The 3π/4 backward TW structure for the ELETTRA 1.5 GeV electron injector

The 3π/4 backward traveling wave (BTW) structures used for the ELETTRA 1.5 GeV Electron Injector have been designed and are now under realization. These accelerating units will be fed by a TH 2132 45 MW-4.5 μs klystron coupled to a Thomson CIDR (Compresseur d'impulsion a Double Resonateur) similar to the CERN design of the SLED. The expected energy gain is equal to 33 MeV/m. This paper justifies the use of the 3π/4 accelerating mode. After a description of the structure design, the choice of RF parameters leading to optimization with RF pulse compressor, evaluations of energy gain and peak field on copper based on simulations and cold tests measurements are presented. RF cold test measurements of the first unit are analyzed