Keyword: radiation
Paper Title Other Keywords Page
MOBA02 Coherence Limits of X-ray FEL Radiation ion, FEL, electron, photon 5
 
  • M.V. Yurkov, E. Schneidmiller
    DESY, Hamburg, Germany
 
  The most simple and robust technique for production of short wavelength radiation is Self Amplified Spontaneous Emission (SASE) FEL. Amplification process in SASE FELs develops from the shot noise in the electron beam, and powerful radiation is produced by single pass of the electron beam through the undulator. Serving as a seed, shot noise effects impose fundamental limits on the coherence properties of the radiation (both, temporal and spatial). FEL theory reached mature status allowing elegant description of the shot noise phenomena, and in this report we present relevant overview.  
slides icon Slides MOBA02 [2.606 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOBA02  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOP010 Constraints on Pulse Duration Produced by Echo-Enabled Harmonic Generation ion, laser, electron, undulator 46
 
  • G. Penn
    LBNL, Berkeley, California, USA
  • B.W. Garcia, E. Hemsing, G. Marcus
    SLAC, Menlo Park, California, USA
 
  Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract Nos. DE-AC02-05CH11231 and DE-AC02-76SF00515.
Echo-enabled harmonic generation (EEHG) is well-suited for producing long, coherent pulses at high harmonics of seeding lasers. There have also been schemes proposed to adapt EEHG to output extremely short, sub-fs pulses by beam manipulations or through extremely short seed lasers, but the photon flux is generally lower than that produced by other schemes. For the standard EEHG layout, it is still interesting to consider different parameter regimes and evaluate how short a pulse can be generated. EEHG at high harmonics uses a large dispersive chicane which can change the relative distance of electrons by substantial distances, even longer than a typical FEL coherence length. We evaluate the ability to produce short pulses (in the femtosecond to 10-fs range) using a combination of theory and simulations.
 
poster icon Poster MOP010 [0.451 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP010  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOP013 Hundred-Gigawatt X-Ray Self-Seeded High-Gain Harmonic Generation ion, FEL, undulator, electron 53
 
  • L. Zeng, S. Huang, K.X. Liu, W. Qin, G. Zhao
    PKU, Beijing, People's Republic of China
  • Y. Ding, Z. Huang
    SLAC, Menlo Park, California, USA
 
  Self-seeded high-gain harmonic generation is a possible way to extend the wavelength of a soft x-ray free-electron laser (FEL). We have carried out simulation study on harmonic generation within the photon energy range from 2 keV to 4.5 keV, which is difficult to achieve due to a lack of monochromator materials. In this work, we demonstrate the third harmonic FEL with the fundamental wavelength at 1.52 nm. Our results shows that, by using undulator tapering technique, sub-terawatt narrow-bandwidth FEL output can be obtained.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP013  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOP014 Harmonic Lasing Towards Shorter Wavelengths in Soft X-Ray Self-Seeding FELs ion, FEL, undulator, photon 57
 
  • L. Zeng, S. Huang, K.X. Liu, W. Qin, G. Zhao
    PKU, Beijing, People's Republic of China
  • Y. Ding, Z. Huang
    SLAC, Menlo Park, California, USA
 
  In this paper, we study a simple harmonic lasing scheme to extend the wavelength of X-ray self-seeding FELs. The self-seeding amplifier is comprised of two stages. In the first stage, the fundamental radiation is amplified but well restricted below saturation, and simultaneously harmonic radiation is generated. In the second stage, the fundamental radiation is suppressed while the harmonic radiation is amplified to saturation. We performed a start-to-end simulation to demonstrate third harmonic lasing in a soft x-ray self-seeding FEL at the fundamental wavelength of 1.52 nm. Our simulations show that a stable narrow-band FEL at GW levels can be obtained.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP014  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOP023 Two-Color Soft X-Ray Generation at the SXFEL User Facility Based on the EEHG Scheme ion, FEL, laser, electron 84
 
  • Z. Qi, C. Feng, B. Liu, W.Y. Zhang, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
 
  We study the two-color soft x-ray generation at the Shanghai soft X-ray Free Electron Laser (SXFEL) user facility based on the echo-enabled harmonic generation (EEHG) scheme. Using the twin-pulse seed laser with different central wavelengths, an preliminary simulation result indicates that two-color soft x-ray FEL radiation with wavelengths at 8.890 nm and 8.917 nm can be obtained from the ultraviolet seed laser. The radiation power is about 600 MW and the time delay is adjustable.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP023  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOP024 Simulation and Optimization for Soft X-Ray Self-Seeding at SXFEL User Facility ion, simulation, FEL, undulator 87
 
  • K.Q. Zhang, C. Feng, D. Wang, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
 
  The simulation and optimization studies for the soft x-ray self-seeding experiment at SXFEL have been presented in this paper. Some critical physical problems have been intensively studied to help us obtain a more stable output and a clearer spectrum. The monochromator is optimized considering various unideal conditions such as the reflection rate, diffraction rate and the roughness of the grating and the mirrors. An integrated self-seeding simulation is also presented. The calculation and simulation results show that the properties of the self-seeding can be significantly improved by using the optimized design of the whole system and the evaluation of grating monochromator shows that the presented design is reliable for soft x-ray self-seeding experiment at SXFEL.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP024  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOP027 Seeding of Electron Bunches in Storage Rings ion, electron, laser, storage-ring 94
 
  • S. Khan, B. Büsing, N.M. Lockmann, C. Mai, A. Meyer auf der Heide, R. Niemczyk, B. Riemann, B. Sawadski, M. Suski, P. Ungelenk
    DELTA, Dortmund, Germany
 
  Funding: Funded by BMBF (05K16PEA), MERCUR (Pr-2014-0047), DFG (INST 212/236-1 FUGG) and the Land NRW.
Seeding schemes for free-electron lasers (FELs) can be adopted to generate ultrashort radiation pulses in storage rings by creating laser-induced microbunches within a short slice of a long electron bunch giving rise to coherent emission at harmonics of the seed wavelength. In addition, terahertz (THz) radiation is produced over many turns. Even without FEL gain, a storage ring is an excellent testbed to study many aspects of seeding schemes and short-pulse diagnostics, given the high repetition rate and stability of the electron bunches. At DELTA, a storage ring operated by the TU Dortmund University in Germany, coherent harmonic generation (CHG) with single and double 40-fs pulses is performed at seed wavelengths of 800 nm or 400 nm. Seeding with intensity-modulated 10-ps pulses is also studied generating tunable narrowband THz radiation. As a preparation for echo-enabled harmonic generation (EEHG), simultaneous seeding with 800/400-nm pulses in two different undulators is performed and several techniques are employed to ensure optimum timing between the seed pulses. The paper describes these experiments and gives an outlook of future applications of seeding at storage rings.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP027  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOP032 Reverse Undulator Tapering for Polarization Control and Background-Free Harmonic Production in XFELs: Results from FLASH ion, undulator, FEL, background 106
 
  • E. Schneidmiller, M.V. Yurkov
    DESY, Hamburg, Germany
 
  Baseline design of a typical X-ray FEL undulator assumes a planar configuration which results in a linear polarization of the FEL radiation. However, many experiments at X-ray FEL user facilities would profit from using a circularly polarized radiation. As a cheap upgrade, one can consider an installation of a short helical afterburner, but then one should have an efficient method to suppress powerful linearly polarized background from the main undulator. There is an efficient method for such a suppression: an application of the reverse taper in the main undulator.* In this contribution, we present the results of experiments with reverse taper at FLASH2 where a high contrast between FEL intensities from the afterburner and from the reverse-tapered main undulator was demonstrated. Another important application of the reverse taper is a possibility to produce FEL harmonics in the afterburner (or in the last part of baseline gap-tunable undulator). We present recent results from FLASH2 where the second and the third harmonics were efficiently generated with a low background at the fundamental.
* E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST Accel. Beams 13-080702 (2013).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP032  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOP035 Optimum Undulator Tapering of SASE FEL: Theory and Experimental Results From FLASH2 ion, undulator, FEL, electron 113
 
  • E. Schneidmiller, M.V. Yurkov
    DESY, Hamburg, Germany
 
  Optimization of the amplification process in FEL amplifier with diffraction effects taken into account results in a specific law of the undulator tapering.* It is a smooth function with quadratic behavior in the beginning of the tapering section which transforms to a linear behavior for a long undulator. In practice, an undulator consists of a sequence of modules of fixed length separated with intersections. Two modes of undulator tapering can be implemented: step tapering and smooth tapering. Step tapering uses a step change of the undulator gap from module to module, while smooth tapering assumes additional linear change of the gap along each module. In this report, we simulate the performance of both experimental options and compare with theoretical limit.
* E.A. Schneidmiller and M.V. Yurkov, Optimization of a high efficiency free electron laser amplifier, Phys. Rev. ST Accel. Beams 18-030705 (2015).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP035  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOP036 Frequency Doubling Mode of Operation of Free Electron Laser FLASH2 ion, undulator, electron, operation 117
 
  • M. Kuhlmann, E. Schneidmiller, M.V. Yurkov
    DESY, Hamburg, Germany
 
  We report on the results of the first operation of a frequency doubler at free electron laser FLASH2. The scheme uses the feature of the variable-gap undulator. The undulator is divided into two parts. The second part of the undulator is tuned to the double frequency of the first part. The amplification process in the first undulator part is stopped at the onset of the nonlinear regime, such that nonlinear higher-harmonic bunching in the electron beam density becomes pronouncing, but the radiation level is still small to disturb the electron beam significantly. The modulated electron beam enters the second part of the undulator and generates radiation at the second harmonic. A frequency doubler allows operation in a two-color mode and operation at shorter wavelengths with respect to standard SASE scheme. Tuning of the electron beam trajectory, phase shifters and compression allows tuning of intensities of the first and the second harmonic. The shortest wavelength of 3.1 nm (photon energy 400 eV) has been achieved with a frequency doubler scheme, which is significantly below the design value for the standard SASE option.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP036  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOP047 Design Calculation on Beam Dynamics and THz Radiation of Delhi Light Source ion, undulator, electron, simulation 153
 
  • V.J. Joshi, R.K. Bhandari, S. Ghosh, D. Kanjilal, B. Karmakar, J. Karmakar, N. Kumar, S. Tripathi
    IUAC, New Delhi, India
  • A. Aryshev
    KEK, Ibaraki, Japan
  • U. Lehnert
    HZDR, Dresden, Germany
 
  Funding: This project is jointly supported by Inter University Accelerator Center and Board of Research in Nuclear Science.
The development of a compact light source facility, Delhi Light Source (DLS), based on a pre-bunched free electron laser, has been initiated at Inter University Accelerator Centre (IUAC).* A photocathode-based normal conducting RF gun will generate a low-emittance 'comb' electron beam with a maximum energy of ~8 MeV which when injected into ~ 1.5 metre compact undulator magnet (~0.4 < Krms < ~2) will produce intense THz radiation in the frequency range of 0.15 THz to 3.0 THz.** Each microbunch of the electron beam is expected to emit super-radiant radiation, and an enhancement in the overall spectral power can be achieved if the frequency (inverse of the spatial separation) of the electron microbunches coincides with that of the THz radiation being emitted. There will be provisions to vary the spatial separation between the successive microbunches of the 'comb' beam so that by varying the undulator magnetic field and/or electron energy, the THz frequency range can be tuned. The results of the beam optics for the entire range of frequencies mentioned above along with the detailed information of the radiation to be generated from the facility will be presented in the paper.
* S. Ghosh et al., NIMB-2017, in press.
** S.Tripathi et al., Proc. of this conference.
 
poster icon Poster MOP047 [0.959 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP047  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOP049 Development of Compact THz Coherent Undulator Radiation Source at Kyoto University ion, undulator, electron, detector 158
 
  • S. Krainara, T. Kii, H. Ohgaki, H. Zen
    Kyoto University, Kyoto, Japan
  • S. Suphakul
    Chiang Mai University, Chiang Mai, Thailand
 
  A new THz Coherent Undulator Radiation (THz-CUR) source has been developed to generate intense quasi-monochromatic THz radiation at the Institute of Advanced Energy, Kyoto University. The system consists of a photocathode RF gun, bunch compression chicane, quadrupole magnets, and short planar undulator. The total length of this system is around 5 meters. At present, this compact accelerator has successfully started giving the THz-CUR in the frequency range of 0.16 - 0.65 THz. To investigate the performance of the source, the relationship between the total radiation energy, peak power and power spectrum as a function of bunch charge at the different undulator gaps were measured. The results are reported in the paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP049  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOP052 First Observation of Coherent THz Undulator Radiation Driven by NSRRC High Brightness Photo-Injector ion, undulator, electron, linac 170
 
  • M.C. Chou, K.T. Hsu, S.Y. Hsu, N.Y. Huang, C.-S. Hwang, J.-Y. Hwang, J.C. Jan, C.K. Kuan, W.K. Lau, A.P. Lee, C.C. Liang, G.-H. Luo, I.C. Sheng
    NSRRC, Hsinchu, Taiwan
  • Y.H. Wen
    NTHU, Hsinchu, Taiwan
 
  Generation and characterization of coherent undulator radiation in the THz region using the NSRRC S-band photo-injector linac system is achieved. The system consists of a laser photocathode RF gun and one 5.2-m long S-band accelerating linac. Electron bunches in the linac can be accelerated and compressed simultaneously by velocity bunching. In this work, narrow-band tunable fully-coherent THz radiation can be produced from a U100 planar undulator when it is driven by a 100 pC electron bunch with effective bunch length of 90 fs. The experimental setup and the measurement of the power and the frequency spectrum of the coherent THz undulator radiation are reported.  
poster icon Poster MOP052 [2.116 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP052  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOP053 High Spectral Density Compton Back-Scattered Gamma-Ray Sources at Fermilab ion, electron, laser, photon 174
 
  • D. Mihalcea, A. Khizhanok, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • B.T. Jacobson, A.Y. Murokh
    RadiaBeam, Santa Monica, California, USA
  • P. Piot, J. Ruan
    Fermilab, Batavia, Illinois, USA
 
  A ~1 MeV gamma-ray source is planned to be built at Fermilab following the completion of the ~300 MeV superconducting linac. The high-energy photons are back-scattered from the interactions between electrons and high-intensity IR laser pulses. In this contribution, we discuss some of the experiment design challenges and evaluate the performances of the gamma-ray source. We expect the peak brilliance to be of the order of 1022 photons/s-(mm-mrad)2-0.1\% BW and the spectral density of the radiation in excess of 3x105 photons/s/eV.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP053  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOP056 Design of Apparatus for a High-Power-Density Diamond Irradiation Endurance Experiment for XFELO Applications ion, vacuum, detector, scattering 185
 
  • S.P. Kearney, K.-J. Kim, T. Kolodziej, R.R. Lindberg, D. Shu, Yu. Shvyd'ko, D. Walko, J. Wang
    ANL, Argonne, Illinois, USA
  • S. Stoupin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
We have designed a diamond irradiation setup capable of achieving multiple kW/mm2 power density. The setup was installed at the 7-ID-B beamline at the Advanced Photon Source (APS) for a successful irradiation experiment, testing the capability of diamond to endure x-ray free electron laser oscillator (XFELO) levels of irradiation (≥ 10 kW/mm2) without degradation of Bragg reflectivity.* Focused white-beam irradiation (50 μm x 20 μm spot size at 12.5 kW/mm2 power density) of a diamond single crystal was conducted in a vacuum environment of 1x10-8 Torr for varying durations of time at different spots on the diamond, and also included one irradiation spot during a spoiled vacuum environment of 4x10-6 Torr. Here we present the apparatus used to irradiate the diamond consisting of multiple subassemblies: the fixed masks, focusing optics, gold-coated UHV irradiation chamber, water-cooled diamond holder, chamber positioning stages (with sub-micron resolution) and detector.
* T. Kolodziej et al., Free Electron Laser Conf. 2017.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-MOP056  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUC02 Thermal and Mechanical Stability of Bragg Reflectors under Pulsed XFEL Radiation ion, FEL, laser, photon 240
 
  • I. Bahns, C.P. Maag, J. Roßbach, P. Thiessen
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • H. Sinn, V. Sleziona
    XFEL. EU, Hamburg, Germany
  • J. Zemella
    DESY, Hamburg, Germany
 
  Funding: BMBF FKZ 05K16GU4
Free-electron laser(FEL) x-ray radiation can deliver pulses with a huge amount of energy in short time duration. X-ray optics like Bragg reflectors therefore must be chosen in a way that they can withstand radiation-material interaction without getting damaged so that they can maintain their technical functionality. Therefore thermal and mechanical reactions of Bragg reflectors to the radiation induced thermal strain and force (radiation pressure) have been considered in this study. The theory of thermoelasticity has been used to simulate the strain conditions at saturation of the amplifying process in an X-ray free-electron laser oscillator(XFELO). One aim of this study was to investigate, if the radiation pressure could be an effect that gives a considerable contribution to the strain propagation. The results of the simulations have shown that, if Bragg backscattering of the X-ray pulse by a diamond crystal with 99% reflectivity and 1% absorptivity is assumed, the value of the thermally induced strain is about two magnitudes higher than the radiation pressure induced strain.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUC02  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUP015 Coherent Transition Radiation from Transversely Modulated Electron Beams ion, electron, experiment, detector 276
 
  • A. Halavanau, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • S.P. Antipov, W. Liu, N.R. Neveu, J.G. Power, C. Whiteford, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • A.I. Benediktovitch
    BSU, Minsk, Belarus, Belarus
  • S.N. Galyamin, A.V. Tyukhtin
    Saint Petersburg State University, Saint Petersburg, Russia
  • D. Mihalcea, P. Piot
    Fermilab, Batavia, Illinois, USA
  • N.R. Neveu
    IIT, Chicago, Illinois, USA
 
  A transverse laser-shaping optical setup using microlens arrays (MLAs), previously developed and employed at Argonne Wakefield Accelerator (AWA), allows the formation of both highly uniform and modulated (patterned) beams. In the latter case, transverse modulation is imposed in the sub-millimeter scale. In the present study, we report the simulations of backward coherent transition radiation (CTR) emitted from a transversely modulated beam. We compare the case of a uniform round beam against different transverse modulation wavelengths by generating CTR on a steel target and measuring the autocorrelation function of the resulting radiation with an interferometer. We particularly focus on the differences between round and patterned beam distributions and discuss possible future applications of this setup in THz radiation generation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP015  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUP024 Stochastic Effects from Classical 3D Synchrotron Radiation ion, electron, simulation, synchrotron 292
 
  • B.W. Garcia, T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
  • R.D. Ryne
    LBNL, Berkeley, California, USA
 
  In most cases, the one-dimensional coherent synchrotron radiation wakefield gives an excellent approximation to the total coherent effect due to classical synchrotron radiation in bend magnets. However, full particle Liénard-Wiechert simulations have revealed that there is non-numerical, stochastic noise which generates fluctuations about the approximate 1D solution. We present a model for this stochastic term in which this noise is due to long-range interaction with a discrete number of synchrotron radiation cones. The nature of this noise and how it depends on the 3D dimensions of the beam are explored.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP024  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUP027 Cancellation of Coherent Synchrotron Radiation Kicks at LCLS ion, emittance, electron, linac 296
 
  • D. Khan, T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
 
  In this paper, we look at the cancellation of Coherent Synchrotron Radiation (CSR) induced emittance growth using a phase-advance manipulation technique pioneered by R. Hajima, and extended in the Courant-Snyder formalism by S. Di Mitri. Bending systems in a linear accelerator are essential for beam transport and bunch compression. With the ever-growing demands of high-energy, short wavelength free electron laser (FEL) drivers, the CSR effect has emerged to be a detrimental factor in emittance stability. Under linear approximation, it is showed that the CSR driven dispersive kicks in successive bending magnet systems can, with proper balancing of the linac optics, cancel each other to nullify transverse emittance growth. This technique of optics balancing in the constant bunch length regime is the focus of this paper. We will present our findings for the emittance measurements generated in Elegant simulations for the current LCLS-I dogleg system.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP027  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUP028 Approximated Expressions for the Coherent Synchrotron Radiation Effect in Bending Magnets ion, electron, FEL, synchrotron 300
 
  • D. Khan, T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
 
  In this paper, we describe the development of simplified analytic expressions for the Coherent Synchrotron Radiation's (CSR) root-mean-square induced energy spread, typically found in the bending magnets of short bunch-length charged particle accelerators. The expressions are derived for a Gaussian longitudinal bunch distribution and compared with the full-rigor CSR wakefield integral expressions while entering, traversing and exiting a bending magnet. The validity of the expressions are then tested against ELEGANT with the simulation of an unchirped beam traveling across a bending magnet into a drift section, and the second stage bunch compressor (BC2) of the proposed LCLS-II beamline.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP028  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUP035 CSR Wake Fields and Emittance Growth with a Discontinuous Galerkin Time Domain Method ion, wakefield, vacuum, synchrotron 317
 
  • D. A. Bizzozero, H. De Gersem, E. Gjonaj
    TEMF, TU Darmstadt, Darmstadt, Germany
 
  Funding: Work supported by DESY.
Coherent synchrotron radiation (CSR) is an essential consideration in modern accelerators and related electromagnetic structures. We present our current method to examine CSR in the time domain. The method uses a 2D Discontinous Galerkin (DG) discretization in the longitudinal and transverse coordinates (z,x) with a Fourier decomposition in the transverse coordinate y. After summation over modes, this treatment describes all electromagnetic field components at each space-time coordinate (z,x,y,t). Additionally, by alignment of mesh element interfaces along a source reference orbit, DG methods can handle discontinuous or thin sources in the transverse x direction. We present an overview of our method, illustrate it by calculating wake functions for a bunch compressor, and discuss a method for estimating emittance growth from the wake fields in future work.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP035  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUP042 Determination of the Slice Energy Spread of Ultra-Relativistic Electron Beams by Scanning Seeded Coherent Undulator Radiation ion, electron, laser, undulator 326
 
  • J. Bödewadt, R.W. Aßmann, C. Lechner, M.M. Mohammad Kazemi
    DESY, Hamburg, Germany
  • L.L. Lazzarino, T. Plath, J. Roßbach
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Modern high-gain free-electron lasers make use of high-brightness ultra-relativistic electron beams. The uncorrelated energy spread of these beams is upon creation of the beam in the sub-permille range and below the resolution of state-of-the-art diagnostics. One method to determine the slice energy spread is to use an external seed laser to imprint a coherent microbunching structure that gives rise to coherent radiation processes, different radiation sources such as transition radiation, synchrotron radiation, or undulator radiation and others. Here, we present a method and show measurements to determine the slice energy spread using an external seed laser with 266 nm wavelength to produce coherent undulator radiation at higher harmonics. The distribution of these harmonics allows retrieval of the electron beam slice energy spread with high precision.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP042  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUP045 Interference-Based Ultrafast Polarization Control at Free Electron Lasers ion, polarization, undulator, electron 329
 
  • S. Serkez, G. Geloni
    XFEL. EU, Schenefeld, Germany
  • E. Saldin
    DESY, Hamburg, Germany
 
  We present a scheme to generate two distinct FEL pulses with different polarization properties and down to 50 fs-order temporal separation. The scheme is based on installation of two consecutive helical undulators, a corrugated structure and emittance spoiler on top of a baseline variable gap undulator, and is exemplified on the SASE3 beamline of the European XFEL. Good temporal coherence by either self or external seeding is preferable. Our schemes can be used for pump-probe experiments and in combination with the "twin-bunch" technique.  
poster icon Poster TUP045 [0.573 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP045  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUP057 Measurement of Short-Wavelength High-Gain FEL Temporal Coherence Length by a Phase Shifter ion, FEL, electron, experiment 344
 
  • G. Zhou
    IHEP, Beijing, People's Republic of China
  • W. Liu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  • W. Qin, T.O. Raubenheimer, J. Wu, C. Yang
    SLAC, Menlo Park, California, USA
  • C.-Y. Tsai
    Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
  • B. Yang
    University of Texas at Arlington, Arlington, USA
  • M. Yoon
    POSTECH, Pohang, Kyungbuk, Republic of Korea
 
  Funding: The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
Short-wavelength high-gain free-electron lasers (FELs) are now well established as a source of ultra-fast, ultra-brightness, longitudinally partial coherent light. Since coherence is one of the fundamental properties of light source, so continual effort is devoted to high-gain free-electron laser coherence measurements. In this work, we propose a possible approach, employing a phase shifter to induce electron beam delay to measure the temporal coherence length. Simple analysis, numerical simulation and preliminary experimental results are presented. This approach can be robust and independent of frequency.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP057  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUP067 Study on Cherenkov Laser Oscillator Using Tilted Electron Bunches ion, electron, experiment, laser 371
 
  • K. Sakaue
    Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
  • M. Brameld, Y. Tadenuma, M. Washio, R. Yanagisawa
    Waseda University, Tokyo, Japan
  • R. Kuroda, Y. Taira
    AIST, Tsukuba, Ibaraki, Japan
  • J. Urakawa
    KEK, Ibaraki, Japan
 
  Funding: This work was supported by a research granted from The Murata Science Foundation and JSPS KAKENHI 26286083.
We have been studying a coherent Cherenkov radiation by using tilted electron bunches. Bunch tilting can enhance the radiation power about 10 times due to the wavefront matching of radiations. Recently, we investigated that this technique can produce high peak power THz pulses with sufficient pulse energy. Resulting pulse energy was more than 30 nJ/pulse and peak power was about 10 kW. Introducing the oscillator cavity with two concave mirrors, it would be possible to achieve lasing using tilted electron bunches. In the calculation, 1 uJ/micro-pulse and 100 uJ/macro-pulse broadband THz pulses are expected to be achieved, which are powerful THz sources compared with the existing THz FELs. In this conference, we will report the experimental results of coherent Cherenkov radiation, calculated results toward lasing and future prospectives.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP067  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUP072 Simulation of Phase Shifters Between FEL Amplifiers in Coherent Electron Cooling ion, FEL, wiggler, electron 386
 
  • Y.C. Jing, V. Litvinenko, I. Pinayev
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
 
  Coherent electron Cooling (CeC) is a proposed advanced beam cooling method that has the potential of reducing the ion beam emittance in significantly shorter amount of time compared to existing cooling methods. A high-gain FEL, composed of three permanent magnet helical wigglers, is acting as an amplifier of the ion's signals picked up by electron beam in CeC. A self-consistent simulation which takes the space and possible phase shifts between wigglers into account is crucial in determining the performance of the FEL. The authors developed an algorithm based on the well-used GENESIS code to properly treat the propagation of particles and radiations in between wigglers and predicted the FEL performance with different beamline layouts. The authors will present their simulation setup and results and provide hardware requirements for future operations and research at CeC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-TUP072  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEP027 Numerical Study of Cherenkov Radiation From Thin Silica Aerogel ion, electron, experiment, diagnostics 479
 
  • H. Hama, K. Nanbu, H. Saito, Y. Saito
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
 
  Funding: This work was supported by JSPS KAKENHI Grant Numbers JP15K13394 and JP17H01070.
Cherenkov radiation (CR) emitted from low-refractive index material such as silica-aerogel is a useful tool for electron beam diagnostics because the opening angle (Cherenkov angle) is small and the CR can be transported onto a detector located far from the radiator. We have prepared a thin (1-mm thick) hydrophobic silica-aerogel with a refractive index of 1.05 that has been developed at Chiba University.* Since the intensity of CR is much stronger than that of optical transition radiation, the CR is a better light source for low-intensity beam diagnostics. In order to apply the CR to measurements of a bunch length of electron beams, we have investigated sources of finite time resolution by a numerical simulation study using the Liénard-Wiechert potentials. We will report results of simulations such as pulse duration of CR and discuss what deteriorates the time resolution.
* M. Tabata et al., Nucl. Instr. and Meth. A 668 (2012) 64.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP027  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEP029 Recent Experimental Results on High-Peak-Current Electron Bunch and Bunch Trains Interacting With a THz Undulator ion, undulator, electron, laser 482
 
  • X.L. Su, Y. C. Du, W. Gai, W.-H. Huang, Y.F. Liang, C.-X. Tang, D. Wang, L.X. Yan
    TUB, Beijing, People's Republic of China
 
  Funding: supported by the National Natural Science Foundation of China (NSFC Grants No. 11475097) and National Key Scientific Instrument and Equipment Development Project of China (Grants No. 2013YQ12034504).
In this paper, experimental results based on THz undulator with widely tunable gap installed at Tsinghua Thomson scattering X-ray (TTX) beamline are introduced. This is a planar permanent magnetic device with 8 regular periods, each 10 cm long. The undulator parameter varies from 9.24-1.39 by changing the magnetic gap from 23mm to 75mm. The coherent undulator radiation can be used as a narrow-band THz source with central frequency ranging from 0.4 THz to 10 THz. The bunch length was figured out from the radiation intensity at different undulator gap, which agreed well with simulations. Furthermore, slice energy modulation was directly observed when high-peak-current bunch trains based on nonlinear longitudinal space charge oscillation passed through the undulator. The demonstrated experiment in THz regime provides a significant scaled tool for FEL mechanism exploration owing to the simplicity of bunch modulation and diagnostics in this range.
* Corresponding author: yanlx@mail.tsinghua.edu.cn
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP029  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEP048 Coherent Undulator Radiation From a Kicked Electron Beam ion, electron, undulator, simulation 515
 
  • J.P. MacArthur, Z. Huang, J. Krzywinski, A.A. Lutman
    SLAC, Menlo Park, California, USA
 
  The properties of off-axis radiation from an electron beam that has been kicked off axis are relevant to recent Delta undualtor experiments at LCLS. We calculate the coherent emission from a microbunched beam in the far-field, and compare with simulation. We also present a mechanism for microbunches to tilt toward a new direction of propagation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP048  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEP054 The Magnetic Field Integral Hysteresis on the European XFEL Gap Movable Undulator Systems ion, undulator, FEL, electron 522
 
  • F. Wolff-Fabris, Y. Li, J. Pflüger
    XFEL. EU, Schenefeld, Germany
 
  The European XFEL GmbH is a new X-ray FEL facility expected to be lasing to users at the end of 2017. Three gap-movable SASE Undulator Systems are designed to produce FELs with tunable wavelengths from 0.05 to 5.2nm.*,** A total of 91 5m long undulator segments and phase shifters were magnetically tuned respecting tight specifications. Magnetic field hysteresis effects due to the gap shift of the Undulator System while changing the FEL radiation wavelength may impact the machine's operational mode. We report on these effects by either opening or closing the gap while performing field integrals measurements with moving wire technique. The undulator segments show negligible magnetic hysteresis and are expected to be operated with no influence to the FEL and beam trajectories in either feed forward or feed backward mode. The phase shifters show first field integrals hysteretic behavior of few G.cm which is comparable in magnitude to the allowed total field integrals and can be associated to the magnetization of the yoke structure. Phase shifters are magnetically tuned for that the feed forward mode (opening gap) fully satisfies the XFEL. EU magnetic specifications for beam operation.
* M. Altarelli et al., Technical Design Rep. DESY 2006-097, July 2007.
** E. Schneidmiller et al., European XFEL Technical Rep. TR-2011-006, Sep. 2011.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP054  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEP056 Effect of Beam Transverse Angle Deflection in TGU on FEL Power ion, electron, FEL, undulator 529
 
  • G. Zhou, J.Q. Wang
    IHEP, Beijing, People's Republic of China
  • J. Wu
    SLAC, Menlo Park, California, USA
 
  Funding: The work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
Recent study shows that electron beams with constant dispersion together with the transverse-gradient undulator (TGU) can reduce the sensitivity to energy spread for free-electron laser (FEL). By inducing dispersion function, electrons with different energy are placed at different positions corresponding to proper magnetic fields. Thus, FEL resonant condition can be kept for electrons with different energy. In this paper, we mainly studied: 1.The effects of electron beam angle deflection at the entrance of the TGU on the radiation power. 2. The utility of a kicker to introduce an angle deflection of electron beam to improve the FEL radiation power.
 
poster icon Poster WEP056 [0.638 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP056  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEP057 Design of a Compact Hybrid Undulator for the THz Radiation Facility of Delhi Light Source (DLS) ion, undulator, electron, FEL 532
 
  • S. Tripathi, R.K. Bhandari, S. Ghosh, D. Kanjilal
    IUAC, New Delhi, India
  • U. Lehnert
    HZDR, Dresden, Germany
  • M. Tischer
    DESY, Hamburg, Germany
 
  Funding: One author, Sumit Tripathi (PH/16-17/0029), would like to acknowledge University Grant Commission (UGC), New Delhi, India for financial support as D.S.Kothari Postdoctoral fellowship.
A compact Free Electron Laser (FEL) facility to produce coherent THz radiation is in the development stage at Inter-University Accelerator Centre (IUAC), New Delhi, India.*,** The name of this facility is Delhi Light Source (DLS) in which a low-emittance electron beam from a photocathode RF gun with a maximum energy of 8 MeV will be injected into a compact undulator magnet to generate THz radiation. To produce the THz radiation in the range of 0.15 to 3.0 THz, the electron beam energy and the undulator gap need to be varied from 4 to 8 MeV and 20 to 45 mm, respectively. The variable gap undulator of 1.5-m length will consist of NdFeB magnets with vanadium permendur poles. The magnet design and dimensions are optimised by using code 3D RADIA.*** The detailed design of the compact hybrid undulator will be presented in this paper.
* S.Ghosh et al., presented at this conference.
** S.Ghosh et al., NIMB-2017 (in press).
*** RADIA. Available at http://www.esrf.eu/Accelerators/ groups/
Insertion Devices/ Software/ Radia.
 
poster icon Poster WEP057 [1.117 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP057  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEP065 Cryogenic Permanent Magnet Undulator for an FEL Application ion, undulator, electron, permanent-magnet 554
 
  • A. Ghaith, T. André, I.A. Andriyash, P. Berteaud, F. Briquez, N. Béchu, M.-E. Couprie, C. Herbeaux, M. Labat, O. Marcouillé, F. Marteau, E. Roussel, M. Sebdaoui, K.T. Tavakoli, M. Tilmont, M. Valléau
    SOLEIL, Gif-sur-Yvette, France
 
  A Cryogenic Permanent Magnet Undulator (CMPU) is capable of achieving high brightness radiation at short wavelengths, by taking advantage of the permanent magnets' enhanced performance at low temperature. A CPMU of period 18 mm (U18) that has been built at Synchrotron SOLEIL is used for the COXINEL project to demonstrate Free Electron Laser (FEL) at 200 nm using a laser plasma acceleration source. Another undulator of period 15 mm (U15) is currently being built to replace U18 undulator for FEL demonstration at 40 nm. A new method is also introduced, using SRWE code, to compute the spectra of the large energy spread beam (few percent) taking into account the variation of the Twiss parameters for each energy slice. The construction of U18 undulator and the magnetic measurements needed for optimization, as well as the mechanical design of U15, are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP065  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEP073 Lie Map Formalism for FEL Simulation ion, undulator, coupling, electron 557
 
  • K. Hwang, J. Qiang
    LBNL, Berkeley, California, USA
 
  Funding: U.S. Department of Energy under Contract No. DE-AC02-05CH11231
Undulator averaging and non-averaging are in compromisation between computational speed and reliability. It is hard to catch the advantages of the both methods simultaneously. In this report, we present a method that compromises the between the averaging and non-averaging methods through Lie map formalism.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP073  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEP074 Simulations of the Dependence of Harmonic Radiation on Undulator Parameters ion, undulator, electron, FEL 560
 
  • G. Penn
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The flux and bandwidth of radiation produced at harmonics of the fundamental are very sensitive to the undulator parameter, and thus the beam energy or undulator period. We look at high-energy XFELs with parameters relevant to the MaRIE FEL design. Both SASE and seeded FELs are considered.
 
poster icon Poster WEP074 [0.414 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP074  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEP078 Period-Averaged Symplectic Maps for the FEL Hamiltonian ion, FEL, electron, wiggler 563
 
  • S.D. Webb
    RadiaSoft LLC, Boulder, Colorado, USA
 
  Funding: This work was carried out with support for the United State Department of Energy, Office of Scientific Research, under SBIR contract number DE-SC0017161.
Conventional treatments of synchrotron radiation in electron beams treat the radiation as a non-Hamiltonian aspect to the beam dynamics. However, the radiation can be modeled with an electromagnetic Hamiltonian. We present a period-averaged treatment of the FEL problem which includes the Hamiltonian aspects of the coupled electron-radiation dynamics. This approach is then applied to two problems: a 3D split-operator symplectic integrator, and a 1D single-mode FEL treated using Hamiltonian perturbation theory.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-WEP078  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
FRB01 Time-Domain Analysis of Attosecond Pulse Generation in an X-Ray Free-Electron Laser ion, FEL, electron, undulator 569
 
  • P. Baxevanis, Z. Huang, A. Marinelli
    SLAC, Menlo Park, California, USA
 
  The method of enhanced self-amplified spontaneous emission (eSASE) is one of the strongest candidates for the generation of sub-femtosecond X-ray pulses in a free-electron laser. The optimization of an eSASE experiment involves many independent parameters, which makes the exploration of the parameter space with 3-D simulations computationally intensive. Therefore, a robust theoretical analysis of this problem is extremely desirable. We provide a self-consistent, analytical treatment of such a configuration using a one-dimensional, time-dependent FEL model that includes the key effects of linear e-beam chirp and linear undulator taper. Verified via comparison with numerical simulation, our formalism is also utilized in parameter studies that seek to determine the optimum setup of the FEL.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-FRB01  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
FRB03 Dynamics of Superradiant Emission by a Prebunched E-Beam and its Spontaneous Emission Self-Interaction ion, electron, wiggler, undulator 572
 
  • R. Ianconescu, A. Gover
    University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
  • C. Emma, P. Musumeci
    UCLA, Los Angeles, USA
  • A. Friedman
    Ariel University, Ariel, Israel
 
  Funding: Partial support by US-Israel Binational Science Foundation (BSF) and by Deutsche-Israelische Projektkooperation (DIP).
In the context of radiation emission from an electron beam, Dicke's superradiance (SR) is the enhanced coherent spontaneous radiation emission from a prebunched beam, and Stimulated-Superradiance (ST-SR) is the further enhanced emission of the bunched beam in the presence of a phase-matched radiation wave.* These processes are analyzed for undulator radiation in the framework of radiation field mode-excitation theory. In the nonlinear saturation regime the synchronicity of the bunched beam and an injected radiation wave may be sustained by wiggler tapering: Tapering-Enhanced Superradiance (TES) and Tapering-Enhanced Stimulated Superradiance Amplification (TESSA).** Identifying these processes is useful for understanding the enhancement of radiative emission in the tapered wiggler section of seeded FELs.***,**** The nonlinear formulation of the energy transfer dynamics between the radiation wave and the bunched beam fully conserves energy. This includes conservation of energy without radiation reaction terms in the interesting case of spontaneous self-interaction (no input radiation).
* A. Gover, Phys. Rev. ST-AB 8, 030701 (2005).
** J. Duris et al., New J.Phys. 17 063036 (2015).
*** E. A. Schneidmiller et al., PRST-AB 18, 03070 (2015).
**** C. Emma et al., this conference.
 
slides icon Slides FRB03 [1.437 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-FRB03  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
FRB04 Canonical Formulation of 1D FEL Theory Revisited, Quantized and Applied to Electron Evolution ion, electron, FEL, undulator 576
 
  • P.M. Anisimov
    LANL, Los Alamos, New Mexico, USA
 
  An original FEL theory relied on quantum analysis of photon generation by relativistic electrons in alternating magnetic field.* In most cases, however, the system of pendulum equations for non-canonical variables and the theory of classical electromagnetism proved to be adequate. As XFELs advance to higher energy photons, quantum effects of electron recoil and shot noise has to be considered. This work presents quantization procedure based on the Hamiltonian formulation of an XFEL interaction in 1D case. The procedure relates the conventional variables to canonical coordinates and momenta and does not require the transformation to the Bambini-Renieri frame.** The relation of a field operator to a photon annihilation operator reveals the meaning of the quantum FEL parameter, introduced by Bonifacio, as a number of photons emitted by a single electron before the saturation takes place.*** The quantum description is then applied to study how quantum nature of electrons affects the startup of XFEL and how quantum electrons become indistinguishable from a classical ensemble of electrons due to their interaction with a ponderomotive potential of an XFEL.
* Madey JMJ 1971 J. Appl. Phys. 42 1906 13.
** Bambini A and Renieri A 1978 Lett. Nuovo Cimento 21 399-404.
*** Bonifacio R, Piovella N, Robb G R M and Schiavi A 2006 PRSTAB 9 090701.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-FRB04  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
FRB05 Wide Bandwidth, Frequency Modulated Free Electron Laser ion, FEL, undulator, electron 581
 
  • L.T. Campbell, B.W.J. MᶜNeil
    USTRAT/SUPA, Glasgow, United Kingdom
 
  The resonant frequency of a free electron laser may be modulated via the undulator or electron beam parameters. This modulation may generate sidebands which can subsequently undergo amplification, analogous to frequency modulation in a conventional cavity laser. However, due to the relative slippage of the light through the relativistic electron beam, the FM-FEL system has a more complex behavior than its conventional laser counterpart. The system may be described in the linear regime by a summation over exponential gain modes, allowing the amplification of multiple light frequencies simultaneously. It is found that, with only small, few percent variations of the FEL parameters, one may generate and amplify multiple modes within a frequency bandwidth which greatly exceeds that of normal FEL operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2017-FRB05  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)