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Di Mitri, S.

Paper Title Page
MOPC007 Status and Upgrade Program of the FERMI@ELETTRA Linac 79
 
  • G. D'Auria, A. O. Borga, S. Di Mitri, O. Ferrando, G. C. Pappas, A. Rohlev, A. Rubino, C. Serpico, M. Trovo, A. Turchet, D. Wang
    ELETTRA, Basovizza, Trieste
 
  FERMI@ELETTRA is a seeded FEL user facility under construction at Sincrotrone Trieste, Italy. It will use the existing normal conducting S-band linac and with the installation of seven accelerating sections received from CERN after the LIL decommissioning, will be operated at 1.2 GeV. After the successful commissioning of the new injector system of ELETTRA, the linac has been disconnected from the storage ring and now is being revised and upgraded with the installation of new important subsystems, i.e., a new photoinjector, bunch compressors, laser heater, additional accelerating structures, etc. Here a description of the upgrade program as well as the ongoing activities on the main parts of the machine are reported and discussed.  
TUPC004 The Diagnostic Line of Elettra Booster 100MeV Pre-injector 1044
 
  • S. Bassanese, L. Badano, M. Bossi, A. Carniel, G. Ciani, S. Di Mitri, M. Ferianis, G. Mian, G. Penco, M. Veronese
    ELETTRA, Basovizza, Trieste
 
  In order to fully characterize the beam of the new 100MeV linac pre-injector for the Elettra Booster, a standard diagnostic set-up has been designed which includes strip line BPMs, scintillating screens and current transformers. During the initial tuning of the pre-injector, a thermo-ionic gun followed by a 500MHz pre bunching cavity, an S-band bunching structure and two LIL accelerating sections, some extra diagnostics have been used to get a deeper understanding of the pre-injector operating point. In particular some prototypes of the FERMI@elettra diagnostics, installed on the same booster pre-injector, have been used to better characterize the beam transverse and longitudinal beam axis. An improved resolution screen system, equipped with a YAG screen, has been used as well as a wideband longitudinal pick-up. The measurement results as well as the tuning procedure are here presented.  
TUPC077 The 100-MeV Beam Diagnostic Station for the FERMI Linac 1230
 
  • G. Penco, S. Di Mitri, S. Spampinati
    ELETTRA, Basovizza, Trieste
 
  In order to transversally match the beam coming out from the injector to the FERMI@Elettra linac lattice, a beam diagnostic station will be placed at 100 MeV. It is equipped with quadrupoles and Optical Transition Radiation (OTR) screens to measure and correct the beam Twiss parameters and to evaluate the transverse emittances through a three-screen technique. Moreover, the second OTR screen is placed close to the laser heater undulator to guarantee that the eletron/photon interaction is achieved at the beam waist. Design optimization studies and simulation results are presented in this paper.  
TUPC079 Beam Emittance Measurement for the New Full Energy Injector at ELETTRA 1236
 
  • G. Penco, L. Badano, S. Bassanese, G. Ciani, P. Craievich, S. Di Mitri, M. Ferianis, M. Predonzani, M. Veronese
    ELETTRA, Basovizza, Trieste
  • A. A. Lutman
    DEEI, Trieste
 
  An emittance measurement station was set up and operated with the quadrupole scan technique to characterize the electron beam transverse phase space at the Elettra laboratory. The diagnostic station, based on a YAG:Ce scintillation screen imaged by a CCD digital camera, was installed at the end of the 100 MeV booster pre-injector together with a beam longitudinal structure monitor. This equipment plays an important role for the bunching system optimization and for the optical matching of the injection transfer line to the booster ring. Experimental results and comparison with multi-particle tracking codes simulation are presented in this paper.  
TUPC080 Fermi Low-energy Transverse RF Deflector Cavity 1239
 
  • P. Craievich, S. Biedron, C. Bontoiu, S. Di Mitri, M. Ferianis, M. Veronese
    ELETTRA, Basovizza, Trieste
  • D. Alesini, L. Palumbo
    INFN/LNF, Frascati (Roma)
  • L. Ficcadenti
    Rome University La Sapienza, Roma
  • M. Petronio
    DEEI, Trieste
 
  The layout of FERMI@Elettra will include a transverse S-band RF deflector that will be located after the first bunch compressor (BC1) at 250 MeV. The deflector will operate in a vertical deflecting mode and coupled to a downstream dipole will be used to measure the electron bunch length and in particular to allow time-resolved beam quality measurements such as horizontal slice emittance and slice energy spread. In this paper we discuss the electron bunch deflection at 250 MeV taking into account the principal elements that dominate the selection of the transverse peak voltage specification: the finite transverse emittance, the resolution of OTR screens and the desired number of the slice divisions along the bunch that we wish to observe. The RF deflector proposed here is a frequency scaled version of the 5-cell standing wave SPARC structure.  
TUPP032 Trajectory Jitter and Single Bunch Beam Break Up Instability 1607
 
  • S. Di Mitri, P. Craievich
    ELETTRA, Basovizza, Trieste
  • M. Borland
    ANL, Argonne, Illinois
  • A. Zholents
    LBNL, Berkeley, California
 
  This paper addresses stability issues related to control of the beam break up (BBU) instability in the FERMI@Elettra linac using local trajectory bumps. Analytical study and simulations using the Elegant code are presented. Three different parameters have been used to characterize the BBU, i.e. the projected emittance, the bunch head-to-tail deviation, and the Courant-Snyder invariant for the slice centroid. It is shown that shot-to-shot trajectory jitter in the injector affects the efficiency of the control of the BBU.  
TUPP033 Alternative Scheme of Bunch Length Compression in Linacs for Free Electron Lasers 1610
 
  • S. Di Mitri, M. Cornacchia, S. V. Milton, S. Spampinati
    ELETTRA, Basovizza, Trieste
 
  The aim of this paper is to investigate the effect of an alternative scheme of bunch compression on the development of the microbunching instability. Two cases have been considered, one in the presence of a linear energy chirp at the compressor end and another without it. It is shown that after removing the linear energy chirp, a properly tuned R56 transport matrix element is able to dilute the initial energy modulation without affecting the bunch length and to damp the associated current spikes. A by-product of this study indicates that the global compression scheme can be further optimized in the direction of a double compression scheme in which the longitudinal Landau damping is enhanced by increasing the compression factor of the first compressor while reducing that of the second one. The limiting case of such a configuration is the single compression scheme at low energy. The study is based on analytical calculations and on the simulation code LiTrack.  
THPC010 Trajectory Correction in the Fermi@Elettra Linac 2993
 
  • S. Di Mitri
    ELETTRA, Basovizza, Trieste
  • A. Zholents
    LBNL, Berkeley, California
 
  The effect of the static magnetic field errors and misalignment of the magnetic elements and linac modules on the beam trajectory in the Fermi@elettra linac [1] has been studied. Analytical description has been used to guide simulations of the trajectory correction using three different techniques. A control over the residual R56 transfer matrix element along the linac lattice has been applied. The importance of the linac structural transverse wake field for a reliable prediction of the bunch centroid dynamics has been demonstrated. Transverse deviations of bunch slices along the electron bunch induced by the wake fields have been calculated.

[1] S. Di Mitri, ST/M–07/01 (2007)