Experimental Study of the FEL with a Tapered Undulator and Numerical Simulations of Short Pulse Free Electron Lasers

Experimental Study of the FEL with a Tapered Undulator and Numerical Simulations of Short Pulse Free Electron Lasers PDF Author: Sergiy Khodyachykh
Publisher:
ISBN:
Category :
Languages : en
Pages : 84

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Experimental Study of the FEL with a Tapered Undulator and Numerical Simulations of Short Pulse Free Electron Lasers

Experimental Study of the FEL with a Tapered Undulator and Numerical Simulations of Short Pulse Free Electron Lasers PDF Author: Sergiy Khodyachykh
Publisher:
ISBN:
Category :
Languages : en
Pages : 84

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Experimental Investigation of Superradiance in a Tapered Free-Electron Laser Amplifier

Experimental Investigation of Superradiance in a Tapered Free-Electron Laser Amplifier PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
We report experimental studies of the effect of undulator tapering on superradiance in a single-pass high-gain free-electron laser (FEL) amplifier. The experiments were performed at the Source Development Laboratory (SDL) of National Synchrotron Light Source (NSLS). Efficiency was nearly tripled with tapering. Both the temporal and spectral properties of the superradiant FEL along the uniform and tapered undulator were experimentally characterized using frequency-resolved optical gating (FROG) images. Numerical studies predicted pulse broadening and spectral cleaning by undulator tapering Pulse broadening was experimentally verified. However, spectral cleanliness degraded with tapering. We have performed first experiments with a tapered undulator and a short seed laser pulse. Pulse broadening with tapering expected from simulations was experimentally confirmed. However, the experimentally obtained spectra degraded with tapering, whereas the simulations predicted improvement. A further numerical study is under way to resolve this issue.

High Efficiency, High Brightness X-ray Free Electron Laser Pulses Via Fresh Bunch Self-seeding and Undulator Tapering

High Efficiency, High Brightness X-ray Free Electron Laser Pulses Via Fresh Bunch Self-seeding and Undulator Tapering PDF Author: CLAUDIO EMMA
Publisher:
ISBN:
Category :
Languages : en
Pages : 193

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The advent of the X-ray Free Electron Laser (XFEL) as the world's brightest light source has opened the door to the study of natural phenomena occurring on Angstrom level spatial scales and femtosecond time intervals. After more than five years of successful operation, there is a demand from the scientific community to further increase the brightness and peak power one hundred times more than the state-of-the art to reach TW power X-ray pulses in the next generation of XFELs. The central subject of this dissertation is the study of strategies to achieve high efficiency, high power XFEL pulses via optimized undulator tapering and the novel technique of fresh bunch self-seeding which we demonstrate experimentally in this work. Our work begins with theoretical and numerical investigations of high efficiency XFELs in which we determine the primary factors which prevent the efficiency from reaching values on the order of 10 %, which correspond to TW-power pulses. The initial studies focus on the dependence of the peak power of a TW-level self-seeded tapered XFEL on the transverse electron distribution. We show via numerical simulations that more uniform transverse distributions (parabolic or flat) can increase the efficiency compared to transversely Gaussian beams from 2.8 % to 4.8 %, corresponding to an increase in peak power from 1.6 TW to 2.6 TW in a 200 m undulator. These numerical studies emphasize the contribution of two physical phenomena, diffraction and the synchrotron sideband instability, as the primary obstacles to reaching TW peak power in a compact undulator system. To circumvent these issues we propose two improvements for high extraction efficiency tapered XFELs: a new development in FEL hardware through the proposal of an Advanced Gradient Undulator (AGU), and a new technique for the efficient generation of high power XFEL radiation which we name fresh bunch self-seeding. We analyze in detail the performance of a high efficiency AGU by carrying out the first dedicated comparative numerical optimization study of a tapered FEL including and intentionally disabling time dependent effects. Combining the AGU design with an optimized undulator taper and a fresh bunch self-seeded system yields a peak efficiency in simulation of 12 % with 6.3 TW of peak power in a 100 m undulator. Following the numerical and theoretical studies of tapered XFELs, the remainder of the work describes the first experimental demonstration of fresh bunch self seeding in an XFEL. With this scheme we are able to generate high power (50 GW) narrow bandwidth ($\delta \omega/\omega_0=8\times 10^{-5}$) short X-ray pulses ($\delta t

Free Electron Lasers 2000

Free Electron Lasers 2000 PDF Author: V.N. Litvinenko
Publisher: Gulf Professional Publishing
ISBN: 9780444509390
Category : Medical
Languages : en
Pages : 790

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Book Description
The 22nd International Free Electron Laser Conference and 7th FEL User Workshop were held August 13-18, 2000 at Washington Duke Inn and Golf Club in Durham, North Carolina, USA. The conference and the workshop were hosted by Duke University's Free Electron laser (FEL) Laboratory. Following tradition, the FEL prize award was announced at the banquet. The year 2000 FEL prize was awarded to three scientists propelling the limits of high power FELs: Steven Benson, Eisuke Minehara and George Neill. The conference program was comprised of traditional oral sessions on First Lasing, FEL theory, storage ring FELs, linac and high power FELs, long wavelength FELs, SASE FELs, accelerator and FEL physics and technology, and new developments and proposals. Two sessions on accelerator and FEL physics and technology reflected the emphasis on the high quality of accelerators and components for modern FELs. The breadth of the applications was presented in the workshop oral sessions on materials processing, biomedical and surgical applications, physics and chemistry as well as on instrumentation and methods for FEL applications. A special oral session was dedicated to FEL center status reports for users to learn more about the opportunities with FELs. As usual, the oral sessions were supplemented by poster sessions with in-depth discussions and communications. The FEL physicists and FEL users had excellent opportunities to interact throughout the duration of the event, culminating a Joint Sessions. The year 2000 was very successful being marked by lasing with two SASE and one storage ring short-wavelength FELs, and by the first human surgery with the use of FEL, to mention but a few. The International Program Committee and chairs of the sessions had the challenging and exciting problem of selecting invived and contributed talks for the conferences and the workshop from the influx of abstracts mentioning new results and ideas. The success of the conference was determined by these contributions. Scientists from 15 countries gave 70 talks, presented 176 posters and submitted 146 papers, which are published in the present volume of proceedings.

Free Electron Lasers 2002

Free Electron Lasers 2002 PDF Author: K.-J. Kim
Publisher: Newnes
ISBN: 0080930425
Category : Science
Languages : en
Pages : 727

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Book Description
This book contains the Proceedings of the 24th International Free Electron Laser Conference and the 9th Free Electron Laser Users Workshop, which were held on September 9-13, 2002 at Argonne National Laboratory. Part I has been reprinted from Nucl. Instr. and Meth. A 507 (2003), Nos. 1-2.

Multimode Simulations of Free Electron Lasers

Multimode Simulations of Free Electron Lasers PDF Author: Joseph Blau
Publisher:
ISBN: 9781423510802
Category : Free electron lasers
Languages : en
Pages : 118

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Book Description
The results of theoretical research on Free Electron Lasers (FELs) are presented. Basic FEL physics is reviewed, using a previously developed classical theory. Numerical simulations based on this theory are described, and numerous examples show how they have been used to increase understanding of existing FELs and to help plan new experiments. Single-mode simulations that follow the evolution of a single-frequency plane wave provide insight into important physical effects in FELs. Results show how these simulations are used to evaluate new FEL designs such as inverse-tapered and step-tapered undulators. Longitudinal multimode simulations model plane waves using finite-length electron and optical pulses. These simulations are used to study coherence evolution in various FEL designs, and to explain effects such as limit-cycle behavior. Transverse multimode simulations that allow for the finite transverse dimensions of the optical wavefronts include the effects of optical mode distortion. These simulations are currently being used to design short Rayleigh length optical cavities that are less sensitive to mirror damage. Four- dimensional simulations are also described, which follow the optical wavefront in x, y, z, and t, including the effects of multiple longitudinal and transverse modes. These simulations are computationally intensive, but may play an important role in the design of future high-power FELs.

The Physics of Free Electron Lasers

The Physics of Free Electron Lasers PDF Author: E.L. Saldin
Publisher: Springer Science & Business Media
ISBN: 3662040662
Category : Technology & Engineering
Languages : en
Pages : 470

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Book Description
The Free Electron Laser (FEL) will be a crucial tool for research and industrial applications. This book describes the physical fundamentals of FELs on the basis of classical mechanics, electrodynamics, and the kinetic theory of charged particle beams, and will be suitable for graduate students and scientists alike. After a short introduction, the book discusses the theory of the FEL amplifier and oscillator, diffraction effects in the amplifier, and waveguide FEL.

Free Electron Lasers - Proceedings Of The Beijing Fel Seminar

Free Electron Lasers - Proceedings Of The Beijing Fel Seminar PDF Author: Jiaer Chen
Publisher: World Scientific
ISBN: 981465678X
Category :
Languages : en
Pages : 482

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Book Description
At this International Seminar, the six invited speakers presented several lectures each on current FEL research. The volume contains papers on the theory and experimental research done on the oscillator, including the Los Alamos, Stanford/TRW program and recent important achievements on Induction FEL at Lawrence Livermore.

Theoretical and Experimental Studies on Novel High-Gain Seeded Free-Electron Laser Schemes

Theoretical and Experimental Studies on Novel High-Gain Seeded Free-Electron Laser Schemes PDF Author: Chao Feng
Publisher: Springer
ISBN: 3662490668
Category : Science
Languages : en
Pages : 118

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Book Description
This dissertation focuses on the study of novel high-gain free-electron laser (FEL) operation schemes with external seed lasers. The technique of manipulating the phase space of the electron beam, which is widely used in novel seeded FEL schemes, is systematically studied. Several novel FEL schemes are proposed for the generation of intense coherent FEL pulses with short wavelength, sub-femtosecond pulse length or multiple carrier frequency properties, which meet the needs of FEL users. Results of experiments are described for the recently proposed FEL schemes such as echo-enabled harmonic generation and cascaded high-gain harmonic generation. New photon/electron beam diagnostic methods are also developed for these experiments and future high-gain FEL facilities.

Simulations of the TJNAF Free Electron Laser with a Negative Taper and Laser Damage Studies

Simulations of the TJNAF Free Electron Laser with a Negative Taper and Laser Damage Studies PDF Author: Adamantios Christodoulou
Publisher:
ISBN: 9781423532866
Category :
Languages : en
Pages : 111

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Book Description
The Free Electron Laser (FEL) is a candidate for a future close-in weapon system that will provide a longer protective range for missile destruction. The FEL is also tunable to wavelengths that would give good atmospheric transmission and optimal target absorption characteristics at the target. This thesis describes single-mode and multimode simulation results of the Thomas Jefferson National Accelerator Facility (TJNAF) FEL operating at far infrared wavelengths. The TJNAF FEL uses inverse tapering and is driven by 34.5 MeV and 47.5 MeV energy electron pulses. Steady-state power, weak-field steady state gain, electron beam energy spread and optical spectrum widths were explored as a function of the desyncinonism and tapering rate. The simulations described FEL pulse evolution and short pulse effects. The simulation results have been presented at an International Conference held at Duke University, Durham, NC in August 2000. in addition, the results of damage to Slip-cast Fused Silica samples by the TJNAF FEL, with and without the effect of airflow are analyzed. A comparison with older damage experiments was done in order to develop scaling rules in the future.