering, light absorption and air toxics along with standard meteorological measurements, i.e. wind speed, wind direction, temperature, and relative humidity. This paper reports on the implementation and status of CASTNet Visibility Network. Also reported are measurement methods, site requirements and selection, and a summary of the statistical evaluations on network sampling frequency and spatial trends interpolation of the proposed network.

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

    SciTech Connect

    Richman, B.A.; DeLong, K.W.; Trebino, R.

    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.

  16. 17th international free electron laser conference and 2nd international FEL users` workshop. Program and abstracts

    SciTech Connect

    1995-12-01

    This workshop and conference were held together to enhance the interaction between FEL builders and users. Current topics of interest in FEL research form the basis for the oral presentations. The program for the User`s workshop was developed in a similar manner. Storage rings, linear accelerators, materials research and applications are all considered topics. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.

  17. The ENEA F-CUBE Facility: Trends in R.F. driven compact FELs and related diagnostics

    SciTech Connect

    Doria, A.; Gallerano, G.P.; Giovenale, E.

    1995-12-31

    The Frascati FEL Facility F-CUBE (FEL-Compact for User Basic Experiment) currently operates in the mm-wave region providing about 600 hrs of beam time per year to users. This FEL is a low cost compact device intended to be the first step in making the FEL a laboratory tool. It exploits some unique features like short pulses with coherent emission seeding and the dispersion properties of a waveguide resonator at {open_quotes}zero slippage{close_quotes} to provide wide band tunability. The system is presently being upgraded to extend these characteristics into the far infrared. A new NdFeB permanent magnet undulator has been built and magnetic measurements have been performed. FEL tunability in the interval from 400 to 900 pm will be provided by the variation of the undulator gap and of the gap of the planar waveguide in the resonator. Due to the short electron bunch duration coherent spontaneous emission is expected also in this wavelength range. Its effect on the FEL performance will be discussed together with a comparison of different coherent emission mechanisms, like coherent transition radiation (CTR), which can be used as a diagnostic tool.

  18. FEL gain as a function of phace displacements induced by undulator intersection gaps

    SciTech Connect

    Varfolomeev, A.A.

    1995-12-31

    Gain characteristics are analytically considered for FEL based on a multisection undulator with short intersection gaps. It is shown that small phase displacements between laser beam and electron beam respectively caused by the above intersection gaps can seriously change the gain resonance frequency as well as gain curve shape. This effect is different from that of OK and can be used for fast undulator tuning or for its tapering. Gain characteristics are analitically considered for FEL based on a multisection undulator with short intersection gaps. It is shown that small phase displacements between laser beam and electron beam respectively caused by the above intersection gaps can seriously change the gain resonance frequency as well as gain curve shape. This effect is different from that of OK and can be used for fast undulator tuning or for its tapering.

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

    SciTech Connect

    Zako, A.; Miyauchi, Y.; Koga, A.

    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.

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

    SciTech Connect

    Litvinenko, V.N.; Madey, J.M.J.

    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.

  1. L- and K-shell emission from X-FEL heated iron

    NASA Astrophysics Data System (ADS)

    Heimann, Philip; Hansen, Stephanie; Loisel, Guillaume; Bailey, James; Gamboa, Eliseo; Glenzer, Siegfried; Mancini, Roberto; Saunders, Alison; Falcone, Roger; Galtier, Eric

    2016-10-01

    At the LCLS MEC instrument, a tightly focused X-ray FEL beam is used to isochorically heat thin iron samples. Two compound refractive lenses produce a focus estimated to be 0.5 microns (FWHM). The L-emission from the hot, solid-density samples is measured by RAP(001) crystal and grating spectrometers. In addition, the K-emission is observed by a Ge(111) crystal spectrometer. The L-shell emission from iron, which is initially photoionized by the X-ray FEL, tests recent measurements indicating higher-than-predicted broadening of the L-shell emission lines. Heating at 7 and 9.2 keV photon energies compares different heating mechanisms.

  2. Neutron dose rate at the SwissFEL injector test facility: first measurements.

    PubMed

    Hohmann, E; Frey, N; Fuchs, A; Harm, C; Hödlmoser, H; Lüscher, R; Mayer, S; Morath, O; Philipp, R; Rehmann, A; Schietinger, T

    2014-10-01

    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.

  3. Design Concept for a Compact ERL to Drive a VUV/Soft X-Ray FEL

    SciTech Connect

    Christopher Tennant ,David Douglas

    2011-03-01

    We explore possible upgrades of the existing Jefferson Laboratory IR/UV FEL driver to higher electron beam energy and shorter wavelength through use of multipass recirculation to drive an amplifier FEL. The system would require beam energy at the wiggler of 600 MeV with 1 mA of average current. The system must generate a high brightness beam, configure it appropriately, and preserve beam quality through the acceleration cycle ? including multiple recirculations ? and appropriately manage the phase space during energy recovery. The paper will discuss preliminary design analysis of the longitudinal match, space charge effects in the linac, and recirculator design issues, including the potential for the microbunching instability. A design concept for the low energy recirculator and an emittance preserving lattice solution will be presented.

  4. An experimental study of an FEL oscillator with a linear taper

    NASA Astrophysics Data System (ADS)

    Benson, S.; Gubeli, J.; Neil, G. R.

    2001-12-01

    Motivated by the work of Saldin, Schneidmiller and Yurkov, we have measured the detuning curve widths, spectral characteristics, efficiency, and energy spread as a function of the taper for low and high Q resonators in the IR Demo FEL at Jefferson Lab. Both positive and negative tapers were used. Gain and frequency agreed surprisingly well with the predictions of a single mode theory. The efficiency agreed reasonably well for a negative taper with a high Q resonator but disagreed for lower Q values both due to the large slippage parameter and the non-ideal resonator Q. We saw better efficiency for a negative taper than for the same positive taper. The energy spread induced in the beam, normalized to the efficiency is larger for the positive taper than for the corresponding negative taper. This indicates that a negative taper is preferred over a positive taper in an energy recovery FEL.

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

    SciTech Connect

    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.

  6. Amplified spontaneous and stimulated Mg L emissions from MgO pumped by FEL pulses

    NASA Astrophysics Data System (ADS)

    Jonnard, Philippe; André, Jean-Michel; Le Guen, Karine; Wu, Meiyi; Principi, Emiliano; Simoncig, Alberto; Gessini, Alessandro; Mincigrucci, Riccardo; Masciovecchio, Claudio; Peyrusse, Olivier

    2017-05-01

    Stimulated emission is a fundamental process in nature that deserves to be investigated and understood in the EUV and X-ray regimes. Today this is definitely possible through high energy density FEL beams. In this context, we show evidence for soft x-ray stimulated emission from a MgO solid target pumped by extreme ultraviolet 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 have developed a 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.

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

    SciTech Connect

    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.

  8. Design and First Characterization of Active and Slim-Edge Planar Detectors for FEL Applications

    NASA Astrophysics Data System (ADS)

    Benkechkache, M. A.; Latreche, S.; Ronchin, S.; Boscardin, M.; Pancheri, L.; Betta, G.-F. Dalla

    2017-04-01

    This paper reports on the development of a dedicated technology for the fabrication of pixelated edgeless sensors to be used in X-ray imaging applications at free electron laser (FEL) facilities. The process was developed with the goal of producing planar sensors suitable for the tight FEL application requirements in terms of collection speed, spatial resolution, and radiation tolerance. At the same time, care has been taken to reduce the dead area at the borders of the sensors, thus minimizing the loss of information and distortion introduced when tiling several dies in a large area imager. Different active-edge and slim-edge terminations, designed with the aid of TCAD simulations, are discussed. Based on numerical simulations, a wafer layout was designed and devices with different configurations were fabricated. The experimental results from the electrical characterization of the produced p-on-n sensors and test structures are presented and discussed.

  9. Transient Mirror Heating Theory and Experiment in the Jefferson Lab IR Demo FEL

    SciTech Connect

    Benson, S.; Michelle D. Shinn.; Neil, G.R.

    2001-01-01

    During commissioning of the IR Demo FEL at Jefferson Lab, we noticed that the FEL exhibited a rapid power drop with time when the first set of 3 mu-m mirrors was used. Thought the rate of power drop was unexpected, it was thought that it could be due to a distortion of the mirrors during a time short compared to a the thermal diffusion time. This transient distortion might affect the laser more than the steady state distortion. This paper presents some analysis of the transient mirror heating problem and some recent experimental results using different mirror substrates and coatings. It is found that the behavior of the first mirror set cannot be reconciled with the observed power fall-off if a linear absorption is assumed. The power drop in more recent experiments is consistent with linear thermal analysis. No anomalous transient effects are seen.

  10. JLAMP: AN AMPLIFIER-BASED FEL IN THE JLAB SRF ERL DRIVER

    SciTech Connect

    Kevin Jordan; Stephen V. Benson; David Douglas; Pavel Evtushenko; Carlos Hernandez-Garcia; George R. Neil

    2007-06-13

    Notional designs for energy-recovering linac (“ERL”) -driven high average power free electron lasers (“FEL”s) often invoke amplifier-based architectures. To date, however, amplifier FELs have been limited in average power output to values several orders of magnitude lower than those demonstrated in optical-resonator based systems; this is due at least in part to the limited electron beam powers available from their driver accelerators. In order to directly contrast the performance available from amplifiers to that provided by high-power cavity-based resonators, we have developed a scheme to test an amplifier FEL in the JLab SRF ERL driver. We describe an accelerator system design that can seamlessly and non-invasively integrate a 10 m wiggler into the existing system and which provides, at least in principle, performance that would support high-efficiency lasing in an amplifier configuration. Details of the design and an accelerator performance analysis will be presented

  11. Status report and biomedical applications of the institute of FEL, Osaka University

    NASA Astrophysics Data System (ADS)

    Awazu, Kunio; Asakawa, Makoto; Horiike, Hiroshi

    2003-07-01

    The Institute of Free-Electron Laser (iFEL) was established in April 2000 at Osaka University. The facility was constructed by the Free-Electron Laser Institute corporation (FELI) from 1992 to 1997. FELI demonstrated lasing in the spectral range from 0.28 to 20 μm. Efforts are still being made by Osaka University in order to extend the lasing range. In the operational period from April 2001 to March 2002, mid-infrared light of 5-20 μm was supplied for over 40 cooperative research programs on fields of semiconductor, bio-medical and environmental chemistry. An effort is ongoing to improve the property of the light. In this paper, the status of iFEL and some biomedical applications research are described.

  12. Proposal for using optical transition radiation for electron beam alignment and emittance measurement for the free emittance measurement for the free electron laser experiments at ATF

    SciTech Connect

    Qiu, Xu Z.; Wang, Xijie; Ben-Zvi, I.

    1994-10-01

    Optical transiton radiation (OTR) produced from thin intercepting foils have been employed to image the spatial profile of the electron beam in several free electron laser experiments. It was found that the images from OTR were significantly sharper than the images produced from phosphor screens. Furthermore, OTR`s sensitivity of its angular distribution and polarization to energy and divergence of the electron beam was exploited to diagnose energy and emittance of the electron beam. OTR has been proven to be vital in electron beam alignment in FEL experiments. This report gives a summary of the basic theory of transition radiation and techniques using transition radiation for electron beam imaging and emittance measurement. The possibility was explored for employing these techniques in the HGHG FEL and the visible FEL experiments in ATF (Accelerator Test Facility).

  13. A high-brightness SRF photoelectron injector for FEL light sources

    NASA Astrophysics Data System (ADS)

    Arnold, A.; Büttig, H.; Janssen, D.; Kamps, T.; Klemz, G.; Lehmann, W. D.; Lehnert, U.; Lipka, D.; Marhauser, F.; Michel, P.; Möller, K.; Murcek, P.; Schneider, Ch.; Schurig, R.; Staufenbiel, F.; Stephan, J.; Teichert, J.; Volkov, V.; Will, I.; Xiang, R.

    2008-08-01

    Most of the proposed electron accelerator projects for future FELs, ERLs or 4th generation light sources require electron beams with an unprecedented combination of high brightness, low emittance, and high average current. In all projects photoguns will be applied: DC-photoguns, normal conducting RF-photoguns (NC-guns), and superconducting RF photoguns (SRF-guns). While the concepts of DC- and NC-guns are well proofed, the SRF-gun development still possesses a high risk. Challenges are the design of the superconducting cavity, the choice of the photocathode type, its life time, a possible cavity contamination, the difficulty of coupling high average power into the gun, and, finally, the risk of beam excitation of higher-order cavity modes. In combination with SRF linacs, the SRF-guns seem to be the best solution for high average currents. Several R&D projects of SRF-gun have been launched. In this paper, we will give an overview of the progress of the SRF photoinjector development. In detail, the technical concept, the performance and the status of the Dresden Rossendorf SRF-gun project, a collaboration of BESSY, DESY, MBI and FZD, will be presented. The main design parameters of this SRF-gun are the final electron energy of 9.5 MeV, 1 mA average current, and transverse normalized emittances (rms) of 1 mm mrad at 77 pC and 2.5 mm mrad at 1 nC bunch charge. The 1.3 GHz cavity consists of three TESLA-shaped cells, a specially designed half-cell where the photocathode is placed and a choke filter in order to prevent RF losses at the cathode side. The normal-conducting photocathode with a Cs 2Te photoemission layer is cooled by liquid nitrogen. The SRF-gun cryostat consists of a stainless steel vacuum vessel, a warm magnetic shield, a liquid nitrogen-cooled thermal shield and a titanium He tank with a two-phase supply tube. The 10 kW fundamental power coupler is adopted from the ELBE cryomodule. In a first commissioning and test period the gun will be operated in

  14. An FEL design for gamma-gamma colliders based on chirped pulse amplification techniques

    SciTech Connect

    Kim, K.J.; Xie, M.; Sessler, A.M.

    1995-12-31

    A next generation e{sup +}-e{sup -} linear collider in the TeV range can be converted into a {gamma}-{gamma} collider by converting it to e{sup -}-e{sup -} operation and then generating {gamma}-rays via Compton backscattering with optical beams. This provides unique access to some areas of fundamental physics as well as highly desirable redundancy to the collisions. The required optical beam (with a wavelength of about 1 micron) must have very high peak power, (about 1 TW) as well as average power (about 10 kW). To achieve a 1 : 1 conversion from an electron to {gamma}-quantum, each micropulse must contain about one Joule and must be about one picosecond long, the micropulse peak power being about one Terawatt. To match the electron beam pulse structure, a macropulse consists of a sequence of about one hundred micropulses separated by about one nanosecond, and the macropulses am repeated at a rate of about 100 Hz. Thus, the time average power is about 10 kW propose and analyze a promising scheme to produce the required optical beam based on the chirped pulse amplification technique. In this scheme, a low power optical beam of the same time structure required for the {gamma}-{gamma} collider is passed through a grating pair to stretch and chirp the picosecond micropulses to about one nanosecond, so that each macropulse will be an almost continuous, 100 nanosecond long pulse, but with chirps (from red to blue) within each nanosecond. The optical beam is then amplified in an FEL, driven by an intense electron beam from an induction linac. The amplified beam is then passed through another grating pair to compress the micropulses, thus recovering the original time structure, but containing about one Joule per micropulse. The requirements for electron beams, about 100 MeV energy, 1 kA current, 50 mm-mrad rms emittance, 10{sup -3} energy spread, are consistent with the state-of-the-art induction linac technology.

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

    SciTech Connect

    Dattoli, G.; Renieri, A.

    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.

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

    SciTech Connect

    Amirmadhi, F.; Becker, K.; Brau, C.A.

    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.

  17. Studies of a Linac Driver for a High Repetition Rate X-Ray FEL

    SciTech Connect

    Venturini, M.; Corlett, J.; Doolittle, L.; Filippetto, D.; Papadopoulos, C.; Penn, G.; Prosnitz, D.; Qiang, J.; Reinsch, M.; Ryne, R.; Sannibale, F.; Staples, J.; Wells, R.; Wurtele, J.; Zolotorev, M.; Zholents, A.

    2011-06-01

    We report on on-going studies of a superconducting CW linac driver intended to support a high repetition rate FEL operating in the soft x-rays spectrum. We present a pointdesign for a 1.8 GeV machine tuned for 300 pC bunches and delivering low-emittance, low-energy spread beams as needed for the SASE and seeded beamlines.

  18. Next Generation Endstation for Concurrent Measurements of Charged Products and Photons in LCLS FEL Experiments

    NASA Astrophysics Data System (ADS)

    Osipov, T.; Rolles, D.; Bostedt, C.; Castagna, J.-C.; Hartmann, R.; Bozek, J. D.; Schlichting, I.; Strüder, L.; Ullrich, J.; Berrah, N.

    2012-11-01

    We are designing and building the next generation multi-purpose instrumentation especially adapted to accommodate unique large-area, single-photon counting pnCCD detectors together with advanced many-particle ion and electron imaging spectrometers (reaction microscope, REMI; velocity map imaging, VMI; magnetic bottle) for simultaneous detection of scattered and fluorescent photons and charged particles in experiments at the LCLS FEL.

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

    NASA Astrophysics Data System (ADS)

    Sawamura, Masaru; Nagai, Ryoji

    2006-02-01

    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).

  20. Spontaneous and amplified radiation at the initial stage of a SASE FEL.

    SciTech Connect

    Huang, Z.; Kim, K.-J.

    2002-11-01

    At the initial stage of a self-amplified spontaneous emission (SASE) free-electron laser (FEL), spontaneous undulator radiation in certain experimental configurations can dominate the amplified signal over an extended undulator distance. In this paper they study both the spontaneous and the amplified radiation in the framework of the paraxial wave equation and determine the transition from the dominance of spontaneous emission to exponential amplification. They compare theoretical expectations with SASE simulation codes GINGER and GENESIS.

  1. Spontaneous and amplified radiation at the initial stage of a SASE FEL

    NASA Astrophysics Data System (ADS)

    Huang, Zhirong; Kim, Kwang-Je

    2003-07-01

    At the initial stage of a self-amplified spontaneous emission (SASE) free-electron laser (FEL), spontaneous undulator radiation in certain experimental configurations can dominate the amplified signal over an extended undulator distance. In this paper we study both the spontaneous and the amplified radiation in the framework of the paraxial wave equation and determine the transition from the dominance of spontaneous emission to exponential amplification. We compare theoretical expectations with SASE simulation codes GINGER and GENESIS.

  2. Use of a miniature Toroidal Grating Monochromator on the FEL Undulator at the NSLS

    SciTech Connect

    Johnson, P.D.; Hulbert, S.L.; Howells, M.R.

    1984-01-01

    The use of a miniature Toroidal Grating Monochromator is described which we intend to use to monochromatize the radiation from the free electron laser (FEL) Undulator at the NSLS. Some of the properties of Undulators are described with reference to the design of beamlines and review the properties of TGM's. The results of ray tracing a beamline using such a device and estimates of the expected flux are given.

  3. Tailoring the amplification of attosecond pulse through detuned X-ray FEL undulator.

    PubMed

    Kumar, Sandeep; Kang, Heung-Sik; Kim, Dong Eon

    2015-02-09

    We demonstrate that the amplification of attosecond pulse in X-ray free electron laser (FEL) undulator can be tailored. The characteristic of the amplification of an isolated attosecond pulse in the FEL undulator is investigated. An isolated 180 attoseconds full width half maximum (FWHM) pulse at 1.25 nm with a spectral bandwidth of 1% is injected into an undulator. The simulation results show that for a direct seeding of 3MW, the seed is amplified to the peak power of 106 GW (40 μJ, an output pulse-width of 383 attoseconds) in the presence of a detuning at FEL resonance condition in 100-m long undulator. We note that the introduction of detuning leads to the better performance compared to the case without detuning: shorter by 15.5% in a pulse-width and higher by 76.6% in an output power. Tapering yields a higher power (116% increases in the output power compared to the case without detuning) but a longer pulse (15.4% longer in the pulse-width). It was observed that ± Δλ(r)/8 (Δλ(r)/λ(r) ~1%) is the maximum degree of detuning, beyond which the amplification becomes poor: lower in the output power and longer in the pulse duration. The minimum power for a seed pulse needs to be higher than 1 MW for the successful amplification of an attosecond pulse at 1.25 nm. Also, the electron beam energy-spread must be less than 0.1% for a suitable propagation of attosecond pulse along the FEL undulator under this study.

  4. High-efficiency FEL-oscillator with Bragg resonator operated in reversed guide field regime

    SciTech Connect

    Kaminsky, A.K.; Sedykh, S.N.; Sergeyev, A.P.

    1995-12-31

    The aim of the present work was to develop a narrow-band FEL-oscillator working in millimeter wavelength with, high efficiency. It looked promising to combine the high selective property of Bragg resonator with high efficiency and other advantages of FEL operation in the reversed guide-field regime. An experimental study of the FEL was performed using lilac LIU-3000 (JINR, Dubna) with the electron energy of 1 MeV, beam current up to 200 A and pulse duration of 200 ns. The beam was injected into the internction region with guide magnetic field of 2.9 kGs. Transverse oscillations of electrons were pumped by the helical wiggler with the period length of 6 cm and the field slowly up-tapering over the initial 6 periods. The FEI electrodynamic system consisted of a circular waveguide with diameter 20 mm and two Bragg reflectors. The H wave of the circular waveguide was shown for operation. Two effective feedback waves were observed in {open_quotes}cold{close_quotes} electrodynamic measurement in correspondence with calculations; the E wave near the frequency of 31. 5 GHz and the E wave - 37.5 GHz. The width of the both reflection resonances was about 2%. In {open_quotes}hot{close_quotes} experiments the radiation on the designed H wave and frequencies corresponding to the both feedback waves was registered separately. Selection of the frequency was realized by varying of the wiggler field strength. The spectrum was measured with a set of the cut--off waveguide filters with inaccuracy less than 2%. Calibrated Semiconductor detectors wire used to measure the radiation power. The radiation with the frequencies of 37.5 and 31.5 GHz was observed in vicinity of the wiggler field amplitude of 2.5 kGs. The measured spectrum width of the output FEL-oscillator radiation did not exceed the width of the Bragg reflector resonances for the both feedback waves.

  5. JINR test facility for studies FEL bunching technique for CLIC driving beam

    SciTech Connect

    Dolbilov, G.V.; Fateev, A.A.; Ivanov, I.N.

    1995-12-31

    SILUND-21 linear induction accelerator (energy up to 10 MeV, peak current about of 1 kA, pulse duration 50 - 70 ns) is constructed at JINR in the framework of experimental program to study free electron laser physics, a problem of two-beam acceleration and microwave electronics. In this paper we present project of an experiment to adopt the FEL bunching technique for generation of the CLIC driving beam.

  6. Infrared: Beyond the Visible

    NASA Image and Video Library

    Infrared: Beyond the Visible, is a fast, fun look at why infrared light matters to astronomy, and what the Webb Space Telescope will search for once it's in orbit. Caption file available at: http:/...

  7. Visible Human Project

    MedlinePlus

    ... videos - requires RealPlayer. A sampler of images and animations from the Project. Belarusian translation of The Visible ... Applications for viewing images Sources of images and animations Products Mirror Sites Tools Media Productions Related Projects ...

  8. Thermal Acoustic Sensor for High Pulse Energy X-ray FEL Beams

    SciTech Connect

    Smith, T.J.; Frisch, J.C.; Kraft, E.M.; Loos, J.; Bentsen, G.S.; /Rochester U.

    2011-12-13

    The pulse energy density of X-ray FELs will saturate or destroy conventional X-ray diagnostics, and the use of large beam attenuation will result in a beam that is dominated by harmonics. We present preliminary results at the LCLS from a pulse energy detector based on the thermal acoustic effect. In this type of detector an X-ray resistant material (boron carbide in this system) intercepts the beam. The pulse heating of the target material produces an acoustic pulse that can be detected with high frequency microphones to produce a signal that is linear in the absorbed energy. The thermal acoustic detector is designed to provide first- and second-order calorimetric measurement of X-ray FEL pulse energy. The first-order calorimetry is a direct temperature measurement of a target designed to absorb all or most of the FEL pulse power with minimal heat leak. The second-order measurement detects the vibration caused by the rapid thermoelastic expansion of the target material each time it absorbs a photon pulse. Both the temperature change and the amplitude of the acoustic signal are directly related to the photon pulse energy.

  9. Harmonic cascade FEL designs for LUX, a facility for ultrafast x-ray science

    SciTech Connect

    Corlett, John; Fawley, William; Penn, Gregory; Wan, Weishi; Zholents, A.; Reinsch, M.; Wurtele, Jonathan

    2004-08-25

    LUX is a design study to develop concepts for future ultrafast x-ray facilities. Presently, LUX is based on an electron beam accelerated to {approx}3-GeV energy in a superconducting, recirculating linac. Included in the design are multiple free-electron laser (FEL) beamlines which use the harmonic cascade approach to produce coherent XUV and soft X-ray emission beginning with a strong input seed at {approx}200-nm wavelength obtained from a ''conventional'' laser. 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 a given 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 certain aspects of the predicted FEL performance. We also discuss lattice considerations pertinent to harmonic cascade FELs, some sensitivity studies and requirements on the undulator alignment, and temporal pulse evolution initiated by short input radiation seeds.

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

    SciTech Connect

    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.

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

    NASA Astrophysics Data System (ADS)

    Schietinger, T.; Pedrozzi, M.; 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, B.; Stingelin, L.; Sturzenegger, W.; Treyer, D. M.; Trisorio, A.; Tron, W.; Vicario, C.; Zennaro, R.; Zimoch, D.

    2016-10-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Sei, Norihiro; Zen, Heishun; Ohgaki, Hideaki

    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.

  13. FERMI @ Elettra -- A Seeded Harmonic Cascade FEL for EUV and SoftX-rays

    SciTech Connect

    Bocchetta, C.; Bulfone, D.; Craievich, P.; Danailov, M.B.; D'Auria,G.; DeNinno, G.; Di Mitri, S.; Diviacco, B.; Ferianis, M.; Gomezel, A.; Iazzourene, F.; Karantzoulis, E.; Parmigiani, F.; Penco, G.; Trovo, M.; Corlett, J.; Fawley, W.; Lidia, S.; Penn, G.; Ratti, A.; Staples, J.; Wilcox, R.; Zholents, A.; Graves, W.; Ilday, F.O.; Kaertner,F.; Wang, D.; Zwart, T.; Cornacchia, M.; Emma, P.; Huang, Z.; Wu, J.

    2005-09-01

    We describe the machine layout and major performance parameters for the FERMI FEL project funded for construction at Sincrotrone Trieste, Italy, within the next five years. 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 {approx}100 nm to {approx}10nm, with pulse duration from 40 fs to {approx} 1 ps, peak power GW, 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 {approx}40 nm to {approx}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 system providing synchronization of rf signals, lasers, and x-ray pulses. Major systems and overall facility layout are described, and key performance parameters summarized.

  14. A high average current DC GaAs photocathode gun for ERLs and FELs

    SciTech Connect

    C. Hernandez-Garcia; T. Siggins; S. Benson; D. Bullard; H. F. Dylla; K. Jordan; C. Murray; G. R. Neil; Michelle D. Shinn; R. Walker

    2005-05-01

    The Jefferson Lab (JLab) 10 kW IR Upgrade FEL DC GaAs photocathode gun is presently the highest average current electron source operational in the U.S., delivering a record 9.1 mA CW, 350 kV electron beam with 122 pC/bunch at 75 MHz rep rate. Pulsed operation has also been demonstrated with 8 mA per pulse (110 pC/bunch) in 16 ms-long pulses at 2 Hz rep rate. Routinely the gun delivers 5 mA CW and pulse current at 135 pC/bunch for FEL operations. The Upgrade DC photocathode gun is a direct evolution of the DC photocathode gun used in the previous JLab 1 kW IR Demo FEL. Improvements in the vacuum conditions, incorporation of two UHV motion mechanisms (a retractable cathode and a photocathode shield door) and a new way to add cesium to the GaAs photocathode surface have extended its lifetime to over 450 Coulombs delivered between re-cesiations (quantum efficiency replenishment). With each photocathode activation quantum efficiencies above 6% are routinely achieved. The photocathode activation and performance will be described in detail.

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

    NASA Astrophysics Data System (ADS)

    Junbiao, Zhu; Yonggui, Li; Nianqing, Liu; Guoqing, Zhang; Minkai, Wang; Gan, Wu; Xuepin, Yan; Yuying, Huang; Wei, He; Yanmei, Dong; Xuejun, Gao

    2001-12-01

    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 μm, 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 2 laser. FTIR absorption spectra in the range of 2.5-15.4 μm for samples of these hard dental substances and pure hydroxyapatite were first examined to decide their chemical components and absorption maximums. Primary experimental results will be presented.

  16. Photon Source Capabilities of the Jefferson Lab THz to VUV FEL

    NASA Astrophysics Data System (ADS)

    Williams, G. P.; Benson, S. V.; Douglas, D.; Evtushenko, P.; Hannon, F. E.; Hernandez-Garcia, C.; Klopf, J. M.; Legg, R. A.; Neil, G. R.; Shinn, M. D.; Tennant, C. D.; Zhang, S.

    2013-03-01

    Jefferson Lab operates a sub-picosecond photon science R&D facility with peak and average brightness values that are many orders of magnitude higher than storage rings in the THz - VUV range. It also has multiphoton capabilities that provide unique opportunities for out of equilibrium dynamical studies at time-scales down to ~ 100 fs FWHM. The facility is based on a superconducting energy recovered linac which is operated with CW RF that powers oscillator-based IR and UV Free Electron Lasers (FELs) with diffraction limited sub-picosecond pulses with > 1013 photons per pulse (1.0% BW) at pulse repetition frequencies up to 75 MHz. Details of the facility and its present performance will be presented along with some example science applications. In addition we will discuss on-going upgrades to the facility that will allow 10 eV lasing in the fundamental. Finally we will present two potential upgrades including the design of an oscillator-based VUV-FEL that would produce 6 × 1012 coherent (0.5% BW) 100 eV photons per pulse at multi-MHz repetition rates in the fundamental, and a dual FEL configuration that would allow simultaneous lasing at THz and UV wavelengths. We acknowledge support from the Commonwealth of Virginia. Jefferson Lab is supported by the U.S. DOE under Contract No. DE-AC05-84-ER40150.

  17. Harmonic Generation at Lower Electron Energies for a Hard X-ray FEL

    SciTech Connect

    Marksteiner, Quinn R.

    2011-01-01

    There are several schemes currently being investigated to pre-bunch the electron beam and step the coherent bunching up to higher harmonics, all which require modulator sections which introduce additional energy modulation. X-ray FELs operate in a regime where the FEL parameter, {rho} is equal to or less than the effective energy spread introduced from the emittance in the electron beam. Because of this large effective energy spread, the energy modulation introduced from harmonic generation schemes would seriously degrade FEL performance. This problem can be mitigated by incorporating the harmonic generation scheme at a lower electron kinetic energy than the energy at the final undulator. This will help because the effective energy spread from emittance is reduced at lower energies, and can be further reduced by making the beam transversely large. Then the beam can be squeezed down slowly enough in the subsequent accelerator sections so that geometric debunching is mitigated. The beam size inside the dispersive chicanes and in the accelerator sections must be carefully optimized to avoid debunching, and each subharmonic modulator section must generate enough energy modulation to overcome the SASE noise without significantly increasing the gain length in the final undulator. Here we show analytical results that demonstrate the feasibility of this harmonic pre-bunching scheme.

  18. Current status of the EUV/soft x-ray FEL beamline at SACLA (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Owada, Shigeki; Nakajima, Kyo; Togashi, Tadashi; Tono, Kensuke; Joti, Yasumasa; Inagaki, Takahiro; Hara, Toru; Tanaka, Takashi; Togawa, Kazuaki; Yamaga, Mitsuhiro; Sugimoto, Takashi; Senba, Yasunori; Yumoto, Hirokatsu; Koyama, Takahisa; Ohashi, Haruhiko; Tanaka, Hitoshi; Yabashi, Makina

    2016-09-01

    SACLA was inaugurated in March 2012 with two beamlines: BL3 for hard X-ray FEL and BL1 for wide range spontaneous emission. Currently, all user experiments have been performed at BL3 and BL2 that was constructed as the second hard XFEL beamline. To enhance research opportunities with softer X-ray FEL, we decided to relocate the SCSS test accelerator, which was a prototype of SACLA and decommissioned in 2013, to the SACLA undulator hall, to connect to BL1, and to generate EUV and soft X-ray FEL independently of the SACLA linac. In addition, we started commissioning of the upgraded BL1 in September 2015, and successfully observe SASE lasing at a photon energy of 36 eV in October. We are now constructing the end station, and will start commissioning in June 2016. We will install two C-band accelerator units that increase an electron beam energy up to 750 MeV with a photon energy up to 100 eV in the summer of 2016. In this presentation, I will report the latest status of the beamline.

  19. Free-Electron Laser (FEL) Utilization in Space Applications (Ship-Borne Pointing Accuracy, Deep-Space Communications, and Orbital Debris Tracking)

    DTIC Science & Technology

    2011-12-01

    Code Modulation PSK Phase Shift-Keying QPSK Quad Phase Shift-Keying SETI Search for Extra-Terrestrial Intelligence SSN Space Surveillance...vision for using a FEL for deep-space communications is that the FEL could supplement or replace the current methods of Active SETI (Search for Extra...receivers on the Rover that are approximately 0.25 meters in diameter obsolete [24]. Finally, we look at using the FEL in assisting with the SETI program

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

    SciTech Connect

    Nakajima, K.; Kawakubo, T.; Nakanishi, H.

    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.

  1. Visible light communication based motion detection.

    PubMed

    Sewaiwar, Atul; Tiwari, Samrat Vikramaditya; Chung, Yeon-Ho

    2015-07-13

    In this paper, a unique and novel visible light communication based motion detection is presented. The proposed motion detection is performed based on white light LEDs and an array of photodetectors from existing visible light communication (VLC) links, thus providing VLC with three functionalities of illumination, communication and motion detection. The motion is detected by observing the pattern created by intentional obstruction of the VLC link. Experimental and simulation results demonstrate the validity of the proposed VLC based motion detection technique. The VLC based motion detection can benefit smart devices control in VLC based smart home environments.

  2. Predicting visibility of aircraft.

    PubMed

    Watson, Andrew; Ramirez, Cesar V; Salud, Ellen

    2009-05-20

    Visual detection of aircraft by human observers is an important element of aviation safety. To assess and ensure safety, it would be useful to be able to be able to predict the visibility, to a human observer, of an aircraft of specified size, shape, distance, and coloration. Examples include assuring safe separation among aircraft and between aircraft and unmanned vehicles, design of airport control towers, and efforts to enhance or suppress the visibility of military and rescue vehicles. We have recently developed a simple metric of pattern visibility, the Spatial Standard Observer (SSO). In this report we examine whether the SSO can predict visibility of simulated aircraft images. We constructed a set of aircraft images from three-dimensional computer graphic models, and measured the luminance contrast threshold for each image from three human observers. The data were well predicted by the SSO. Finally, we show how to use the SSO to predict visibility range for aircraft of arbitrary size, shape, distance, and coloration.

  3. Measuring visibility using smartphones

    NASA Astrophysics Data System (ADS)

    Friesen, Jan; Bialon, Raphael; Claßen, Christoph; Graffi, Kalman

    2017-04-01

    Spatial information on fog density is an important parameter for ecohydrological studies in cloud forests. The Dhofar cloud forest in Southern Oman exhibits a close interaction between the fog, trees, and rainfall. During the three month monsoon season the trees capture substantial amounts of horizontal precipitation from fog which increases net precipitation below the tree canopy. As fog density measurements are scarce, a smartphone app was designed to measure visibility. Different smartphone units use a variety of different parts. It is therefore important to assess the developed visibility measurement across a suite of different smartphones. In this study we tested five smartphones/ tablets (Google/ LG Nexus 5X, Huawei P8 lite, Huawei Y3, HTC Nexus 9, and Samsung Galaxy S4 mini) against digital camera (Sony DLSR-A900) and visual visibility observations. Visibility was assessed from photos using image entropy, from the number of visible targets, and from WiFi signal strength using RSSI. Results show clear relationships between object distance and fog density, yet a considerable spread across the different smartphone/ tablet units is evident.

  4. Predicting Visibility of Aircraft

    PubMed Central

    Watson, Andrew; Ramirez, Cesar V.; Salud, Ellen

    2009-01-01

    Visual detection of aircraft by human observers is an important element of aviation safety. To assess and ensure safety, it would be useful to be able to be able to predict the visibility, to a human observer, of an aircraft of specified size, shape, distance, and coloration. Examples include assuring safe separation among aircraft and between aircraft and unmanned vehicles, design of airport control towers, and efforts to enhance or suppress the visibility of military and rescue vehicles. We have recently developed a simple metric of pattern visibility, the Spatial Standard Observer (SSO). In this report we examine whether the SSO can predict visibility of simulated aircraft images. We constructed a set of aircraft images from three-dimensional computer graphic models, and measured the luminance contrast threshold for each image from three human observers. The data were well predicted by the SSO. Finally, we show how to use the SSO to predict visibility range for aircraft of arbitrary size, shape, distance, and coloration. PMID:19462007

  5. Three-dimensional study of the multi-cavity FEL

    SciTech Connect

    Krishnagopal, S.; Kumar, V.

    1995-12-31

    The Multi-Cavity Free-Electron Laser has been proposed earlier, as a new configuration to obtain short, intense pulses of radiation, the key idea being to pre-bunch the electron beam in a number of very short cavities. Those studies were one-dimensional. Here we use three-dimensional simulations to study the viability of this concept when three-dimensional effects are included, particularly with regard to the transverse modes of the optical beam.

  6. Visible Battle Rhythm

    DTIC Science & Technology

    2006-06-01

    2006 Oculus Info Inc. COP21 TD 1 Visible Battle Rhythm Brian Cort1, Alain Bouchard2, Denis Gouin2, Pascale Proulx1, Bill Wright1 June 21, 2006 1...Oculus Info Inc. 2 DRDC Valcartier www.oculusinfo.com www.drdc-rddc.gc.ca © 2006 Oculus Info Inc. COP21 TD 2 Battle Rhythm “Process where the...commander to make timely decisions.” −Duffy et al, 2004 © 2006 Oculus Info Inc. COP21 TD 3 Visible Battle Rhythm • Real-time coordination and synchronization

  7. Visibility and Cloud Lidar

    NASA Astrophysics Data System (ADS)

    Werner, Christian; Streicher, Jürgen; Leike, Ines; Münkel, Christoph

    In summary it can be stated that visibility lidar is an accepted technology wherever impaired vision must be detected to impose speed limits to road or takeoff and landing restrictions to air traffic. Visibility lidars known as ceilometers have reached a degree of maturity to work 24 hours a day in the required fully-automated, hands-off operation mode. The development of much smaller systems for use under restricted space conditions and of systems small and cheap enough to be used as a truck and car accessory is in progress, with good chances to reach full commercial availability soon.

  8. FEL indulators with the hollow-ring electron beam

    SciTech Connect

    Epp, V.; Bordovitsyn, V.; Kozhevnikov, A.

    1995-12-31

    A conceptual design of undulators with a modulated longitudinal magnetic field is proposed. The magnetic field is created by use of a solenoid with axis coincident with the electron beam axis. In order to modulate the magnetic field we propose an insertion of a row of alternating ferromagnetic and superconducting diaphragms in line with electron beam. The simulation of two-dimensional distribution of the magnetic field in the plane containing undulator axis was made using the computer code {open_quotes}Mermaid{close_quotes}. The magnetic field was analysed as a function of the system geometry. The dependence on the spacing l between superconducting diaphragms, inner a and outer b radii of the last ones is investigated. Two versions of the device are considered: with ferromagnetic rings made of magnetically soft material placed between the superconducting diaphragms and without them. It is shown that the field modulation depth increases with ratio of b/l and can exceed 50% in case of the ferromagnetic insertions. An approximate analytical calculation of the magnetic field distribution is performed as follows. The axial-symmetrical magnetic field can be defined by the vector potential with only one nonzero component A(r,{phi}) where r and {phi} are the cylindrical coordinates. The solution of the Laplace`s equation is found under the assumption that the magnetic field is infinitely extended and periodic along the z-axis. The boundary conditions are defined by the undulator design. The result is used for the calculation of the particle dynamics and for the investigations of the trajectory stability. The spectral and angular distribution of the radiation emitted from the described systems is found. The estimations show that the proposed design allows to create relatively high magnitude of the magnetic field (up to 1 T) with a short period about 1 cm or less.

  9. Feasibility of a ring FEL at low emittance storage rings

    NASA Astrophysics Data System (ADS)

    Agapov, I.

    2015-09-01

    A scheme for generating coherent radiation at latest generation low emittance storage rings such as PETRA III at DESY (Balewski et al., 2004 [1]) is proposed. The scheme is based on focusing and subsequent defocusing of the electron beam in the longitudinal phase space at the undulator location. The expected performance characteristics are estimated for radiation in the wavelength range of 500-1500 eV. It is shown that the average brightness is increased by several orders of magnitude compared to spontaneous undulator radiation, which can open new perspectives for photon-hungry soft X-ray spectroscopy techniques.

  10. Evaluation of Visible Plumes.

    ERIC Educational Resources Information Center

    Brennan, Thomas

    Developed for presentation at the 12th Conference on Methods in Air Pollution and Industrial Hygiene Studies, University of Southern California, April, 1971, this outline discusses plumes with contaminants that are visible to the naked eye. Information covers: (1) history of air pollution control regulations, (2) need for methods of evaluating…

  11. Evaluation of Visible Plumes.

    ERIC Educational Resources Information Center

    Brennan, Thomas

    Developed for presentation at the 12th Conference on Methods in Air Pollution and Industrial Hygiene Studies, University of Southern California, April, 1971, this outline discusses plumes with contaminants that are visible to the naked eye. Information covers: (1) history of air pollution control regulations, (2) need for methods of evaluating…

  12. Bi Youth Becoming Visible

    ERIC Educational Resources Information Center

    Hutchins, Loraine

    2006-01-01

    If young people can not learn about same-sex desire at school, queer young people especially get the message loud and clear that their desire is illegitimate and, in such settings, it is much harder for them to feel real and visible, much less entitled to health and happiness. However the even stronger message, to all young people, is that…

  13. Bi Youth Becoming Visible

    ERIC Educational Resources Information Center

    Hutchins, Loraine

    2006-01-01

    If young people can not learn about same-sex desire at school, queer young people especially get the message loud and clear that their desire is illegitimate and, in such settings, it is much harder for them to feel real and visible, much less entitled to health and happiness. However the even stronger message, to all young people, is that…

  14. Visible Traces. Teacher's Guide.

    ERIC Educational Resources Information Center

    ASIA Society, New York, NY.

    This teacher's guide is based on the exhibition, "Visible Traces: Rare Books and Special Collections from the National Library of China," a collaborative effort of the Queens Borough Public Library and the National Library of China; it links rare treasures from the National Library of China to curriculum standards. The following themes…

  15. Making Invisible Histories Visible

    ERIC Educational Resources Information Center

    Hanssen, Ana Maria

    2012-01-01

    This article features Omaha Public Schools' "Making Invisible Histories Visible" program, or MIHV. Omaha's schools have a low failure rate among 8th graders but a high one among high school freshmen. MIHV was created to help at-risk students "adjust to the increased demands of high school." By working alongside teachers and…

  16. Visibility: science and regulation.

    PubMed

    Watson, John G

    2002-06-01

    The 1999 Regional Haze Rule provides a context for this review of visibility, the science that describes it, and the use of that science in regulatory guidance. The scientific basis for the 1999 regulation is adequate. The deciview metric that tracks progress is an imperfect but objective measure of what people see near the prevailing visual range. The definition of natural visibility conditions is adequate for current planning, but it will need to be refined as visibility improves. Emissions from other countries will set achievable levels above those produced by natural sources. Some natural events, notably dust storms and wildfires, are episodic and cannot be represented by annual average background values or emission estimates. Sulfur dioxide (SO2) emission reductions correspond with lower sulfate (SO4(2-)) concentrations and visibility improvements in the regions where these have occurred. Non-road emissions have been growing more rapidly than emissions from other sources, which have remained stable or decreased since 1970. Simpler models representing transport, limiting precursor pollutants, and gas-to-particle equilibrium should be used to understand where and when emission reductions will be effective, rather than large complex models that have insufficient input and validation measurements. Examples of model-based source attribution show large differences among estimates from various modeling systems and with ambient measurements.

  17. Visible light effects in plasma plume ignition

    NASA Astrophysics Data System (ADS)

    Nie, L.; Xian, Y.; Lu, X.; Ostrikov, K.

    2017-04-01

    The breakdown delay time of a closed plasma plume excited by a high-voltage pulse is investigated. The visible monochromatic light of 404, 532, and 662 nm wavelength and narrow-waveband light at a central wavelength of 400, 430, 450, 470, 500, 530, 570, 610, and 630 nm are used to pre-ionize the gas. It is found that the breakdown delay time decreases when the visible light illuminates the discharge tube. The light is most effective when it is applied at the position near the high-voltage electrode. Besides, the tube material and size are important for enhancing the effect. The jet using quartz tube and larger inner diameter make the effect stronger. The effect of visible light is found to inversely relate to the wavelength, manifested by the longer breakdown delay times for longer wavelengths. With increasing the frequency and the pulse width of the voltage, the visible light shortens the delay time more effectively. These observations can be explained by the visible light-enhanced generation of free electrons before the ignition. The proposed mechanisms of free-electron generation are the optically stimulated exoelectron emission from the inner surface of the discharge tube wall and the vibrational excitation of nitrogen molecules. The effects of visible light weaken with the addition of oxygen as a result of electron affinity to oxygen.

  18. A few hundred femtosecond FEL with a few kW average and one GW peak power for academic and industrial applications

    NASA Astrophysics Data System (ADS)

    Minehara, Eisuke J.; Hajima, Ryoichi; Sawamura, Masaru; Nagai, Ryoji; Nishimori, Nobuyuki; Kikuzawa, Nobuhiro; Sugimoto, Masayoshi; Yamauchi, Toshihiko; Hayakawa, Taketo; Shizuma, Toshiyuki

    2003-02-01

    The JAERI FEL group has successfully discovered, and realized the brand-new FEL lasing of 255fs ultrafast pulse, 6-9% high-efficiency, one gigawatt high peak power, a few kilowatts average power, and wide tenability of medium and far infrared wavelength regions at the same time. The new lasing was named to be "high-degeneracy superradianct lasing of FEL". Using the new lasing, we could realize a powerful and efficient free-electron laser(FEL) for industrial uses, for examples, pharmacy, medical, defense, shipbuilding, semiconductor industry, chemical industries, environmental sciences, space-debris, 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 JAERI compact, stand-alone and zero-boil-off super-conducting rf linac with an energy-recovery geometry. Our discussions on the FEL will cover market-requirements and roadmap for the industrial FELs, some answers from the JAERI compact, stand-alone and zero-boil-off cryostat concept and operational experience over these 10 years, our discovery of the new highly-efficient, high-power, and ultra-short pulse lasing mode, and the energy-recovery geometry.

  19. Comparing an optical parametric oscillator (OPO) as a viable alternative for mid-infrared tissue ablation with a free electron laser (FEL).

    PubMed

    Mackanos, Mark A; Simanovskii, Dmitrii M; Contag, Christopher H; Kozub, John A; Jansen, E Duco

    2012-11-01

    Beneficial medical laser ablation removes material efficiently with minimal collateral damage. A Mark-III free electron laser (FEL), at a wavelength of 6.45 μm has demonstrated minimal damage and high ablation yield in ocular and neural tissues. While this wavelength has shown promise for surgical applications, further advances are limited by the high overhead for FEL use. Alternative mid-infrared sources are needed for further development. We compared the FEL with a 5-μs pulse duration with a Q-switched ZGP-OPO with a 100-ns pulse duration at mid-infrared wavelengths. There were no differences in the ablation threshold of water and mouse dermis with these two sources in spite of the difference in their pulse structures. There was a significant difference in crater depth between the ZGP:OPO and the FEL. At 6.1 μm, the OPO craters are eight times the depth of the FEL craters. The OPO craters at 6.45 and 6.73 μm were six and five times the depth of the FEL craters, respectively. Bright-field (pump-probe) images showed the classic ablation mechanism from formation of a plume through collapse and recoil. The crater formation, ejection, and collapse phases occurred on a faster time-scale with the OPO than with the FEL. This research showed that a ZGP-OPO laser could be a viable alternative to FEL for clinical applications.

  20. Step-tapered operation of the FEL: Efficiency enhancement and two-colour operation

    SciTech Connect

    Jaroszynski, D.A.; Prazeres, R.; Glotin, F.

    1995-12-31

    We present new measurements of the temporal and spectral properties of radiation produced from two step-tapered undulator free-electron lasers (FEL), CLIO in France and FELIX in the Netherlands. Using a two section undulator with independently adjustable deflection parameters (K) the FEL will operate either with enhanced efficiency and improved spectral properties (with a small positive {Delta}K step) or will operate simultaneously at two frequencies (for large {Delta}K). The first experiments demonstrating at two-colour operation were restricted to a maximum wavelength difference, {delta}{lambda}/{lambda} < 0.15 because of the influence of optical dispersion in the cavity introduced by a dielectric output coupling plate. Using a dispersion-free hole output coupler the maximum {delta}{lambda}/{lambda} has been extended to more than 0.6. We present these new dispersion-less two-colour operation results and show that quenching of one of the wavelength unless the optical cavity is detuned significantly so that the FEL operates with reduced efficiency and lower intracavity power. To overcome this problem a larger fraction of the radiation will need to be coupled in the future to limit the intracavity power. To determine the temporal distribution of the optical radiation at the two wavelengths we have carried out second order autocorrelation measurements using a nonlinear crystal and established that the optical pulses are very short, a few hundreds of femtoseconds long, and overlapping. To establish how the two colours build up in the cavity we have also measured the spectral and temporal evolution of the macropulse. To establish the efficiency over a wide range of {Delta}K values we have measured the electron spectra of the electrons leaving the undulator and find that the efficiency is enhanced significantly over normal undulator operation.

  1. Calibration status and plans for the charge integrating JUNGFRAU pixel detector for SwissFEL

    NASA Astrophysics Data System (ADS)

    Redford, S.; Bergamaschi, A.; Brückner, M.; Cartier, S.; Dinapoli, R.; Ekinci, Y.; Fröjdh, E.; Greiffenberg, D.; Mayilyan, D.; Mezza, D.; Mozzanica, A.; Rajeev, R.; Ramilli, M.; Ruder, C.; Schädler, L.; Schmitt, B.; Shi, X.; Thattil, D.; Tinti, G.; Zhang, J.

    2016-11-01

    JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional hybrid pixel detector under development for photon science applications at free electron laser and synchrotron facilities. In particular, JUNGFRAU detectors will equip the Aramis end stations of SwissFEL, an X-ray free electron laser currently under construction at the Paul Scherrer Institut in Villigen, Switzerland. JUNGFRAU has been designed specifically to meet the challenges of photon science at XFELs, including high frame rates, single photon sensitivity in combination with a high dynamic range, vacuum compatibility and tilable modules. This has resulted in a charge integrating detector with three dynamically adjusting gains, a low noise of 55 ENC RMS, readout speeds in excess of 2 kHz, single photon sensitivity down to 2 keV (with a signal to noise ratio of 10) and a dynamic range covering four orders of magnitude at 12 keV. Each JUNGFRAU module consists of eight chips of 256 × 256 pixels, each 75 × 75 μm2 in size. The chips are arranged in 2 × 4 formation and bump-bonded to a single silicon sensor 320 μm thick, resulting in an active area of approximately 4 × 8 cm2 per module. Multi-module vacuum compatible systems comprising up to 16 Mpixels (32 modules) will be used at SwissFEL. The design of SwissFEL and the JUNGFRAU system for the Aramis end station A will be introduced, together with results from early prototypes and a characterisation using the first batch of final JUNGFRAU modules. Plans and first results of the pixel-by-pixel calibration will also be shown. The vacuum compatibility of the JUNGFRAU module is demonstrated for the first time.

  2. Vibrational spectroscopy at interfaces by IR-VIS sum-frequency generation using CLIO FEL

    SciTech Connect

    Peremans, A.; Tadjeddine, A.; Wan Quan, Z.

    1995-12-31

    IR-vis sum-frequency generation (SFG) has developed into a versatile technique for probing the vibrational structure of interfaces. To overcome the limited spectral range accessible by benchtop IR lasers, we have developed an SFG spectrometer that makes use of the broad band tuneable infrared beam provided by the CLIO-FEL. We will evaluate the gain in sensitivity of the FEL-SFG spectrometer in comparison to that of benchtop lasers, taking account of the surface damage by laser heating. Thereafter, we review the different research projects undertaken using this facility: (1) The interface selectivity of SFG makes it particularly suitable for probing buried liquid/solid interface. We took advantage of the spectrometer sensitivity to monitor the electrochemical deposition of hydrogen on platinum single crystals at under- and overpotential (2) Because of its sensitivity to the molecular symmetry, SFG allows probing the conformation of self assembled monolayers deposited on metals. We discuss SFG spectra of {omega}(4-nitroanilino)-dodecane adsorbed on polycrystalline gold and silver films; in the 1550 - 900 cm{sup -1} spectral range. (3) We have undertaken a spectroscopic approach for the investigation of polymer films adhesion on glass. Polyurethane/glass interface is investigated in the 2200 - 1600 cin{sup -1} spectral region. (4) The use of the CLIO FEL allows probing of the vibrational dynamics of the prominent IR active vibrations between 1500 and 500 cm{sup -1} of fullerene epitaxial films. These modes are modified upon charge transfer from the substrate to the C{sub 60} molecules. Preliminary SFG spectra of C{sub 60}/Ag interface are presented. (5) Site specific detection of CO adsorption and CO + O coadsorption on Pd(111) are studied.

  3. Performance of cesium telluride photocathodes as an electron source for the Los Alamos FEL

    SciTech Connect

    Kong, S.H.; Kinross-Wright, J.; Nuguyen, D.C.; Sheffield, R.L.; Weber, M.E.

    1994-09-01

    The Los Alamos Advanced FEL was successfully operated with a Cs{sub 2}Te photocathode driven by a frequency quadrupled Nd:YLF laser as the electron source. Lasing was achieved at 5-6 microns. Cs{sub 2}Te photocathodes with quantum efficiencies of 12-18% at 254 nm were fabricated in an ultrahigh-vacuum chamber and transferred under high vacuum to the FEL. 263 mn light from the drive laser was focused to an 8 mm spot on the center of the photocathode. The authors estimated the operational life time of Cs{sub 2}Te photocathodes to be at least 20 times that for K{sub 2}CsSb photocathodes. The measured dark current of 0.3 mA in an electric field of 22-24 MV/m is well within the acceptable level. The maximum amount of charge extracted was observed to be limited by space charge to about 3.5 nC per micropulse. The emittance of the beam was estimated by fitting the data from a quadrupole scan. The authors measured an emittance that is comparable with the emittance measured with a K{sub 2}CsSb photocathode in their system. A pulse length of 9.3 {+-} 2 ps for 1.3 {+-} 0.2 nC electron micropulses and a pulse length of 7.1 {+-} 0.7 ps for the laser pulses were measured with a streak camera. Therefore, the response of the Cs{sub 2}Te photocathode to the laser pulse is sufficiently fast for FEL applications.

  4. Sensitivity and alternative operating point studies on a high charge CW FEL injector test stand at CEBAF

    SciTech Connect

    Liu, H.; Kehne, D.; Benson, S.

    1995-12-31

    A high charge CW FEL injector test stand is being built at CEBAF based on a 500 kV DC laser gun, a 1500 MHz room-temperature buncher, and a high-gradient ({approx}10 MV/m) CEBAF cryounit containing two 1500 MHz CEBAF SRF cavities. Space-charge-dominated beam dynamics simulations show that this injector should be an excellent high-brightness electron beam source for CW UV FELs if the nominal parameters assigned to each component of the system are experimentally achieved. Extensive sensitivity and alternative operating point studies have been conducted numerically to establish tolerances on the parameters of various injector system components. The consequences of degraded injector performance, due to failure to establish and/or maintain the nominal system design parameters, on the performance of the main accelerator and the FEL itself are discussed.

  5. GIS-based topographic reconstruction and geotechnical modelling of the Köfels Rockslide (Austria)

    NASA Astrophysics Data System (ADS)

    Körfgen, Annemarie; Mergili, Martin; Zangerl, Christian

    2014-05-01

    Investigating fossil landslides may help to predict possible future events. The larger than 3 km2 Köfels rockslide, located in the Ötztal Valley (Tyrol, Austria) represents one of the largest landslides in metamorphic rock masses in the Alps. It occurred in the early Holocene approx. 8700 years BP and has been subject of numerous studies. So far no reconstruction of the pre-failure topography and volume determination based on high resolution airborne laser scanning digital elevation models (DEM) and up-to-date GIS methods was done. In addition, only a few numerical studies using numerical modelling techniques focusing on the failure as well as deformation process and the rock mass strength properties were performed. The present work will attempt to close this gap. The Köfels rockslide is reanalyzed with regard to its actual and initial topography as well as the involved failure and deposition volumes based on a recent DEM. The complex topographic situation of the study site requires four different models of the terrain in order to calculate the volume of the failure and deposition mass. Therefore the following topographies are reconstructed: (i) the pre-failure topography representing the situation before the event, (ii) the topography of the failure surface without the deposition mass in the valley, (iii) the topography after the event but before valley incision and deposition of the alluvium north and south of the rock slide deposit, and (iv) the up-to-date DEM, which represents the present topographic situations in the area. The volumes of the failure and deposition masses of the Köfels rock slide are estimated by comparing the four terrain models. Besides geomorphological considerations based on the DEM, published data from boreholes and an investigation adit are used to reconstruct the pre-failure valley topography. For the geotechnical analysis the 2-D discrete element code UDEC by Itasca is applied to a geological cross section of the Köfels rock slide

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

    SciTech Connect

    Marcouille, O.; Berset, J.M.; Glotin, F.

    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.

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

    SciTech Connect

    Amirmadhi, F.; Brau, K.A.; Becker, C.

    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.

  8. LONGITUDINAL PHASE SPACE CHARACTERIZATION OF ELECTRON BUNCHES AT THE JLAB FEL FACILITY

    SciTech Connect

    Shukui Zhang; Stephen Benson; David Douglas; David Hardy; George Neil; Michelle D. Shinn

    2006-08-27

    We report longitudinal phase space measurements of short electron bunches at the 10kW Free-Electron Laser Facility at Jefferson Lab using broadband synchrotron radiation and a remotely controlled fast streak camera. Accurate measurements are possible because the optical transport system uses only reflective components that do not introduce dispersion. The evolution of longitudinal phase space of the electron beam can be observed in real time while phases of accelerator RF components are being adjusted. This fast and efficient diagnostic enhances the suite of machine setup tools available to JLab FEL operators and applies to other accelerators. The results for certain beam setups will be presented.

  9. SwissFEL instrument ESB femtosecond pump-probe diffraction and scattering

    SciTech Connect

    Ingold, G. Rittmann, J. Beaud, P.; Divall, M.; Erny, C.; Flechsig, U.; Follath, R.; Hauri, C. P.; Hunziker, S.; Juranic, P.; Mozzanica, A.; Pedrini, B.; Sala, L.; Patthey, L.; Patterson, B. D.; Abela, R.

    2016-07-27

    The ESB instrument at the SwissFEL ARAMIS hard X-ray free electron laser is designed to perform pump-probe experiments in condensed matter and material science employing photon-in and photon-out techniques. It includes a femtosecond optical laser system to generate a variety of pump beams, a X-ray optical scheme to tailor the X-ray probe beam, shot-to-shot diagnostics to monitor the X-ray intensity and arrival time, and two endstations operated at a single focus position that include multi-purpose sample environments and 2D pixel detectors for data collection.

  10. Resonantly enhanced multiphoton ionization under XUV FEL radiation: a case study of the role of harmonics

    NASA Astrophysics Data System (ADS)

    Nikolopoulos, G. M.; Lambropoulos, P.

    2015-12-01

    We provide a detailed quantitative study of the possible role of a small admixture of harmonics on resonant two-photon ionization. The motivation comes from the occasional presence of 2nd and 3rd harmonics in FEL radiation. We obtain the dependence of ionic yields on the intensity of the fundamental, the percentage of 2nd harmonic and the detuning of the fundamental from resonance. Having examined the cases of one and two intermediate resonances, we arrive at results of general validity and global behaviour, showing that even a small amount of harmonic may seem deceptively innocuous.

  11. An Rf-gun-driven recirculated linac as injector and FEL driver.

    SciTech Connect

    Andersson, A.; Biedron, S.; Eriksson, M.; Freund, H.; Werin, S.

    1999-08-23

    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 run.

  12. FEL's with bragg reflection resonators: cyclotron auto resonance masers versus ubitrons

    SciTech Connect

    Bratman, V.L.; Denisov, G.G.; Ginzburg, N.S.; Petelin, M.I.

    1983-03-01

    FEL's based on the stimulated undulator radiation (ubitrons) are compared with those based on the stimulated cyclotron radiation (cyclotron autoresonance masers (CARM's)). If the high-current accelerators are used as electron injectors, then from the viewpoint of simplicity of oscillatory electron energy pumping, criticality with respect to electron velocity dispersion, and efficiency, CARM's seem to be more effective than ubitrons at mm and sbmm waves. For such HF generators, resonators based on selective Bragg reflection of electromagnetic waves in corrugated metallic tubes are most attractive. CARM's of this type yield 6 MW at a 4 mm wavelength and 10 MW at a 2 mm wavelength in the single-mode regime.

  13. Observations of z-dependent microbunching harmonic intensities using COTR in a SASE FEL.

    SciTech Connect

    Lumpkin, A. H.; Biedron, S. G.; Dejus, R. J.; Berg, W. J.; Borland, M.; Chae, Y. C.; Erdmann, M.; Huang, Z.; Kim, K. -J.; Li, Y.; Lewellen, J. W.; Milton, S. V.; Moog, E.; Sajaev, V.; Yang, B. X.

    2002-09-24

    The nonlinear generation of harmonics in a self-amplified spontaneous emission (SASE) free-electron laser (FEL) continues to be of interest. Complementary to such studies is the search for information on the electron beam microbunching harmonic components, which are revealed by coherent optical transition radiation (COTR) experiments. An initial z-dependent set of data has been obtained with the fundamental at 530 nm and the second harmonic at 265 nm. The latter data were collected after every other undulator in a nine-undulator string. These results are compared to estimates based on GINGER and an analytical model for nonlinear harmonic generation.

  14. A 4 to 0.1 nm FEL Based on the SLAC Linac

    SciTech Connect

    Pellegrini, C.; /UCLA

    2012-06-05

    The author show that using existing electron gun technology and a high energy linac like the one at SLAC, it is possible to build a Free Electron Laser operating around the 4 nm water window. A modest improvement in the gun performance would further allow to extend the FEL to the 0.1 nm region. Such a system would produce radiation with a brightness many order of magnitude above that of any synchrotron radiation source, existing or under construction, with laser power in the multigawatt region and subpicosecond pulse length.

  15. Parameter Selection and Longitudinal Phase Space Simulation for a Single Stage X-Band FEL Driver at 250 MeV

    SciTech Connect

    Sun, Yipeng; Raubenheimer, Tor; Wu, Juhao; /SLAC

    2011-08-19

    Hard x-ray Free electron lasers (FEL) are being built or proposed at many accelerator laboratories as it supports wide range of applications in many aspects. Most of the hard x-ray FEL design is similar with the SLAC Linac Coherent Light Source (LCLS), which features a two (or multiple) stage bunch compression. For the first stage of the bunch compression, usually the beam is accelerated in a lower-frequency RF section (such as S-band for LCLS), and then the longitudinal phase space is linearized by a higher-frequency RF section (harmonic RF, such as X-band for LCLS). In this paper, a compact hard x-ray FEL design is proposed, which is based on X-band RF acceleration and eliminating the need of a harmonic RF. The parameter selection and relation is discussed, and the longitudinal phase space simulation is presented. The FEL coherence condition of the electron beam in the undulators requires a large charge density, a small emittance and small energy spread. The RMS electron bunch length from the injector is in the ps scale, with a bunch charge in the range of hundreds pC to several nC, which means that the current is roughly 0.1 kA. According to the requirement from soft x-ray lasing and hard x-ray lasing, a peak current of 1 kA and 3 kA is needed respectively. Thus the bunch has to be compressed. Usually a two stage bunch compression or multipole stage bunch compression is adopted. The z-correlated energy chirp is normally established by letting the beam pass through a section of RF cavities, with a RF phase off crest. As stated above, S-band RF (3 GHz) acceleration could be applied in this section. Due to the nature of RF acceleration wave, the chirp on the bunch is not linear, but has the RF curvature on it. In order to linearize the energy chirp, a harmonic RF section with higher frequency is needed. For LCLS a short X-band RF section (12 GHz) is used which is a fourth order harmonic. The linearized bunch is then passing by a dispersive region, in which the

  16. Incorporation of a PbSe Array Based Spectrograph into EPICS using LabView at the JLab FEL Facility

    SciTech Connect

    D. Hardy; S.V. Benson; Michelle D. Shinn; S. Zhang

    2005-08-21

    A real-time spectrograph with a 1Hz update rate was designed and installed at the JLab FEL facility using a Cal Sensors PbSe array and a Roper Scientific SpectraPro 300 monochrometer. This paper describes the implementation of EPICS channel access on a remote PC running LabView with modification of vendor supplied LabView VI's to allow display of FEL light spectra in real-time on a remote workstation. This allows PC based diagnostics to be used in EPICS.

  17. Beam Dynamics Study of X-Band Linac Driven X-Ray FELS

    SciTech Connect

    Adolphsen, C.; Limborg-Deprey, C.; Raubenheimer, T.O.; Wu, J.; Sun, Y.; /SLAC

    2011-12-13

    Several linac driven X-ray Free Electron Lasers (XFELs) are being developed to provide high brightness photon beams with very short, tunable wavelengths. In this paper, three XFEL configurations are proposed that achieve LCLS-like performance using X-band linac drivers. These linacs are more versatile, efficient and compact than ones using S-band or C-band rf technology. For each of the designs, the overall accelerator layout and the shaping of the bunch longitudinal phase space are described briefly. During the last 40 years, the photon wavelengths from linac driven FELs have been pushed shorter by increasing the electron beam energy and adopting shorter period undulators. Recently, the wavelengths have reached the X-ray range, with FLASH (Free-Electron Laser in Hamburg) and LCLS (Linac Coherent Light Source) successfully providing users with soft and hard X-rays, respectively. FLASH uses a 1.2 GeV L-band (1.3 GHz) superconducting linac driver and can deliver 10-70 fs FWHM long photon pulses in a wavelength range of 44 nm to 4.1 nm. LCLS uses the last third of the SLAC 3 km S-band (2.856 GHz) normal-conducting linac to produce 3.5 GeV to 15 GeV bunches to generate soft and hard X-rays with good spatial coherence at wavelengths from 2.2 nm to 0.12 nm. Newer XFELs (at Spring8 and PSI) use C-band (5.7 GHz) normal-conducting linac drivers, which can sustain higher acceleration gradients, and hence shorten the linac length, and are more efficient at converting rf energy to bunch energy. The X-band (11.4 GHz) rf technology developed for NLC/GLC offers even higher gradients and efficiencies, and the shorter rf wavelength allows more versatility in longitudinal bunch phase space compression and manipulation. In the following sections, three different configurations of X-band linac driven XFELs are described that operate from 6 to 14 GeV. The first (LOW CHARGE DESIGN) has an electron bunch charge of only 10 pC; the second (OPTICS LINEARIZATION DESIGN) is based on optics

  18. Making Heat Visible

    PubMed Central

    Goodhew, Julie; Pahl, Sabine; Auburn, Tim; Goodhew, Steve

    2015-01-01

    Householders play a role in energy conservation through the decisions they make about purchases and installations such as insulation, and through their habitual behavior. The present U.K. study investigated the effect of thermal imaging technology on energy conservation, by measuring the behavioral effect after householders viewed images of heat escaping from or cold air entering their homes. In Study 1 (n = 43), householders who received a thermal image reduced their energy use at a 1-year follow-up, whereas householders who received a carbon footprint audit and a non-intervention control demonstrated no change. In Study 2 (n = 87), householders were nearly 5 times more likely to install draught proofing measures after seeing a thermal image. The effect was especially pronounced for actions that addressed an issue visible in the images. Findings indicate that using thermal imaging to make heat loss visible can promote energy conservation. PMID:26635418

  19. Spitzer Makes Invisible Visible

    NASA Image and Video Library

    2004-04-13

    Hidden behind a shroud of dust in the constellation Cygnus is a stellar nursery called DR21, which is giving birth to some of the most massive stars in our galaxy. Visible light images reveal no trace of this interstellar cauldron because of heavy dust obscuration. In fact, visible light is attenuated in DR21 by a factor of more than 10,000,000,000,000,000,000,000,000,000,000,000,000,000 (ten thousand trillion heptillion). New images from NASA's Spitzer Space Telescope allow us to peek behind the cosmic veil and pinpoint one of the most massive natal stars yet seen in our Milky Way galaxy. The never-before-seen star is 100,000 times as bright as the Sun. Also revealed for the first time is a powerful outflow of hot gas emanating from this star and bursting through a giant molecular cloud. The colorful image is a large-scale composite mosaic assembled from data collected at a variety of different wavelengths. Views at visible wavelengths appear blue, near-infrared light is depicted as green, and mid-infrared data from the InfraRed Array Camera (IRAC) aboard NASA's Spitzer Space Telescope is portrayed as red. The result is a contrast between structures seen in visible light (blue) and those observed in the infrared (yellow and red). A quick glance shows that most of the action in this image is revealed to the unique eyes of Spitzer. The image covers an area about two times that of a full moon. http://photojournal.jpl.nasa.gov/catalog/PIA05734

  20. Spitzer Makes 'Invisible' Visible

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Hidden behind a shroud of dust in the constellation Cygnus is a stellar nursery called DR21, which is giving birth to some of the most massive stars in our galaxy. Visible light images reveal no trace of this interstellar cauldron because of heavy dust obscuration. In fact, visible light is attenuated in DR21 by a factor of more than 10,000,000,000,000,000,000,000,000,000,000,000,000,000 (ten thousand trillion heptillion).

    New images from NASA's Spitzer Space Telescope allow us to peek behind the cosmic veil and pinpoint one of the most massive natal stars yet seen in our Milky Way galaxy. The never-before-seen star is 100,000 times as bright as the Sun. Also revealed for the first time is a powerful outflow of hot gas emanating from this star and bursting through a giant molecular cloud.

    The colorful image is a large-scale composite mosaic assembled from data collected at a variety of different wavelengths. Views at visible wavelengths appear blue, near-infrared light is depicted as green, and mid-infrared data from the InfraRed Array Camera (IRAC) aboard NASA's Spitzer Space Telescope is portrayed as red. The result is a contrast between structures seen in visible light (blue) and those observed in the infrared (yellow and red). A quick glance shows that most of the action in this image is revealed to the unique eyes of Spitzer. The image covers an area about two times that of a full moon.

  1. Evacuation under limited visibility

    NASA Astrophysics Data System (ADS)

    Frank, Guillermo A.; Dorso, Claudio O.

    2015-06-01

    A multiplicity of situations can trigger off an evacuation of a room under panic conditions. For "normal" (with "normal" meaning absence of obstacles, perfect visibility, etc.) environmental conditions, the "faster is slower" effect dominates the dynamics of this process. It states that as the pedestrians desire to reach the exit increases, the clogging phenomena delays the time to get out of the room. But, environmental conditions are usually far from "normal." In this work, we consider that pedestrians have to find their way out under low visibility conditions. Some of them might switch to a herding-like behavior if they do not remember where the exit was. Others will just trust on their memory. Our investigation handles the herding and memory effects on the evacuation of a single exit room with no obstacles. We also include a section on how signaling devices affect the evacuation process. Unexpectedly, some low visibility situations may enhance the evacuation performance. This can be resumed as a second paradoxical result, since we demonstrated in an earlier investigation that "clever is not always better" G. A. Frank and C. O. Dorso, Physica A 390, 2135 (2011).

  2. Dielectric wakefield accelerator to drive to the future FEL light sourcei.

    SciTech Connect

    Power, J.G.; Zholents, A.; Jing, C.; Kanareykin, A. )

    2011-01-01

    X-ray free-electron lasers (FELs) are expensive instruments and the accelerator holds the largest portion of the cost of the entire facility. Using a high-energy gain dielectric wake-field accelerator (DWA) instead of the conventional accelerator may facilitate reduction of the facility size and significant cost saving. We show that a collinear dielectric wake-field accelerator can, in principle, accelerate low charge and high peak current electron bunches to a few GeV energy with up to 100 kHz bunch repetition rate. Several such accelerators can share the same tunnel and same CW superconducting linac (operating with a few MHz bunch repetition rate) whose sole purpose is feeding the DWAs with wake producing low energy, high charge electron bunches with a desirable periodicity. Then, ten or more x-ray FELs can operate independently, each using its own linac. In this paper, we present an initial case study of a single stage 850 GHz DWA based on a quartz tube with a {approx}100MV/m loaded gradient sufficient to accelerate a 50 pC main electron beam to 2.4 GeV at a 100 kHz bunch repetition rate in just under 30 meters.

  3. The Physics and Applications of High Brightness Beams: Working Group C Summary on Applications to FELS

    SciTech Connect

    Nuhn, Heinz-Dieter

    2003-03-19

    This is the summary of the activities in working group C, ''Application to FELs,'' which was based in the Bithia room at the Joint ICFA Advanced Accelerator and Beam Dynamics Workshop on July 1-6, 2002 in Chia Laguna, Sardinia, Italy. Working group C was small in relation to the other working groups at that workshop. Attendees include Enrica Chiadroni, University of Rome ape with an identical pulse length. ''La Sapienza'', Luca Giannessi, ENEA, Steve Lidia, LBNL, Vladimir Litvinenko, Duke University, Patrick Muggli, UCLA, Alex Murokh, UCLA, Heinz-Dieter Nuhn, SLAC, Sven Reiche, UCLA, Jamie Rosenzweig, UCLA, Claudio Pellegrini, UCLA, Susan Smith, Daresbury Laboratory, Matthew Thompson, UCLA, Alexander Varfolomeev, Russian Research Center, plus a small number of occasional visitors. The working group addressed a total of nine topics. Each topic was introduced by a presentation, which initiated a discussion of the topic during and after the presentation. The speaker of the introductory presentation facilitated the discussion. There were six topics that were treated in stand-alone sessions of working group C. In addition, there were two joint sessions, one with working group B, which included one topic, and one with working group C, which included two topics. The presentations that were given in the joint sessions are summarized in the working group summary reports for groups B and D, respectively. This summary will only discuss the topics that were addressed in the stand-alone sessions, including Start-To-End Simulations, SASE Experiment, PERSEO, ''Optics Free'' FEL Oscillators, and VISA II.

  4. The new IR and THz FEL facility at the Fritz Haber Institute in Berlin

    NASA Astrophysics Data System (ADS)

    Schöllkopf, Wieland; Gewinner, Sandy; Junkes, Heinz; Paarmann, Alexander; von Helden, Gert; Bluem, Hans P.; Todd, Alan M. M.

    2015-05-01

    A mid-infrared oscillator FEL has been commissioned at the Fritz Haber Institute. The accelerator consists of a thermionic gridded gun, a subharmonic buncher, and two S-band standing-wave copper structures. It provides a final electron energy adjustable from 15 to 50 MeV, low longitudinal (< 50 keV ps) and transverse emittance (< 20 πmm mrad), at more than 200 pC bunch charge with a micro-pulse repetition rate of 1 GHz and a macro-pulse length of up to 15 µs. Pulsed radiation with up to 100 mJ macro-pulse energy at about 0.5% FWHM bandwidth is routinely produced in the wavelength range from 4 to 48 µm. A characterization of the FEL performance in terms of pulse energy, bandwidth, and micro-pulse shape of the IR radiation is given. In addition, selected user results are presented. These include, for instance, spectroscopy of bio-molecules (peptides and small proteins) either conformer selected by ion mobility spectrometry or embedded in superfluid helium nano-droplets at 0.4 K, as well as vibrational spectroscopy of mass-selected metal-oxide clusters and protonated water clusters in the gas phase.

  5. Application of the green function formalism to nonlinear evolution of the low gain FEL oscillator

    SciTech Connect

    Shvets, G.; Wurtele, J.S.; Gardent, D.

    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.

  6. Simple Limits on Achieving A Quasi-Linear Magnetic Compression for an FEL Driver

    SciTech Connect

    Sun, Yipeng; /SLAC

    2012-02-16

    Free electron lasers (FEL) need a very bright electron beam in three dimensions and a high peak charge density. In order to compress an initially longer electron bunch generated from the photoinjector, magnetic bunch compression systems are widely employed. In this paper, first harmonic RF linearization and its associated requirements are reviewed. Meanwhile it is also briefly discussed what is the relation between a proper initial bunch length and main RF frequency, when a harmonic RF linearization is included. Then given a reasonable bunch compression ratio, a proper initial bunch length as a function of the main RF frequency and RF phase is estimated analytically by several approaches, assuming that no harmonic RF section is needed to linearize the energy modulation introduced during main RF acceleration, and at the same time still linearly compress the bunch length. Next the upper limit of the bunch compression ratio in a single stage is evaluated analytically. The analytical relations derived on choosing a proper initial bunch length as a function of main RF frequency are confirmed by numerical simulation. These simple limit provide rough estimations and may be beneficial for choosing bunch compression ratios in different stages of an FEL driver, especially in a first stage bunch compression where there is usually a harmonic RF linearization applied. It may also be useful in evaluating the possibility of low charge operation mode without any harmonic RF linearization, where a shorter initial bunch length can be achieved from the photoinjector.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. High gradient, high reliability, and low wakefield accelerating structures for the FERMI FEL

    NASA Astrophysics Data System (ADS)

    Serpico, Claudio; Shafqat, Nuaman; Grudiev, Alexej; Vescovo, Roberto

    2017-07-01

    The FERMI seeded free-electron laser (FEL), located at the Elettra laboratory in Trieste, is a 4th generation light source operating in the vacuum ultraviolet to soft X-rays range. The FEL design is based on an external seeding scheme which improves the output pulse coherence and the central wavelength control and reduces the spectral bandwidth. FERMI has achieved its original energy target by producing photon energies above 300 eV from a 1.50 GeV, 600 A peak current, electron beam. However, there is a strong scientific motivation to push the energy envelop further higher to photon energy up to 600 eV to cover both the x-ray absorption edges of nitrogen K (400 eV) and oxygen K (532 eV). To achieve this goal, the electron beam energy will be increased from 1.50 GeV to 1.80 GeV and the peak beam current will be pushed towards 1 kA. This requires essentially the development of more reliable high gradient S-band accelerating structures, with low wakefields contribution up to 1 nC charge per bunch. Accordingly, in the following, we present the design of high gradient, high reliability, and low wakefield S-band accelerating structures for the upgrade program of the FERMI linac.

  9. Growth of nano-dots on the grazing-incidence mirror surface under FEL irradiation.

    PubMed

    Kozhevnikov, I V; Buzmakov, A V; Siewert, F; Tiedtke, K; Störmer, M; Samoylova, L; Sinn, H

    2016-01-01

    A new phenomenon on X-ray optics surfaces has been observed: the growth of nano-dots (40-55 nm diameter, 8-13 nm height, 9.4 dots µm(-2) surface density) on the grazing-incidence mirror surface under irradiation by the free-electron laser (FEL) FLASH (5-45 nm wavelength, 3° grazing-incidence angle). With a model calculation it is shown that these nano-dots may occur during the growth of a contamination layer due to polymerization of incoming hydrocarbon molecules. The crucial factors responsible for the growth of nano-dots in the model are the incident peak intensity and the reflection angle of the beam. A reduction of the peak intensity (e.g. replacement of the FEL beam by synchrotron radiation) as well as a decrease of the incident angle by just 1° (from 3° to 2°) may result in the total disappearance of the nano-dots. The model calculations are compared with surface analysis of two FLASH mirrors.

  10. Identification and characterization of major cat allergen Fel d 1 mimotopes on filamentous phage carriers.

    PubMed

    Luzar, Jernej; Molek, Peter; Šilar, Mira; Korošec, Peter; Košnik, Mitja; Štrukelj, Borut; Lunder, Mojca

    2016-03-01

    Cat allergy is one of the most prevalent allergies worldwide and can lead to the development of rhinitis and asthma. Thus far, only allergen extracts from natural sources have been used for allergen-specific immunotherapy. However, extracts and whole allergens in immunotherapy present an anaphylaxis risk. Identification of allergen epitopes or mimotopes has an important role in development of safe and effective allergen-specific immunotherapy. Moreover, with a suitable immunogenic carrier, the absence of sufficient immune response elicited by short peptides could be surmounted. In this study, we identified five structural mimotopes of the major cat allergen Fel d 1 by immunoscreening with random peptide phage libraries. The mimotopes were computationally mapped to the allergen surface, and their IgE reactivity was confirmed using sera from cat-allergic patients. Importantly, the mimotopes showed no basophil activation of the corresponding cat-allergic patients, which makes them good candidates for the development of hypoallergenic vaccine. As bacteriophage particles are becoming increasingly recognized as immunogenic carriers, we constructed bacteriophage particles displaying multiple copies of each selected mimotope on major phage coat protein. These constructed phages elicited T cell-mediated immune response, which was predominated by the type 1 T cell response. Mimotopes alone contributed to the type 1 T cell response by promoting IL-2 production. Fel d 1 mimotopes, as well as their filamentous phage immunogenic carriers, represent promising candidates in the development of hypoallergenic vaccine against cat allergy.

  11. State-of-the-art thin film X-ray optics for synchrotrons and FEL sources

    NASA Astrophysics Data System (ADS)

    Hertlein, Frank; Wiesmann, Jörg; Michaelsen, Carsten; Störmer, Michael; Seifert, Andreas

    2007-05-01

    Selected aspects of simulation, preparation and characterization of total reflection and multilayer X-ray optics will be discussed. The best multilayer is found by calculating the optical properties of the coating. Sophisticated improvements in deposition technology allow the precise realization of the specified parameters when manufacturing the X-ray optics. The quality of the shape of the substrate for the optics is measured with the aid of profilometry. X-ray reflectometry measures both film thickness as well as their lateral gradient. Last but not least we will be showing results of the development of carbon coatings as total reflection mirrors for FEL (free electron laser) sources. Over the past years we have developed optimized optics for the XUV range up to 200 eV. First FEL irradiation tests have shown that carbon coatings offer high reflectivity > 95%, high radiation stability, good uniformity in thickness and roughness. An optimized coating of two stripes for different beam energies was produced especially for a tomography beamline, where a Ru/C multilayer was chosen for energies between 10 and 22 keV and a W/Si multilayer for energies between 22 and 45 keV.

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

    NASA Astrophysics Data System (ADS)

    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.

  13. The Jefferson Lab VUV-FEL at 10 eV and above

    NASA Astrophysics Data System (ADS)

    Williams, Gwyn; Fel Team

    2011-03-01

    We will present details of the vacuum ultraviolet performance of the Jefferson Lab Free Electron Laser. The JLab FEL is oscillator-based and uses a superconducting energy recovered linac for CW RF operation at up to 75 MHz. Lasing at a fundamental wavelength of 372 nm, the third harmonic is at 124 nm, corresponding to a photon energy of 10 eV. The energy per pulse in the fundamental is 20 microJoules, which at 9 MHz yields an average power of 180 Watts. The pulses have a FWHM of order 300 fs, which essentially determines the optical bandwidth. The third harmonic, which is a 0.1 - 1% fraction of this, is considerably brighter than any other source in the region. Further, being an FEL, there is a wide range of tunability in the 1 eV to 15 eV range. Additional reach is possible with increased electron beam energy, and some options will be discussed in the talk. We acknowledge funding from ONR, AFRL and DOE-BES under contract AC05-060R23177.

  14. Development of a pump-probe facility with sub-picosecond time resolution combining a high-power ultraviolet regenerative FEL amplifier and a soft X-ray SASE FEL

    NASA Astrophysics Data System (ADS)

    Faatz, B.; Fateev, A. A.; Feldhaus, J.; Krzywinski, J.; Pflueger, J.; Rossbach, J.; Saldin, E. L.; Schneidmiller, E. A.; Yurkov, M. V.

    2001-12-01

    This paper presents the conceptual design of a high power radiation source with laser-like characteristics in the ultraviolet spectral range at the TESLA Test Facility (TTF). The concept is based on the generation of radiation in a regenerative FEL amplifier (RAFEL). The RAFEL described in this paper covers a wavelength range of 200-400 nm and provides 200 fs pulses with 2 mJ of optical energy per pulse. The linac operates at 1% duty factor and the average output radiation power exceeds 100 W. The RAFEL will be driven by the spent electron beam leaving the soft X-ray FEL, thus providing minimal interference between these two devices. The RAFEL output radiation has the same time structure as the X-ray FEL and the UV pulses are naturally synchronized with the soft X-ray pulses from the TTF FEL. Therefore, it should be possible to achieve synchronization close to the duration of the radiation pulses (200 fs) for pump-probe techniques using either an UV pulse as a pump and soft X-ray pulse as a probe, or vice versa.

  15. Broadband polygonal invisibility cloak for visible light.

    PubMed

    Chen, Hongsheng; Zheng, Bin

    2012-01-01

    Invisibility cloaks have recently become a topic of considerable interest thanks to the theoretical works of transformation optics and conformal mapping. The design of the cloak involves extreme values of material properties and spatially dependent parameter tensors, which are very difficult to implement. The realization of an isolated invisibility cloak in the visible light, which is an important step towards achieving a fully movable invisibility cloak, has remained elusive. Here, we report the design and experimental demonstration of an isolated polygonal cloak for visible light. The cloak is made of several elements, whose electromagnetic parameters are designed by a linear homogeneous transformation method. Theoretical analysis shows the proposed cloak can be rendered invisible to the rays incident from all the directions. Using natural anisotropic materials, a simplified hexagonal cloak which works for six incident directions is fabricated for experimental demonstration. The performance is validated in a broadband visible spectrum.

  16. Verification of image processing based visibility models

    SciTech Connect

    Larson, S.M.; Cass, G.R.; Hussey, K.J.; Luce, F.

    1988-06-01

    Methods are presented for testing visibility models that use simulated photographs to display results of model calculations. An experimental protocol is developed and used to obtain input data including standard photographs of chosen scenes on a clear day and during a smog event at Pasadena, CA. With clear day photograph as a substrate, pollutant properties measured on the smoggy day are introduced into the visibility model, and results of the model calculations are displayed as a synthetic photograph of the expected appearance of the smog event. Quantitative comparisons are made between the predicted and actual appearance of the smog event. Diagnostic techniques developed are applied to the visibility modeling procedure proposed by Malm et al. That model is shown to reproduce the contrast reduction characteristic of urban air pollution but produces synthetic photographs with sky elements that differ substantially from a real photograph of the actual smog event.

  17. Socially visible midwives.

    PubMed

    Chinn, Teresa; Clarke, Jenny

    2016-02-01

    Social media are playing a bigger and bigger part in our personal lives and what's more they are now infiltrating our professional lives, too. Moving from just 'being on' social media to using social media effectively as a midwife, is a huge challenge that many midwives are facing. To be effective and to really utilise social media to their full potential, midwives need to consider role-modelling, leading, social capital, digital footprint, visibility and continuing professional development. If all of these aspects are considered and midwives take a more considered approach to social media, they can really start to benefit from engaging in these online spaces.

  18. Comparison of different undulator schemes with superimposed alternating gradients for the VUV-FEL at the TESLA Test Facility

    SciTech Connect

    Pflueger, J.; Nikitina, Y.M.

    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.

  19. Experimental results of a sheet-beam, high power, FEL amplifier with application to magnetic fusion research

    SciTech Connect

    Cheng, S.; Destler, W.W.; Granatstein, V.L.

    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.

  20. Design of a high average-power FEL driven by an existing 20 MV electrostatic-accelerator

    SciTech Connect

    Kimel, I.; Elias, L.R.

    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.

  1. Temporal and spectral evolution of a storage ring FEL source: Experimental results on Super-ACO and new theoretical approach

    SciTech Connect

    Hara, T.; Couprie, M.E. ||

    1995-12-31

    The Super-ACO FEL source in UV is now used for applications like a time-resolved fluorescence in biology and two colors experiments coupling FEL and Synchrotron Radiation, which are naturally synchronized. The stability of the FEL is then a critical issue for the users. Detailed experimental studies conducted on the temporal characteristics of the laser micropulse showed various phenomena, such as a longitudinal micropulse jitter and a deformation of a longitudinal micropulse distribution. A similar analysis has been performed on the laser spectral evolution with a scanning Fabry-Perot interferometer, showing a spectrum narrowing, and a wavelength drift. A longitudinal feedback system developed after the first user experiment, allowed to reduce significantly the longitudinal jitter, the intensity fluctuation and the spectral drift. Nevertheless, the stability of the FEL is very dependent on any perturbation, and the observed phenomena can not be described by former models like super-mode assuming a stationary regime. A new theoretical model has then been developed, in order to simulate dynamic behaviors. A simple iterative method is employed to obtain the laser spectrum. The access to the temporal distribution requires additional complexity, because the Fourier transformation has to be performed for each pass. The comparison between the experimental data and the simulation results will be given.

  2. Transient absorption spectroscopy in biology using the Super-ACO storage ring FEL and the synchrotron radiation combination

    NASA Astrophysics Data System (ADS)

    Renault, Eric; Nahon, Laurent; Garzella, David; Nutarelli, Daniele; De Ninno, Giovanni; Hirsch, Matthias; Couprie, Marie Emmanuelle

    2001-12-01

    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, such as the time-resolved absorption study of the first excited state of Acridine.

  3. Endangered Languages and the Media. Proceedings of the Fifth FEL Conference (Agadir, Morocco, September 20-23, 2001).

    ERIC Educational Resources Information Center

    Moseley, Christopher, Ed.; Ostler, Nicholas, Ed.; Ouzzate, Hassan, Ed.

    Papers for the fifth Foundation for Endangered Languages (FEL) Conference include the following papers: "The State and the Global Marketplace in the Provision of Minority Media Services" (George Jones); "Local Language Media: What Does It Take?" (Paul Lewis); "Power of the Media for the Good of Small Languages: An Indian…

  4. Endangered Languages and the Media. Proceedings of the Fifth FEL Conference (Agadir, Morocco, September 20-23, 2001).

    ERIC Educational Resources Information Center

    Moseley, Christopher, Ed.; Ostler, Nicholas, Ed.; Ouzzate, Hassan, Ed.

    Papers for the fifth Foundation for Endangered Languages (FEL) Conference include the following papers: "The State and the Global Marketplace in the Provision of Minority Media Services" (George Jones); "Local Language Media: What Does It Take?" (Paul Lewis); "Power of the Media for the Good of Small Languages: An Indian…

  5. LCLS X-Ray FEL Output Performance in the Presence of HighlyTime-Dependent Undulator Wakefields

    SciTech Connect

    Bane, Karl L.F.; Emma, Paul; Huang, Heinz-Dieter Nuhn; Stupakov,Gennady; Fawley, William M.; Reiche, Sven

    2005-08-25

    Energy loss due to wakefields within a long undulator, if not compensated by an appropriate tapering of the magnetic field strength, can degrade the FEL process by detuning the resonant FEL frequency. The wakefields arise from the vacuum chamber wall resistivity, its surface roughness, and abrupt changes in its aperture. For LCLS parameters, the resistive-wall component is the most critical and depends upon the chamber material (e.g., Cu) and its radius. Of recent interest[1] is the so-called ''AC'' component of the resistive-wall wake which can lead to strong variations on very short timescales (e.g., {approx} 20 0fs). To study the expected performance of the LCLS in the presence of these wakefields, we have made an extensive series of start-to-end SASE simulations with tracking codes PARMELA and ELEGANT, and time-dependent FEL simulation codes GENESIS1.3 and GINGER. We discuss the impact of the wakefield losses upon output energy, spectral bandwidth, and temporal envelope of the output FEL pulse, as well as the benefits of a partial compensation of the time-dependent wake losses obtained with a slight z-dependent taper in the undulator field. We compare the taper results to those predicted analytically[2].

  6. LCLS X-Ray FEL Output Performance in the Presence of Highly Time-Dependent Undulator Wakefields

    SciTech Connect

    Fawley, W.M.; Bane, K.L.F.; Emma, P.; Huang, Z.; Nuhn, H.-D.; Stupakov, G.; Reiche, S.; /UCLA

    2005-09-30

    Energy loss due to wakefields within a long undulator, if not compensated by an appropriate tapering of the magnetic field strength, can degrade the FEL process by detuning the resonant FEL frequency. The wakefields arise from the vacuum chamber wall resistivity, its surface roughness, and abrupt changes in its aperture. For LCLS parameters, the resistive-wall component is the most critical and depends upon the chamber material (e.g., Cu) and its radius. Of recent interest[1] is the so-called ''AC'' component of the resistive-wall wake which can lead to strong variations on very short timescales (e.g., {approx} 20 fs). To study the expected performance of the LCLS in the presence of these wakefields, we have made an extensive series of start-to-end SASE simulations with tracking codes PARMELA and ELEGANT, and time-dependent FEL simulation codes GENESIS1.3 and GINGER. We discuss the impact of the wakefield losses upon output energy, spectral bandwidth, and temporal envelope of the output FEL pulse, as well as the benefits of a partial compensation of the time-dependent wake losses obtained with a slight z-dependent taper in the undulator field. We compare the taper results to those predicted analytically[2].

  7. Optimization of the LCLS X-Ray FEL Output Performance in the Presence of Strong Undulator Wakefields

    SciTech Connect

    Reiche, S.; Bane, K.L.F.; Emma, P.; Huang, Z.; Nuhn, H.D.; Stupakov, G.V.; Fawley, W.M.; /LBL, Berkeley

    2006-03-17

    The Linac Coherent Light Source (LCLS) Free-Electron Laser will operate in the wavelength range of 1.5 to 15 Angstroms. Energy loss due to wakefields within the long undulator can degrade the FEL process by detuning the resonant FEL frequency. The wakefields arise from the vacuum chamber wall resistivity, its surface roughness, and abrupt changes in its aperture. For LCLS parameters, the resistive component is the most critical and depends upon the chamber material (e.g. Cu) and its radius. To study the expected performance in the presence of these wakefields, we make a series of start-to-end simulations with tracking codes PARMELA and ELEGANT and time-dependent FEL simulation codes Genesis 1.3 and Ginger. We discuss the impact of the wakefield on output energy, spectral bandwidth, and temporal envelope of the output FEL pulse, as well as the benefits of a partial compensation obtained with a slight z dependent taper in the undulator field. We compare these results to those obtained by decreasing the bunch charge or increasing the vacuum chamber radius. We also compare our results to those predicted in concurrent analytical work.

  8. Simulation of the fundamental and nonlinear harmonic output from an FEL amplifier with a soft x-ray seed laser

    SciTech Connect

    Biedron, S. G.; Freund, H. P.; Li, Y.; Milton, S. V.

    2000-07-05

    A single-pass, high-gain free-electron laser (FEL) x-ray amplifier was simulated using the 3D, polychromatic simulation code MEDUSA. The seed for the system is a table-top, soft x-ray laser. The simulated fundamental and nonlinear harmonic x-ray output wavelengths are discussed.

  9. Endangered Languages and Literacy. Proceedings of the Fourth FEL Conference (Charlotte, North Carolina, September 21-24, 2000).

    ERIC Educational Resources Information Center

    Ostler, Nicholas, Ed.; Rudes, Blair, Ed.

    Papers for the fourth Foundation for Endangered Languages (FEL) Conference include the following: "Endangered languages and Literacy" (Nicholas Ostler, Blair Rudes); "Keynote Address: On Native Language Literacy: a Personal Perspective" (Ofelia Zepeda); "A Community's Solution to Some Literacy Problems: The Mayangna of…

  10. Endangered Languages and Literacy. Proceedings of the Fourth FEL Conference (Charlotte, North Carolina, September 21-24, 2000).

    ERIC Educational Resources Information Center

    Ostler, Nicholas, Ed.; Rudes, Blair, Ed.

    Papers for the fourth Foundation for Endangered Languages (FEL) Conference include the following: "Endangered languages and Literacy" (Nicholas Ostler, Blair Rudes); "Keynote Address: On Native Language Literacy: a Personal Perspective" (Ofelia Zepeda); "A Community's Solution to Some Literacy Problems: The Mayangna of…

  11. Development of a Waveguide FEL Seeded in the 1-3 THz Range for Microbunching Experiment at the Neptune Laboratory

    NASA Astrophysics Data System (ADS)

    Sung, C.; Tochitsky, S. Ya.; Reiche, S.; Gottschalk, S. C.; Kimura, W. D.; Rosenzweig, J. B.; Pellegrini, C.; Joshi, C.

    2006-11-01

    IFEL and FEL techniques can be used to modulate an electron beam on the scale of the radiation wavelength. However, the lack of a high power radiation source in the 100-300 μm range hinders the progress on THz IFEL microbunching. In this paper, we discuss microbunching of an electron beam using a single-pass FEL seeded with a low power THz pulse generated by frequency mixing of CO2 laser lines in a GaAs nonlinear crystal. A narrowband THz seed source is pumped by a dual beam TEA CO2 laser and can be tuned in the 1-3 THz range. The THz radiation is guided through a hollow waveguide inside the planar FEL undulator driven by a photoinjector. By using a time-dependent FEL code GENESIS 1.3, we optimized the undulator parameters and analyzed the dynamics of the modulated electron beam. By using a ˜ 8 MeV electron beam with a peak current of 40 A and a ˜1kW THz seed with wavelength 200 μm, the energy modulation up to 1.3% can be achieved in a ˜1.8-m long undulator with a constant period of 2.7 cm. At present, the THz seed source is built and fully characterized. The results of transmission measurements for THz waveguides are also discussed.

  12. Proposal for Research on High-Brightness Cathodes for High-Power Free-Electron Lasers (FEL)

    DTIC Science & Technology

    2013-05-09

    DEFENSE TECHNICAL INFORMATION CENTER DTICf’has determined on tp // ///£ that this Technical Document has the Distribution Statement checked...below. The current distribution for this document can be found in the DTICf Technical Report Database. I* DISTRIBUTION STATEMENT A. Approved for...in reason) (date of determination). Other requests for this document shall be referred to (insert controlling DoD office). ] DISTRIBUTION STATEMENT

  13. Time dependence of FEL-induced surface photovoltage on semiconductor interfaces measured with synchroton radiation photoemission spectroscopy

    SciTech Connect

    Marsi, M.; Delboulbe, A.; Garzella, D.

    1995-12-31

    During the last year, the first surface science experiments simultaneously using a Free Electron Laser (FEL) and Synchrotron Radiation (SR) have been performed on SuperACO at LURE (Orsay, France). These {open_quotes}two color{close_quotes} experiments studied the surface photovoltage (SPV) induced on semiconductor surfaces and interfaces by the SuperACO FEL, a storage ring FEL delivering 350 nm photons which am naturally synchronized with the SR; the SPV was measured by synchrotron radiation core-level photoemission spectroscopy on the high-resolution SU3 undulator beamline. We will describe the experimental setup, which allowed us to convey the FEL light onto the samples sitting in the SU3 experimental station by means of a series of mirrors, and show the results we obtained for prototypical systems such as Ag/GaAs(110) and Si(111) 2 x 1. The dependence of the SPV was studied in function of various parameters, changing sample doping and photon flux; but our efforts were mainly devoted to studying its dependence on the time delay between the FEL pump and the SR probe. On SuperACO, such delay can be varied between 1 and 120 ns, the limits being given by the time duration of a SR pulse and by the interval between two consecutive positron bunches, respectively. The results show a clear temporal dependence of the amount of SPV on cleaved Si surfaces, where as the Ag/GaAs(110) does not show any difference on the ns time scale. We will discuss these results in terms of the role of surface recombination in the dynamics of the photoinduced electron-hole pairs. These studies follow the evolution of the density of electrostatic charge at surfaces and interfaces on a nanosecond time scale, and might pave the way for a new series of experiments: for example, one might explore what are the physical mechanisms limiting the time response of Schottky diodes.

  14. Wavefront sensor based diagnostic of FERMI FEL photon beam (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Raimondi, Lorenzo; Mahne, Nicola; Manfredda, Michele; Svetina, Cristian; Cocco, Daniele; Capotondi, Flavio; Pedersoli, Emanuele; Kiskinova, Maya; Zangrando, Marco

    2016-09-01

    FERMI is the first seeded EUV-SXR free electron laser (FEL) user facility, and it is operated at Elettra Sincrotrone Trieste. Two of the four already operating beamlines, namely LDM (Low Density Matter) and DiProI (Diffraction and Projection Imaging), use a Kirkpatrick-Baez (K-B) active X-ray optics system for focusing the FEL pulses onto the target under investigation. A wafefront sensor is used as diagnostic for the characterization of the focused spot and for the optimization of the parameters of these active optical systems as well. The aim of this work is, first, to describe in detail the optimization procedure using the wavefront sensor through the minimization of the Zernike coefficients, and second, report on the final results obtained on the K-B optical system at the DiProI endstation. The wavefront sensor, mounted out of focus behind the DiProI chamber, allows to compute the intensity distribution of the FEL beam, typically a mix between several modes resulting in a "noisy hyper-Gaussian" intensity profile, and the wavefront residual from ideal propagation shape and after tilt correction. Combining these two measures we can obtain the electric field of the wave out of focus. Propagating back the electric field we reconstruct the focal spot in far field approximation. In this way the sensor works as a diagnostic reconstructing the focal spot. On the other hand, after modelling the electric field with a Zernike polynomial it is easy and fast to optimize the mirror bending and the optical system angles by minimizing the aberrations, quantified in terms of Zernike coefficients. Since each coefficient corresponds to a single parameter, they can be minimized one at the time. Online wavefront measurements have made possible the optimization of the bending acting on the mirror curvature, and of the (pitch and roll) angle positions of the K-B system. From the wavefront measurements we have inferred a focal spot for DiProI of 5.5 μm x 6.2 μm at 32 nm wavelength

  15. A Compact X-Band Linac for an X-Ray FEL

    SciTech Connect

    Adolphsen, Chris; Huang, Zhirong; Bane, Karl L.F.; Li, Zenghai; Zhou, Feng; Wang, Faya; Nantista, Christopher D.; /SLAC

    2011-09-12

    With the growing demand for FEL light sources, cost issues are being reevaluated. To make the machines more compact, higher frequency room temperature linacs are being considered, specifically ones using C-band (5.7 GHz) rf technology, for which 40 MV/m gradients are achievable. In this paper, we show that an X-band (11.4 GHz) linac using the technology developed for NLC/GLC can provide an even lower cost solution. In particular, stable operation is possible at gradients of 100 MV/m for single bunch operation and 70 MV/m for multibunch operation. The concern, of course, is whether the stronger wakefields will lead to unacceptable emittance dilution. However, we show that the small emittances produced in a 250 MeV, low bunch charge, LCLS-like S-band injector and bunch compressor can be preserved in a multi-GeV X-band linac with reasonable alignment tolerances. The successful lasing and operation of the LCLS [1] has generated world-wide interest in X-ray FELs. The demand for access to such a light source by researchers eager to harness the capabilities of this new tool far exceeds the numbers that can be accommodated, spurring plans for additional facilities. Along with cost, spatial considerations become increasingly important for a hard X-ray machine driven by a multi-GeV linac. The consequent need for high acceleration gradient focuses attention on higher frequency normal conducting accelerator technology, rather than the superconducting technology of a soft X-ray facility like FLASH. C-band technology, such as used by Spring-8, is a popular option, capable of providing 40 MV/m. However, more than a decade of R&D toward an X-band linear collider, centered at SLAC and KEK, has demonstrated that this frequency option can extend the gradient reach to the 70-100 MV/m range. The following design and beam dynamics calculations show an X-band linac to be an attractive choice on which to base an X-ray FEL.

  16. Understanding Visible Perception

    NASA Technical Reports Server (NTRS)

    2003-01-01

    One concern about human adaptation to space is how returning from the microgravity of orbit to Earth can affect an astronaut's ability to fly safely. There are monitors and infrared video cameras to measure eye movements without having to affect the crew member. A computer screen provides moving images which the eye tracks while the brain determines what it is seeing. A video camera records movement of the subject's eyes. Researchers can then correlate perception and response. Test subjects perceive different images when a moving object is covered by a mask that is visible or invisible (above). Early results challenge the accepted theory that smooth pursuit -- the fluid eye movement that humans and primates have -- does not involve the higher brain. NASA results show that: Eye movement can predict human perceptual performance, smooth pursuit and saccadic (quick or ballistic) movement share some signal pathways, and common factors can make both smooth pursuit and visual perception produce errors in motor responses.

  17. Understanding Visible Perception

    NASA Technical Reports Server (NTRS)

    2003-01-01

    One concern about human adaptation to space is how returning from the microgravity of orbit to Earth can affect an astronaut's ability to fly safely. There are monitors and infrared video cameras to measure eye movements without having to affect the crew member. A computer screen provides moving images which the eye tracks while the brain determines what it is seeing. A video camera records movement of the subject's eyes. Researchers can then correlate perception and response. Test subjects perceive different images when a moving object is covered by a mask that is visible or invisible (above). Early results challenge the accepted theory that smooth pursuit -- the fluid eye movement that humans and primates have -- does not involve the higher brain. NASA results show that: Eye movement can predict human perceptual performance, smooth pursuit and saccadic (quick or ballistic) movement share some signal pathways, and common factors can make both smooth pursuit and visual perception produce errors in motor responses.

  18. DEMONSTRATION OF 3D EFFECTS WITH HIGH GAIN AND EFFICIENCY IN A UV FEL OSCILLATOR

    SciTech Connect

    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.

  19. Experience with Multi-Beam and Multi-Beamline FEL-Operation

    NASA Astrophysics Data System (ADS)

    Rönsch-Schulenburg, J.; Faatz, B.; Honkavaara, K.; Kuhlmann, M.; Schreiber, S.; Treusch, R.; Vogt, M.

    2017-07-01

    DESY’s free-electron laser FLASH provides soft X-ray pulses for scientific users at wavelengths down to 4nm simultaneously in two undulator beamlines. They are driven by a common linear superconducting accelerator with a beam energy of up to 1.25 GeV. The superconducting technology allows the acceleration of electron bunch trains of several hundred bunches with a spacing of 1 microsecond or more and a repetition rate of 10 Hz. A fast kickerseptum system directs one part of the bunch train to FLASH1 and the other part to FLASH2 keeping the full 10 Hz repetition rate for both. The unique setup of FLASH allows independent FEL pulse parameters for both beamlines. In April 2016, simultaneous operation of FLASH1 and FLASH2 for external users started. This paper reports on our operating experience with this type of multi-beam, multi-beamline set-up.

  20. Control of linear accelerator noise in the Los Alamos free-electron laser (FEL)

    SciTech Connect

    Lynch, M.T.

    1986-01-01

    The Los Alamos FEL requires tight control of the amplitudes and phases of the fields in two linear accelerator tanks to obtain stable lasing. The accelerator control loops must establish constant, stable, repeatable amplitudes and phases of the rf fields and must have excellent bandwidth to control high-frequency noise components. A model of the feedback loops has been developed that agrees well with measurements and allows easy substitution of components and circuits, thus reducing breadboarding requirements. The model permits both frequency and time-domain analysis. This paper describes the accelerator control scheme and our model and discusses the control of noise in feedback loops, showing how low-frequency-noise components (errors) can be corrected, but high-frequency-noise components (errors) are actually amplified by the feedback circuit. Measurements of noise in both open- and closed-loop modes are shown and comparison is made with results from the model calculations.