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Title: Operation of the Free-Electron Laser at DESY and First Scientific Experiments

Abstract

The free-electron laser at DESY in Hamburg (FLASH) is the first free-electron laser built for the vacuum-ultraviolet (VUV) and soft X-ray region. It started user operation in summer 2005 and has been operated routinely for scientific experiments at 32 nm wavelength providing up to 150 pulses per second with GW peak power and a pulse duration between 20 and 50 fs. Recently also shorter wavelengths at 25.5 nm and {approx}13 nm have been used for experiments. The FEL beam can be switched between four experimental stations by movable mirrors. A synchronised optical laser system is available for pump-probe experiments. Diagnostics has been implemented to monitor the pulse energy and its timing with respect to the optical laser. The current status of the facility is reviewed and examples of first user experiments are presented.

Authors:
 [1]
  1. Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, D-22607 Hamburg (Germany)
Publication Date:
OSTI Identifier:
21043418
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 879; Journal Issue: 1; Conference: 9. international conference on synchrotron radiation instrumentation, Daegu (Korea, Republic of), 28 May - 2 Jun 2006; Other Information: DOI: 10.1063/1.2436043; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BEAM MONITORING; BEAM PRODUCTION; DESY; FAR ULTRAVIOLET RADIATION; FREE ELECTRON LASERS; LASER RADIATION; MIRRORS; OPERATION; PHOTON BEAMS; PROBES; PULSES; SOFT X RADIATION; WAVELENGTHS; X-RAY DIFFRACTION

Citation Formats

Feldhaus, Josef. Operation of the Free-Electron Laser at DESY and First Scientific Experiments. United States: N. p., 2007. Web. doi:10.1063/1.2436043.
Feldhaus, Josef. Operation of the Free-Electron Laser at DESY and First Scientific Experiments. United States. doi:10.1063/1.2436043.
Feldhaus, Josef. Fri . "Operation of the Free-Electron Laser at DESY and First Scientific Experiments". United States. doi:10.1063/1.2436043.
@article{osti_21043418,
title = {Operation of the Free-Electron Laser at DESY and First Scientific Experiments},
author = {Feldhaus, Josef},
abstractNote = {The free-electron laser at DESY in Hamburg (FLASH) is the first free-electron laser built for the vacuum-ultraviolet (VUV) and soft X-ray region. It started user operation in summer 2005 and has been operated routinely for scientific experiments at 32 nm wavelength providing up to 150 pulses per second with GW peak power and a pulse duration between 20 and 50 fs. Recently also shorter wavelengths at 25.5 nm and {approx}13 nm have been used for experiments. The FEL beam can be switched between four experimental stations by movable mirrors. A synchronised optical laser system is available for pump-probe experiments. Diagnostics has been implemented to monitor the pulse energy and its timing with respect to the optical laser. The current status of the facility is reviewed and examples of first user experiments are presented.},
doi = {10.1063/1.2436043},
journal = {AIP Conference Proceedings},
number = 1,
volume = 879,
place = {United States},
year = {Fri Jan 19 00:00:00 EST 2007},
month = {Fri Jan 19 00:00:00 EST 2007}
}
  • A general theoretical approach based on the decomposition of statistical fields into a sum of independently propagating transverse modes was used for the analysis of the coherence properties of the new free-electron laser source FLASH operated at 13.7 nm wavelength. The analysis shows that several transverse modes are contributing to the total radiation field of FLASH. The results of theoretical calculations are compared with measurements using Young's double-slit experiment. The coherence lengths in the horizontal and in the vertical directions 20 m downstream from the source are estimated at 300 and 250 {mu}m, respectively.
  • We present particle-in-cell simulations for future laser-plasma wakefield experiments with external bunch injection at the REGAE accelerator facility at DESY, Hamburg, Germany. Two effects have been studied in detail: emittance evolution of electron bunches externally injected into a wake, and longitudinal bunch compression inside the wakefield. Results show significant transverse emittance growth during the injection process, if the electron bunch is not matched to its intrinsic betatron motion inside the wakefield. This might introduce the necessity to include beam-matching sections upstream of each plasma-accelerator section with fundamental implications on the design of staged laser wakefield accelerators. When externally injected atmore » the zero-field crossing of the laser-driven wake, the electron bunch may undergo significant compression in longitudinal direction and be accelerated simultaneously due to the gradient in the acting force. The mechanism would allow for production of single high-energy, ultra-short (on the order of one femtosecond) bunches at REGAE. The optimal conditions for maximal bunch compression are discussed in the presented studies.« less
  • A storage-ring free-electron laser oscillator has been operated above threshold at a visible wavelength lambdaapprox. =6500 A.
  • A wiggler-focused, sheet beam free electron laser (FEL) amplifier utilizing a short-period wiggler magnet has been proposed as a millimeter-wave source for current profile modification and/or electron cyclotron resonance heating of tokamak plasmas. As proposed, such an amplifier would operate at a frequency of approximately 100--200 GHz with an output power of 1--10 MW CW. Electron beam energy would be in the range 500--1000 keV. To test important aspects of this concept, an initial sheet beam FEL amplifier experiment has been performed using a 1 mm[times]2 cm sheet beam produced by a pulse line accelerator with a pulse duration ofmore » 100 ns. The 500--570 keV, 4--18 A sheet beam is propagated through a 56 period uniform wiggler ([lambda][sub [ital w]]=9.6 mm) with a peak wiggler amplitude of 2--5 kG. Linear amplification of a 5--10 W, 94 GHz signal injected in the TE[sub 01] rectangular mode is observed. All features of the amplified signal, including pulse shape and duration, are in accordance with the predictions of numerical simulation. Amplified signal gain has been measured as a function of injected beam energy, current, and wiggler field amplitude and is also in good agreement with simulation results. Continuation of this experiment will involve studying nonlinear amplifier operation and adding a section of tapered wiggler.« less