| Paper | Title | Page |
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| MOPPH054 | FERMI @ Elettra: A Seeded FEL Facility for EUV and Soft X-Rays | 166 |
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| We describe the conceptual design and major performance parameters for the FERMI FEL project funded for construction at the Sincrotrone Trieste, Italy. This user facility complements the existing storage ring light source at Sincrotrone Trieste, and will be the first facility to be based on seeded harmonic cascade FELs. Seeded FELs provide high peak-power pulses, with controlled temporal duration of the coherent output allowing tailored x-ray output for time-domain explorations with short pulses of 100 fs or less, and high resolution with output bandwidths of the order of meV. The facility uses the existing 1.2 GeV S-band linac, driven by electron beam from a new high-brightness rf photocathode gun, and will provide tunable output over a range from ~100 nm to ~10 nm, and APPLE undulator radiators allow control of x-ray polarization. Initially, two FEL cascades are planned, a single-stage harmonic generation to operate over ~100 nm to ~40 nm, and a two-stage cascade operating from ~40 nm to ~10 nm or shorter wavelengh, each with spatially and temporally coherent output, and peak power in the GW range. | ||
| MOPPH057 | Design and Performance of the FERMI at Elettra FEL | 174 |
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The FERMI project* at Sincrotrone Trieste is the first user facility based on seeded, harmonic cascade FELs. The second stage FEL will produce tunable output in the 10-40nm wavelength range and will rely upon two stages of harmonic up-conversion. A major goal for this FEL is good longitudinal output coherence (i.e., small spectral bandwidth). At present, we are examining the performance characteristics of two possible configurations. The first "fresh bunch" option is a classic harmonic cascade, where the output radiation from the first radiator is used to seed a fresh part of the electron bunch in the second-stage modulator. The second "whole bunch" scheme seeds the entire e-beam pulse, uses a much shorter first radiator and completely eliminates the second modulator, with the second radiator involving many e-folds of gain. Relying both upon time-steady input parameter sensitivity studies and full start-to-end time-dependent simulations**, we examine the predicted performance of the two configurations and compare with users requirements.
* C. Bocchetta et al., this meeting ** S. Di Mitri et al., this meeting |
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| MOPPH058 | Start-to-end Time-Dependent Study of FEL Output Sensitivity to Electron-beam Jitters for the First Stage of the FERMI@Elettra Project | 178 |
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| Sensitivity of the output laser pulse to electron-beam jitters is one of the major issues affecting the expected performance of both SASE and seeded FEL's. Focusing on the first stage of the FERMI@Elettra project, in this paper we present results of time-dependent numerical simulations in which the codes GENESIS and GINGER have been used to process a large number of electron-beam distributions generated at the gun using the code GPT and propagated through the linac using the code ELEGANT. | ||
| TUPPH020 | Dynamics Control of the Elettra Storage Ring Free-Electron Laser with Digital Feedbacks | 356 |
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| The laser dynamics of a storage-ring free-electron laser (FEL) has two main sources of instabilities. First of all, as it is known, dynamical instabilities are developed as the FEL is moved away from the exact tuning between the period of the electron bunch(es) circulating into the ring and that of the photon pulse stored in the optical cavity. In addition, external (low-frequency) noise sources have a strong influence on the dynamical behaviour of the system and can perturb its dynamic. Different feedback techniques have been proposed in order to control dynamical instabilities and stabilize the FEL output. We present here a numerical and experimental investigation on the control of the Elettra SRFEL dynamics using the simultaneous combination of different feedbacks techniques that have been experimentally implemented by means of a Field ProgrammableGate Aarray (FPGA). | ||
| TUPPH044 | Free Electron Laser Study of Free Carbon Clusters | 423 |
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| UV absorption from carbon nanoparticles is a very interesting astrophysical topic. The prominent hump centered at 217.5nm is the most dominant feature in the interstellar extinction curve and also the most controversial and a long-standing problem in astrophysics. Actual models lack of experimental data about carbon dust in gas phase. At the University of Milano an experimental set-up based on a PulsedμPlasma Source has been developed for the investigation of free clusters at the Elettra Gas Phase beamline (CESyRA: Cluster Experiments with Synctrotron RAdiation). The cluster source produces very intense cluster beams with tunable size distribution. The design of the apparatus is extended with a chamber for gas phase reaction (water vapor, CO, H2…) providing a unique opportunity to study the gas phase properties of carbonaceous particles in different environment. We plan to investigate Resonant Raman scattering of free carbon particles tuning the high brilliance UV/VIS storage ring FEL of ELETTRA across the region of 217nm where the UV absorption hump in astrophysical data is observed and where a number of electronic transitions exist for variable size linear carbon chains. |