Author: Veronese, M.
Paper Title Page
TUAL1 Longitudinal Phase Space Characterization at FERMI@Elettra 303
  • E. Ferrari, E. Allaria, P. Cinquegrana, M. Ferianis, L. Fröhlich, L. Giannessi, G. Penco, M. Predonzani, F. Rossi, P. Sigalotti, M. Veronese
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • E. Ferrari
    Università degli Studi di Trieste, Trieste, Italy
  The seeded FEL FERMI@Elettra has completed the commissioning of FEL1 line, and it is now providing the User Community with a coherent and tunable UV radiation (from 70nm to 20nm) in a number of different configurations, including an original twin-seeded pump-probe scheme. Among the key sub systems for the operation of FERMI@Elettra, there are the femto second optical timing system, some dedicated longitudinal diagnostics, specifically developed for FERMI@Elettra and, of course, state of art laser systems. In this paper, after a short review of the FERMI@Elettra optical timing system and of its routinely achieved performances, we focus on the results obtained from the suite of longitudinal diagnostics (Bunch Arrival Monitor, Electro Optical sampling station and RF deflectors) all operating in single shot and with 10s fs resolution which demonstrate the FERMI@Elettra achieved performances. The results from these longitudinal diagnostics are compared and shot to shot correlated with the results obtained from an independent longitudinal measurement technique, based on a spectrometer measurement of a linearly chirped electron bunch, which further validate the FERMI@Elettra operation.  
slides icon Slides TUAL1 [10.689 MB]  
TUAL3 Absolute Bunch Length Measurements at Fermi@ELETTRA FEL 312
  • R. Appio
    MAX-lab, Lund, Sweden
  • P. Craievich, G. Penco, M. Veronese
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • P. Craievich
    PSI, Villigen PSI, Switzerland
  Electron bunch length measurements are of crucial importance for many types of accelerators, including storage rings, energy recovery linacs, free electron lasers. Many devices and instrumentation have been developed to measure and control the electron bunch length. A very powerful class of diagnostic tools is based on the coherent radiation power emitted by the electron bunch, that allows a non-destructive shot by shot measurement, well suitable for bunch length control feedback implementation. However they usually provide measurements of the bunch length relative variation, and external instrumentation like a transverse RF deflecting cavity is usually needed to calibrate them and to obtain absolute bunch length estimations. In this paper we present a novel experimental methodology to self-calibrate a device based on diffraction radiation from a ceramic gap. We indeed demonstrate the possibility to use coherent radiation based diagnostic to provide absolute measurements of the electron bunch length. We present the theoretical basis of the proposed approach and validate it through a detailed campaign of measurements that have been carried on in the FERMI@Elettra FEL linac.  
slides icon Slides TUAL3 [1.126 MB]  
WEPF22 Non Invasive Optical Synchrotron Radiation Monitor Using a Mini-Chicane 860
  • R.B. Fiorito, R.A. Kishek, A.G. Shkvarunets
    UMD, College Park, Maryland, USA
  • D. Castronovo, M. Cornacchia, S. Di Mitri, M. Veronese
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • C. Tschalär
    MIT, Middleton, Massachusetts, USA
  Funding: Office of Naval Research and DOD Joint Technology Office
We are developing a design for a minimally perturbing mini-chicane which utilizes the optical synchrotron radiation (OSR) generated from magnetic bends to measure the rms emittance and other optical parameters of the beam. The beam is first externally focused at the first bend and the OSR generated there is used to image the beam. Subsequently, any pair of bends produces interferences (OSRI) whose visibility can used to determine the beam divergence. The properties of different configuration of bends in the chicane have been analyzed to provide an optimum diagnostic design for a given set of beam parameters which: 1) provides a sufficient number of OSRI fringes to allow a measurement of the beam divergence; 2) minimizes the competing effect of energy spread on the fringe visibility; 3) minimizes the effect of coherent synchrotron radiation and space charge on the beam emittance; and 4) minimizes the effect of compression on the bunch length, as the beam passes through the chicane. Diagnostic designs have been produced for 100-300 MeV beams with a normalized rms emittance of about 1 micron for application to Fermi@Elettra and similar high brightness free electron lasers.
poster icon Poster WEPF22 [0.642 MB]  
WEPF27 Coherent Ultraviolet Radiation Measurements of Laser Induced Bunching in a Seeded FEL 879
  • M. Veronese, A. Abrami, E. Allaria, M. Ferianis, E. Ferrari, M. Trovò
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • F. Cianciosi
    ESRF, Grenoble, France
  Optimization of the bunching process in a seeded FEL like FERMI@Elettra is an important aspect for machine operation. In this paper we discuss about the power detection of coherent radiation in the UV range as a valuable method for optimizing the bunching induced by the seeding process on the electron beam. Experimental results obtained at FERMI@Elettra are presented here. Measurements of UV coherent transition and diffraction radiation have been used to quantify the bunching produced by the seed laser at lower laser harmonics. The dependence of the laser induced CUVTR signal on various parameters is experimentally studied. Future upgrades and possibilities for bunching measurements at shortest wavelengths are also discussed.