Author: Giannessi, L.
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.  
 
MOP077 Measurements of the FEL-bandwidth Scaling with Harmonic Number in a HGHG FEL 227
 
  • E. Allaria, M.B. Danailov, W.M. Fawley, E. Ferrari, L. Giannessi
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • E. Ferrari
    Università degli Studi di Trieste, Trieste, Italy
  • L. Giannessi
    ENEA C.R. Frascati, Frascati (Roma), Italy
  
  In this work we re­port re­cent mea­sure­ments done at FERMI show­ing the de­pen­dence of the FEL band­width with re­spect to the seed laser har­monic at which the FEL is op­er­ated. Com­par­i­son of FEL spec­tra for dif­fer­ent Fourier-limit seed and chirp pulses is also re­ported.  
 
TUB02 Generation of Intense XVUV Pulses with an Optical Klystron Enhanced Self- amplified Spontaneous Emission Free Electron Laser 332
 
  • G. Penco, E. Allaria, G. De Ninno, E. Ferrari, L. Giannessi
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • G. De Ninno
    University of Nova Gorica, Nova Gorica, Slovenia
  • L. Giannessi
    ENEA C.R. Frascati, Frascati (Roma), Italy
  
  Fermi is a seeded FEL op­er­at­ing in high gain har­monic gen­er­a­tion mode. The FEL lay­out is con­sti­tuted by a mod­u­la­tor and six ra­di­a­tors sep­a­rated by a dis­per­sive sec­tion. The mod­u­la­tor and the ra­di­a­tors can be tuned to the same res­o­nant fre­quency to set up an asym­met­ric op­ti­cal kly­stron con­fig­u­ra­tion where self am­pli­fied spon­ta­neous emis­sion can be gen­er­ated and stud­ied. This paper pre­sents the ex­per­i­ment con­sist­ing in the analy­sis of the en­hance­ment of the self-am­pli­fied spon­ta­neous emis­sion (SASE) ra­di­a­tion by the dis­per­sion in the op­ti­cal kly­stron. The FEL pulses pro­duced with the op­ti­cal kly­stron con­fig­u­ra­tion are sev­eral order of mag­ni­tude more in­tense than in pure SASE mode with the dis­per­sion set to zero, The ex­per­i­men­tal ob­ser­va­tions are in good agree­ment with sim­u­la­tion re­sults and the­o­ret­i­cal ex­pec­ta­tions. A com­par­i­son with the typ­i­cal high-gain har­monic gen­er­a­tion seeded Fel op­er­a­tion is also pro­vided.  
slides icon Slides TUB02 [12.835 MB]  
 
TUP085 FERMI Status Report 564
 
  • M. Svandrlik, E. Allaria, F. Bencivenga, C. Callegari, F. Capotondi, D. Castronovo, P. Cinquegrana, M. Coreno, R. Cucini, I. Cudin, G. D'Auria, M.B. Danailov, R. De Monte, G. De Ninno, P. Delgiusto, A.A. Demidovich, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, P. Finetti, L. Fröhlich, P. Furlan Radivo, G. Gaio, D. Gauthier, F. Gelmetti, L. Giannessi, M. Kiskinova, S. Krecic, M. Lonza, N. Mahne, C. Masciovecchio, M. Milloch, F. Parmigiani, G. Penco, L. Pivetta, O. Plekan, M. Predonzani, E. Principi, L. Raimondi, P. Rebernik Ribič, F. Rossi, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, C. Spezzani, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  
  FERMI, the seeded FEL lo­cated at the Elet­tra lab­o­ra­tory in Tri­este, Italy, is now in reg­u­lar op­er­a­tion for users with its first FEL line, FEL-1, which cov­ers the wave­length range be­tween 100 and 20 nm. We will give an overview of the typ­i­cal op­er­at­ing modes of the fa­cil­ity for users and we will re­port on the sta­tus of beam­lines and ex­per­i­men­tal sta­tions. Three beam­lines are now opened for users, three more are in con­struc­tion. Mean­while, the sec­ond FEL line of FERMI, FEL-2, a HGHG dou­ble stage cas­cade cov­er­ing the wave­length range 20 to 4 nm is still under com­mis­sion­ing; we will re­port on the lat­est re­sults in par­tic­u­lar at the short­est wave­length, 4 nm in the fun­da­men­tal.  
 
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  
slides icon Slides THA02 [5.383 MB]  
 
MOB01 Pulse Control in a Free Electron Laser Amplifier 9
 
  • L. Giannessi
    ENEA C.R. Frascati, Frascati (Roma), Italy
  
  Funding: Work supported by MIUR (DM1834 RIC.4-12-2002 and Grants No. FIRB- RBAP045JF2 and No. FIRB-RBAP06AWK3), and by the EU Commission in the Sixth Framework Program, Contract No. 011935- EUROFEL.
A sig­nif­i­cant progress has been made in con­trol­ling the prop­er­ties of the ra­di­a­tion emit­ted by a FEL am­pli­fier. Ex­per­i­ments have demon­strated the pos­si­bil­ity both to in­crease the tem­po­ral co­her­ence and to re­duce the am­pli­fier length to reach sat­u­ra­tion, by seed­ing it with an ex­ter­nal source. This may be a solid state, short pulse, laser (Ti:Sa,OPA..), dou­bled or tripled in a crys­tal, or a high order har­monic pulse gen­er­ated in gas. The co­her­ence im­prove­ment and the in­creased com­pact­ness of the source are only the first ben­e­fi­cial off­spring of this mar­riage be­tween the op­ti­cal laser world and that of FELs. Non-lin­ear ef­fects in the seeded FEL dy­nam­ics may be ex­ploited to shorten the pulse length be­yond that al­lowed by the FEL nat­ural gain band­width. Mul­ti­ple seed pulses can be used to gen­er­ate pulses whose tem­po­ral dis­tance and prop­er­ties are also con­trolled. Sim­i­larly, the FEL gain can be adapted to match the seed prop­er­ties by tai­lor­ing the elec­trons phase space to gen­er­ate ul­tra-short out­put pulses at un­par­al­leled in­ten­si­ties. I had the honor (and luck) to par­tic­i­pate in many rel­e­vant ex­per­i­ments at the SPARC and FERMI FELs and I will give my per­sonal overview. 		 
slides icon Slides MOB01 [29.932 MB]  
 
MOP077 Measurements of the FEL-bandwidth Scaling with Harmonic Number in a HGHG FEL 227
 
  • E. Allaria, M.B. Danailov, W.M. Fawley, E. Ferrari, L. Giannessi
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • E. Ferrari
    Università degli Studi di Trieste, Trieste, Italy
  • L. Giannessi
    ENEA C.R. Frascati, Frascati (Roma), Italy
  
  In this work we re­port re­cent mea­sure­ments done at FERMI show­ing the de­pen­dence of the FEL band­width with re­spect to the seed laser har­monic at which the FEL is op­er­ated. Com­par­i­son of FEL spec­tra for dif­fer­ent Fourier-limit seed and chirp pulses is also re­ported.  
 
MOP079 Generation of Multiple Coherent Pulses in a Superradiant Free-Electron Laser 233
 
  • X. Yang, S. Seletskiy
    BNL, Upton, Long Island, New York, USA
  • L. Giannessi
    ENEA C.R. Frascati, Frascati (Roma), Italy
  
  We an­a­lyze the struc­ture of the tail of a su­per­ra­di­ant pulse, which is con­sti­tuted by a train of sub-pulses with de­cay­ing am­pli­tudes. We show how a trail­ing pulse, with pi phase ad­vance from the lead­ing pulse, is gen­er­ated at the falling edge of the lead­ing su­per­ra­di­ant pulse, where the cor­re­spond­ing phase space is deeply sat­u­rated and the elec­trons be­come de-trapped by the re­duced pon­dero­mo­tive po­ten­tial. Once the trail­ing pulse gains enough en­ergy, it gen­er­ates a sec­ond trail­ing pulse, and the process takes place again. By per­form­ing de­tailed sim­u­la­tions of the re­sult­ing elec­tron phase space dis­tri­b­u­tion and the FEL pulse spec­tral and tem­po­ral struc­ture with PERSEO, we con­firm that the de­for­ma­tion and re-bunch­ing of the lon­gi­tu­di­nal phase space cre­ate a se­quence of pulses. These re­sults are com­pared to 3D sim­u­la­tions using the FEL code GEN­E­SIS 1.3 show­ing a good agree­ment.  
 
MOP080
 Two Color Experiments at SPARC: External and Intra-bunch Seeding  
 
  • D. Alesini, M.P. Anania, M. Bellaveglia, M. Castellano, E. Chiadroni, D. Di Giovenale, G. Di Pirro, M. Ferrario, A. Gallo, G. Gatti, R. Pompili, S. Romeo, V. Shpakov, C. Vaccarezza, F. Villa
    INFN/LNF, Frascati (Roma), Italy
  • M. Artioli
    ENEA-Bologna, Bologna, Italy
  • A. Bacci, A.R. Rossi
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • M.C. Carpanese, F. Ciocci, G. Dattoli, E. Di Palma, L. Giannessi, A. Petralia, E. Sabia, I.P. Spassovsky
    ENEA C.R. Frascati, Frascati (Roma), Italy
  • A. Cianchi
    INFN-Roma II, Roma, Italy
  • F. Filippi, A. Giribono
    INFN-Roma, Roma, Italy
  • L. Innocenti
    Università di Roma II Tor Vergata, Roma, Italy
  • N.S. Mirian, V. Petrillo
    Universita' degli Studi di Milano & INFN, Milano, Italy
  • A. Mostacci
    Rome University La Sapienza, Roma, Italy
  • J.V. Rau
    ISM-CNR, Rome, Italy
  
  The FEL-SPARC op­er­a­tion with two bunches at dif­fer­ent en­er­gies has been char­ac­ter­ized using dif­fer­ent tools. The ef­fect of the e-beam match­ing on the SASE op­er­a­tion has been ex­plored by con­trol­ling the trans­port with an ad hoc de­vel­oped con­trol sys­tem, al­low­ing ei­ther the trans­port in match­ing con­di­tions and in dif­fer­ent con­fig­u­ra­tions. Since the two bunches have, at the en­trance of the un­du­la­tor, dif­fer­ent phase space char­ac­ter­is­tics we used this ef­fect as a knob to en­hance or sup­press one or the other FEL mode. We in­ves­ti­gated the ef­fect of seed­ing on both fre­quen­cies and ob­served beat­ing waves, fur­ther­more we ob­served ef­fects of in­tra-bunch seed­ing when only one of the modes is seeded.  
 
TUB02 Generation of Intense XVUV Pulses with an Optical Klystron Enhanced Self- amplified Spontaneous Emission Free Electron Laser 332
 
  • G. Penco, E. Allaria, G. De Ninno, E. Ferrari, L. Giannessi
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • G. De Ninno
    University of Nova Gorica, Nova Gorica, Slovenia
  • L. Giannessi
    ENEA C.R. Frascati, Frascati (Roma), Italy
  
  Fermi is a seeded FEL op­er­at­ing in high gain har­monic gen­er­a­tion mode. The FEL lay­out is con­sti­tuted by a mod­u­la­tor and six ra­di­a­tors sep­a­rated by a dis­per­sive sec­tion. The mod­u­la­tor and the ra­di­a­tors can be tuned to the same res­o­nant fre­quency to set up an asym­met­ric op­ti­cal kly­stron con­fig­u­ra­tion where self am­pli­fied spon­ta­neous emis­sion can be gen­er­ated and stud­ied. This paper pre­sents the ex­per­i­ment con­sist­ing in the analy­sis of the en­hance­ment of the self-am­pli­fied spon­ta­neous emis­sion (SASE) ra­di­a­tion by the dis­per­sion in the op­ti­cal kly­stron. The FEL pulses pro­duced with the op­ti­cal kly­stron con­fig­u­ra­tion are sev­eral order of mag­ni­tude more in­tense than in pure SASE mode with the dis­per­sion set to zero, The ex­per­i­men­tal ob­ser­va­tions are in good agree­ment with sim­u­la­tion re­sults and the­o­ret­i­cal ex­pec­ta­tions. A com­par­i­son with the typ­i­cal high-gain har­monic gen­er­a­tion seeded Fel op­er­a­tion is also pro­vided.  
slides icon Slides TUB02 [12.835 MB]  
 
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  
slides icon Slides THA02 [5.383 MB]