| 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. | ||
| THPPH025 | Design of the Cavity BPM for FERMI@ELETTRA | 613 |
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| The Beam Position Monitors (BPM) are fundamental diagnostics for a seeded FEL, like FERMI@ELETTRA, as they allow to measure the electron beam trajectory non destructively and on a shot-by shot basis. A cavity BPM provides sub-micrometer resolution relying on excitation of the TM110 dipoles modes by beam when it passes through the cavity off axis. Therefore for the seeded FEL FERMI, we adopted a set of cavity BPMs to be located upstream the modulating undulator to correct the electron beam trajectory to the micrometer level. In this paper we first discuss the requirements for this cavity BPM including that for beam based alignment. The scaling from an X-band design to the final C-band design is presented. The resolution to stay below one micrometer has been cross-checked both analytically and numerically, The losses of the common mode TM010 have been checked for too, leading to the final dimensions preserving the losses of the X-band cavity BPM. | ||
| THPPH029 | The Diagnostics of the FERMI@Elettra Bunch Compressors | 629 |
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Bunch compressors are key components of the single pass Linac based seeded FEL FERMI@ELETTRA. Assuring their stable operation, to reliably produce sub-psec electron bunches, requires multiple non-destructive diagnostics. Most of these diagnostics provide the error signals to the feedback systems used to stabilize the energy and the peak current of the electron bunch which are crucial parameters for optimum FEL operation. The different operation regimes foreseen for FERMI* call for a flexible set-up, for both the bunch compressors and the associated diagnostics. In this paper we present the adopted diagnostics for the measurement of position, energy and energy spread; both "energy" BPM, in between BC, and OTR screen plus wire scanner will be used. The design of a relative bunch length monitor needed for the determination of the optimal compression and for peak current stabilization is presented as well. The scheme is based on non-invasive techniques, namely the detection of the coherent synchrotron radiation (CSR) from the last bending of the BC plus the coherent diffraction radiation (CDR) from a downstream slit. Finally, a technique for the bunch phase measurement is presented.
* Study of the Electron Beam Dynamics in the FERMI @ ELETTRA Linac, M. Cornacchia, et al., Proc. of EPAC 2006 Conf., Scotland, UK (June 2006), to be published. |