WEOA  —  Seeding and Seeded FELs   (25-Aug-10   08:30—10:00)

Chair: D. Garzella, CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette

Paper Title Page
WEOAI1 Pulse-Splitting in Short Wavelength Seeded Free Electron Laser 329
 
  • M. Labat, M.-E. Couprie
    SOLEIL, Gif-sur-Yvette
  • S. Bielawski, C. Szwaj
    PhLAM/CERCLA, Villeneuve d'Ascq Cedex
  • C. Bruni
    LAL, Orsay
  • N. Joly
    University of Erlangen-Nuremberg, Erlangen-Nuremberg
 
 

We investigate a dynamical behaviors occurring in single-pass free electron lasers (FELs), depending on the electron beam, undulator and seed laser parameters. We put in evidence a complex spatiotemporal deformation of the amplified pulse, leading ultimately to a pulse splitting effect with two sub-pulses. This phenomenon has been first observed in PERSEO simulations in the case of ARC-EN-CIEL project studies, and then been analyzed more in details with the Colson-Bonifacio FEL equations. This studies reveal that slippage length as well as the seed laser pulse wings are the main ingredients of this dynamics [1]. We show that the splitting results from the nonhomogeneous saturation of the gain by the optical field copropagating with the electron beam.


M.Labat et al. “Pulse-splitting in short wavelength seeded free electron laser,” Phys. Rev. Lett. {10}3, 264801 (2009)

 

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WEOAI2 sFLASH - First Results of Direct Seeding at FLASH 330
 
  • J. Bödewadt, A. Azima, F. Curbis, H. Delsim-Hashemi, M. Drescher, E. Hass, U. Hipp, Th. Maltezopoulos, V. Miltchev, M. Mittenzwey, M. Rehders, J. Roßbach, J. Rönsch-Schulenburg, R. Tarkeshian, M. Wieland
    Uni HH, Hamburg
  • S. Bajt, S. Düsterer, J. Feldhaus, K. Honkavaara, T. Laarmann, H. Schlarb
    DESY, Hamburg
  • R. Ischebeck
    PSI, Villigen
  • S. Khan
    DELTA, Dortmund
 
 

The free-electron laser facility FLASH at DESY (Hamburg) was upgraded during a five month shutdown in winter 2009. Part of this upgrade was the installation of a direct seeding experiment in the XUV spectral range. Beside all components for transport and diagnostics of the photon beam in and out of the accelerator environment, a new 10m long variable gap undulator was installed upstream of the existing FLASH undulator system. The seed pulses are generated within a noble gas jet by focusing 40 fs long Ti:Sa laser pulses into it resulting a comb of higher harmonics. In the first phase of the experiment the 21st harmonic of the 800nm drive laser will be used to seed the FEL process. The commissioning of the experiment has started in April and the first results are expected after the FLASH commissioning period mid of summer 2010. The experimental setup and the commissioning procedures as well as first result will be presented.

 

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WEOA3 Commissioning the Echo-Seeding Experiment ECHO-7 at SLAC 336
 
  • S.P. Weathersby, E.R. Colby, M.P. Dunning, A. Gilevich, C. Hast, R.K. Jobe, D.J. McCormick, J. Nelson, T.O. Raubenheimer, K. Soong, G.V. Stupakov, Z.M. Szalata, D.R. Walz, M. Woodley, D. Xiang
    SLAC, Menlo Park, California
  • P.L. Pernet
    EPFL, Lausanne
 
 

ECHO-7 is a proof-of-principle echo-enabled harmonic generation FEL experiment in the Next Linear Collider Test Accelerator (NLCTA) at SLAC. The experiment aims to generate coherent radiation at 318 nm and 227 nm, which are the 5th and 7th harmonic of the infrared seed laser. In this paper we present the experimental results from the commissioning run of the completed experimental setup which started in April 2010.

 

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WEOA4 First Results of Coherent Harmonic Generation at the MAX-Lab Test Fel 340
 
  • S. Werin, N. Čutić, F. Lindau, S. Thorin
    MAX-lab, Lund
  • J. Bahrdt, K. Holldack
    HZB, Berlin
  • C. Erny, A. L'Huillier, E. Mansten
    Lund University, Division of Atomic Physics, Lund
 
 

The first generation of coherent harmonic radiation from the MAX-lab test FEL have recently been achieved. The 380 MeV electron beam has been seeded by a 263 nm Ti:Sapphire laser and coherent radiation in the harmonics 1 to 4 (263 – 66 nm) has been produced both in linear and circular polarization mode. The facility consists of a photo cathode RF gun, the MAX injector (two 95 MeV linacs placed in a recirculator), beam transport including compression optics and the two undulators (modulator and radiator) separated by a four magnet chicane for bunching control. The radiator undulator is of Apple type providing tunable polarization. The basic characterization of the source with dynamic studies of laser energy, undulator gap and chicane influence on the coherent harmonic signal will be reported.

 

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