Author: Rau, J.V.
Paper Title Page
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 icon Slides WEOB3 [5.198 MB]  
 
WEOCI2
 Ultrashort Single Spike Pulse Generation at the SPARC Test Facility  
 
  • D. Filippetto
    LBNL, Berkeley, California, USA
  • A. Bacci, M. Bellaveglia, M. Castellano, E. Chiadroni, L. Cultrera, G. Di Pirro, M. Ferrario, L. Ficcadenti, A. Gallo, G. Gatti, E. Pace, B. Spataro, C. Vaccarezza, C. Vicario
    INFN/LNF, Frascati (Roma), Italy
  • 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
  • F. Frassetto, L. P. Poletto
    LUXOR, Padova, Italy
  • M. Moreno, M. Serluca
    INFN-Roma, Roma, Italy
  • A. Mostacci
    Rome University La Sapienza, Roma, Italy
  • V. Petrillo, A.R. Rossi
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • J.V. Rau, V. Rossi Albertini
    ISM-CNR, Rome, Italy
  
  We re­port the first ex­per­i­men­tal im­ple­men­ta­tion of a method based on si­mul­ta­ne­ous use of an en­ergy chirp in the elec­tron beam and a ta­pered un­du­la­tor, for the gen­er­a­tion of ul­tra­short pulses in a Self Am­pli­fied Spon­ta­neous Emis­sion mode Free Elec­tron Laser (SASE FEL). The ex­per­i­ment, per­formed at the SPARC FEL test fa­cil­ity, demon­strates the pos­si­bil­ity of com­pen­sat­ing the nom­i­nally detri­men­tal ef­fect of the chirp by a proper taper of the un­du­la­tor gaps. Lon­gi­tu­di­nal phase space ro­ta­tion via ve­loc­ity bunch­ing is used to gen­er­ate the en­ergy chirp, which also in­creases the peak cur­rent and the FEL per­for­mances. An in­crease of more than one order of mag­ni­tude in the pulse en­ergy is ob­served in com­par­i­son to the un­ta­pered case, ac­com­pa­nied by FEL spec­tra where the typ­i­cal SASE spik­ing is sup­pressed.  
slides icon Slides WEOCI2 [16.008 MB]