Author: Craievich, P.
Paper Title Page
MOOCNO01 Emittance Control in the Presence of Collective Effects in the FERMI@Elettra Free Electron Laser Linac Driver 6
 
  • S. Di Mitri, E. Allaria, D. Castronovo, M. Cornacchia, P. Craievich, M. Dal Forno, G. De Ninno, W.M. Fawley, E. Ferrari, L. Fröhlich, L. Giannessi, E. Karantzoulis, A.A. Lutman, G. Penco, C. Serpico, S. Spampinati, C. Spezzani, M. Trovò, M. Veronese
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • P. Craievich
    PSI, Villigen PSI, Switzerland
  • M. Dal Forno
    University of Trieste, Trieste, Italy
  • G. De Ninno, S. Spampinati
    University of Nova Gorica, Nova Gorica, Slovenia
  • E. Ferrari
    Università degli Studi di Trieste, Trieste, Italy
  • L. Giannessi
    ENEA C.R. Frascati, Frascati (Roma), Italy
  • A.A. Lutman
    SLAC, Menlo Park, California, USA
 
  Recent beam transport experiments conducted on the the linac driving the FERMI@Elettra free electron laser have provided new insights concerning the transverse emittance degradation due to both coherent synchrotron radiation (CSR) and geometric transverse wakefield (GTW), together with methods to counteract such degradation. For beam charges of several 100's of pC, optics control in a magnetic compressor results to minimize the CSR once the H-function is considered*. We successfully extended this approach to the case of a modified double bend achromat system, opening the door to relatively large bending angles and compact transfer lines**. At the same time, the GTWs excited in few mm diameter iris collimators*** and accelerating structures have been characterized in terms of the induced emittance growth. A model integrating both CSR and GTW effects suggests that there is a limit on the maximum obtainable electron beam brightness in the presence of such collective effects.
* S. Di Mitri et al., PRST-AB 15, 020701 (2012)
** S. Di Mitri et al., PRL 110, 014801 (2013)
*** S. Di Mitri et al., PRST-AB 15, 061001 (2012)
 
slides icon Slides MOOCNO01 [6.919 MB]  
 
WEPSO22 FERMI@Elettra Status Report 546
 
  • L. Giannessi, E. Allaria, F. Bencivenga, C. Callegari, F. Capotondi, D. Castronovo, P. Cinquegrana, P. Craievich, I. Cudin, G. D'Auria, M. Dal Forno, M.B. Danailov, R. De Monte, G. De Ninno, A.A. Demidovich, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, L. Fröhlich, P. Furlan Radivo, G. Gaio, M. Kiskinova, M. Lonza, B. Mahieu, N. Mahne, C. Masciovecchio, F. Parmigiani, G. Penco, M. Predonzani, E. Principi, L. Raimondi, F. Rossi, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, S. Spampinati, C. Spezzani, M. Svandrlik, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • P. Craievich
    PSI, Villigen PSI, Switzerland
  • L. Giannessi
    ENEA C.R. Frascati, Frascati (Roma), Italy
  • B. Mahieu
    CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France
 
  Funding: Work supported in part by the Italian Ministry of University and Research under grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3
In this paper we report about the status of FERMI, the seeded Free Electron Laser located at the Elettra laboratory in Trieste, Italy. The facility welcomed the first external users on FEL-1 between December 2012 and March 2013, operating at wavelengths between 65 and 20 nm. Variable polarization and tunability of the radiation wavelength were widely used. Photon energies attained up to 200 microJoule, depending on the grade of spectral purity requested and on the selected wavelength. Pump-probe experiments were performed, both by double FEL pulses obtained via double pulse seeding of the electron beam and by providing part of the seed laser to the experimental stations as user laser. The FEL-2 line, covering the lower wavelength range between 20 and 4 nm thanks to a double stage cascaded HGHG scheme, operating in the "fresh bunch injection” mode, generated its first coherent photons in October 2012 and has seen further progress during the commissioning phases in 2013, at higher electron beam energy. In fact we will also report on the linac energy increase to 1.5 GeV and on the repetition rate upgrade from 10 to 50 Hz and eventually comment on the FEL operability and uptime.
 
 
TUPSO03 Dark Current Transport and Collimation Studies for SwissFEL 209
 
  • S. Bettoni, P. Craievich, M. Pedrozzi, S. Reiche, L. Stingelin
    PSI, Villigen PSI, Switzerland
 
  In all accelerating cavities a non negligible background of electrons can be generated by field emission (dark current), transported and further accelerated. A careful estimate of the transport of the dark current is crucial in order to minimize radiation damage to the components and activation of the machine. This paper describes the generation and the transport of dark current from the SwissFEL photo injector downstream of the accelerator. The analysis is based on numerical simulations and experimental measurements performed at the SwissFEL Injector Test Facility (SITF). In the simulations the charge distribution is generated by an emission model based on the Fowler-Nordheim equation taking into account the filling time of the cavity and then tracked through the machine. This model has been used to analyze the impact of a low energy collimation system upstream of the first travelling wave accelerating structure on the dark current transport. A slit with several apertures has been installed in the SITF to benchmark the simulations and to verify the impact of the wakefields on the nominal beam.  
 
TUPSO04 Simulations of a Corrugated Beam Pipe for the Chirp Compensation in SwissFEL 214
 
  • S. Bettoni, P. Craievich, M. Pedrozzi, S. Reiche
    PSI, Villigen PSI, Switzerland
 
  In short wavelength FEL designs, bunch compression is obtained by making the beam passing through a magnetic chicane with an energy chirp typically of a percent level. At SwissFEL, before injection into the undulator it is foreseen to remove the residual chirp using the wakes in the C-band accelerating structures of the linac. This scheme works well for the hard X-ray undulator line, which includes the largest accumulation of wakefields, but it leaves a residual chirp in the other undulator line for the soft X-ray beam line, midway in the main linac. Another possibility to remove the residual chirp consists in using the longitudinal wakefields generated by a corrugated beam pipe, as recently proposed by G. Stupakov et al. Before planning a dechirper section in a FEL, an experimental verification of the analytical formulae describing the wakefields is crucial. The SwissFEL injector test facility (SITF) fulfils all the necessary criteria to perform such a proof of principle. We are investigating the technical implementation to perform an experiment in SITF in the second half of 2014. In this paper we present the tracking studies performed to optimize the experiment layout.  
 
TUPSO14 Transverse Deflecting Structures for Bunch Length and Slice Emittance Measurements on SwissFEL 236
 
  • P. Craievich, R. Ischebeck, F. Löhl, G.L. Orlandi, E. Prat
    PSI, Villigen PSI, Switzerland
 
  The SwissFEL project, under development at the Paul Scherrer Institut, will produce FEL radiation in a wavelength range from 0.1 nm to 7 nm. The facility consists of an S-band rf-gun and booster, and a C-band main linac which accelerates the beam up to 5.8 GeV. Two magnetic chicanes will compress the beam between 2.5 fs rms and 25 fs rms depending on the operation mode. The bunch length and slice parameters will be measured after the first bunch compressor (330 MeV) by using an S-band transverse deflecting structure (TDS). A C-band TDS will be employed to measure the longitudinal parameters of the beam just upstream the undulator beamline (5.8 GeV). With the designed transverse beam optics, an integrated deflecting voltage of 70 MV is required in order to achieve a longitudinal resolution on the femtosecond time scale. In this paper we present the TDS measurement systems to be used at SwissFEL, with a particular emphasis on the new C-band device, including hardware, lattice layout and beam optics.  
 
WEPSO22 FERMI@Elettra Status Report 546
 
  • L. Giannessi, E. Allaria, F. Bencivenga, C. Callegari, F. Capotondi, D. Castronovo, P. Cinquegrana, P. Craievich, I. Cudin, G. D'Auria, M. Dal Forno, M.B. Danailov, R. De Monte, G. De Ninno, A.A. Demidovich, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, L. Fröhlich, P. Furlan Radivo, G. Gaio, M. Kiskinova, M. Lonza, B. Mahieu, N. Mahne, C. Masciovecchio, F. Parmigiani, G. Penco, M. Predonzani, E. Principi, L. Raimondi, F. Rossi, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, S. Spampinati, C. Spezzani, M. Svandrlik, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • P. Craievich
    PSI, Villigen PSI, Switzerland
  • L. Giannessi
    ENEA C.R. Frascati, Frascati (Roma), Italy
  • B. Mahieu
    CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France
 
  Funding: Work supported in part by the Italian Ministry of University and Research under grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3
In this paper we report about the status of FERMI, the seeded Free Electron Laser located at the Elettra laboratory in Trieste, Italy. The facility welcomed the first external users on FEL-1 between December 2012 and March 2013, operating at wavelengths between 65 and 20 nm. Variable polarization and tunability of the radiation wavelength were widely used. Photon energies attained up to 200 microJoule, depending on the grade of spectral purity requested and on the selected wavelength. Pump-probe experiments were performed, both by double FEL pulses obtained via double pulse seeding of the electron beam and by providing part of the seed laser to the experimental stations as user laser. The FEL-2 line, covering the lower wavelength range between 20 and 4 nm thanks to a double stage cascaded HGHG scheme, operating in the "fresh bunch injection” mode, generated its first coherent photons in October 2012 and has seen further progress during the commissioning phases in 2013, at higher electron beam energy. In fact we will also report on the linac energy increase to 1.5 GeV and on the repetition rate upgrade from 10 to 50 Hz and eventually comment on the FEL operability and uptime.