Author: Rosenzweig, J.B.
Paper Title Page
TUOA3
 Three-dimensional Kinetic Theory of Longitudinal Space-charge Interactions in a Thermal Relativistic Electron Beam  
 
  • A. Marinelli, E. Hemsing, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  
  We develop an analytical model of space-charge interactions leading to longitudinal plasma oscillations and space-charge induced microbunching amplification. Our theory is based on a modal description of space-charge waves which includes energy spread, emittance, betatron motion and geometrical effects due to the finite size of the beam. In analogy with the three-dimensional theory of free-electron lasers, we derive a dispersion relation for the space-charge oscillation modes that can be expressed in terms of four dimensionless parameters. We find approximate variational solutions as well as numerical solutions with a discretization method. Finally we we apply this model to the optimization of a longitudinal space-charge amplification experiment.  
slides icon Slides TUOA3 [3.254 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 icon Slides WEOB3 [5.198 MB]