Author: Bettoni, S.
Paper Title Page
Temporal Profile Reconstruction Based on a Passive Streaker  
  • S. Bettoni, P. Craievich, M. Pedrozzi
    PSI, Villigen PSI, Switzerland
  A time resolved measurement of the beam is important to optimize the final performances of an accelerator and in particular it is crucial for Free Electron Lasers. A transverse deflecting cavity, as an iris loaded wave guide or multi cell-standing wave structures, is conventionally used to image the longitudinal profile of a streaked beam on a downstream screen. In this paper we present an alternative method to passively deflect the electron bunch by using the dipole wakefield excited by the electron bunch passing off-axis through a dielectric-lined or a corrugated pipe. Measurements of a proof-of-principle experiment performed at the SwissFEL Injector Test Facility compared with the simulations are also discussed here.  
THP049 High Power RF Test and Analysis of Dark Current in the SwissFEL-gun 843
  • P. Craievich, S. Bettoni, M. Bopp, A. Citterio, C. Ozkan, M. Pedrozzi, J.-Y. Raguin, M. Schaer, A. Scherer, T. Schietinger, L. Stingelin
    PSI, Villigen PSI, Switzerland
  To fulfill the beam quality and operational requirements of the SwissFEL project, currently under construction at the Paul Scherrer Institut, a new RF photocathode gun for the electron source was designed and manufactured in house. A 2.6 cell S-band gun operating with near-perfect rotationally symmetric RF field was designed to operate with a 100MV/m cathode field at a repetition rate of 100Hz with average power dissipation of 0.9kW with pulse duration of 1us. The first SwissFEL-gun is now fabricated and installed in the SwissFEL Injector Test Facility (SITF). The frequency spectrum and field balance, through bead-pulling, have been directly verified in-situ and then the gun has been operated with high-power RF. The results of bead-pull measurements and high-power tests are presented and discussed. In addition the emitted dark current was also measured during the high-power tests and the charge within the RF pulse was measured as a function of the peak cathode field at different pulse durations. Faraday cup data were taken for cathode peak RF fields up to 100MV/m for the case of a diamond-turned polycrystalline copper cathode.  
THC02 Thermal Emittance Measurements at the SwissFEL Injector Test Facility 970
  • E. Prat, S. Bettoni, H.-H. Braun, M.C. Divall, R. Ganter, C.P. Hauri, T. Schietinger, A. Trisorio, C. Vicario
    PSI, Villigen PSI, Switzerland
  • C.P. Hauri
    EPFL, Lausanne, Switzerland
  In a laser-driven RF-gun the ultimate limit of the beam emittance is the transverse momentum of the electrons as they exit the cathode, the so-called intrinsic or thermal emittance. In this contribution we present measurements of the thermal emittance at the SwissFEL Injector Test Facility for electron beam charges down to a few tens of fC. We have studied the thermal emittance and QE dependence on the laser wavelength, the RF-gun gradient and the cathode material (Cu and Cs2Te).  
slides icon Slides THC02 [1.063 MB]