FEL2011 - Table of Session: WEOB (Seeded FEL)

Paper

Title

Page

WEOBI1

FEL Commissioning at FERMI@Elettra

E. Allaria, P. Craievich, S. Di Mitri, W.M. Fawley, L. Fröhlich, G. Penco, C. Spezzani, M. Trovò
ELETTRA, Basovizza, Italy
G. De Ninno, S. Spampinati
University of Nova Gorica, Nova Gorica, Slovenia
L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy

The FERMI@Elettra Free Electron Laser (FEL) produced the first coherent photons in December 2010 at the end of the first commissioning phase. Starting from February 2011 the commissioning has continued, leading to an improvement of the FEL performance. In agreement with to the design, FEL-1, the first of the two FERMI free electron lasers, has been producing coherent FEL pulses in the 60 to 20 nm wavelength range. Benefits of the seeded scheme adopted for FERMI have been immediately evident also in the case of a non-optimized electron beam.

Slides WEOBI1 [4.528 MB]

WEOB3

Seeding Experiments at SPARC

M. Labat, F. Briquez, M.-E. Couprie
SOLEIL, Gif-sur-Yvette, France
D. Alesini, M. Bellaveglia, M. Castellano, E. Chiadroni, G. Di Pirro, A. Drago, M. Ferrario, L. Ficcadenti, A. Gallo, G. Gatti, A. Ghigo, E. Pace, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
A. Bacci, V. Petrillo, A.R. Rossi, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
M. Bougeard, B. Carré, D. Garzella
CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
F. Ciocci, G. Dattoli, M. Del Franco, L. Giannessi, A. Petralia, M. Quattromini, C. Ronsivalle, E. Sabia, I.P. Spassovsky, V. Surrenti
ENEA C.R. Frascati, Frascati (Roma), Italy
L. Cultrera
CLASSE, Ithaca, New York, USA
D. Filippetto
LBNL, Berkeley, California, USA
F. Frassetto, L. P. Poletto
LUXOR, Padova, Italy
G. Lambert
LOA, Palaiseau, France
G. Marcus, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
M. Migliorati, A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy
J.V. Rau
ISM-CNR, Rome, Italy
M. Serluca
INFN-Roma, Roma, Italy
C. Vicario
PSI, Villigen PSI, Switzerland

The SPARC FEL amplifier has been configured as a single stage HGHG FEL with a modulator and a radiator operating at the second harmonic. The HGHG cascade has been seeded with harmonics generated in a gas cell where a Ti:Sa laser pulse of 120 fs of duration is converted into higher harmonics. The cascaded FEL configuration obtained by tuning the undulator gaps has been studied by varying the number of modulators and radiators to optimize the conversion efficiency. The process of harmonic generation in a free electron laser operating in superradiant regime has been also analysed. Harmonic generation is expected to be efficient because of the quasi steady-state distribution of the e-beam phase space predicted in this regime. Harmonics up to the 11th have been experimentally observed.

Slides WEOB3 [5.198 MB]

WEOB4

Demonstration of High Harmonics from Echo-enabled Harmonic Generation with Small Energy Modulation

D. Xiang
SLAC, Menlo Park, California, USA

Funding: This work was supported by the US DOE under Contract No. DE-AC02-76SF00515.
5th harmonic from EEHG has been observed at SLAC's NLCTA [1], yet with energy modulation amplitudes about 80 times larger than beam slice energy spread. While the experiment demonstrated that long-term memory of phase space correlations could be preserved, it was incapable of providing insight into the underlying physics of EEHG that high harmonics can be generated with small energy modulation. Here we report generation of the 7th harmonic from EEHG technique in realistic scenarios where the laser energy modulation is comparable to the beam slice energy spread. The experiment demonstrates the supreme up-frequency conversion efficiency of EEHG technique and indicates that scaling to X-ray wavelength may be possible.
[1] D. Xiang et al., Phys. Rev. Lett, 105, 114801 (2010).

Slides WEOB4 [0.981 MB]