• M. Veronese, R. Appio, T. Borden, G. Ciani, P. Craievich, R. De Monte, S. Di Mitri, M. Ferianis, G. Gaio, S. Grulja, G. Scalamera, M. Tudor
  ELETTRA, Basovizza

Both absolute and relative bunch length measurement are key information for FERMI@Elettra commissioning and operation. In this paper we present the relative Bunch Length Monitor (BLM) system that has been designed and implemented at Sincrotrone Trieste. The first BLM station has been installed downstream the first bunch magnetic compressor (BC1) of FERMI@Elettra. In this paper we report about the first operation of the BLM system; it is based on the power measurement of the coherent radiations. To allow for efficient performances in the extended range of the foreseen bunch lengths for FERMI@Elettra, the system has adopted a pyro detector for coherent edge radiation from the last dipole. Also, the coherent diffraction radiation generated in a ceramic gap located downstream of BC1 is detected by a set of mm-wave diodes. The design of the system, along with its layout, is presented as well as the first measurement results obtained from the FERMI@Elettra compressed bunches.

• P. Craievich, S. Biedron, M. Ferianis, D. La Civita
  ELETTRA, Basovizza
• D. Alesini, L. Palumbo
  INFN/LNF, Frascati (Roma)
• L. Ficcadenti
  Rome University La Sapienza, Roma
• M. Petronio, R. Vescovo
  DEEI, Trieste

A RF deflector is a useful tool to completely characterize the beam phase space by means of measurements of the bunch length and the transverse slice emittance. At FERMI@Elettra, a soft X-ray next-generation light source under development at the Sincrotrone Trieste laboratory in Trieste, Italy, we are installing low-energy and high-energy deflectors. In particular, two deflecting cavities will be positioned at two points in the linac. One will be placed at 1.2 GeV (high energy), just before the FEL process starts; the other at 250 MeV (low energy), after the first bunch compressor (BC1). This paper concerns only the low-energy deflector. The latter was built over the past year in collaboration with the SPARC project team at INFN-LNF-Frascati, Italy and the University of Rome. In this paper we will describe the RF measurements performed to characterize the standing wave cavity before the installation in the FERMI@Elettra linac, and we will compare them with the simulations done using the electromagnetic code HFSS.