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| THPPH025 |
Design of the Cavity BPM for FERMI@ELETTRA
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613 |
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- P. Craievich, D. Castronovo, M. Ferianis
ELETTRA, Basovizza, Trieste
- M. Poggi
INFN/LNL, Legnaro, Padova
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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.
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