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Title |
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| MOO2A03 |
FERMI@elettra Diagnostics
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20 |
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- M. Ferianis
ELETTRA, Basovizza, Trieste
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FERMI@elettra is the fourth generation light source currently under construction at the Sincrotrone Trieste Laboratory. It is a seeded FEL based on the existing 1.0GeV Linac which will be fitted with FEL specific sub-systems like a new photoinjector and two bunch compressors to obtain in front of the undulator chain a stable and high quality beam. Due to the challeging beam parameters, the diagnostics play a key role for the successfull commissioning first, and then for a reliable operation of the new faciltiy. In this paper we give an overview on the FERMI diagnostics operating in the 6-D phase space along with some keynotes on the timing system which is an integral part of the longitudinal diagnostics.
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| TUPC06 |
Coherent Radiation Studies For The FERMI@Elettra Relative Bunch Length Diagnostics
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156 |
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- M. Veronese, S. Di Mitri, M. Ferianis
ELETTRA, Basovizza, Trieste
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Bunch compressors are key components of the seeded FEL FERMI@elettra. Assuring their stable operation requires multiple non-destructive diagnostics to provide error signals to the feedback systems. Both the energy and the peak current of the electron bunch have to be stabilized by the feedback systems. The peak current stabilization implies charge and bunch length stabilization. The latter will be achieved by a redundant diagnostics based on Coherent Synchrotron Radiation (CSR) and Coherent Diffraction Radiation (CDR). In this paper we describe a study of Coherent Radiation emission downstream bunch compressors as the source of a relative bunch length measurement diagnostics. The study evaluates the most critical parameters in the design of such a diagnostic using numerical integration to calculate the spectral angular properties of the radiation for both CSR and CDR.
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| TUPC09 |
Design of the cavity BPM system for FERMI@elettra
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165 |
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- P. Craievich, C. Bontoiu, M. Ferianis, G. Trovato
ELETTRA, Basovizza, Trieste
- M. Poggi
INFN/LNL, Legnaro, Padova
- V. V. Smaluk
BINP SB RAS, Novosibirsk
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The cavity Beam Position Monitor (BPM) is a fundamental instrument for a seeded FEL, as FERMI@elettra. It allows the measurement of the bunch trajectory non-destructively, on a shot-by shot basis and with sub-micron resolution. The high resolution the cavity BPM is providing relies on the excitation of the dipole mode, originated when the bunch passes off axis in the cavity. Here we present the electromagnetic (EM) design and the cold test of the prototype BPM developed for the FERMI@elettra. The design adopted a C-band cavity with its dipole mode at fDIP=6.5GHz. The prototype is actually fitted with two cavities: one for the position measurement and one for the generation of the reference signal for the demodulator. Furthermore, the design of the prototype electronics for the acquisition and processing of the BPM signals is presented. The adopted scheme consists of a down converter from C-band to the intermediate frequency, followed by an IQ demodulator to generate the base-band signal, proportional to the transverse beam position. The performed simulation session is presented as well which we run before building the hardware for bench tests.
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| TUPC10 |
A transverse RF deflecting cavity for the FERMI@elettra project
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168 |
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- P. Craievich, S. Di Mitri, M. Ferianis, M. Veronese
ELETTRA, Basovizza, Trieste
- D. Alesini
INFN/LNF, Frascati (Roma)
- M. Petronio
DEEI, Trieste
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The layout of FERMI@elettra includes a high energy transfer line (TL) which brings the accelerated electron bunch to the FEL undulator chains. The TL optics has been designed according to several space constraints and with the purpose of including diagnostics for the complete characterization of the electron bunch just before the FEL process starts. Basing on such optics, this paper reports the study of the electron bunch deflection at nominal energy of 1.2 GeV for the measurement of the bunch length, of the transverse slice emittance and of the slice energy spread, coupled to a downstream dipole. The effect of the cavity on the electron beam was simulated by tracking code and the specification on the deflecting voltage was thus confirmed. Furthermore the RF design and electromagnetic simulations are also presented here.
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| TUPC11 |
The Beam Diagnostics System for the FERMI@elettra Photoinjector
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171 |
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- L. Badano, M. Ferianis, M. Trovo, M. Veronese
ELETTRA, Basovizza, Trieste
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The quality of the photoinjector high brightness electron beam plays a crucial role for the performance of the seeded FERMI@elettra FEL. Optimization of the gun is possible with an extensive characterization of the 5 MeV electron beam longitudinal and transverse phase space. The photoinjector diagnostics system includes interceptive instrumentation as YAG:Ce screens for transverse position and profile measurements and Faraday cups for the absolute beam charge measurements; a Cherenkov radiator coupled to a streak camera provides an accurate reconstruction of the longitudinal profile and a pepper pot is foreseen for the transverse emittance measurement. Information on beam transverse position and charge is obtained non-disruptively with respectively stripline BPMs and a current transformer. A dispersive beamline is also foreseen for the beam energy, energy spread and longitudinal phase space measurements. The diagnostics system performances and design principles are presented.
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| WEPC02 |
Developments at Elettra of the Electronics for the Bunch-Arrival Monitor
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310 |
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- L. Pavlovič, T. Korošec, M. Vidmar
Uni LJ, Ljubljana
- M. Ferianis, F. Rossi
ELETTRA, Basovizza, Trieste
- K. E. Hacker, F. Löhl, H. Schlarb
DESY, Hamburg
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Within the framework of the EUROFEL project, a task has been started in 2006 for a joint development of a Bunch Arrival Monitor (BAM), based on the original idea from DESY. ELETTRA is responsible for the development of the VME-controlled clock-delay board of the BAM system. A variable clock-delay circuit (a phase shifter) is required to adjust the acquisition sampling point of the pick-up-modulated optical pulses of the master-laser oscillator. Since the optical pulses have a repetition rate of 40.625MHz (54MHz in the future) and the acquisition sampling frequency is double of this value, the clock-delay module operates in the 80-120MHz frequency range. The clock timing jitter of the acquisition system greatly affects the measurements of the system: the output timing jitter from the clock-delay board should be less than 0.5ps-rms. Therefore, due to the very strict additive timing-jitter requirements, three phase shifter versions were designed, built and phase-noise evaluated. Low-pass-filter implementation achieved 563fs (at 283fs source jitter) of total-system timing jitter, integrated IQ multiplier 365fs (at 188fs of source) and passive IQ modulator 265fs (at 208fs of source).
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| WEO1A03 |
Instrumentation for Longitudinal Beam Gymnastics in FEL's and in the CLIC test facility 3
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215 |
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- T. Lefèvre, H.-H. Braun, E. Bravin, S. Burger, R. Corsini, S. Döbert, L. Søby, F. Tecker, P. Urschütz, C. P. Welsch
CERN, Geneva
- D. Alesini, C. Biscari, B. Buonomo, O. Coiro, A. Ghigo, F. Marcellini, B. Preger
INFN/LNF, Frascati (Roma)
- P. Craievich, M. Ferianis, M. Veronese
ELETTRA, Basovizza, Trieste
- A. E. Dabrowski, M. Velasco
NU, Evanston
- A. Ferrari
UU/ISV, Uppsala
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Built at CERN by an international collaboration, the CLIC Test Facility 3 (CTF3) aims at demonstrating the feasibility of a high luminosity 3TeV e+-e- collider by the year 2010. One of the main issues to be demonstrated is the generation of a high average current (30A) high frequency (12GHz) bunched beam by means of RF manipulation. At the same time, Free Electron Lasers (FEL) are developed in several places all over the world with the aim of providing high brilliance photon sources. These machines all rely on the production of high peak current electron bunches. The required performances put high demands on the diagnostic equipment and innovative longitudinal monitors have been developed during the past years. This paper gives an overview of the longitudinal instrumentation developed at ELETTRA and CTF3, where a special effort was made in order to implement at the same time non-intercepting devices for online monitoring, and destructive diagnostics which have the advantage of providing more detailed information.
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| WEPC11 |
FERMI@elettra Timing System: Design and Recent Synchronization Achievements
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334 |
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- M. Ferianis
ELETTRA, Basovizza, Trieste
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FERMI@elettra is the fourth generation light source under construction at Sincrotrone Trieste. Being a seeded-FEL source, the requirements for the timing system are very tight as the final goal is a stable seeding process with sub-picosecond electron bunches and seeding laser pulses. Based on demonstrated results achieved in the main laboratories worldwide active in the field, like DESY, LBNL and MIT, an hybrid timing system scheme has been proposed which is currently under development. Both "pulsed" and "continuous wave (CW)" optical timing systems are being deployed, the choice being based on the differences among the different timing system clients; a Low Level Radio Frequency processor is a "quasi-CW" client whereas the lasers and some "longitudinal" diagnostics are "time discrete" clients. In this paper the FERMI@elettra timing system and the recent advances are presented. A pulsed optical clock has been locked to an ultra stable reference; its output pulses distributed over stabilized fiber optic links. As a benchmark client, a femto-second laser oscillator has been synchronized to the optical clock testing different possible schemes.
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| WEPC22 |
Synchronization of a 3GHz Repetition Rate Harmonically Mode-Locked Fiber Laser for Optical Timing Applications
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358 |
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- L. Banchi, M. Ferianis, F. Rossi
ELETTRA, Basovizza, Trieste
- A. Bogoni, P. Ghelfi, L. Poti'
CNIT, Pisa
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We have successfully stabilized a 3GHz Harmonically Mode-Locked fiber ring laser by a PLL feedback control of the cavity length to reduce the pulses RMS timing jitter. The laser cavity is composed of all PM fibers and components to eliminate polarization instabilities and to reduce the vibration sensitivity. The laser stability in terms of timing jitter was around 9ps in the range 10Hz-10MHz. Using a PLL scheme we synchronized the laser repetition rate to an ultra stable RF generator. The noise characteristics of the laser output were measured by observing the SSB noise spectra of the 1st harmonic, from 10Hz to the Nyquist frequency (1.5GHz). We have obtained a global reduction of fiber laser timing jitter value down to less than 100fs in the range 10Hz-10MHz; a complete overlapping between the laser and the RF generator spectral profiles in the loop bandwidth has been observed. An extended investigation has been performed to estimate the phase noise spectra and timing jitter up to 1.5GHz. By doing so, the contribution of the laser supermodes to the phase noise has been taken into account as well, to quantify the true value of the total RMS timing jitter of the optical pulses.
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