Author: Mahieu, B.
Paper Title Page
MOP073
 Chirped Pulse Amplification in a Seeded Free-electron Laser: Design of a Test Experiment at FERMI  
 
  • G. De Ninno, E. Allaria, I. Cudin, M.B. Danailov, A.A. Demidovich, S. Di Mitri, E. Ferrari, D. Gauthier, L. Giannessi, N. Mahne, G. Penco, L. Raimondi, P. Rebernik Ribič, C. Spezzani, L. Sturari, C. Svetina, M. Zangrando
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • H. Dacasa, B. Mahieu, P. Zeitoun
    LOA, Palaiseau, France
  • M. Fajardo
    IPFN, Lisbon, Portugal
  • E. Ferrari
    Università degli Studi di Trieste, Trieste, Italy
  • F. Frassetto, L. P. Poletto
    LUXOR, Padova, Italy
  • D. Gauthier
    University of Nova Gorica, Nova Gorica, Slovenia
  • L. Giannessi
    ENEA C.R. Frascati, Frascati (Roma), Italy
  
  In solid-state lasers, fre­quency chirp­ing is em­ployed to stretch a short pulse prior to am­pli­fi­ca­tion, mit­i­gat­ing the prob­lems re­lated to high power in the ac­tive medium. After am­pli­fi­ca­tion, the chirp is com­pen­sated in order to re­cover short pulse du­ra­tion and, hence, high peak power. Chirped pulse am­pli­fi­ca­tion (CPA) in seeded FEL’s re­lies on a sim­i­lar prin­ci­ple: the seed pulse is stretched in time be­fore in­ter­act­ing with the elec­tron beam. This per­mits one to cre­ate bunch­ing on a larger num­ber of elec­trons, and to (ap­prox­i­mately) lin­early in­crease the out­put en­ergy of the gen­er­ated FEL pulse. In ideal con­di­tions, the chirp car­ried by the phase of the seed pulse is trans­mit­ted to the out­put phase of the FEL pulse. Chirp com­pen­sa­tion after the last un­du­la­tor al­lows pro­duc­tion of a short (ide­ally Fourier-trans­formed) pulse and, there­fore, a larger peak power with re­spect to what ob­tained, for the same con­di­tions, in stan­dard (i.e., no-chirp-on-the-seed) op­er­a­tion mode. In this paper, we pre­sent the prepara­tory stud­ies (i.e., nu­mer­i­cal sim­u­la­tions and com­pres­sor de­sign), which have been car­ried out at FERMI, in view of per­form­ing the first test ex­per­i­ment of CPA on a seeded FEL.  
 
THA02 Experimental Characterization of FEL Polarization Control with Cross Polarized Undulators 644
 
  • E. Ferrari, E. Allaria, G. De Ninno, B. Diviacco, D. Gauthier, L. Giannessi, G. Penco, C. Spezzani
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • J. Buck, M. Ilchen
    XFEL. EU, Hamburg, Germany
  • G. De Ninno, D. Gauthier
    University of Nova Gorica, Nova Gorica, Slovenia
  • L. Giannessi
    ENEA C.R. Frascati, Frascati (Roma), Italy
  • Z. Huang, A.A. Lutman
    SLAC, Menlo Park, California, USA
  • G. Lambert, B. Mahieu
    LOA, Palaiseau, France
  • J. Viefhaus
    DESY, Hamburg, Germany
  
  Po­lar­iza­tion con­trol of the co­her­ent ra­di­a­tion is be­com­ing an im­por­tant fea­ture of re­cent and fu­ture short wave­length free elec­tron laser fa­cil­i­ties. While po­lar­iza­tion tun­ing can be achieved tak­ing ad­van­tage of spe­cially de­signed un­du­la­tors, a scheme based on two con­sec­u­tive un­du­la­tors emit­ting or­thog­o­nally po­lar­ized fields has also been pro­posed. De­vel­oped ini­tially in syn­chro­tron ra­di­a­tion sources, crossed po­lar­ized un­du­la­tor schemes could ben­e­fit from the co­her­ent emis­sion that char­ac­ter­ize FELs. In this work we re­port the first de­tailed ex­per­i­men­tal char­ac­ter­i­za­tion of the po­lar­iza­tion prop­er­ties of an FEL op­er­ated with crossed po­lar­ized un­du­la­tors in the Soft-X-Rays. As­pects con­cern­ing the av­er­age de­gree of po­lar­iza­tion and the shot to shot sta­bil­ity are in­ves­ti­gated to­gether with a com­par­i­son of the per­for­mance of var­i­ous schemes to con­trol and switch the po­lar­iza­tion  
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